Download Foraminifera and Nannoplankton in Palaeoceanography

Foraminifera and Nannoplankton in Palaeoceanography
The Micropalaeontological Society's Foraminifera and
Nannofossil Groups Joint Spring Meeting
The National Oceanography Centre Southampton, 15th-17th June 2005
Abstracts and Programme
Sponsors
Ameranda Hess (Denmark) ApS (Emma, is that right?)
Chevron Texaco Energy Technology Company
Leibniz-Institute of Marine Sciences IFM-GEOMAR, Kiel
The Micropalaeontological Society
The National Oceanography Centre, Southampton
Shell Exploration and Production Europe
Statoil Norway ASA
Organizing committee
Emma Sheldon (Geological Survey of Denmark and Greenland, Copenhagen)
Ralf Schiebel (The National Oceanography Centre, Southampton)
Daniela Schmidt (Department of Earth Sciences, University of Bristol)
Joachim Schönfeld (Leibniz-Institute of Marine Science, Kiel)
Jeremy Young (The Natural History Museum, London)
The aim of the meeting
The Micropalaeontological Society's Foraminifera and Nannofossil Groups Joint
Spring Meeting 2005 continues the tradition of promoting contact and exchange of
ideas between workers in their respective groups, and of encouraging cross-links
between the disciplines and the expertise from the host institution. The National
Oceanography Centre, Southampton is one of the world's leading centres for
research and education in marine sciences, earth sciences and ocean technology,
and it has developed into a major centre of palaeoceanography. This meeting will
focus on palaoceanographic use of microfossils, insights into their palaeobiology from
palaeoceanographic research, and proxy calibration.
Programme
Wednesday, 15th June
18:00 - 21:00 Icebreaker party (Cafeteria of the NOCS)
Thursday, 16th June (Lecture Theatre, NOCS)
9:00-9:20
Ralf Schiebel: Welcome
Mesozoic and Cenozic Oceans I (Convenor – J. Schönfeld)
Oliver Friedrich, J. Erbacher and J. Mutterlose: Cenomanian/Turonian
(OAE2) benthic foraminiferal faunas of the Demerara Rise depth transect
(ODP Leg 207).
9:40 - 10:00 Nick Hogg: Lower Eocene Oceanography, UK CNS; a core calibrated
interdisciplinary study.
10:00 - 10:20 Robert P. Speijer, S.R. Ernst, E. Guasti and C.Dupuis: Foraminiferal
response to transient climatic warming at Paleocene/Eocene boundary.
10:20 - 10:40 Philip F. Sexton, P.A. Wilson and R.D. Norris: The Stability of Eocene
Warmth and Carbon Cycling - New Records in Foraminiferal Calcite from
Demerara Rise.
9:20 - 9:40
10:40 - 11:00 Coffee break
Mesozoic and Cenozic Oceans II (Convenor – J. Schönfeld)
11:00 - 11:20 Emma Sheldon, S. Lassen, J.A.E. Rasmussen and P. Schiøler:
Multidisciplinary palaeoecology of Upper Maastrichtian chalks in the Danish
Central Graben – record of a sea-level lowstand.
11:20 - 11:50 Tanja J. Kouwenhoven and G.J. van der Zwaan: An overview of late
Miocene benthic foraminiferal data from the Mediterranean.
11:50 - 12:10 Mike Rogerson, T.J. Kouwenhoven, G.J. van der Zwaan, B.J. O’Neill, C.J.
van der Zwan, G. Postma, K. Kleverlaan, and H.J. Tijbosch: Benthic
Foraminifera from the El Buho Canyon and Fan (Late Miocene of the
Tabernas Basin, SE Spain).
12:10 - 12:30 Daniela N. Schmidt and M. Kucera: Neogene origin of the modern pelagic
niche and its consequences for pelagic carbonate production.
12:30 - 14:00 Lunch time
14:00 – 16:00 Poster Session (in the area outside the lecture theatre)
Pleistocene palaeoceanography (Convenor - J. Young)
16:00 - 16:20 Els Ufkes and D. Kroon: Globorotalia truncatulinoides in the South Atlantic
during the mid-late Pleistocene.
16:20 - 16:40 Maryline J. Vautravers, and N.J. Shackleton: Subtropical North Atlantic
Oceanic Variability During MIS3: The Planktonic Foraminiferal Record.
16:40 - 17:00 Elena Colmenero-Hidalgo, J.-A. Flores, and F.J. Sierro: Nutricline/pycnocline
and water temperature variations in the South Iberian Margin during the Last
Glaciation as revealed by Florisphaera profunda.
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17:00 - 17:20 Elena V. Ivanova, L. Beaufort, and L. Vidal: Planktic foraminifer and
coccolithophorid assemblages of Core MD02-2529 as indicators of climate
changes in the Eastern Equatorial Pacific during the last 135 kyr.
Friday, 16th June (Lecture Theatre, NOCS)
Proxies (Convenor - D. Schmidt)
Clémentine Griveaud, F. Jorissen, E. Michel and P. Anschutz: Deep-sea
benthic foraminifera faunas and stable isotopes from the Portugal margin:
preliminary results.
9:20 - 9:40
Hiroshi Kitazato, H. Nomaki, T. Toyofuku and M. Tsuchiya: Foraminifera as
paleoceanographic proxies; biological constraints both from in situ and
laboratory experiments.
9:40 - 10:00 Yunyan Ni, B. Foster, B. Haley, T. Bailey and T. Elliott: Core top calibrations
of Boron isotope paleo-pH proxy.
10:00 - 10:20 Derek Vance: Radiogenic isotopes in foraminiferal carbonate as tracers of
continental input to the oceans and ocean circulation.
9:00 - 9:20
10:20 - 10:50 Coffee break
Ecology I (Convenor - D. Schmidt)
10:50 - 11:10 Lea Numberger, K. von Bröckel, J. Schönfeld and M. Spindler: Observation of
a spring bloom at Kiel Bight, depositional events and reaction of the benthic
foraminiferal community.
11:10 - 11:30 Joachim Schönfeld, W.-Chr. Dullo, P. Linke, O. Pfannkuche and A.
Rüggeberg: Benthic foraminifera from Deep-Water Coral Mounds in the
Porcupine Seabight, NE Atlantic.
11:30 - 11:50 Alexander V. Altenbach, U. Struck, and M. Hiss: Remarks on the ecology
and palaeoecology of the genus Virgulinella Cushman 1932.
11:50 - 12:10 Stefanie Schumacher, F.J. Jorissen, D. Dissard, A.J. Gooday, and K. Larkin:
Benthic foraminifera from the oxygen minimum zone of the Pakistan
continental margin - a proxy of bottom water oxygenation.
12:10 - 13:40 Lunch time
Ecology II (Convenor - E. Sheldon)
13:40 - 14:00 Gérald Duchemin, C. Fontanier and F.J. Jorissen: Small sized (63-150 µm)
live foraminifera from inner shelf to mid bathyal environments in the Bay of
Biscay during an eutrophic event.
14:00 - 14:20 Michal Kucera: Stationarity of planktonic foraminifer niche since the last
glacial maximum.
14:20 - 14:40 Maria E. Pérez, A.E. Rathburn, J.F. Adamic, J.B. Martin, J. Gieskes, W.
Ziebis, J.C. Herguera and C. Paull: Ecology and stable isotopes of living
benthic foraminifera at different methane seeps (Alaskan margin, California
margin, Gulf of California): Implications for the fossil record.
14:40 - 15:10 Coffee break
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New approaches (Convenor - E. Sheldon)
15:10 - 15:30 Ralf Schiebel, J. Bollmann and H.R. Thierstein: Automated particle analysis
in micropalaeontology.
15:30 - 15:50 Magali Schweizer, J. Pawlowski, T.J. Kouwenhoven and G.J. van der Zwaan:
Comparison between morphological and genetic species concepts in the
genera Cibicides and Uvigerina (calcareous benthic foraminifera).
15:50 - 16:10 Kate E. Larkin, A.J. Gooday, D.W. Pond, and B.J. Bett: Fatty acid analysis
unravels the role of benthic foraminifera in carbon cycling within the Pakistan
margin oxygen minimum zone.
16:10 - 16:30 Nils Cornelius, A.J. Gooday and T. Cedhagen: Are deep-sea benthic
foraminiferans really cosmopolitan?
Saturday, 16th June and Sunday, 17th June
Excursion to the Isle of Wight
Poster presentations:
Lúcia d'Abreu, A. Narciso, E. Salgueiro, A.Voelker, F. Abrantes, M. Cachão, M. and N.J.
Shackleton: Changes in upper water-column structure off the Western Iberian
margin during the penultimate glacial (MIS 6): an attempt to unravel the
oxygen isotope signal of planktonic foraminifera.
Karl-Heinz Baumann and H. Meggers: Coccolithophores and planktonic foraminifera off NW
Africa: Response to abrupt climate events during the last 45,000 years.
Natasha Bubenshchikova and D. Nürnberg: Benthic foraminifera reflecting the last glacial
interglacial environmental changes on the southeastern Sakhalin slope (the
Okhotsk Sea).
Kate Darling, M. Kucera and C.M. Wade: The coiling direction paradox in Neogloboquadrina
pachyderma.
Paula Diz, I.R. Hall, R. Zahn and E. Molyneux: Benthic foraminiferal assemblage changes at
the southern Agulhas Plateau during the past 140,000 years.
Kirsty Edgar, P.A. Wilson and P.F. Sexton: Global climate change and fluctuations in the
CCD during the middle Eocene: New records from ODP Leg 207, Demerara
Rise.
Samantha Gibbs, T.J. Bralower, P.R. Bown and T. Dunkley Jones: Spatial variation in
phytoplankton productivity across the Paleocene-Eocene Thermal Maximum:
Exceptionally well-preserved nannofossil shelf assemblages from New Jersey
and Tanzania.
Elisa Guasti, R.P. Speijer, H. Brinkhuis, J. Smit and E. Steurbaut: Paleoenvironmental
change at the Danian-Selandian transition in Tunisia: planktic foraminifera,
calcareous nannofossil and organic-walled dinoflagellate cyst records.
Jens O. Herrle, U. Heimhofer, P.A. Hochuli and H. Weissert: Contrasting origins of midCretaceous black shales in the Vocontian Basin: Evidence from palynological
and calcareous nannofossil records.
Mike Kaminski and F.M. Gradstein: An atlas of Paleogene cosmopolitan deep-water
agglutinated foraminifera.
Meral Köbrich and K.-H. Baumann: Seasonal and interannual variability of coccolithophores
fluxes and species composition in sediment traps off Cape Blanc (NW-Africa).
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Karoliina Koho, T.J. Kouwenhoven, G.J. van der Zwaan, H.C. de Stigter and T.C.E. van
Weering: Recent (Rose Bengal stained) benthic foraminifera from Portuguese
margin canyons.
Regina Krammer, K.-H. Bauman and R. Henrich: Middle to Late Miocene fluctuations in the
initial Benguela Upwelling System revealed by coccolith assemblages (ODP
Site 1085A).
Jenny Lezius and H. Kinkel: Coccolith evolution and stable isotopes during the Late
Miocene/early Pliocene Biogenic Bloom in the Eastern Equatorial Pacific.
Kenneth Mertens and S. Louwye: Dissolution as indicated by coccoliths in the Cariaco
Basin, Venezuela.
Alla-Valeria Mikhalevich: The new subfamily Starobogatovellinae (Foraminifera).
Kurt S.S. Nielsen: Palaeomagnetic and Planktonic foraminiferal biostratigraphy of a PlioPleistocene section, Rhodes (Greece).
Lennart de Nooijer, I.A.P. Duijnstee and G.J. van der Zwaan: Novel application of MTTreduction: a viability assay for benthic foraminifera.
Sabrina Renaud and D. N. Schmidt: Morphometrics of the planktic foraminifers G.
truncatulinoides and G. ruber: Evolution and ecology affect the response to
Pleistocene climatic variability.
Aranda da Silva, A.J. Gooday, T. Cedhagen, N. Cornelius and J. Pawlowski: Gromiid
protozoans in the deep sea.
Bettina Schenk, M. Kling and J. Rohrmüller: Cenomanian Foraminifera of Eastern Bavaria.
Jorinde Sprong, E. Guasti, E. Fornaciari and R.P. Speijer: A foraminifera-based
paleoenvironmental reconstruction of the Danian/Selandian transition in Egypt.
Donata Violanti, S. Trenkwalder, F. Dela Pierre and A. Irace: The Miocene/Pliocene
boundary in Piedmont (North-Western Italy). Micropalaeontological analyses
on outcrop (Moncucco quarry) and subsurface (Narzole corehole)
assemblages.
Silke Voigt, A. Zacke, A.S. Gale and M. Joachimski: Shark teeth oxygen isotopic evidence
for salinity changes and water column stratification in the Palaeocene-Eocene
North Sea Basin
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Abstracts
Changes in upper water-column structure off the Western Iberian
margin during the penultimate glacial (MIS 6): an attempt to unravel
the oxygen isotope signal of planktonic foraminifera
de Abreu, L. (1, 2), Narciso, A. (3), Salgueiro, E. (1), Voelker, A. (1), Abrantes, F.(1),
Cachão, M. (3), and Shackleton, N.J. (2)
(1) INETI I.P., Departamento de Geologia Marinha e Costeira, Estrada da Portela, Alfragide;
Portugal.
(2) Godwin Laboratory, University of Cambridge, New Museums Site, Cambridge CB2 3SA;
United Kingdom. [email protected]
(3) Departmento de Geologia, Faculdade de Ciencias, Universidade de Lisboa, Campo
Grande, 1749-016 Lisboa; Portugal
Sediments of core MD95-2040 were studied in high-resolution to reveal changes in the
hydrographic conditions during glacial stage 6. The multi-proxy approach includes various
planktonic foraminifera-based proxy records and the distribution of Coccolithus pelagicus.
The influence of northern Atlantic ice-rafting episodes is evidenced by a polar to subpolar
fauna and cold SST. In between the cold spells the influence of a warm surface water mass,
probably similar to the modern Azores frontal waters, is indicated by the presence of
subtropical fauna. This would partially explain the observed variation in the planktonic
isotopes and the increment in mid-Stage 6 of the large C. pelagicus morphotype, presently
with its ecological niche in the Azores region. In full glacial conditions a polar planktonic
foraminifera assemblage coincides with the presence of a small C. pelagicus morphotype,
that is associated with Heinrich events during the last glacial, and with the deposition of icerafting debris. The oxygen isotopic composition of dextral Neogloboquadrina pachyderma
and Globorotalia inflata is often lighter than the one of Globigerina bulloides, suggesting that
calcification took place in distinctive water masses and probably during well-individualised
seasons, thus increasing the thermal and the isotopic contrast. A second ecological mode
was identified, during which different species of planktonic foraminifera show a convergence
in their habitat, with similar isotopic values. This may indicate enhanced mixing in the upper
water column during parts of MIS 6, in agreement with some of the palaeoproductivity
proxies.
Remarks on the ecology and palaeoecology of the genus
Virgulinella Cushman 1932
Altenbach, A.V.(1), Struck, U. (1) and Hiss, M.(2)
(1) GeoBio-CenterLMU, Richard-Wagner-Str. 10, D-80333 Muenchen; Germany.
[email protected], [email protected]
(2) Geologischer Dienst Nordrhein-Westfalen, De-Greiff-Strasse 195, D-47803 Krefeld;
Germany. [email protected]
The taxon Virgulinella was considered an extinct Miocene to Pliocene subgenus or genus for
long. First reports of its tests in modern sediments appeared in 1957, followed by the
description of the modern remnant species Virgulinella fragilis Grindel and Collen in 1976.
