Download What are Sediments?

What are Sediments?
Residues of
algae and
mussels
Diatoms
(brown)
Sulfur
Sand
FeS
WS 2009/10
Practical course
Feb 88-Mar 5
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Recommended books
- Brock. Biology of Microorganisms
- Ehrlich H. L. (1996) Geomicrobiology, Marcel Dekker, New York
- Richard Y. Morita (1997) Bacteria in Oligotrophic Environments, Chapman & Hall
- L.A. Meyer-Reil, M. Köster (1993) Mikrobiologie des Meeresbodens. Fischer
- Daniel M. Alongi (1998) Coastal Ecosystem Processes. CRC Press
- Susan M. Libes (1992) An Introduction to marine biogeochemistry, John Wiley
- Tom Fenchel and Bland J. Finlay (1995) Ecology and Evolution in Anoxic Worlds,
Oxford University Press
- Jame K. Fredrickson, Madilyn Fletcher (ed. 2001) Subsurface Microbiology and
Biogeochemistry, Wiley
- Amy P.S., Haldeman D.L (ed., 1997) The Microbiology of the Terrestrial Deep
Subsurface, Lewis Publ. New York
-Schulz HD, Zabel M (ed., 2000) Marine Geochemistry. Springer, Berlin
Literature on the web
- http://www.icbm.de/pmbio/litlinks.htm (many
(many journals!)
journals!)
- http://portal.isiknowledge.com (Web
(Web of Science - from University IP)
IP)
- http://scholar.google.com (Science
(Science at Google)
Google)
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What are sediments?
latin: sedere = sit sedimentum = what has settled down
• Particulate material accumulated on the floor
- of lakes (lacustrine, limnic)
- of rivers (riverine, fluvial)
- of the sea (marine, tidal, coastal...)
Sedimentation rates in aquatic systems
Which factors govern sediment formation rates?
- Productivity (primary production)
- Input of allochthoneous material (rivers, shore; e.g. leaves)
- Settling time (depth, degradation while sedimentation)
- Water chemistry (e.g. carbonates)
Annual sedimentation rates [mm]
Oligotrophic lakes
Eutrophic lakes
Marine upwelling areas
Deep sea
0.1 – 2
1–5
0.05 – 0.3
0.001 – 0.02
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What is the origin of marine sedimentary material?
- aeolian = via the air
- terrigenous = from the land
- marine, autochthonous = from water column
Aeolian input to sediments
Sahara sand coming across
the alpes
Sahara sand above the
Atlantic Ocean
• Input of minerals, especially Fe as an important limiting factor
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Ash eruptions from vulcanoes
Ash layer in
Mediterranean sediment
Lena river delta (Sibiria)
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From the mountains to the sea and back
Erosion and destruction
- Night frost results in cracking of rocks
- Rocks break during landslides
- Destruction of destabilized minerals via dew formation and rainfall
Night frost
Rock
fan
Tarbuck & Lutgens:
Allgemeine Geol ogie, mod.
Rock
fan
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From the mountains to the sea and back
Erosion and destruction
- Night frost results in cracking of rocks
- Rocks break during landslides
- Destruction of destabilized minerals via dew formation and rainfall
Transport of fragments and single minerals
- Water (creeks, rivers, ocean currents)
- Wind
- Ice (glaciers)
Sedimentation
= Accumulation and consolidation of weathering products
- Formation of porous sediments
- Overlay with further sediments lead to
→ Enhanced temperatures and pressure
- Squeezing of porewater from porous sediments
- Consolidation and cementation by recristallisation to sedimentary rocks
10 cm
Tidal-flat sediment „Neuharlingersieler Nacken“
20 cm
30 cm
40 cm
50 cm
60 cm
70 cm
80 cm
90 cm
Swartberg-Pass (South africa)
100 cm
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Deformation of sedimentary rocks
Deformation
Laminated
sediments
Tarbuck & Lutgens:
Allgemeine Geol ogie, mod.
Swartberg-Pass (South africa)
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Disturbed sediment
Mediterranean sediment
disturbed by hang slip
Disturbed sediment: Turbidites
Submarine
canyons
Turbidite
Turbidite deposition
Turbidites
Deep sea
fans
Graduated layers
Tarbuck & Lutgens:
Allgemeine Geol ogie, mod.
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Distribution of chlorophyll in the ocean
How fast do sediments accumulate?
Euphotic zone <= 200 m
marine:
146 109 t CO2 a-1
terrestrial:
129 109 t CO2 a-1
Average production of the
oceans: 69 g C m-2 a-1
Note:
~ 1 chocolate bar
per year and m2
Only 0.1 to 1 % of the
primary production reach
the sediment. Marine
sediments often grow a few
mm per 1000 years, only .
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Varves
Sandy sediments
North Sea
tidal flat
Puerto Rico
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SedimentSediment-forming organisms
Carbonates
• biogic in sheats of algae (Coccolithophorides), Foraminifera, ...