Due to the highly variable test morphology of modern Virgulinella, the most distinct
morphological separation from ancient species is given by the extreme delicacy of it's test
(wall thickness ca. 1.2 micron). Miocene species of Virgulinella are ubiquitous, most
commonly found in shelf sediments enriched in phosphorites or glauconite. In congruence
with the literature, we may consider their environment as "normal marine". The modern
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remnant, V. fragilis, shelters anoxic bacteria in endosymbiosis, and thus it is linked to oxygen
depleted conditions appropriate for the symbionts. Migration surpassing oxic environments
would be excluded for this reason, and thus immigration by ships ballast water was made
reasonable for the spotty occurrence of modern populations.
Comparing the Miocene and modern environments of Virgulinella, we have to face a very
unpleasant contradiction for our modern view on the functional morphology of benthic
foraminifera: the ecological layout of this genus would have changed from "normal marine" in
the Miocene to modern oxygen depleted environments with bacterial symbiosys,
accompanied only by negligible morphological changes. But 13C ratios of Virgulinella already
show additional effects to altered pore water chemistry in the Miocene (-1 to -3 ‰ δ13C).
They are depleted by 1.5 - 3.5 ‰ and 2.5 - 4.5 ‰ in comparison to Miocene endobenthic and
epifaunal foraminifera respectively. Modern Virgulinella from oxygen depleted environments
range at -10 to -12 ‰. In addition, teratological test formations are commonly observed in
modern populations off India and Namibia (up to 80%). This seems to indicate a still
persistent adjustment to most extreme modern environmental conditions, on the edge of
survival.
The Stensioeina granulata lineage and its impact on Late
Cretaceous biostratigraphy.
Bailey, H.W.
Network Stratigraphic Consulting Ltd., Harvest House, Cranborne Road, Potters Bar,
Hertfordshire. EN6 3JF. [email protected]
The Stensioeina granulata lineage is thought to have originated from S. pokornyi first found
in Late Cenomanian sediments of the Carpathian trough in Slovakia. Subsequent
subspecies, S. g. interiecta, S. g. humilis and S. g. kelleri, defined by Koch (1977), were
described from Turonian sediments in Germany and are frequently recorded in hydrocarbon
well sections drilled in the Dutch, German and Danish offshore areas of the North Sea Basin.
The earliest member of the lineage encountered in the Anglo-Paris Basin is the Early
Coniacian subspecies S. granulata levis which is known from southern England and the
Boulonnais region of France, possibly introduced into the basin in association with a late
Early Coniacian transgressive pulse.
Subspecies from Coniacian to mid Santonian chalks (S. g. granulata and S. g. polonica) are
ubiquitous in their distribution throughout Europe, reflecting their association with successive
transgressive phases. Conversely Late Santonian and Early Campanian subspecies (S. g.
perfecta and S. g. incondita), also described originally from Germany, are less widely
distributed, possibly as a result of section loss at this stratigraphic level as a result of regional
tectonic activity.
The lineage appears to come to an abrupt end in mid-Campanian times, with no obvious
successor to S. g. incondita. This study suggests possible reasons for the apparent
extinction of the group, together with the possible alternative suggestion of an extended
version of this resilient lineage through into the Paleogene.
Coccolithophores and planktonic foraminifera off NW Africa:
Response to abrupt climate events during the last 45,000 years
Baumann, K.-H. and Meggers, H.
FB Geowissenschaften, University of Bremen, Post Box 330440, 28334 Bremen; Germany.
[email protected]; [email protected]
Various archives from the northern hemisphere such as ice core records and ocean
sediments were studied in the past decades giving strong evidence of abrupt climatic change
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occurring in high frequency during the last 60 kyrs. Here, we present a sediment core record
(GeoB 5546 recovered off Cape Yubi, 27.5°N) of the subtropical NE Atlantic resolving both
Heinrich Events and Dansgaard-Oeschger Cycles in the glacial section. The abrupt climatic
changes strongly modulated the precessional forced palaeoproductivity signal in the NE
Atlantic and also influenced the calcareous plankton community.
Coccolithophores and planktonic foraminifera react in a decoupled, almost opposite, way to
the abrupt climatic changes of the last glacial. High contents of planktonic foraminifera
together with high TOC contents but rather low numbers of coccolithophores occur during
interstadials, in particular during stage 3. However, species such as Globigerina bulloides
and Calcidiscus leptoporus are indicative for the increased interstadial productivity. In
contrast, low numbers of planktic foraminifera and relatively high numbers of
coccolithophores occur during stadials of stage 3 as well as during whole stage 2. We
speculate that the contrast in the calcareous plankton assemblages may be related to
changes in the summer season insolation. Enhanced terrigenous input derived from
wadis/rivers probably is responsible for a near-shore enhancement of the paleoproductivity
but also increased turbidity of the surface water, favouring planktonic foraminifera production
during the interstadials of stage 3. Since the terrigenous induced enhancement of the marine
productivity outside the insolation maximum is much lower, coccolithophorid production is
enhanced in particular during stage 2.
Benthic foraminifera reflecting the last glacial interglacial
environmental changes on the southeastern Sakhalin slope (the
Okhotsk Sea)
Bubenshchikova, N.
P.P.Shirshov Institute of Oceanology, Nakhimovsky 36, Moscow 117997; Russia.
[email protected]
The last glacial-interglacial sediments of two cores were investigated for sediment
biogeochemistry, benthic and planktonic foraminifera in order to reconstruct the past
environments. The cores are located on the southern and eastern Sakhalin slope at 12651370 m water depth within the present Okhotsk Sea Oxygen Minimum Zone (OMZ). We
suppose that past faunal variations are controlled by the organic matter flux and water mass
changes including the outflow of well oxygenated Okhotsk Sea Intermediate Water (OSIW)
and the inflow of calcite undersaturated North Pacific Deep Water (NPDW). These processes
determined the development of OMZ on the Sakhalin slope.
In the last glacial, the Uvigerina auberiana assemblage and sediment biogeochemistry data
document the low productivity alternated by the periods of the NPDW inflow in the MIS3
(Marine Isotope Stage 3) and the OSIW outflow in the MIS2. The anomalously low contents
of planktonic and benthic foraminifera are found predominantly in the MIS3. These events
are likely a combined result of productivity minima and enhanced inflow of the carbonate
aggressive NPDW in the cores locations. In the MIS2 the local increase of the oxic indicator
Cibicidoides group shows slightly higher deep intermediate water oxygenation and/or bottom
current activity. We suggest that the OMZ in the MIS2 was slackened essentially due to the
enhanced OSIW production. The biogeochemical data and benthic fauna dominated by
Takayanagia delicata and Uvigerina akitaensis show the first lower peak of productivity at the
Melt Water Pulses (MWP) 1A and the second higher maxima of productivity at the MWP1B
caused by deglacial climate warming and the sea level rising. After the MWP1B benthic
fauna indicates the strengthening of the OMZ by the growth of dysoxic indicator Brizalina
spissa associated with maximal productivity and reduced OSIW ventilation. In the Holocene
the Islandiella norcrossi assemblage is characterized by anomalously low abundances and,
thus, does not reflect adequately the relatively high productivity recorded by the total organic
carbon, opal, carbonate and planktonic foraminifera. A combined effect of the relatively high
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organic matter flux, the inflow of calcite undersaturated NPDW and substrate changes are
suggested to have a principal impact on benthic foraminifera in the Holocene.
Nutricline/pycnocline and water temperature variations in the South
Iberian Margin during the Last Glaciation as revealed by
Florisphaera profunda
Colmenero-Hidalgo, E. (1, 2), Flores, J.-A. (1) and Sierro, F. J. (1)
(1) Área de Paleontología, Dept. Geología, Universidad de Salamanca, Plaza La Merced
S/N, 37008 Salamanca, Spain. [email protected], [email protected]
(2) Present address: School of Earth, Ocean and Planetary Sciences, Cardiff University,
Park Place, Main Building, Cardiff CF10 3YE, Wales, United Kingdom. [email protected]
Quantitative studies on coccolithophore populations have been carried out in marine
sediment cores MD95-2043 (36º9‚N, 2º37‚W; 1841 m water depth; Alboran Sea, Western
Mediterranean) and M39029-7 (36º2.5‚N, 8º13.8‚W; 1917 m water depth; Gulf of Cadiz, NE
Atlantic). Coccolithophore assemblages from both cores provide high-resolution records of
MIS 1 to 3 allowing detailed palaeoceanographic and palaeoclimatic reconstructions of the
last 50 kyrs (Colmenero-Hidalgo et al., 2004).
Florisphaera profunda is the only lower photic zone calcareous nannoplankton species in
both cores, usually living between 80-120 m deep with a minimum temperature threshold at
that depth of 10-12ºC. Variations in its abundance have been frequently used to monitor
changes in turbidity or in the position of the nutricline. Maximum peaks in the Gulf of Cadiz
(up to 40%) during the coldest intervals of the Last Glacial period (i. e. Heinrich Events and
some of Dansgaard-Oeschger Stadials) have been interpreted as the probable result of high
upper photic zone turbidity and upper water column stratification. On the contrary, its
behaviour in the Alboran Sea shows that despite nutricline shallowing and nutrient
enrichment in its depth during these same cold events (Pérez-Folgado et al., 2003),
temperatures were far below 10-12ºC. In the Deglaciation, the incipient temperature increase
was probably enough to trigger increases of Florisphaera profunda at H1 and YD, the
intervals of shallower nutricline/pycnocline in the area.
Colmenero-Hidalgo, E., Flores, J.-A., Sierro, F.J., Bárcena, M.A., Löwemark, L., Schönfeld, J. and
Grimalt, J.O., 2004. Ocean surface water response to short-term climate changes revealed by
coccolithophores from the Gulf of Cadiz (NE Atlantic) and Alboran Sea (W Mediterranean).
Palaeogeography, Palaeoclimatology, Palaeoecology, 205, 317-336.
Pérez-Folgado, M., Sierro, F.J., Flores, J.-A., Cacho, I., Grimalt, J.O., Zahn, R. and Shackleton, N.,
2003. Western Mediterranean planktic foraminifera events and millennial climatic variability during
the last 70 kiloyears. Marine Micropaleontology, 48, 49-70.
Are deep-sea benthic foraminifera really cosmopolitan?
Cornelius, N. (1), Gooday, A.J. (1) and Cedhagen, T. (2)
(1) Southampton Oceanography Centre, Empress Dock, European Way, Southampton SO14
3ZH, UK. [email protected]
(2) Department of Marine Ecology, University of Aarhus, Finlandsgade 14, 8200 Aarhus N,
Denmark. [email protected]
Wet-sorting of entire‚ live foraminiferal assemblages (i.e. including soft-walled species) from
multi- and box-corer samples collected during the ANDEEP II expedition in the Weddell Sea
(1100 - 4975 m water depth) and S. Sandwich Trench (6300 m water depth) has revealed
abundant and diverse foraminiferal assemblages. Densities generally decreased with water
depth. The proportion of calcareous species also decreased with depth while
monothalamous taxa and komokiaceans increased, but considerable numbers of calcareous
foraminifera were still present well below the Calcium Carbonate Compensation Depth
(CCD). The samples yielded 205 live foraminiferal species, of which only 93 were described.
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These observations are reinforced by preliminary data from the recent ANDEEP III
expedition (Jan 22nd to April 6th 2005) to the Weddell and Bellingshausen Seas during which
we recognized about 330 benthic foraminiferal species, of which less than 100 are described.
Most of the undescribed species in ANDEEP samples are komokiaceans or soft-shelled
monothalamous forms. Some are highly distinctive and may be confined to the Southern
Ocean. On the other hand, the majority of the described species are well known from the
Northern Hemisphere, for example, the upwelling area off NW Africa, the Greenland
Norwegian Sea and the Barents Sea. Examples include Ammolagena clavata,
Cribrostomoides subglobosa, Adercotryma glomeratum, Cyclammina cancellata,
Hormosinella distans, Edgertonia floccula, Bulimina marginata, Nuttallides umbonatus,
Epistominella exigua and Oridorsalis umbonatus. However, these identifications are based
on morphological criteria. During ANDEEP II, we collected specimens of many species for
molecular analyses. We plan to compare DNA sequences from these species with those
from similar morphospecies obtained at deep-sea Arctic sites during expeditions this
summer. This comparison will form a basis for exploring the question: are cosmopolitan
deep-sea foraminiferal morphospecies really single species or do they include a number of
morphologically similar cryptic species?
The coiling direction paradox in Neogloboquadrina pachyderma.
Darling, K. (1), Kucera, M. (2) and Wade, C. M. (3)
(1) Grant Institute of Earth Science/Institute of Evolutionary Biology, University of Edinburgh,
Edinburgh, UK. [email protected]
(2) Institut für Geowissenschaften, Eberhard-Karls Universität Tübingen, Tübingen,
Germany. [email protected]
(3) Institute of Genetics, University of Nottingham, Nottingham, UK.
[email protected]
Planktonic foraminifera with trochospirally arranged chambers can produce shells with two
different coiling directions. Some morphospecies show a strong preference for either righthanded (dextral) or left-handed (sinistral) coiling, while other morphospecies appear in mixed
coiling proportions varying around a midpoint value. Some display a pattern of distinct shifts
in their coiling ratios spatially and through time. Although the underlying mechanisms
controlling coiling direction are not understood, many workers have assumed it to be a
morphological feature reflecting ecophenotypic variation and have used coiling ratios
extensively for palaeoenvironmental reconstruction. Recent genetic studies now clearly
demonstrate that coiling direction in planktonic foraminifera is a genetic trait, heritable
through time and not environmentally controlled. Previously reported links between coiling
and environmental factors result from the different ecological preferences of the genetically
distinct coiling types.
Neogloboquadrina pachyderma is the most important provider of palaeoproxies on the state
and variation of high latitude oceans in the Quaternary. It has two distinct coiling forms with
virtually exclusive distributions that appear to be controlled by water temperature. The
genetic evidence shows that the two opposite coiling morphotypes diverged many millions of
years ago and they have distinctly different ecologies. In combination with fossil evidence,
biogeography and ecology, the degree of genetic distinction between the two coiling types of
Ne. pachyderma strongly implies that they should be considered different species. The
genetic evidence also demonstrates a low level (< 3%) aberrant coiling associated with each
morphotype posing a serious nomenclature problem for taxonomists and
palaeoceanographers alike. The presence of aberrant coiling and the continual need for
palaeoceanographers to refer to coiling direction in the literature demands the reclassification of the right coiling Ne. pachyderma genotypes as a distinct species to simplify
nomenclature and reference. We propose the adoption of the widely recognised name
incompta for the dextral morphospecies.
9
Benthic foraminiferal assemblage changes at the southern Agulhas
Plateau during the past 140,000 years
Diz, P. (1), Hall, I.R. (1), Zahn, R. (1, 2) and Molyneux, E. (1)
(1) School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park
Place, CF10 3YE Cardiff, United Kingdom.
(2) Institució Catalana de Recerca i Estudis Avançats, ICREA, i Universitat Autónoma de
Barcelona, Institut de Ciencia i Tecnología Ambientals, ICTA, Edifici Cn Campus UAB, E08193 Bellaterra, Spain.
Benthic foraminiferal assemblages and stable oxygen and carbon isotopes from
Epistominella exigua along core MD02-2589 (41º26.03´S, 25º15.30´E, 2660 m water depth)
are used to infer palaeo-productivity changes at the South Agulhas Plateau. The core is
located at the position of the present day Subtropical Front (STF) within the Agulhas
Retroflection current regime. It is optimally located to monitor leakage of warm Indian Ocean
waters into the south Atlantic Ocean and changes in productivity associated with the frontal
system formed by the Agulhas Return Current (ARC) and the Subtropical Convergence
(STC).
Stratigraphy for core MD02-2589 is based on AMS 14C dates and a high resolution planktonic
oxygen isotope record along the core (Molyneaux et al., unpublished data). The
sedimentation rate varied between 3.3 and 29 cm/kyr with an average of 8.7 cm/kyr. The
core shows substantial down-core fluctuations in faunal composition. Relative abundance of
phytodetritus exploiting species Alabaminella weddellensis and E. exigua (Gooday, 1993)
are unrelated. A. weddellensis is the most common species throughout the core, but E.
exigua is more abundant during MIS 1 and 5e, indicating periods of occasionally high but
pulsed deposition of organic matter at the sea floor. More sustained food supply occurred at
the end of Terminations I and II and during MIS 5a and 5b when N. iridea and Uvigerina spp.
(TI, TII) and E. vitrea (MIS 5a, b) compete with and outnumber E. exigua and A.
weddellensis. High percentages of N. iridea, a shallow infaunal species (Gooday and
Hudges, 2002), at the Last Glacial Maximum suggest a measurable increase in the overall
organic carbon flux arriving at the seafloor probably caused by increased productivity in
response to enhanced wind stress and a southward moving STF.
Preliminary measurements of stable carbon isotopes in E. exigua show that δ13C values are
low (-0.4‰ to -1.0‰), with minimum values occurring at the LGM coincident with peak N.
iridea abundance. These data are consistent with a contribution of 12C enriched pore waters
derived from the decomposition of the phytodetritus layer deposited at the seafloor.
Tentatively we use the δ13C record of E. exigua as a proxy of organic carbon flux and primary
productivity as suggested by Corliss et al. (2001).
Gooday, A.J., 1993. Deep-sea benthic foraminiferal species which exploit phytodetritus: characteristic
features and controls on distribution. Marine Micropaleontology, 22, 187-205
Gooday, A.J. & Hudges, J.A., 2002. Foraminifera associated with phytodetritus deposits at a bathyal
site in the northern Rockall Trough (NE Atlantic): seasonal contrast and a comparison of stained
and dead assemblages. Marine Micropaleontology, 46, 83-110.
Corliss, B.H., Sun, X., Brown, Ch.W., McCorkle, D.C., Showers, W.J. & Hidgon, D.M., 2001. The
influence of primary productivity and seasonality of productivity on deep-sea benthic foraminifera.
GSA Annual Meeting, November 5-8, 2001.
10
Small sized (63-150 µm) live foraminifera from inner shelf to mid
bathyal environments in the Bay of Biscay during an eutrophic
event
Duchemin, G., Fontanier, C. and Jorissen F.J.
Laboratory of Recent and Fossil Bio-Indicators, University of Angers, 2 boulevard Lavoisier,
49045 ANGERS cedex 01; France. LEBIM, Ker Châlon, 85350 ILE D'YEU; France.
[email protected], [email protected], [email protected]
Living foraminiferal faunas of the 63-150 µm size fraction have been investigated along a
composite transect from inner shelf (80 m water depth) to lower middle slope (2000 m water
depth) in the Bay of Biscay. The eleven stations were sampled in April 2002 and March
2004. Earlier studies on the temporal variability of phytoplankton primary production indicate
that our stations were sampled at the most eutrophic period of the year. In response to the
decreasing exported organic matter flux to the sea floor with increasing water depth,
foraminiferal standing stocks show a trend from high values (about 1400-2000 specimens
per 50 cm3) on the continental shelf (100-140 m water depth) and the upper slope (550 m) to
much lower values at mid bathyal stations (about 400 specimens per 50 cm3). At all stations,
the faunas contain an important amount of small opportunistic species that are favoured by
seasonal phytodetritus inputs. From coastal to mid bathyal stations, foraminiferal faunas are
dominated successively by: (1) Textularia porrecta (coastal area); (2) Nonionella iridea,
Cassidulina carinata and Bolivina ex. gr. dilatata (northern outer shelf) or Bolivina
dilatata/spathulata and Bolivina subaenariensis (southern outer shelf); (3) Epistominella
exigua and Uvigerina peregrina (upper middle bathyal); and (4) Nuttallides pusillus and
Gavelinopsis translucens (lower middle bathyal). This faunal succession could be related to
the water depth, which influences directly the amount of organic matter exported to the seafloor, and perhaps to the quality of this organic matter, which could explain differences of
foraminiferal composition between the northern and southern part.
Global climate change and fluctuations in the CCD during the
middle Eocene: New records from ODP Leg 207, Demerara Rise.
Edgar, K. M., Wilson, P. A. and Sexton, P. F.
Southampton Oceanography Centre, School of Ocean and Earth Science, European
Way, Southampton, SO14 3ZH, UK. [email protected]
The middle Eocene (37-49 Ma) is traditionally regarded as a period of long-term cooling that
represents the transition between the early Eocene greenhouse and the early Oligocene
icehouse. However, because of the poor quality of deep sea sedimentary sequences
recovered of this age, the nature of this transition remains relatively badly constrained. The
majority of studies are confined to Southern Ocean sites and suggest that the middle Eocene
was in fact punctuated by at least several short stable isotope excursions superimposed on
the underlying long term cooling trend. One of the most prominent of these excursions is a
pronounced warming event at 41.6 Ma seen in surface and intermediate water temperatures
at Site 690. Elsewhere, work in the Pacific has demonstrated that the onset of major
Antarctic ice sheets across the Eocene/ Oligocene boundary was intimately associated with
a pronounced decrease in ocean acidity (CCD deepening) (Coxall et al, 2005).
Here we report new stable isotope records in benthic foraminiferal calcite of middle Eocene
age from ODP Leg 207 (Demerara Rise) in the tropical Atlantic. A high sedimentation rate of
~2cm/kyr combined with a well-defined magnetostratigraphy facilitates high resolution
examination of the stability of global climate during this transition interval.
Boharty, S. M. and Zachos, J. C., 2003. Significant Southern Ocean warming event in the late middle
Eocene. Geology, 31, 1017-1020.
11
Coxall, H. K., Wilson, P. A., Pälike, H., Lear, C. H. and Backman, J. 2005. Rapid stepwise onset of
Antarctic glaciation and deeper calcite compensation in the Pacific Ocean. Nature, 433: 53-57.
doi:10.1038/nature03135.
Cenomanian/Turonian (OAE2) benthic foraminiferal faunas of the
Demerara Rise depth transect (ODP Leg 207)
Friedrich, O. (1), Erbacher, J. (2) and Mutterlose, J. (3)
(1) Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, 30655 Hannover;
Germany. [email protected]
(2) Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, 30655 Hannover;
Germany. [email protected]
(3) Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum,
Universitätsstrasse 150, 44801 Bochum; Germany. [email protected]
ODP Leg 207 recovered thick successions of Late Cretaceous organic-rich strata along a
depth transect of 5 sites (3192 – 1899 mbsl) on Demerara Rise, 400 km north off Surinam,
western tropical Atlantic. Cenomanian to Turonian sediments with Oceanic Anoxic Event 2
(OAE2) were recovered from different sites. This interval is characterised by very high TOC
values of up to 29 %. Based on high resolution δ13Corg-records from four Sites, a
chemostratigraphic framework was established for Demerara Rise black shale sediments
including OAE2. This chemostratigraphy allows us to correlate changes in the benthic
foraminiferal assemblages of four sites around OAE2. Along the depth transect, Site 1258 is
the deepest and shows high fluctuations in the assemblages that correlate to changing TOC
values in the sediments. Samples without benthic foraminifera are characterized by very high
TOC values (above ~10%), whereas samples with lower TOC values contain benthic
foraminifera. Generally, the faunas are characterized by only few taxa that are tolerant to
oxygen deficiency, like Bolivina, Praebulimina, and Neobulimina. Very high benthic
foraminiferal numbers (BFN) occur some meters below OAE2, whereas the excursion
interval is characterized by low BFN and diversity, indicating very low oxygen contents, but
not complete anoxia during distinctive intervals of OAE2. Above the excursion, slowly
increasing BFN and diversities indicate slightly increasing oxygen content which is
interrupted by several phases of complete anoxia.
Benthic foraminiferal assemblages of the shallower Site 1261 reflect anoxic conditions during
most of the studied interval and therefore a more stable position within a proposed oxygen
minimum zone (OMZ). Times of oxygen availability, as indicated by the occurrence of benthic
foraminifera can be correlated to high BFN in Site 1258. First results from the shallowest Site
1259 and from the very condensed OAE2 of Site 1260 support the existence of a fluctuating
OMZ.
Spatial variation in phytoplankton productivity across the
Paleocene-Eocene Thermal Maximum: Exceptionally well-preserved
nannofossil shelf assemblages from New Jersey and Tanzania
Gibbs, S. J. (1), Bralower T. J. (1), Bown, P. R. (2) and Dunkley Jones, T. (2)
(1) Department of Geosciences, The Pennsylvanian State University, University Park,
Pennsylvania 16802, USA. [email protected], [email protected]
(2) Department of Earth Sciences, University College London, Gower Street, London WC1E
6BT, UK. [email protected], [email protected]
Significant transformations in the global biosphere accompanied dramatic global warming
and profound perturbation of the carbon cycle during the Paleocene-Eocene Thermal
Maximum (PETM, ~55 Ma). These abrupt environmental changes have been linked to a
massive release of carbon into the ocean-atmosphere system. Increased phytoplankton
productivity has been invoked to cause subsequent CO2 drawdown, cooling, and
12
environmental recovery. However, interpretations of geochemical and biotic data differ on
where this increased productivity occurred. Here we present high-resolution nannofossil
assemblage data from a number of shelf sections including the U.S. Geological Survey drill
hole at Wilson Lake, Ocean Drilling Program (ODP) Leg 174X Bass River drill hole (both
New Jersey), and Kilwa, Tanzania (drilled as part of the Tanzanian Drilling Project). We also
show data from an open-ocean location, ODP Site 1209 (palaeo-equatorial Pacific).
Nannofossil assemblage changes indicate highly variable responses to this climatic event
across the environmental trophic spectrum. Low productivity, open ocean sites demonstrate
a global but transient increase in oligotrophy, which may have resulted from a widespread
deepening of the thermocline. In contrast, shelf-slope productivity variations were more
localized with mesotrophic communities spatially restricted to areas close to nutrient sources
via increased runoff. The relatively limited area of shallow shelves may have provided a
disproportionately large carbon sink and this phytoplankton productivity may have played an
important role in driving the massive drawdown of CO2 after the peak of the PETM.
Deep-sea benthic foraminifera faunas and stable isotopes from the
Portugal margin : preliminary results
Griveaud, C. (1), Jorissen, F. (1), Michel, E. (2) and Anschutz, P. (3)
(1) Laboratoire d‚Etude des Bio-indicateurs Actuels et fossiles, UPRES EA2644, Université
d‚Angers, 2bd Lavoisier, 49045 Angers Cedex (France)
(2) Laboratoire des Sciences du Climat et de l'Environnement CNRS-CEA, Allée de la
Terrasse, 91198 Gif/Yvette cedex (France)
(3) Département de Géologie et Océanographie, UMR CNRS 5805 EPOC, Université
Bordeaux1, Avenue des facultés, 33405 Talence cedex (France)
The ecology (faunal density, composition, microhabitats) of benthic foraminifera from three
deep stations (1000m, 2000m and 3000m) of the Portugal margin (Northwest Atlantic, 3738°N) has been studied. Six cores were picked for each station. In order to improve the
understanding of factors controlling the spatial distribution of the faunas, the chemistry of the
sediment (O2, NO3-∑) has also been analysed. Stable isotopes measurements (δ18O, δ13C)
from species of four key genera that have different microhabitats (Cibicidoides/Fontbotia,
Uvigerina, Melonis and Globobulimina) are still in process. We will show here preliminary
results.
Faunal densities decrease with increasing water depth, following as expected the diminishing
organic matter flux that reaches the see floor at greater depths. However one core at station
FP9 (3000m) exhibits a surprisingly high density due to the presence of a worm burrow, with
the apparition of reactive species such as Pullenia bulloides, Fursenkoina sp., and Pyrgo
elongata. The deep infaunal Globobulimina affinis shows in each station a maximum of
abundance at "oxygen zero” depth, which is in agreement with previous studies.
Interspecific differences in stable isotopic composition are related to the different
microhabitats, with deep infaunal species (Globobulimina affinis) having lighter values than
shallow infaunal species (Uvigerina mediterranea). The Uvigerina species, however, show a
wide scatter in δ18O as well as δ13C in function of the size of the specimen measured but
further analysis are still expected to confirm this trend.
13
Paleoenvironmental change at the Danian-Selandian transition in
Tunisia: planktic foraminifera, calcareous nannofossil and organicwalled dinoflagellate cyst records
Guasti, E.(1), Speijer, R.P.(2), Brinkhuis, H. (3), Smit, J. (4) and Steurbaut, E., (5)
(1) Department of Geosciences (FB 5), Bremen University, P.O.Box 330440, 28334
Bremen, Germany. [email protected]
(2) Department of Geography and Geology, K.U.Leuven, Redingenstraat 16, 3000 Leuven,
Belgium. [email protected]
(3) Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584
CD Utrecht, The Netherlands. [email protected]
(4) Department of Sedimentology, Faculty of Earth and Life Sciences Vrije Universiteit, de
Boelelaan 1085 1081HV Amsterdam, the Netherlands. [email protected]
(5) K.B.I.N., Vautierstraat 291000 Brussel Belgium. [email protected]
We document paleoenvironmental change across the Danian-Selandian transition (planktic
foraminiferal interval P2-P3b; Calcareous Nannofossil Zone NP4, Subzones NTp7-NTp8A;
61-59 Ma) in three localities in NW Tunisia (Ain Settara, Elles and El Kef). Diversification of
Paleogene planktic foraminifera with the evolution of muricate and photosymbiotic lineages
Acarinina, Morozovella and Igorina is recorded during this interval. The present study aims to
understand early Paleogene geo-biosphere changes in the southern Tethys, analyzing the
evolution of surface water conditions. All the studied localities represent outer neritic
deposition. Paleoenvironmental changes are explored by combining planktic foraminiferal
and organic dinocyst assemblages and relative proxies (planktic/benthic ratio, numbers of
planktic foraminifera per gram, peridinioid/gonyaulacoid ratio; terrestrial/marine ratio). Our
records indicate that the environment evolved from an initially oligotrophic, open marine,
outer neritic setting in Zone P2-P3a towards a shallower and nutrient-rich setting from the
base of Subzone P3b. This change is marked by a sudden change in organic-dinocyst
assemblages, characterized by a peak of P-cysts (Cerodinium and Lejeunecysta) and an
upwards decrease in deeper benthic taxa. Associated to these dinocysts assemblages, the
lowest occurrence of Apectodinium is recorded suggesting major environmental (and
climate) perturbations. The start of the P-cysts peak corresponds to a substantial change in
calcareous nannofossil assemblages, marked by the first appearance of Fasciculithus and a
slight, but distinct increase in near-shore taxa (essentially Pontosphaera).
Contrasting origins of mid-Cretaceous black shales in the
Vocontian Basin: Evidence from palynological and calcareous
nannofossil records
Herrle, J.O.(1), Heimhofer, U.(2), Hochuli, P. A.(3) and Weissert, H. (4)
(1) Southampton Oceanography Centre, School of Ocean & Earth Science, European Way,
SO14 3ZH Southampton, UK [email protected]
(2) University of Oxford, Oxford OX1 3PR, UK uli.heimhofer@earth
(3) Palaeontological Institute, University of Zurich, Karl Schmid-Strasse 4, 8006 Zurich, CH
[email protected]
(4) Geological Institute, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, CH
[email protected]
Detailed records of spore-pollen assemblages, particulate organic matter (OM), dinoflagellate
cysts and calcareous nannofossils provide new insights into the palaeoclimatic and
palaeoceanographic conditions during formation of mid-Cretaceous black shales in the
Vocontian Basin (SE France). The early Aptian Niveau Goguel, which corresponds to the
OAE1a, and the regionally distributed late Aptian Niveau Jacob have been studied with
14
regard to changes in terrestrial vegetation patterns, terrigenous inputs and surface water
productivity.