• precipiatated via enhanced temperature or photosynthesis
Silikates
• biogeic in sheats of Diatoms or Radiolarians
• chemical as clay minerals via inflow
Coccolithophorides
www.unibas .ch/z mb/
Foraminifera
caliban.mpiz-koel n.mpg.
de/~stueber/haeckel/k unstformen/
Tafel_002.html
Radiolarians
www.unibas .ch/z mb/
Diatoms
www.reclot.de/bilddat/geolog/
d44mik/mikro03.htm
Coccolithophorids
Cell size: 2-20 mm
Cell wall: CaCO3 coccoliths or
scales
Chloroplasts: none, single
thylakoid membrane
PhotoPhoto-pigments: chlorophyll a
& c, carotenoids
Emiliania huxleyi
Reproduction: simple cell
division, rarely sexual
reproduction
Ecological roles: biflagellated,
produce chalk deposits
Common genus: Emiliania
Botanical Bulletin of Academia Sinica,
Vol. 42, 2001
lat. coccus = round, gr. lithos = stone, gr. pherein = carry
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Foraminifera
... a paleoclimate proxy?
lat. foramen = hole, lat. ferre = carry
Deutsch: Foraminiferen, Kammerlinge,
Klasse der Rhizopoda (Wurzelfüßer)
Foraminifera
"Sand" at the Bight of Alcudia, Mallorca
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Diatoms (Kieselalgen)
Pacific sediment (Peru margin)
Pacific diatoms
North Sea diatoms (tidal flat)
Radiolarians (Strahlentierchen)
From Haeckel:
"Kunstformen der Natur"
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Oxygen isotope fractionation as proxy for the ocean water
temperature
-> Natural 18O:16O ratio about 1:500
determined in microfossils, that use oxygen for shell formation
(benthic and planktonic foraminifers, coccolithophorids)
-> Variation of delta 18 O values controlled by temperature:
preferred evaporation of light H 216 O molecules
compared to heavier H218 O.
-> Cold air carries relatively less H 218O,
which remains enriched in the water.
-> 1% increase of delta 18 O corresponds to
about 1 °C temperature decrease.
Sediment Temperature
-> Seafloor mostly around 0 - 2 °C
-> Temperature increase with depth,
depending on geological parameters
-> Hydrothermal vents with temperatures
above 300 °C
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How old are sediments?
Only 200 Mio. years before
present there was only one
continent, Pangaea
Online Biology Book
Mike Farabee
www.emc.maricopa.edu/faculty/far
abee/BIOBK/BioBookTOC.html
Plate tectonics
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Plate tectonics govern sediment age
http://www.ngdc.noaa.gov
Mid-oceanic ridges (spreading centers)
• Form the longest mountain chain on earth
Inorganic reduced compounds are released, e.g., 30 Mio t H2S per year
(Ocean water moves through the earth crust on average in 8 Mio a)
• Hydrothermal vent production, 0.02 % of total primary production
= 10 % of the sea-floor production
• Rich communities based of bacterial chemosynthesis
e.g. Riftia pachyptila: huge worm without mouth and after
living from symbiotic autotrophic H2S oxidizers
• Energy from the oxidation of H2S, H2 , Fe2+ etc. with oxygen (from photosynthesis!)
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Life at Mid-oceanic ridges
By which properties are sediments characterized?
- TOC (total organic carbon): 0.2 - 2 %, sapropels up to 30 %
- 50% carbonaceous Sediments (50 - 90 % TIC), less with silicates (Diatoms etc.)
- Water: porosity and permeability decreasing with depth and age
- Varying particle size: mud, silt 63 - 200 µm, sand > 63 µm,
- Varying density: ~1.5 to ~2.5 g/cm3
- Oxygen: upper mm to meters
- Nitrate: slightly below oxygen
- Ammonia as a product of degradation
- Fe3+, Mn4+ -> Fe2+, Mn2+ with increasing depth
- Sulfides
- Methane hydrates
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How can we detect processes inside the sediment column?
Gradients!
Janssand
Neuharlingersieler Nacken
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Oxygen profile
Seawater
Diffusive boundary
layer
Oxygen
Sandkorn
Sediment
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SulfateSulfate- methane interfaces
ODP Site 1229
- Methanogenesis and sulfate reduction as dominant terminal processes
- Anaerobic methane oxidation as important process
MethaneMethane-bearing
deep--sea sediment
deep
1 bar pressure increase per 10 m
water depth
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Methane hydrate
(ODP Site 1230)
The most important reservoir of
reduced carbon on earth
24072407-2410
Meteor Leg M40-4 (1998)
Sapropel layers with up to 30 % organic carbon and
increased microbial activity
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Swamps
Biogenic sediments:
From peat to coal
Peat
(plant material)
Coverage
Consolidation
Lignite
(brown coal)
Enhanced
Coverage
Consolidation
Pitch coal
(soft black coal)
Metamorphosis
Peat in the backbarrier tidal flat of
Spiekeroog, a former moor
Tension
Tarbuck & Lutgens:
Allgemeine Geol ogie, mod.
Anthracite
(hard coal)
Microbial mats
Farbstreifen-- Sandwatt
Saltmarsh pond (South africa)
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Stromatolite
(pillow stone)
1.3 Ga
Ga = Giga years or
billion years
Undisturbed
development in the
absence of grazers
Attention:
Attention
Engl. Billion = german Milliarde
Shark Bay,
Australia
Banded Iron Formations (BIF's,
gebänderte Eisensteine)
without microfossils, but
showing isotope fractionation
of 12C/13C as indicator for
biological activity
Periodic changes between reducing and oxidizing conditions
Oxidation of Fe2+ to Fe3+ by
(oxygenic?) photosynthesis,
Precipitation of oxidized iron salts
Ditch, Oldenburg University
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Sediment slurries at ODP Site 1231
Oxidized iron and manganese as important electron
accptors in lowlow-carbon sediments
Age
Productivity and external input
Thickness
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