Palynological results from both black shales exhibit a rich and stable floral pattern,
dominated by various ferns, different types of cycads, bennettites as well as by several
conifer families. Dinoflagellate cyst assemblages and the calcareous nannofossil-based
nutrient-index show no prominent changes in surface water productivity across both black
shale intervals. Significant variations are observed in terrestrial detrital input indicated by
changes in abundances of marine and terrestrial palynomorphs. The laminated, OM-rich
horizons of the Niveau Goguel interval reflect deposition during times of reduced siliciclastic
input. These episodes of pronounced condensation were accompanied by anoxic conditions
preventing degradation of the marine-derived OM. In contrast, the Niveau Jacob is
characterised by a strong increase in terrestrial palynomorphs, most probably reflecting an
abrupt increase in riverine runoff. The enhanced terrestrial OM input may have triggered
oxygen-depletion in bottom waters, resulting in increased OM preservation.
Our results highlight the variety of processes, controlling the accumulation of OM in the
Vocontian Basin and illustrate, that enhanced surface water productivity is not an
indispensable prerequisite for the formation of mid-Cretaceous black shales. Discrepancies
between the results from the Vocontian Basin and data from other Tethyan localities might
be explained by differing regional palaeoceanographic settings, resulting in different
responses to global palaeoenvironmental change. An important precondition for black shales
formation was most probably given by the rather low deep-water oxygen concentrations of
the mid-Cretaceous ocean basins, resulting in a strong propensity towards anoxic bottom
waters.
Lower Eocene Oceanography, UK CNS; a core calibrated
interdisciplinary study.
Hogg, N.
[email protected]
An unprecedent integrated, multidisciplinary opportunity to study the Lower Eocene
(Ypresian) North Sea ocenaographic reconnection has been afforded in cored wells from
Shell's Gannet D Field, UK Central North Sea (CNS). A full description and discussion will be
presented of micropalaeontological, palynological and ichnological responses to the opening
up of the restricted North Sea basin in the lowermost Horda Formation, following restricted
conditions posed on the basin across the Paleocene/Eocene boundary.
Planktic foraminifer and coccolitophorid assemblages of Core
MD02-2529 as indicators of climate changes in the Eastern
Equatorial Pacific during the last 135 kyr
Ivanova, E.V. (1), Beaufort, L. (2) and Vidal, L. (2)
(1) Shirshov Institute of Oceanology RAS, Nakhimovsky Prosp. 36, Moscow, 117997,
Russia. [email protected]
(2) CEREGE, Europole de l'Arbois, Aix en Provence, Cedex 04, F-13545 France.
[email protected]
A quantitative study of planktic foraminiferal and coccolithophore assemblages in the upper
18 m of Core MD02-2529 (08°12.5' N, 84° 07.5' W, w.d. 1619 m) retrieved below the
southeastern edge of the Costa Rica dome provides a new insight into productivity variations
and ENSO dynamics in EEP during the last 135 kyr. PCA carried out on the combined phytoand zooplankton data demonstrates that species distribution in both groups mainly reflect
bioproductivity, i.e. thermocline depth, and dissolution intensity. We found pronounced
temporal variations in microfossil assemblages. Whereas interglacial assemblages are
15
characterized by high content of deep-dwelling G. menardii, rather oligotrophic surfacedwelling G. ruber and G. trilobus,and deep photic zone species F. profunda, species related
to fertile upwelling waters as G. bulloides, G. glutinata, diverse coccolitophorids and deepdwelling cold-water N. dutertrei and N. pachyderma generally proliferate during glacials and
deglaciations. A persistent occurrence of minor deep-dwelling species G. inflata, known to
be typical of eastern margins of subtropical gyres, likely points to a relatively short-term
events of lateral advection of cooler subsurface waters during MIS 2 and 4, sometimes
decoupled with the events of intensified upwelling and shoaling of the thermocline when G.
bulloides and G. glutinata increase in abundance. The end of MIS 2 is characterized by a
maximum of calcareous microfossils preservation, followed by a gradual increase of
dissolution from the end of Termination I to Holocene, except for a short-term spike of high
planktic and benthic foraminiferal abundance related to a better preservation at Termination
I. An increase in productivity during glacials and deglaciations most probably indicative of the
thermocline shoaling in turn may be controlled by a glacial extension of Costa Rica dome
and/or by stronger Papayago winds coming from the Caribbean Sea. These finding are in
line with more frequent La-Ninas or stronger tradewinds during glacials.
An Atlas of Paleogene Cosmopolitan Deep-Water Agglutinated
Foraminifera
Kaminski, M.A (1) and Gradstein, F.M. (2).
(1) Department of Earth Sciences, University College London, London WC1E6BT, UK.
(2) Museum of Geology, University of Oslo, N-0318 Oslo, Norway.
As a step towards the documentation of the global deep water agglutinated foraminiferal
faunas through geologic time, we have prepared an illustrated Atlas of Paleogene DeepWater Agglutinated taxa. These faunas started to flourish in deeper water basins as early as
Middle Jurassic, with major phases of evolutionary expansion in the Aptian-Turonian,
Campanian, late Paleocene, Early Eocene and Middle Miocene.
The Atlas, which we began as a taxonomic project in 1979 at the Bedford Institute of
Oceanography in Dartmouth, N.S., is intended to serve as a reference guide for
micropalaeontologists working with agglutinated benthic foraminifers in deep marine,
siliciclastic strata of Paleogene age around the world, and is intended to be a companion
volume to the "Van Morkhoven et al. Atlas” of deep-water calcareous benthic foraminifera.
Some of the agglutinated taxa covered in the Atlas are stratigraphically long ranging, while
others either appeared in Late Creta-ceous time or extend into Neogene.
The 130 Agglutinated Taxa are grouped in Linnean taxonomic units using fossil shell
morphology, which represent the majority of species to be expected in deep-marine clastic
sediments. For each of these valid species we provide illustrations – mostly based on type
material – with one or more plates of SEM and optical photographs, and/or hand drawings.
There is concise description for each species, followed by a discussion of its paleogeography
and stratigraphic occurrence. The Atlas begins with an intro-duction outlining the history of
investigations, and discusses the most important collections. The second chapter summarises the Paleoecology and its spin-off Paleobathymetry, a subject that is in demand for the
study of deep water basins. Chapter three deals with biostratigraphical record of DWAF in
offshore eastern Canada, in the North Sea, Offshore Norway, Norwegian Sea, Barents Sea,
Carpathian Basins, southern European Tethyan basins, India, and Trinidad/Venezuela.
Each main area of investigation has a stratigraphic range chart for key taxa. The following
section contains the main course of this Atlas: Systematic Taxonomy. This is followed by the
master reference listing and the species index. The "Atlas of Paleogene Cosmopolitan DeepWater Agglutinated Foraminifera” is available from the Grzybowski Foundation.
Kaminski, M.A. & Gradstein, F.M. (2005). Atlas of Paleogene Cosmopolitan Deep-Water Agglutinated
Foraminifera. Grzybowski Foundation Special Publication, 10, 547 pp.
16
Foraminifera as paleoceanographic proxies; biological constraints
both from in situ and laboratory experiments.
Kitazato, H. (1), Nomaki, H. (1), Toyofuku, T. (1) and Tsuchiya, M. (2)
(1) Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth
Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, JAPAN
[email protected], [email protected], [email protected]
(2) JSPS Research Fellow, Extremobiosphere Research Center (XBR), Japan Agency for
Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 2370061, JAPAN [email protected]
Foraminifera are known as an excellent indicator both for modern and ancient oceanic
environments. This is mainly supported by the empirical evidences that foraminifera change
their test morphologies and/or chemical compositions in response to ambient environmental
conditions. However, we have no concrete proofs how foraminifera adapt their shapes or
chemical compositions to ambient environments. Both culture experiments and DNA
analyses are direct ways to understand foraminiferal biology as theoretical constraints for
paleo-environmental proxies.
Obviously, several assumptions are existed at the time when we use foraminifera for
reconstructing paleoceanographic condition. Foraminiferal tests are sensitive test-tube for
indicating ambient environments. Foraminiferal communities are important components of
global biogeochemical cycle. Changes in test morphologies of foraminifera through geologic
time control mainly by genetic information. Through series of culture experiments, we can
answer whether or not these assumptions are true or false. Here, we give two examples.
1) Mg/Ca concentration in foraminiferal tests changes in proportion to temperature gradients.
Currently, many of paleoceanographers use this proxy for reconstructing paleotemperature.
However, there are several points before adopt this proxy to natural samples. For instance,
we should select genera and species. Because, Mg/Ca values change from genera to
genera. The value is also different from part to part within one specimen and even within one
chamber. On the other side, this new results indicate that we can detect daily or seasonal
changes of water temperature using these facts.
2) Both DNA analyses and breeding experiments are another smart approaches for
understanding either genotypic or ecophenotypic variations of foraminiferal test morphology.
For instance, both breeding experiment and DNA analyses for genus Planoglabratella clearly
show that both ecophenotypic and genotypic variations exist in morphological variations. We
can easily establish new environmental proxies through these approaches.
Seasonal and interannual variability of coccolithophores fluxes and
species composition in sediment traps off Cape Blanc (NW-Africa).
Köbrich, M.I. and Baumann, K.-H.
FB Geowissenschaften, Universität Bremen, Postfach 330440, 28334 Bremen.
[email protected], [email protected]
It is known that coccolithophores can be assigned to particular water masses or to photic
zone characteristics and, therefore, species or whole assemblages can be used as
oceanographical indicators. A prerequisite for palaeoceanographic studies or paleaeoclimatic
reconstructions using coccolith assemblages is the under-stan-ding of the ecological affinities
of extant species.
Coccolithophore flux variations in sediment traps of the time-series station CB (Cape Blanc),
located at about 20°N 20°W, were recorded for the time interval from March 1988 to
November 1991. The cup particle traps were deployed at 2200 to 3500 m below sea surface,
and sampling intervals ranged from ten days to three weeks. Qualitative and quantitative
analyses of the coccolithophores were performed with the scanning electron microscope
17
(SEM). Each coccolith and coccosphere was counted and identified to the lowest taxonomic
level as possible.
The downward fluxes of coccolithophores showed significant variations in species
composition during the four years period. Highest coccolith fluxes of 1158 x 107 coccoliths m2 -1
d occurred at the end of February 1991, whereas only of 9 x 107 coccoliths m-2 d-1 were
recorded in May 1991. The coccolithophore assemblages were dominated by Emiliania
huxleyi, the most ubiquitous species on earth, together with the deep-living species
Florisphaera profunda, and Gladiolithus flabellatus. At about the time of the coccolith flux
maximum a distinct change in species composition occurred. In addition to the above
mentioned taxa, species of Umbellosphaera and Syracosphaera also reached high
abundances after the total coccolithophore flux maximum.
The presentation gives insight into the seasonal variation of coccolithophore export and the
influencing abiotic factors. It focuses on the determination of seasonal variation in the
coccolithophore species composition, their relationship to the hydrographical conditions of
the upwelling area, as well as their relationship to the overall carbonate flux.
Recent (Rose Bengal stained) benthic foraminifera from Portuguese
margin canyons
K.A. Koho (1), T.J. Kouwenhoven (1), G.J. van der Zwaan (1), H.C. de Stigter (2), T.C.E. van
Weering (2)
(1) Utrecht University, Faculty of Geosciences, the Netherlands, [email protected]
(2) Royal Netherlands Institute for Sea Research, the Netherlands
Submarine canyons are dynamic environments that transport and trap vast quantities of
sediment, nutrients and organic carbon. Excess 210Pb values in sediments from the Nazaré
Canyon are found to be an order of magnitude higher than in the adjacent shelf and slope
environment, reflecting increased particle settlement fluxes in the canyon. In addition, the
sediment accumulation rates over a period of time are by far highest in the canyon and have
high C-org values. The combination of these parameters together with the physical
disturbance due to functioning of the canyon will result in an extraordinary and adapted
ecosystem.
Preliminary results will be presented from a detailed quantitative analysis of living (Rose
Bengal stained) benthic foraminiferal assemblages from Nazaré and Lisbon-Setúbal
canyons, which are located on the Portuguese continental margin. These canyons have a
comparable oceanographic setting, including narrow shelf, summer upwelling regime and
exposure to southwesterly storms in winter. However, while the Lisbon-Setúbal canyons are
fed by the rivers Sado and Tagus, the Nazaré canyon has no direct river influence.
The total standing stocks (TSS) appear to be highest at the head of each canyon and decline
in general with depth. However, the axis of the Nazaré canyon appears to be nearly barren in
contrast to Lisbon-Setúbal canyons. Nevertheless, in a previous study carried out at royal
NIOZ van den Berg and de Stigter (data not published) found abundant foraminifera
populations along the axis of the Nazaré canyon. Agglutinated taxa are present in great
numbers at many locations and sometimes dominate the assemblages of the Portuguese
margin canyons. This is in contrast with previous canyon studies which revealed that the
foraminifera assemblages in canyons off New Jersey and Gulf of Lions are dominated by
calcareous foraminifera species such as Uvigerina spp. and Bulimina spp..
18
An overview of late Miocene benthic foraminiferal data from the
Mediterranean
Kouwenhoven. T.J. (1) and van der Zwaan, G.J. (1, 2)
(1) Department of Earth Sciences, Utrecht University, The Netherlands. [email protected]
(2) Department of Ecology / Biogeology, Radboud University Nijmegen, The Netherlands.
[email protected]
Historically, it has proven problematic to derive reliable palaeoenvironmental information
from pre-Messinian Mediterranean sediments. Consequently, the sequence of events
preceding the late Messinian evaporative phase, commonly referred to as the Messinian
salinity crisis (MSC) is still uncertain. Where integrated dating methods (bio-, cyclo-,
magnetostratigraphy) allow us to place important bio-events within a well-constrained time
frame, the events themselves are still not fully resolved. A generally accepted scenario is that
severance of the Betic and Rif Corridors (SE Spain and NW Morocco, respectively) isolated
the Mediterranean more or less completely from the Atlantic in the course of the late
Miocene. Different stages in the Messinian restriction of the Mediterranean are tentatively
correlated with uplift in different areas of the Rif Corridor. We will present an overview of data
derived from benthic foraminiferal faunas covering the late Tortonian and the Messinian up to
the start of the evaporative phase. Palaeoenvironmental reconstructions were made at
several locations and at different depths of deposition, and together with data from other
sources they allow us to develop a picture of the actual pre-crisis events.
Middle to Late Miocene fluctuations in the initial Benguela
Upwelling System revealed by coccolith assemblages (ODP Site
1085A)
Krammer, R. (1), Baumann K.-H. (2) and Rüdiger Henrich (2)
(1) Research Center Ocean Margins, University of Bremen, Germany ([email protected])
(2) Department of Geosciences, University of Bremen, Postfach 330440, 28334 Bremen,
Germany
The Middle to Late Miocene is known as an interval of major changes in the climate system,
such as the expansion of the Antarctic ice sheets, the cooling of surface and deep water
masses, as well as the start of the Isthmus of Panama (e.g., Zachos et al., 2001). These
changing boundary conditions had significant impacts on ocean circulation, nutrient supply
and, thus, on the productivity of the oceans. Previous investigations of the Miocene history of
the upwelling off SW-Africa concluded that the onset of high productivity was at about 12 Ma
(Diester-Haass et al., 2004).
We analysed coccolith data of ODP Site 1085 from the SE-Atlantic to document changes in
surface-ocean circulation, upwelling initiation, and associated productivity. Our data show
that coccoliths constitute a significant part of the carbonate content. Highest numbers of
coccoliths were observed during the intervals 9.9 to 9.7 and 8.7 to 8.0 Ma. These elevated
numbers of coccoliths may generally be linked to the initiation of upwelling at about 10 Ma in
the studied region. In contrast, diminished numbers of coccoliths, as in the interval 9.6 to 9.0
Ma, probably characterise time intervals of weaker upwelling and thus a drastic decrease in
coccolith contents of the sediments. Coccoliths account for more than half of the carbonate,
with peak contribution up to 80 % at 8.8 Ma. Generally, a correlation between productivity in
the initiated upwelling and carbonate production by coccoliths seems reasonable.
Diester-Haass, L., Meyers, P.A., Bickert, T., 2004. Carbonate crash and biogenic bloom in the Late
Miocene: Evidence from ODP Sites 1085, 1086, and 1087 in the Cape Basin,southeast Atlantic
Ocean. Paleoceanography, 19, PA 1007, doi: 10.1029/2003PA000933.
19
Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K., 2001. Trends, rhythms, and aberrations in
global climate 65 Ma to present. Science, 292, 686-693.
Stationarity of planktonic foraminifer niche since the last glacial
maximum
Kucera, M.
Institut für Geowissenschaften, Eberhard-Karls Universität Tübingen, Sigwartstrasse 10, DE72076 Tübingen; Germany. [email protected]
All empirically calibrated microfossil paleoproxies, be it transfer functions or geochemical
signals, rely on the assumption that the properties of modern species remained the same in
the past. This assumption is certainly valid for short periods of time, like centuries or
millennia, but on geological time-scales, its validity must be questioned. Species are not
constant through time and their ecological properties change. As a result, the validity of
empirical calibrations is always restricted to a limited part of the range of a given species. A
similar limitation applies for the rage and variety of environmental conditions in the past:
empirical calibrations are bound to the realm of ecological circumstances represented in the
calibration dataset. Paleoceanographers using microfossil-based proxies are thus faced with
a fundamental problem: to what degree is a fossil estimate affected by the unquantifiable, yet
omnipresent, effect of "no-analog” situations?
Using the recently compiled MARGO database of census counts of planktonic foraminifer
assemblages, I have attempted to determine how significant the problem of "no-analog”
situations is for the nearest Quaternary climatic extreme: the Last Glacial Maximum (LGM).
Analysis of the MARGO database indicates that glacial foraminifer faunas occupied the
same, or a slightly smaller portion of the multivariate space defined by abundances of
modern species. This implies that LGM oceans showed a similar range of environments as
modern oceans and that planktonic foraminifera responded to subsequent warming mainly
by expansion of their geographical ranges. I will also demonstrate that the "no-analog”
problem is of subdued importance in LGM transfer function applications, compared to
uncertainties arising from the use of different computational techniques. The same approach
can be adopted from any other time slice in the past as an effective means to assess the
extent of ecological difference between modern and fossil faunas.
Fatty acid analysis unravels the role of benthic foraminifera in
carbon cycling within the Pakistan margin oxygen minimum zone
Larkin, K. E. (1), Gooday, A. J. (1), Pond, D. W. (2) and Bett, B. J. (1)
(1) DEEPSEAS Group, Southampton Oceanography Centre, Empress Dock, European Way,
Southampton SO14 3ZH, U.K. [email protected]
(2) British Antarctic Survey, British Antarctic Survey, High Cross, Madingley Road,
CAMBRIDGE, CB3 0ET, United Kingdom. [email protected].
Deep-Sea benthic environments provide key sites for carbon cycling, with complex
interactions occurring between the sediment biogeochemistry and infaunal organisms. In
Oxygen Minimum Zones (OMZ‚s), where dissolved oxygen concentration is < 0.5 ml l-1,
hypoxia will influence the biogeochemical cycling of elements and the structure of benthic
communites where it impinges on the continental margin. Foraminiferans are a major
component of benthic biomass in OMZ‚s, as they display tolerance and adaptations to low
oxygen conditions. However, the role of foraminiferans in elemental cycling within OMZs is
unclear. Fatty acid biomarkers are being used as a powerful tool to investigate the diets of
this diverse group of protists across an OMZ on the Pakistan Margin, northeast Arabian Sea.
At 300m, within the core of the OMZ (O2 < 0.1 ml l-1), our results indicate that individual
foraminiferan species feed selectively. In situ and shipboard feeding experiments, using 13C
20
labelled diatoms as an artificial food source, have enabled the tracking, using GC-MS, of
carbon uptake into individual fatty acids of Uvigerina peregrina, the first time this has been
achieved in the case of a foraminiferan. This shallow infaunal calcareous species exhibited a
rapid response to the labile food source, suggesting that it is an important consumer of
organic carbon on the sea floor, especially in low oxygen environments such as the Pakistan
margin OMZ where it dominates the foraminiferal assemblage and macrofaunal and
megafaunal organisms are rare or absent. Previous studies have shown that the abundance
of Uvigerina peregrina is related to concentrations of organic carbon at the seafloor rather
than to bottom-water oxygen concentrations. Nevertheless, its high population densities in
modern laminated sediments on the Pakistan Margin suggests that Uvigerina peregrina
could be used as an indicator of past fluctuations in the extent of the Arabian Sea Oxygen
Minimum Zone.
Coccolith evolution and stable isotopes during the Late Miocene /
Early Pliocene Biogenic Bloom in the Eastern Equatorial Pacific
Lezius, J. and Kinkel, H.
Research Unit Ocean Gateways, Institute for Geosciences, University of Kiel, LudewigMeyn-Straße 10, 24118 Kiel, Germany; [email protected]
During the Late Miocene/Early Pliocene an event of unususal increase in the carbonate
accumulation rate has been observed in all ocean basins. This "Biogenic Bloom" is
pronounced mainly due to enhanced coccolithophorid productivity and the presence of larger
coccoliths, compared to younger intervals.
We investigate the coccolithophorid assemblage in ODP Site 1241 with respect to their
species composition, morphometry and stable isotopes. At this site the Biogenic Bloom is
expressed as a 5-fold increase in the carbonate accumulation rate, the sand fraction never
exceeds 8%, thus foraminifera are neglectable concerning the overall carbonate budgets.
The coccolithophorid assemblage composition, dominated by small to medium
Reticulofenestra, clearly shows enhanced productivity during the Biogenic Bloom interval. On
average the relative abundance of the lower photic zone species (Florisphaera profunda) is
low, suggesting an increased nutrient supply to the upper photic zone, though we detect an
increase in this taxa and additionally in Sphenolithus and Discoaster indicating a decrease in
productivity at the end of the Biogenic Bloom. Here we observe a distinct floral shift at 6.3 Ma
and changed contribution to the total coccolith carbonate due to varying size portions of
coccoliths. The decrease of coccoliths of the genus Reticulofenestra is closely following a
distinct decrease in the stable-carbon isotope composition of the carbonate fine-fraction. To
evaluate whether the carbon isotope shift is real or reflects changes in coccolithophorid
species composition (preclude species specific vital effects), comparisons are made of bulk
fine fraction (<63µm, <20µm) and different sub-fractions representing different
coccolithophorid species assemblages.
Dissolution as indicated by coccoliths in the Cariaco Basin,
Venezuela
Mertens, K.N. and Louwye, S.
Research Unit Palaeontology, Department of Geology and Soil Science, Ghent University,
S8, Krijgslaan 281, 9000 Gent, [email protected]
The Tropical regions are nowadays more and more actively implicated in Quaternary climate
regulation. The aim of this study is to establish a reconstruction of the palaeoclimate in the
Cariaco Basin during the last 21 ka, using nannofossil fluctuations as proxies.
The Cariaco Basin is an anoxic pull-apart basin on the continental shelf of Venezuela. The
region is under the influence of the migrating intertropical convergence zone (ITCZ) which is
21
reflected in the light-dark coloured cycles in the sediment (varves). The question arose,
whether these migrations are observable on a stadial/interstadial scale.
A high-resolution analysis of ODP-core 1002C demonstrated that increases in Emiliania
huxleyi go hand in hand with decreases of Gephyrocapsa oceanica and vice versa. Since
ecological models give no satisfactory explanations of this trend, one can only resort to
pinning down carbonate dissolution as the main cause. Moreover, since a wide range of
preservation states is observed, and there is a clear regression with the rain ratio, it must be
a case of supralysoclinal dissolution caused by decomposition of organic material.
Dissolution of carbonate results in an enrichment of resistant Gephyrocapsa oceanica, in
contrast to fragile Emiliania huxleyi. We propose a new dissolution index GEX based on the
ratio of relative abundances of these taxa. Dissolution was more intense during stadials,
associated with decreased inorganic carbon loss in the water column.
Lower accumulations of coccoliths during anoxic settings, can be linked to reduced
biocalcification due to increased Dissolved Inorganic Carbon contents (DIC). These
variations in DIC are coupled to upwelling of Subtropical UnderWater (SUW), and linked to
shifts of the ITCZ during precession-minima. There appear to be a clear asynchronicity
between shifts observed in the equatorial region and the northern latitudes, and this suggests
a more active role in regulation of the thermohaline circulation in this region.
The new subfamily Starobogatovellinae (Foraminifera).
Mikhalevich, V.
Zoological Institute RAS; Universitetskaya nab.1, 199034, St. Petersburg, Russia.
[email protected]
Following the customary approach when the shell wall composition was considered as the
most important taxonomic feature Starobogatovella Mikhalevich, 1994 was initially placed
into the family Ammoscalariidae Mikhalevich, 1982. The septa between the chambers are
organic in this genus as well as in the Ammoscalaria Hoeglund, 1947. But their morphology
differs significantly. Basing myself on the predominant significance of the morphological
features and supposing that the shell wall can change from the tectinous to the agglutinated
one independently in different phyletic lines Starobogatovella is separated here from the
Ammoscalaria.
Order LITUOLIDA Lankester, 1885. Superfamily Lituoloidea de Blainville, 1827. Lituolidae
de Blainville, 1827. Starobogatovellinae Mikhalevich subfam. nov. Type genus:
Starobogatovella Mikhalevich, 1994.
Test with evolute planospirally coiled part and very short, narrow and fragile rectilinear
uncoiled part rounded in section, chambers subcylindrical, very slowly increasing in size, up
to 10 -16 in the last whorl; wall agglutinated, with tectinous inner septa; aperture - open end
of the last tubular chamber equal in diameter to chamber lumen, apertures of the preceding
chambers - small openings in the middle of tectinous septa having a short tectinous collar.
Holocene.
Remarks. This subfamily differs from Ammoscalariinae in the character of the test: evolute
rather than involute coiled part with multiple whorls, short and cylindrical rather than well
developed flattened rectilinear part, and in the form of the chambers, from the subfamilies
Ammobaculitinae and Lituolinae - in the character of the chambers bearing the tubular
features, in the weak development of the uncoiled part and in the fully evolute initial part. It
differs from all the other lituolids in its tectinous inner septa. This subfamily has an
intermediate character between Lituotubidae and Lituolidae.
22
Core top calibrations of Boron isotope paleo-pH proxy
Ni, Y. (1), Foster, G. (1), Haley, B. (1), Bailey, T. (2) and Elliott, T. (1)
(1) Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens
Road, BS8 1RJ, Bristol, U.K.
(2) National Museums and Galleries of Wales, Cathays Park, CF10 3NP, Cardiff, U.K.
The use of boron isotopes to look at palaeo-ocean pH and ultimately pCO2 has great
potential for constraining climate reconstructions. However, there have recently been
discussions concerning the accuracy of the technique. Hence we have developed a
completely new methodology to measure B isotopes and use this approach to further ground
truth the boron isotope proxy by examining 5 common species of planktonic foraminifera in
core top samples from two tropical equatorial sites (ODP 806B, C Pacific; ODP 664C
Atlantic). Our new total evaporation method of boron isotope analyses enables the analysis
of relatively small numbers of forams (as few as 10 individuals), and the combination of these
measurements with elemental analyses on the same dissolutions, to examine potential
species and size fraction effects on the measured δ11B. In general we found no systematic
change in δ11B with sample size for the surface dwelling species, indicting that physiological
processes have no clear influence on the δ11B in the planktonic foraminiferal shells. The δ11B
for both cores is estimated to be 24 ± 1‰ for the surface dwelling species, G. sacculifer and
G. ruber. For deeper dwelling species in core 664C we find that δ11B decreases with depth
habitat as would be expected from modern seawater pH profiles; namely 20 ± 1‰ for N.
dutertrei and G. tumida. For G .truncatulinoides the δ11B decreases from 19 ‰ to 17‰ with
increasing size fractions, which is consistent with changes of habitat depth during their life
cycle. For the same samples Mg/Ca, U/Ca ratios increase and Sr/Ca ratios decrease with
increasing shell size compatible with the hypothesis that smaller individuals calcifying faster
than larger individuals and larger individuals form calcite that more closely reflects seawater
temperature and composition. We stress however that, in contrast to previously published
studies we find no such effect for the boron isotope proxy.
Palaeomagnetic and Planktonic foraminiferal biostratigraphy of a
Plio-Pleistocene section, Rhodes (Greece)
Nielsen, K. S. S.
Geological Institute, Universtity of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen,
Denmark; [email protected]
The Island of Rhodes makes up the easternmost part of the Aegean Arch, located near the
Turkish mainland, in the Eastern Mediterranean Sea. The Tsambika profile is located on the
road to Tsambika Beach, approximately 25 km from the centre of Rhodes City at the
southeastern coast of the Island. The investigated section consists of 40 m of marine
sediment (limestone, silt/clay). Both the foraminiferal and palaeomagnetic data suggest that
the section is of Late Plio-Pleistocene age.
A total of 60 planktonic species have been recorded. More than ten of those species have
not previously been recorded in the Mediterranean Plio-Pleiostocene.
The results show that most species which have an FAD/LAD, near the Plio-Pleistocene
boundary in the Vrica section are diachronous when compared to the Tsambika section. The
only four possible exceptions are the FAD of G. crassaformis, B. praepumilio, B. riedeli and
N. eggeri (dutertrei?). However, neither B. praepumilio nor B. riedeli have been observed in
the Vrica section. The FAD of N. eggeri in the Tsambika section and the FAD of N. dutertrei
in the Vrica section seems to be synchronous but the taxonomical uncertainty regarding
these species seem to exclude these as marker species.
Further, the coiling of N. parchyderma is dextral throughout the Tsambika profile whereas the
specimens observed in the Vrica section are sinistral near the Plio-Pleistocene boundary.
23
Also the benthic foraminifera Hyalina baltica has been recorded, but the FAD of this species
predates the Plio-Pleistocene boundary in the Tsambika section as indicated by the
paleomagnetic data. It is concluded that it is not possible to correlate between the Tsambika
and the Vrica sections based on foraminiferal biostratigraphy.
Novel application of MTT-reduction: a viability assay for benthic
foraminifera
de Nooijer, L.J.(1), Duijnstee, I.A.P.(1,2) and van der Zwaan, G.J.(1,2)
(1) Department of Stratigraphy and Paleontology, Faculty of Geosciences, Utrecht University
Budapestlaan 4, 3584 CD Utrecht, The Netherlands. [email protected]
(2) Department of Biogeology, Faculty of Sciences, Radboud University, Toernooiveld 1,
6525 ED Nijmegen, The Netherlands.
Studies on living foraminifera commonly involve staining samples with Rose Bengal (RB) to
distinguish living from dead individuals. Since RB does stain individuals that have died
recently and are not yet fully decayed, foraminiferal communities seem larger than they
actually are. We present a new viability assay based on the reduction of MTT by enzymes in
living foraminifera. The tetrazolium salt MTT is converted from a yellow, soluble form to a
red/purple crystal. Living individuals convert MTT slowly and become stained within 24
hours. Dead foraminifers, despite keeping their enzymatic activity for several days, yield a
different coloration from stained living foraminifers, making the identification of false positives
possible.
Observation of a spring bloom at Kiel Bight, depositional events
and reaction of the benthic foraminiferal community
Numberger, L. (1), von Bröckel K. (1), Schönfeld, J. (1) and Spindler, M. (2)
(1) Leibniz-Institute of Marine Science IFM-GEOMAR, Wischhofstr. 1-3, D-24148 Kiel;
Germany. [email protected]
(2) Institut für Polarökologie, Wischhofstr. 1-3, D-24148 Kiel; Germany
A spring bloom and the benthic foraminiferal response were investigated between January
and July 2004 at Kiel Bight, Western Baltic Sea (54°32`N and 10°02`E, 23,5 m water depth).
The purpose was to ascertain the correlation between production and deposition of
phytoplankton and the reaction of the benthic foraminiferal community. Three depositional
events of organic detritus into the surface sediment were recorded. Food preferences were
observed for Reophax dentaliniformis and Elphidium excavatum clavatum with reference to
their nutrition dynamics. The comparision between the actual investigation and earlier studies
from the 1970´ies showed long term changes of living benthic foraminiferal communities. A
change in surface sediment texture and salinity of near bottom water was also recognised.
Reproduction of Elphidium e. clavatum was stimulated by an increased availability of food
particles. The growth and reproduction cycle of Elphidium e. clavatum lasted 2 to 3 weeks
only. The results revealed a similar timescale of benthic pelagic coupling in a shallow-water
enviroment as compared to the deep sea.
24
Ecology and stable isotopes of living benthic foraminifera at
different methane seeps (Alaskan margin, California margin, Gulf of
California): Implications for the fossil record
Pérez, M. E. (1), Rathburn, A. E. (2), Adamic, J. F. (2), Martin, J. B. (3), Gieskes, J. (4),
Ziebis, W. (5), Herguera, J.C. (6), Paull, C. (7)
(1) Palaeontology Dept., The Natural History Museum, Cromwell Road, London, SW7 5BD,
UK. [email protected]
(2) Geography, Geology, and Anthropology, Indiana State Univ., Science Building 159, Terre
Haute, IN 47809
(3) Geological Science, Univ. of Florida, Box 112120, Gainesville, FL 32611
(4) Integrative Oceanography Division, Scripps Institution of Oceanography, 9500 Gilman
Drive, La Jolla, CA 92093-0236
(5) Biological Sciences Department, Univ. of Southern California, Los Angeles, CA 90089
(6) CICESE, Km 107 Carretera Tijuana-Ensenada, Ensenada, 22860 Mexico
(7) Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA
95039-9644
Despite an increasing number of foraminiferal studies at methane seeps, our knowledge of
their ecology and isotopic composition is poor and the use of benthic foraminifera as
indicators of methane release in the past is still in debate. A previously unknown methane
seep was discovered in July 2004 during an extensive exploration of the seafloor with ROV
Jason II along the Aleutian margin off Unimak Island. This seep has many characteristics of
methane seeps elsewhere including sulfide-oxidizing fauna (Calyptogena clams and
pogonophorans) and authigentic carbonate minerals cementing detrital sediments. But in
contrast to other methane seeps, pore waters of this seep show little evidence of methane
oxidation (e.g., increased sulfide and alkalinity concentrations).
Here we compare the species distributions and isotopic composition patterns of living benthic
foraminifera (rose Bengal stained) of this newly discovered seep with those from seeps that
we have previously studied in Monterey Bay (California) and Guaymas Basin (Gulf of
California) in order to gain insight into how different seep types affect foraminiferal
assemblages and the geochemistry of their test.
Preliminary data suggest that in general foraminiferal abundance is lower in methaneinfluenced sites than in the sites characterized by low methane discharge. The foraminiferal
assemblage in the seeps from Monterey Bay and Guaymas Basin are dominated by
calcareous species (Uvigerina peregrina, Bulimina mexicana, Globobulimina pacifica,
Epistominella pacifica), whereas the assemblage in the Aleutian margin seep is dominated
by agglutinated taxa. Of special interest is the occurrence of numerous specimens of
Cibicidoides wuellerstorfi attached to the pogonophoran tubes associated with this seep.
Carbon isotope values of living benthic foraminifera at all seeps are not much lower than
those observed in non-seep environments. These data question the extent to which strong
isotopically-light δ13C signals in the geological record are primary or diagenetic features.
25
Morphometrics of the planktic foraminifers G. truncatulinoides and
G. ruber: Evolution and ecology affect the response to Pleistocene
climatic variability
Renaud, S. (1) and Schmidt, D.N. (2)
(1) UMR 5125 CNRS UCB Lyon 1, Campus de la Doua, 69622 Villeurbanne, France.
[email protected]
(2) Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ
United Kingdom. [email protected]
The morphometric variation of two species of planktic foraminifers was investigated in a core
located in the subtropical gyre of the SE Atlantic covering the last 1 Million years. The
morphology of the foraminifers was quantified using a Fourier analysis of their outline in two
orthogonal views, size of the test, and coiling direction (for G. truncatulinoides). Both species
appeared to be structured in morphotypes and/or cryptic species with presumably different
ecological habits. The morphological variations observed through time therefore combine
mixing of the different morphotypes in various proportions depending on the environmental
context, and a potential long-term evolution.
The deep dwelling G. truncatulinoides showed a strong test-shape / climate relationship over
the last 140 kyr, whereas no clear signal can be found prior to that during the last 1 Ma.
Molecular evidences show that this taxon radiated 120-170 kyr ago into four clades with each
specific environmental preferences. This habitat specialisation could be the prerequisite for
the test-shape / climate relationship observed during the last 140 kyr, since this relationship
seems to be related to the mixing of the different clades with specific morphologies. Before
the radiation event, G. truncatulinoides ancestor clade responded to the climatic changes in
a non-analogous way compared to the post-140 kyr condition. Its response may include both,
long-term evolution and a plastic response initiating the differentiation and specialisation into
the four modern clades.
G. ruber shows a mixture of three morphotypes. The relative frequency of each morphotype
is related to glacial-interglacial changes over the 1-myr period. This result shows that the
climatic variability in the subtropical gyre was sufficient to cause a shape response of the
planktic foraminifer since this shape response mainly involved habitat tracking by established
morphotypes: this process does not involve long-term evolution and allows a fast response to
the Pleistocene climatic variability.
The comparison of the two species shows that the ability of a species to respond to rapid
environmental fluctuations depends on its evolutionary history. When clades with different
ecological habits are established within the taxon, the response of the foraminifer to climatic
changes occurs through habitat tracking, a process that leads to a good relationship between
morphometric data and paleoenvironmental proxies. When long-term evolution is the
dominant process, however, deciphering the relationship between climate and foraminifer
shape variation becomes more intricate.
26
Benthic Foraminifera from the El Buho Canyon and Fan (Late
Miocene of the Tabernas Basin, SE Spain).
Rogerson, M. (1), Kouwenhoven, T.J. (1), van der Zwaan, G.J. (1,2), O’Neill, B.J. (3), van der
Zwan, C.J. (1,4), Postma, G. (1), Kleverlaan, K. (5) and Tijbosch, H.J. (1)
(1) Faculty of Earth Sciences, University of Utrecht, 3584 CD Utrecht, Netherlands.
(2) Faculty of Biology, University of Nijmegen, 6525 ED, Netherlands.
(3) Shell International Exploration and Production plc, New Orleans, Louisiana, 70151-1510,
USA.
(4) Shell International Exploration and Production plc, 2280 AB, Rijkswijk, Netherlands.
(5) Zeeburgerdijk 585, 1095 AE Amsterdam, Netherlands/The sedimentology and
micropalaeontology of an exhumed Miocene age canyon and fan system from the Tabernas
Basin (SE. Spain) has been investigated. Four sections from the El Buho canyon
encompassing proximal canyon, distal canyon and adjacent slope environments have been
logged on a centimeter scale and the 150-595_m size range of 174 samples have been
examined for their benthic foraminiferal content. Two further sections from the timeequivalent fan have also been investigated, and benthic foraminiferal census data has been
collected for a further 28 samples. The assemblages revealed are similar across all of the
environments and individuals of Genus Cibicidoides (esp. C. dutemplei) generally dominate.
However, several taxa show strong associations with a particular sub-facies.
Agglutinated taxa generally show a strong preference for the extra-canyon environments, as
do several calcareous taxa (Cassidulina obtusa, Uvigerina rutila and Cibicidoides
robertsonianus). These taxa are systematically excluded along the gradient of increasing
sediment flow activity within the canyon and fan system, resulting in a declining diversity of
the assemblage in increasingly high energy environments. Minimum diversity is achieved in
barren samples recovered from the sand-dominated deposits of the proximal canyon and
canyon axis. A similar trend is found within foraminiferal density data.
Presence of Cassidulina laevigata near-exclusively within energy minimum zones within the
canyon indicates a strong preference of this species to environments that are sheltered from
direct disturbance, but that have differing environmental characteristics to the open slope.
This most likely reflects elevated food supply within the canyon. 9 samples, mainly from the
fan (5), display an assemblage dominated by Genus Globobulimina (up to 55%). These
assemblages are characteristic of environments that are oxygen-limited, and thus probably
indicate periods / locations where the food supply was sufficiently enhanced to promote
dysoxia.
The presence of good presence/absence indicators and unique assemblages within
particular environments allows delineation of slope, canyon and fan environments with
certainty within the Tabernas Basin by micropaleontology alone. Environmentally sensitive
whole-assemblage indices give additional insight into disturbance periodicity, and provide a
method by which further environments within the canyon can potentially be recognized.
Benthic foraminiferal assemblage data therefore hold significant potential for the
development of predictive tools for delineating environment of deposition in analogous
marine systems.
27
Cenomanian Foraminifera of Eastern Bavaria
Schenk, B. (1), Kling, M. (2) and Rohrmüller, J. (3)
(1) Department für Geo- und Umweltwissenschaften, Sektion Paläontologie, RichardWagner-Str. 10 / II, 80333 München. [email protected]
(2) Department für Geo- und Umweltwissenschaften, Sektion Mineralogie, Petrologie und
Geochemie, Theresienstr. 41, 80333 München. [email protected]
(3) Bayerisches Geologisches Landesamt, Außenstelle Marktredwitz, Leopoldstr. 30, 95615
Marktredwitz. [email protected]
The research area is situated near the town of Roding/Germany, 60 km east of Regensburg,
at the southern border of the Bodenwöhr Basin, a half-graben structure filled with clastic
sediments of upper cretaceous age. This half-graben structure stretches about 70 km in
WNW-ESE direction inside the Bavarian Forest, roughly following the "Pfahl" Shear Zone
and is surrounded by metamorphic and magmatic rocks of variscian age. The cretaceous
sedimets are usually flat lying or dip gently to the north, the maximum thickness of the
sediments reaches several 100 meters.
The two occurences where the investigated samples were taken, show a different
stratigraphic profile. The quarry at Grub/Roding shows a black shale with small pebbels at
the base. It is overlied by glauconite bearing coarse sandstone and a greyish-blue sandy
marl. Above are glauconite bearing coarse sandstone and marl. Then follows a fine grained
carbonaceous sandstone, the Reinhausen-Formation. The abandonend quarry at
Obertrübenbach shows a conglomerate horizon, overlied by a glauconite bearing
carbonaceous sandstone and a sandy marl. Again the fine grained sandstones of the
Reinhausen-Formation lie on top of the sequence.
19 sediment samples (15 from Grub, 4 from Obertrübenbach) were wet-sieved, and the
specimens were picked out from the > 63 µm residue. Three samples contain no foraminifera
at all. Because of abrasion the specimens sometimes could not be clearly determinated. All
samples show clear marine settings (e.g. fish teeth, radiolaria, sponge spiculae) without any
brackish influence. Surprisingly no single planctonic specimen have been found, either.
Agglutinanted foraminifera are also very rare. These factors indicate an nearshore
environment (Sen Gupta, B. K., 1999). The comparison of the species with Bohemian and
Moravian ones (e.g. Hercogova, J. 1974, Hanzliková, E. 1970) indicate a cenomanian age
for the two locations. Even upper cenomanian in the case of the quarry of Grub/Roding.
Hanzliková, E. (1972): Carpathian Upper Cretaceous Foraminiferida of Moravia (Turonian Maastrichtian). Rozpravy Ústredniho ústavu geologického, 39: 5-160.
Hercogova, J. (1974): Foraminifers from the Cenomanian of the Bohemian Massif. Sbornik
Geologickyoh ved, paleontologie,16: 69-103.
Sen Gupta, B. K. [Hrsg.]: Modern Foraminifera: 3 - 6; Dordrecht (Kluwer Academic Publishers).
Automated particle analysis in micropalaeontology
Schiebel, R.(1), Bollmann, J.(2) and Thierstein H.R.(2)
(1) School of Earth & Ocean Science, Southampton Oceanography Centre, European Way,
Southampton SO14 3ZH, UK. [email protected]
(2) Geological Institute, Swiss Federal Institute of Technology Zurich, Sonneggstrasse 5,
8092 Zurich, Switzerland
Analyses of the abundance and assemblage composition of microplankton, and of the
chemical and stable isotopic composition of their shells, have been among the most
successful methods in palaeoceanography and palaeoclimatology. Micropalaeontological
projects are often limited by the number of samples that can be processed and analyzed
within a certain time. For statistical reasons faunal counts have to include at least 300
specimens (normal case). For stable isotope analyses and for C-14-measurements at least
~10 and 800 medium sized planktic foraminifers are needed.
28
The manual collection of statistically significant quantities of unbiased, reproducible
microfossil data is time consuming. Consequently, automated microfossil analysis and
species recognition has been a long-standing goal in micropaleontology. Our target is to
speed up and standardize palaeoceanographic data acquisition using an automated incident
microscope for obtaining digital images, and artificial neural networks (ANNs) for
identification of particles, groups and species.
Identification does critically depend on pre-processing of the images and is carried out on PC
computers by the Windows®-based artificial neural network software package COGNIS. All
successful neural network runs were carried out with a similar setup, using a convolutional 5layer network (layer 1 and 3: convolutional, 8 layers, 5x5/4; layer 2 and 4 sub-sampling, 2x2;
one output layer), which will help to significantly speed up palaeoceanographic data
acquisition. Average recognition rate of 75% (max. 88%) for 6 taxa (N. dutertrei, N.
pachyderma dextral, N. pachyderma sinistral, G. inflata, G. menardii/tumida group, O.
universa, represented by 50 images each for 20 classes (separation of spiral and umbilical
views, and of sinistral and dextral forms). Our investigation indicates that neural networks
hold great potential for the automated classification of planktic foraminifers and offers new
perspectives in micropalaeontology, palaeoceanography and palaeoclimatology.
Bollmann, J., Quinn, P.S., Vela, M., Brabec, B.,Brechner, S., Cortés, M.Y., Hilbrecht, H., Schmidt,
D.N., Schiebel, R., and Thierstein, H.R., 2004. Automated particle analysis: Calcareous
microfossils. In: Francus, P. (Editor), Image Analysis, Sediments and Paleoenvironments. Kluwer
Academic Publishers, Dordrecht, The Netherlands.
Neogene origin of the modern pelagic niche and its consequences
for pelagic carbonate production
Schmidt, D. N. (1) and Kucera, M. (2)
(1) Department of Earth Science, Wills Memorial Building, University of Bristol, BS8 1RJ,
Bristol, UK [email protected]
(2) Institut für Geowissenschaften, Sigwartstr. 10, 72076 Tübingen, Germany
[email protected]
Biologically mediated fluxes of carbonate between the upper and deep ocean depend on
calcification of marine microplankton and lead, over geological time, to massive
accumulations of calcite in ocean sediments. Changes in the size of pelagic carbonate
producers influence the amount of material exported to the deep ocean. The size of
carbonate producers is known to have varied considerably over geological time (Young,
1990; Schmidt et al., 2004) with as yet unquantified implications for modelling of pelagic
export production. Here we investigate the relationship between tectonic/oceanographic
changes in the Neogene, plankton size and carbonate accumulation rates.
We have analysed foraminiferal size record and carbonate accumulation patterns in four midand low latitude Neogene sites at an average resolution of 70 kyrs and compared it with
existing data on size in calcareous nannoplankton and radiolaria. Carbonate preservation is
good during the last 10 Ma and hence does not influence size or accumulation rates. Or
results indicate that the dramatic size increase in foraminiferal assemblages is limited to the
oligotrophic tropical environments and does not occur in temperate of upwelling areas. The
changes in size do not reflect evolution of new, larger species, but they affect existing
lineages.
Sand fraction accumulation rate, representing production of planktonic foraminifer shells,
have doubled in the last 10 Ma with the largest change between 4-3 Ma in both tropics and
mid latitudes. At the same time, the total carbonate accumulation has decreased.
Furthermore, during the Neogene, large forms of coccolithophorids disappeared (Young,
1990; Knappertsbusch et al., 1997). As a consequence, the contribution of foraminifera to
pelagic carbonate production has rocketed from 20% in the mid-Miocene to about 50%
today. The similarity in the timing of the effective closure of the circum-tropical seaways and
evolution of unprecedented large sizes among foraminifera suggest that this novel tectonic
29
constellation has had a profound effect on the pelagic niche and on pelagic carbonate
production.
Knappertsbusch, M., Cortes, M.Y., Thierstein, H.R., 1997. Morphologic variability of the
coccolithophorid Calcidiscus leptoporus in the plankton, surface sediments and from the Early
Pleistocene. Marine Micropaleontology, 30: 293-317.
Schmidt, D.N., Thierstein, H.R., Bollmann, J., Schiebel, R., 2004. Abiotic Forcing of Plankton Evolution
in the Cenozoic. Science, 303: 207-210.
Young, J.R., 1990. Size variation of Neogene Reticulofenestra coccoliths from Indian Ocean DSDP
cores. Journal of Micropalaeontology, 9: 71-86.
Benthic foraminifera from Deep-Water Coral Mounds in the
Porcupine Seabight, NE Atlantic.
Schönfeld, J., Dullo, W.-Chr., Linke, P., Pfannkuche, O. and Rüggeberg, A.
Leibniz-Institute of Marine Sciences IFM-GEOMAR, Wischhofstrasse 1-3, 24148 Kiel;
Germany. [email protected]
Cold-water coral ecosystems on mound-alike structures are common on the upper slope of
the northwestern European continental margin. These ecosystems are generally
characterized by a high diversity and population density in a strong hydrodynamic
environment. Distribution and ecology of foraminifera from coral mounds are studied in the
EU-funded HERMES programme (Hotspot Ecosystems Research on the Margins of
European Seas). The foraminiferal associations are dominated by epibenthic species. Their
proportion and the diversity of the total assemblage decreases while the standing stock
increases with distance to the carbonate mounds. Benthic colonisation experiments were
deployed for 107 days with a deep-sea observatory (GEOMAR Modular Lander) in a coral
thicket on top of Galway Mound, Porcupine Seabight. The observatory recorded physical and
biological parameters in order to assess the environmental dynamics. The colonisation
experiment comprised a variety of natural hard and soft substrates mounted to the footplates
of the lander. Hard substrates as ferrigenous sandstones, basalts, and coral fragments were
colonised by at least one specimen per object, but PVC and steel construction parts were
recruited as well. The epizoans concentrate at 20 to 30 cm immediately above the coral
thicket. Average current velocities are comparatively low at this level. Newly recruited
foraminifera are Discanomalina coronata, Planulina ariminensis, Discanomalina
semipunctata, Epistominella rugosa, Cibicides lobatulus and others. This epibenthic
assemblage is typical for deep high-energy environments in the northeastern Atlantic, and it
has been recorded in sediment cores from this area. Most foraminiferal specimes were
already of adult size. Thus, their rapid growth during three months or less necessitates a reevaluation of growth-dependant processes, in particular the incorporation of stable isotopic
and geochemical signals, which were hitherto referred to hydrographic annual average
values. In situ experiments in the deep-sea are a promising approach for proxy calibration in
relation to monitored environmental factors.
30
Benthic foraminifera from the oxygen minimum zone of the
Pakistan continental margin - a proxy of bottom water oxygenation
Schumacher, S.(1); Jorissen, F.J.(1); Dissard, D.(2); Gooday, A.J.(3) and Larkin, K.(3)
(1) Laboratory of Recent and Fossil Bio-Indicators, University of Angers, 2 Bd Lavoisier,
49045 Angers Cedex, France. [email protected]
(2) Foundation Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen
12, 27570 Bremerhaven, Germany
(3) Southampton Oceanography Centre, DEEPSEAS Benthic Biology Group, Empress Dock,
European Way, Southampton SO14 3ZH, United Kingdom
Live (Rose Bengal stained) and dead benthic foraminifera (hard-shelled species only)
communities from the oxygen minimum zone (OMZ) of the Pakistan Continental margin have
been studied to determine the correlation between faunal distribution and oxygenation of
bottom and pore water. Samples were taken from 133 m water depth down to 1800 m water
depth in spring before the southwest monsoon and in autumn immediately following the
northeast monsoon.
In the upper part of the OMZ, between 150 and 500 m water depth where bottom water
oxygen concentrations are <0.2 ml/l, living foraminifera are frequent. The live and dead
faunas are dominated by few calcareous species, diversities (Shannon-Weaver index and
Fischer Alpha index) are low. The fauna contains significant numbers "endemic” species and
rare numbers of typical deep-infaunal species. In the lower part of the OMZ (600-1200 m) the
living fauna of the fraction larger than 150 micron is much poorer and is dominated by
arrenaceous foraminifera, the smaller fraction contains significant numbers of living
individuals including also a large number of calcareous species. Diversities of live and dead
faunas are higher and the faunas inhabit more cosmopolitan and deep infaunal species.
Everywhere in the OMZ live foraminiferal faunas are limited to the uppermost centimetre,
whereas above and below the OMZ benthic foraminifera occur also deeper in the sediment.
The relation between benthic foraminiferal faunas and oxygen concentrations in the OMZ is
complex, because of the absence of deep-infaunal species and the abundance of "endemic”
species in the upper part of the OMZ. Therefore, proxies based on the abundance of deepinfaunal taxa give poor results. We will present an ameliorated version of a previous
described proxy for bottom water oxygenation.
Comparison between morphological and genetic species concepts
in the genera Cibicides and Uvigerina (calcareous benthic
foraminifera)
Schweizer, M. (1,2), Pawlowski, J. (2), Kouwenhoven, T.J. (1) and van der Zwaan, G.J. (1, 3)
(1) Department of Earth Sciences, Utrecht University, Netherlands; [email protected]
(2) Department of Zoology and Animal Biology, University of Geneva, Switzerland
(3) Department of Biogeology, Radboud University Nijmegen, Netherlands
Cibicides and Uvigerina are cosmopolitan genera of calcareous benthic foraminifera, which
are widely used for isotopic analyses and palaeoenvironment studies. In spite of the fact that
they are important proxies, their evolutionary trends are not well known. The different species
are distinguished on morphological criteria, but it is not always easy to ascertain whether
morphotypes belong to the same, or to different species.
The 11 species of Cibicides we study are classified, on morphological grounds, in 5 different
genera belonging to 3 different superfamilies. However, the fact that intermediate
morphotypes are observed between these species shows they certainly belong all to the
same genus, Cibicides. For Uvigerina, the situation is less complex. The 11 studied species
are classified within the same genus.
31
The first molecular results based on two fragments, of 1000 nucleotides each, of the small
subunit of ribosomal DNA (SSU rDNA) show that the six species of Cibicides we obtained
form a monophyletic group. The status of the different morphospecies is confirmed in certain
cases, but not in others. One fragment of 1000 nucleotides of the SSU rDNA was employed
to investigate the phylogeny of Uvigerina. Two species belonging to closely related genera,
Trifarina earlandi and Rectuvigerina phlegeri, are closer to U. peregrina than U.
mediterranean and U. elongatastriata. This suggests a revision of the taxonomic status of
Uvigerina is needed. Another fragment of rDNA (the ITS) was studied to explore the variation
inside one morphologically highly variable population of U. peregrina: the genetic variability
was rather low. These first molecular results will provide a different point of view in the
resolution of the taxonomic problems encountered in the classification of Cibicides and
Uvigerina.
The Stability of Eocene Warmth and Carbon Cycling - New Records
in Foraminiferal Calcite from Demerara Rise
Sexton P. F. (1), Wilson P. A. (1) and Norris, R. D. (2)
(1) School of Ocean & Earth Science, Southampton Oceanography Centre, European Way,
Southampton, SO14 3ZH, UK. [email protected], [email protected].
(2) Geosciences Research Division, Scripps Institution of Oceanography, MS-0244, La Jolla,
CA 92093-0244, USA. [email protected].
Reconstructions of Early Cenozoic climates based on both marine and terrestrial
geochemical and fossil evidence suggest that the Eocene was the last interval of acute
global warmth. Yet virtually nothing is known of the magnitude and stability of Eocene
climatic warmth and carbon cycle behaviour on anything but a long-term (multi-Myr)
timescale. Our dearth of knowledge arises largely from a lack of appropriate deep sea
sections on which to work. Globally, deep sea sedimentary sections through the Eocene are
plagued by recovery problems associated with widespread chert deposition, spot coring
associated with earlier Deep Sea Drilling Project drilling strategies, condensation horizons,
hiatuses spanning multiple biozones and poor preservation of carbonate microfossils. This is
particularly true across the lower/middle Eocene boundary which is represented in the deep
ocean drill sections essentially by a global ~1 to 2 Myr-long hiatus.
Recently, Ocean Drilling Program (ODP) Leg 207 ("Demarara Rise: Equatorial Cretaceous
and Palaeogene Palaeoceanographic Transect, Western Atlantic") recovered lower and
middle Eocene deep ocean sediments (incl. a complete lower/middle Eocene boundary).
Here we present new stable isotope records using planktic and benthic foraminiferal calcite
from ODP Sites 1258 and 1260 with excellent age control to improve constraints on Eocene
climatic evolution from the 'Early Eocene Climatic Optimum' through the so-called middle
Eocene 'doubthouse' interval.
Our ~100 kyr resolution record from the early to middle Eocene (~53 to 40 Ma) yields stable
isotope values with consistent interspecies offsets among Demarara Rise benthic
foraminifera. These data, in addition to pilot Mg/Ca data, document the long term climatic
cooling following the Early Eocene Climatic Optimum and provide clear support for a
temporary reversal (~44-42 Ma) in this trend of climatic deterioration.
Our ~6 kyr resolution records for the early to middle Eocene (~50 to 45 Ma) reveal high
amplitude stable isotope excursions (~1 per mil) across the early/middle Eocene boundary,
indicating significant instability in Earth's climate and carbon cycle during the transition out of
early Eocene 'greenhouse' warmth.
32
Multidisciplinary palaeoecology of Upper Maastrichtian chalks in
the Danish Central Graben – record of a sea-level lowstand.
Sheldon, E. (1), Lassen, S. (1), Rasmussen, J. A.(2) and Schiøler, P (1).
(1) Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350,
Copenhagen K, Denmark. [email protected]
(2) Geological Museum, Øster Voldgade 5-7, DK-1350, Copenhagen K, Denmark
The most important hydrocarbon reservoirs in the Danish sector of the North Sea are Upper
Cretaceous –Paleocene chalks. Effective production from existing fields and exploration in
the future will not only be increasingly dependent on an improved high-resolution chalk
stratigraphy, but also on an understanding of the processes that create variations in reservoir
parameters within the chalks.
Integration of nannofossil, foraminiferal and dinoflagellate biostratigraphy with stable isotope
chemostratigraphy and sedimentology has resulted in detailed palaeoecological
interpretation of the Upper Maastrichtian chalks of 2 wells from the Danish Central Graben.
Based on evidence from this multidisciplinary study, two contrasting oceanographic systems
are thought to have been in operation in the Late Maastrichtian in this area. In the lower part
of the cored sections, a cool water, oligotrophic stable system prone to stratification is
inferred. A gradual fall in sea level is suggested to have proceeded resulting in the
breakdown of this stable environment, and culminating with a sea–level lowstand. A more
dynamic setting incorporating warm water influx, sea-level changes and variable productivity
followed almost to the end of the Maastrichtian.
Of particular interest to the hydrocarbon industry is the afore-mentioned lowstand level
recorded immediately following the breakdown of the stable oceanographic system, just
above the bases of the UC20d nannofossil and the P. grallator dinoflagellate zones. This
lowstand event correlates precisely with the most important reservoir unit within the Danish
Central Graben, the M1b1 reservoir unit of the Dan Field.
Gromiid protozoans in the deep sea
Aranda da Silva, A. (1), Gooday, A.J. (1), Cedhagen, T. (2), Cornelius, N. (1) and J.
Pawlowski (3)
(1) Southampton Oceanography Centre, Empress Dock, European Way, Southampton
SO14 3ZH, UK. [email protected]
(2) Department of Marine Ecology, University of Aarhus, Finlandsgade 14, 8200 Aarhus N,
Denmark. [email protected]
(3) Department of Zoology and Animal Biology, University of Geneva, 30 Quai ErnestAnsermet, 1211 Geneva 4, Switzerland
Until recently, gromiids (large testate protists closely related to the Foraminifera) were known
from a single morphospecies (Gromia oviformis – probably a complex of cryptic species)
found in coastal habitats around the world. However, recent campaigns on the Oman and
Pakistan margins of the Arabian Sea (1994, 2002, 2003) have revealed the presence of
spherical, sausage- and grape-shaped gromiid morphotypes at bathyal depths (1000-2000
m). Analysis of the SSU rDNA and ITS rDNA genes indicated that these gromiids are closely
related to shallow-water morphotypes. We identified seven distinctive lineages, five forming a
monophyletic group branching as a sister group to shallow water species. Six can be defined
morphologically, while one includes specimens that look identical to specimens from two
other lineages. Each lineage probably represents a separate species, suggesting that deepsea gromiid diversity is much higher than indicated by their simple morphology. During
Polarstern Cruise XXII/3 (January-April 2005), we found many gromiids belonging to a similar
variety of morphotypes in trawl and core samples from the continental slope off the Antarctic
continent. The samples were obtained off Neumayer Station, Kap Norvegica, and the
33
Antarctic Peninsula (depths 1100-4450 m). Twenty morphospecies, all undescribed, were
tentatively recognised. Particularly notable were: 1) a spherical species which was very
abundant at 1580 m off the Peninsula; 2) a species from 3000-4500 m off Kap Norvegica
with a test wall divided into honeycomb-like cells - a similar wall structure is recognised in
one of the Arabian Sea species; 3) a species from 2600 m off the Peninsula in which the
organic test is sometimes partly enclosed within an agglutinated casing. This new evidence
from the Southern Ocean suggests that deep-water gromiids are widespread and diverse in
deep water on continental margins around the world and represent a hitherto overlooked
component of deep-sea benthic faunas.
Foraminiferal response to a transient climatic warming event
(PETM) as recorded in the GSSP section of the Paleocene/Eocene
boundary at Dababiya, Egypt
Speijer, R.P.(1), Ernst, S.R.(1), Guasti, E.(3) and Dupuis, C.(4)
(1) Department of Geography and Geology, K.U.Leuven, Redingenstraat 16, B-3000,
Belgium. [email protected], [email protected]
(2) Department of Geosciences, Bremen University, P.O.box 330 440, 28334 Bremen,
Germany. [email protected]
(3) Faculté Polytechnique de Mons, rue de Houdain 9, B-7000, Mons, Belgium.
[email protected]
In 2004, the Dababiya section near Luxor, Egypt was chosen to host the GSSP for the
Paleocene/Eocene boundary. Although the stratigraphy of this section was studied
intensively prior to this decision, the benthic foraminiferal record hardly was. This was a
serious omission, especially since the P/E boundary coincides with one of the biggest
extinctions amongst deep-sea benthic foraminifera, associated with the Paleocene/Eocene
thermal maximum (PETM). However, benthic foraminiferal records of nearby successions in
eastern Egypt have been explored more intensively, showing lower extinction rates on the
shelf than in the deep-sea (25% vs. 40% extinction). Here, we present the results of a
quantitative survey of benthic and planktic foraminifera across the PETM at Dababiya.
Statistical analyses enable a subdivision into three main foraminiferal assemblages: 1) A late
Paleocene assemblage suggesting mesotrophic conditions with relatively high productivity
and (fluctuating) low oxygen levels. Just below the P/E boundary diversity and densities drop
steeply, coinciding with the onset of the PETM. During the first stages of the PETM a noncalcareous laminated clay bed was deposited under anoxic conditions. The seafloor
remained nearly permanently anoxic and a-biotic during this early PETM interval. One
sample contained poorly preserved shallow-dwelling planktic foraminifera (Acarinina), an
indication that surface waters remained oxygenated during the early PETM. 2) During the
middle PETM very low densities of a low-diversity/high-dominance benthic fauna indicate
occasional re-oxygenation of the basin, followed by short periods of repopulation of the
benthic environment. 3) During the late PETM, long-term stable communities of foraminifera
developed under mesotrophic conditions. Our data underscore the idea that even against a
background of a general greenhouse climate, rapid warming events can have devastating
effects on various marine ecosystems. Further anomalous events in the early Paleogene are
being targeted now to explore the uniqueness of the PETM and its effects on microbiota.
34
A foraminifera-based paleoenvironmental reconstruction of the
Danian/Selandian transition in Egypt
Sprong, J. (1), Guasti, E. (2), Fornaciari, E. (3) and Speijer, R.P. (1)
(1) Laboratory of Stratigraphy, Historical geology, Katholieke Universiteit Leuven,
Redingenstraat 16, B-3000, Leuven, Belgium. [email protected]
[email protected]
(2) Geochronology, Geosciences, University of Bremen, P.O. Box 330 440, 28334, Bremen,
Germany. [email protected]
(3) Department of Geology, Palaeontology and Geophysics, University of Padua, via Giotto
1, 35137, Padova, Italy. [email protected]
The Danian/Selandian (D/S) transition may comprise the first of a series of brief intervals of
extremely warm oceans (hyperthermals), of which the Paleocene-Eocene Thermal Maximum
is the best-known example. With paleoenvironmental reconstructions changes across the
D/S transition will be determined and placed in the context of global signatures of climatic
and sea-level change during the middle Paleocene. In Egypt monotonous marls and shales
of the Dakhla Formation are interrupted within the D/S transition by a dark-brown bed, rich in
organic carbon and fish-remains, and with an anomalously high P/B- ratio. Three sites
located on the stable shelf of Egypt, Gebel Duwi, Qreiya and Aweina (from middle to outer
neritic water depth, respectively), were sampled across this anomalous bed. Both planktic
and benthic foraminiferal data were used to obtain a picture of paleoenvironmental changes
around the D/S. Planktic foraminiferal assemblages show two main patterns within the D/S
transition. An increase of Acarinina and Parasubbotina suggests lowered salinity and
increased nutrient supply through enhanced river discharge, causing stronger water column
stratification in the central part of the Nile basin (Qreiya and Aweina). Flourishing of
Morozovella and blooming of small Prinsius martinii suggests increased upwelling in the
eastern part of the basin (Duwi). Benthic foraminiferal records suggest a sea-level cycle. The
disappearance of outer neritic taxa, like Angulogavelinella avnimelechi and Anomalinoides
affinis, indicates a sea-level low at the end of the Danian. At the D/S transition invasion of
opportunistic middle neritic Neoeponides duwi and disappearance of almost all other benthic
taxa, is a response to eutrophic conditions and poor seafloor oxygenation during the
transgression. As sea-level rose further N. duwi disappeared and normal assemblages
restored. Records from other continental margins suggest a eustatic signature of this sealevel cycle. It remains unclear how a large scale sea-level cycle can be matched with a
constant greenhouse climate.
Globorotalia truncatulinoides in the South Atlantic during the midlate Pleistocene.
Ufkes, E. (1) and Kroon, D. (2)
(1) Vrije Universiteit Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands.
[email protected]
(2) Vrije Universiteit Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands.
[email protected]
Today, the planktonic foraminifer Globorotalia truncatulinoides is locally present in the South
Atlantic. Dextrally-coiled specimens are present at low latitudes, whereas sinistrally-coiled
ones are found sporadically in the (sub)tropics and are more abundantly at higher latitudes,
south of 20°S. To reveal the history of the abundance and evolution of G. truncatulinoides,
we analyzed core T89-40 (21°36' S, 6°47' E) retrieved from Walvis Ridge, SE Atlantic.
To examine to what extent the various morphotypes varying in coiling direction and shape reflect different habitats during the last million years, their isotopic composition and
interspecific correlations are studied.
35
During the last 190 ky, oxygen isotope data of single specimens show a distinct difference in
δ18O values between high-conical and flat morphotypes, both sinistral and to a lesser extent
also dextral morphotypes. The heavier values of the flat ones point to another habitat, to a
possible subantarctic source area. During the mid-Pleistocene also flat morphotypes are
found occasionally. However, they show no significance difference in δ18O values.
Downcore, isotopic values of the various morphotypes show large variations in time which
appear to be related to changes in orbital variations and their effect on the local and regional
oceanography.
Radiogenic isotopes in foraminiferal carbonate as tracers of
continental input to the oceans and ocean circulation
Vance, D.
Department of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ,
UK. [email protected]
Together with the ice-core record of the atmosphere, the foraminiferal carbonate record of
physicochemical conditions in the oceans has revolutionised our view of the past
environment of the Earth. The variability in the oceanic isotopic composition of elements with
a radiogenic isotope, and whose residence times in the ocean are shorter than the mixing
timescale (e.g. neodymium(Nd)), reflects local continental inputs and the rate and intensity of
ocean circulation (i.e. mixing). Foraminiferal carbonate, given the other information derived
from it, is clearly the ideal substrate for recording the past radiogenic isotopic composition of
the oceans. Here I outline the progress that has been made over the past few years in
developing this substrate as well, as some of the early applications. Neodymium (Nd)
contents of foraminiferal carbonate are low. One of the key obstacles to be overcome in its
use as a substrate for recording the Nd isotopic composition of the oceans, is the resultant
susceptibility to post-mortem diagenetic additions. The most serious problem is ubiquitous
Mn-oxide coatings, acquired in the sediment and potentially containing large quantities of Nd.
Recent work has shown that these can be cleaned off using well-established techniques and
that the remaining Nd is demonstrably of seawater origin. One remaining puzzle, however, is
the nature of the phase that carries this seawater Nd. Concentrations in cleaned foraminifera
appear to be too high to be contained in the carbonate lattice. Nd isotopes in planktic
foraminifera been used for such diverse purposes as quantifying the strength of the Indian
monsoon through time, understanding the role of the river Nile in the genesis of
Mediterannean anoxic events, and characterising the glacial inputs to the North Atlantic as a
function of Pleistocene ice-volume changes. Some of these applications will be discussed.
Subtropical North Atlantic Oceanic Variability During MIS3: The
Planktonic Foraminiferal Record
Vautravers, M.J. and Shackleton, N.J.
Department of Earth Sciences, University of Cambridge, The Godwin Laboratory, New
Museum Site, CB3 2SA, UK. [email protected]
We have studied ODP Site 1060 on the Blake Outer Ridge, which lies beneath the Gulf
Stream and MD01-2444, off South Portugal. We focus on Marine Isotope Stage 3, 60 to 25
thousand years before present (ka). Sea surface temperatures (SSTs) inferred both from
foraminiferal fauna, counts of iceberg melt-out debris, as well as stable isotope analyses,
enable our record to be interpreted in terms of regional hydrographic changes. At site 1060
the observed SSTs record is consistent with the air temperature record from the Greenland
ice cores. However, this record also exhibits differences in detail compared with the ice core
record, and when compared to other sites within the North Atlantic, significant longitudinal
differences emerge. At Site 1060 in the western Atlantic all Greenland stadials (GS) whether
36
associated with Heinrich Events (HEs) or not, show a similar small amplitude of cooling;
mean faunal-based SSTaug during GS is only 1.5ºC colder than during Greenland
interstadials (GIS). In addition, during GS the coldest SSTs are limited to apparently brief
events. At site MD01-2444 in the eastern Atlantic the present surface hydrography is
characterised by a strong seasonal variability governed by the intensity/direction changes of
the offshore winds. In Spring/Summer as the Azores high pressure intensifies, and migrates
North, the Portugal Current develops, driving upwelling, that cools the core site. In winter the
Azores high migrates South, decreasing in intensity, and driving the northward flowing warm
Portugal Counter Current. As a result, the upwelling reduces and the area warms. Extreme
summer conditions correspond to more positive North Atlantic Oscillation phases, whereas
extreme winters correspond to more negative phases. Concentrating on the faunal results,
we find that large amplitude coolings identified by the presence of polar species correspond
to major events Heinrich events (HE), whereas other cold Dansgaard-Oeschger events are
not as marked. Although in general supporting the correlation with GRIP this group shows a
puzzling evolution, (percentages are minimal before each HE). In contrast with the polar
group, the tropical group shows a remarkable correlation with both surface and Greenland
18-O records. The percentages of the upwelling-related species show that upwelling was
strongest during HE6, HE5, HE4 and HE3 but was also very pronounced during the stadial
preceding the Greenland interstadial (GIS) 5 pointing to a reinforced (NAO+), whereas it was
particularly reduced during GIS16, 9 and 5 (NAO-).
The Miocene/Pliocene boundary in Piedmont (North-Western Italy).
Micropalaeontological analyses on outcrop (Moncucco quarry) and
subsurface (Narzole corehole) assemblages.
Violanti, D.(1), Trenkwalder, S. (2), Dela Pierre, F. (3), and Irace, A.(4).
(1) Earth Sciences Department, Turin University, via Valperga Caluso, 35, 10125 Turin; Italy.
[email protected]
(2) C.N.R, Geosciences and Georesources Institute, Turin Section, Via Accademia delle
Scienze 5, 10123 Turin; Italy. [email protected]
(3) Earth Sciences Department, Turin University, via Valperga Caluso, 35, 10125 Turin; Italy.
[email protected]
(4) C.N.R, Geosciences and Georesources Institute, Turin Section, Via Accademia delle
Scienze 5, 10123 Turin; Italy. [email protected]
The renewed interest for the Messinian salinity crisis had led to new researches in the
Piedmont region (North-Western Italy). At the Moncucco quarry (Northern Piedmont), a
Tortonian-Pliocene succession is well preserved, even if marked by severe tectonics
accidents. Moreover, the Messinian/Pliocene boundary has been also recovered in the
Narzole (Central Piedmont) corehole, stored at the Turin Regional Museum of Natural
Sciences.
Both at Moncucco and in the Narzole corehole, the Miocene/Pliocene boundary is marked by
a 0.7/1 meter thick black arenitic bed separating the Messinian clayey marls of "Congeria”
beds from the Lower Pliocene marls (Argille Azzurre Fm.). Micropalaeontological content of
the "Congeria” beds consists of Tortonian and Lower Messinian planktonic foraminifers
(Globorotalia conomiozea, Gt. suterae) and rare deep shelf to bathyal benthic species
(Uvigerina rutila), all interpreted as reworked. Brackish ostracods (Loxochonca djaffarovi) are
very rare. The black arenitic bed, described in many sections of the Northern Apennines, is
generally barren and very rich in organic matter.
Foraminiferal assemblages of the Pliocene marine succession are rich and diversified. Both
in the outcrop and in the corehole samples, the marls basal part is referable to the Zanclean
MPL1 biozone, on the presence of rare to common Sphaeroidinellopsis seminulina.
Planktonic specimens are frequent (P/(P+B=60-70%), deep outer neritic to bathyal benthic
foraminifers (Anomalinoides helicinus, Hoeglundina elegans, Lingulina seminuda, Uvigerina
37
rutila, Vaginulinopsis carinata etc.) are common. Ostracods are rare, with typical openmarine taxa (Bythocypris obtusata).
The microfaunal composition of the basal Pliocene layers is extremely significant, allowing
the correlation with similar assemblages of the Southern Piedmont, undated for the absence
of plankton zonal markers, and documents a deep, open marine palaeoenvironment in the
central Piedmont Basin at the beginning of Pliocene.
Shark teeth oxygen isotopic evidence for salinity changes and
water column stratification in the Palaeocene-Eocene North Sea
Basin
Voigt, S. (1), Zacke, A. (1), Gale, A. S. (2), Joachimski, M. (3)
(1) Institute of Geology and Mineralogy, University of Cologne, Zülpicher Str. 49a, 50674
Köln, Germany. [email protected], [email protected]
(2) Department of Earth and Environmental Sciences, University of Greenwich, Chatham
Maritime, Kent, ME4 4TB, UK, and Department of Palaeontology, Natural History Museum,
London, SW7 5BD, UK. [email protected]
(3) Institute of Geology and Mineralogy, University of Erlangen, Schlossgarten 5, 91054
Erlangen, Germany. [email protected]
Fossil shark teeth apatite is a useful geochemical archive in shelf sea environments. The
microcrystalline enamel of shark teeth is precipitated in isotopic equilibrium, is highly
resistant to diagenetic effects, and can be used when calcareous microfossils are absent or
poorly preserved. The orders and families of fossil sharks occupied similar ecological niches
as their modern counterparts, hence providing important and testable palaeoenvironmental
information. We studied the oxygen isotopic composition of Palaeocene-Eocene shark teeth
apatite from marginal and basinal North Sea successions. The teeth represent six families,
which differ in their habitat and swimming activity. Most of the teeth belong to the surface
dwelling family Odontaspididae, which are active swimming predators. Representatives of
bottom dwelling groups (e. g. Heterodontidae, Squalidae and Carcharinidae) live more
stationary. The oxygen isotope record derived from Palaeocene to Eocene shark teeth
displays a broad range of values ranging from 12 to 23 ‰ SMOW. Oxygen isotope variability
among teeth from the same time interval is large, reaches highest values in the early
Ypresian (6-7 ‰) and decrease in the late Lutetian to Priabonian (3-4 ‰). The comparison of
surface and bottom dwelling species shows the surface dwelling Odontaspidids to be
depleted in 18O by 4-6 ‰ indicating the presence of a pronounced surface-to-bottom water
gradient and water column stratification. The most prominent feature is a 5 ‰ negative 18O
excursion during the Palaeocene-Eocene transition, a time interval that witnessed rapid and
severe global warming and the onset of North Atlantic flood basalt volcanism. Much of the
18
O excursion indicates changes in seawater isotopic composition and is suggestive for a
massive input of isotopic light freshwater. Assuming the modern w-salinity relationship to be
valid in the Eocene North Sea, the 18O decrease would account for a 14-17 ‰ salinity
decrease and the formation of brackish surface waters in the early Ypresian North Sea.
38