Download The early interaction between the Caribbean Plateau and the NW

doi: 10.1111/j.1365-3121.2006.00688.x
The early interaction between the Caribbean Plateau and the NW
South American Plate
Cristian Vallejo,1 Richard A. Spikings,2 Leonard Luzieux,1 Wilfried Winkler,1 David Chew2 and Laurence
Page3
1
Geological Institute, ETH Zürich, CH-8092 Zürich, Switzerland; 2Department of Mineralogy, University of Geneva, CH-1205 Geneva,
Switzerland; 3Department of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden
ABSTRACT
The determination of accurate and precise ages for the timing
of collision between oceanic plateaus and continental crust
requires an understanding of how the indenting and buttressing
plates respond to the collision. We present geochronological,
thermochronological, geochemical and isotopic analyses of
magmatic rocks from the Ecuadorian Andes, which relate to the
collision of the Late Cretaceous Caribbean Plateau and Great
Arc sequence with NW South America. The cessation of
subduction magmatism during 65–64 Ma beneath the eastern
edge of Caribbean Plateau was synchronous with accelerated
Introduction
There is a consensus that a majority
of thickened, allochthonous oceanic
mafic material exposed in the western part of the Northern Andes in
Ecuador and Colombia represents
relict fragments of the Caribbean
Plateau, which erupted above an
oceanic hotspot. Several studies have
proposed that the Caribbean Plateau
erupted above the Galápagos hotspot
(e.g. Duncan and Hargraves, 1984;
Ross and Scotese, 1988; Hoernle
et al., 2004), whereas other authors
suggest it may have erupted above
more than one hotspot, some of
which may have a southern Pacific
origin (e.g. Reynaud et al., 1999;
Kerr and Tarney, 2005). Knowledge
of the timing of accretion of the
plateau with the continental margin
is paramount to any plate reconstruction model of the Caribbean
Plate, as it temporally constrains
the onset of its fragmentation. Previous estimates of the timing of
collision between the Caribbean Plateau and the Ecuadorian continental
margin cluster at either 85–65 Ma
Correspondence: Dr Cristian Vallejo, Geologisches Institut, ETH Zentrum HAD,
Haldenbachstrasse 44, 8092 Zürich, Switzerland. Tel.: +41 1 632 6129; fax: +41 4
4632 1422; e-mail: cristian.vallejo@erdw.
ethz.ch
264
surface uplift and exhumation within the buttressing continental margin during 75–65 Ma. We interpret this as the collision
of the leading edge of the Caribbean Plateau and arc sequence
with the South American Plate at 75–65 Ma. A U/Pb (zircon)
SHRIMP age of 87.10 ± 1.66 (2r) Ma, yielded by an accreted
fragment of the plateau, precludes previous estimates of
collision at 85–80 Ma if the plateau erupted above the
Galápagos hotspot.
Terra Nova, 18, 264–269, 2006
(e.g. Lebrat et al., 1987; Aspden
et al., 1992; Kerr et al., 2002; Spikings et al., 2005) or the Late Campanian–Maastrichtian
(e.g.
75–
65 Ma; Spikings et al., 2001; Hughes
and Pilatasig, 2002; Jaillard et al.,
2004). We present new geochronological, geochemical and isotopic evidence from the accreted oceanic
rocks, which, when combined with
previous
sedimentological
and
thermochronological analyses, argues
against previous models of accretion
during 85–80 Ma and strongly
supports a model of Late Campanian–Maastrichtian (75–65 Ma) collision between the Caribbean Plate
and the Ecuadorian continental
margin.
The age and origin of the mafic
oceanic basement in western
Ecuador
Basaltic lavas and hyaloclastites of
the Pallatanga Unit, which form the
basement of the Pallatanga Terrane,
represent fragments of the Caribbean
Plateau that collided against the
South American Plate (Kerr et al.,
2002). These rocks are exposed in
fault-bound slivers along the eastern
margin of the Western Cordillera
(Fig. 1). Their major oxides, trace
elements and isotope geochemistry
suggest that they erupted in an
oceanic plateau setting (Reynaud
et al., 1999; Lapierre et al., 2000;
Kerr et al., 2002; Mamberti et al.,
2003), with geochemical similarities
with mafic rocks of the Caribbean–
Colombian Oceanic Plateau. Ultramafic cumulates and gabbros of the
San Juan Unit are in faulted contact
with the Pallatanga Unit and are
considered to represent the ultramafic root component of an oceanic
plateau sequence (Cosma et al., 1998;
Lapierre et al., 2000; Mamberti
et al., 2004).
Radiometric ages from the mapped
San Juan Unit range between 123 and
87 Ma, suggesting that the lithologically defined unit may comprise unrelated
rock sequences. Lapierre et al. (2000)
report an Early Cretaceous amphibole–plagioclase–whole rock internal
Sm/Nd isochron age of 123 ± 13 Ma
(2r) from a gabbro (their sample
98SJ13) in the San Juan Unit. Mamberti et al. (2004) presented a weighted
mean 40Ar/39Ar (hornblende) age of
99.2 ± 1.3 Ma (2r) from a gabbro,
which is mapped as part of the San
Juan Unit. This 40Ar/39Ar age is
derived from the youngest steps of a
saddle-shaped age spectrum, which is
typical of mineral phases that contain
excess 40Ar, and their age should be
considered as a maximum age (e.g.
Harrison and McDougall, 1981). Finally, zircons extracted from a layered
gabbro of the San Juan Unit yield a
weighted mean U/Pb (SHRIMP) age
2006 Blackwell Publishing Ltd
Terra Nova, Vol 18, No. 4, 264–269
C. Vallejo et al. • Caribbean Plateau–South American Plate collision
.............................................................................................................................................................
Fig. 1 Simplified geology of Ecuador showing the juxtaposition of oceanic mafic
rocks of the Pallatanga Terrane (which includes the San Juan Unit, Pujilı́ Mélange,
Yunguilla Unit and the Rio Cala Arc sequence) and continental rocks of the Eastern
Cordillera and the Amotape Terrane.
of 87.10 ± 1.66 Ma (2r; Fig. 2). Lapierre et al. (2000) interpreted their
Early Cretaceous Sm/Nd age as evidence for a distinct, oceanic plateau
sequence that predates the Pallatanga
Unit (e.g. Jaillard et al., 2004), whereas
we interpret our Late Cretaceous U/Pb
age as the time of crystallization of
mafic components of the Pallatanga
Unit. Consequently, we suggest that
the San Juan unit is inaccurately
mapped, and both Early and Late
Cretaceous ultramafic and mafic rocks
define the basement sequence in the
easternmost Western Cordillera. The
U/Pb (zircon) age obtained in this
study overlaps with the peak of ages
(92–88 Ma) obtained from basalts of
the present day Caribbean Plateau
using the 40Ar/39Ar method (Sinton
et al., 1998; Kerr et al., 2003). The U/
Pb age is also indistinguishable from a
plateau hornblende 40Ar/39Ar age of
88.8 ± 1.6 Ma (2r), obtained from
geochemically defined oceanic plateau
rocks of the Piñón Fm. in the coastal
2006 Blackwell Publishing Ltd
forearc of Ecuador (Luzieux et al.,
2005), suggesting that both units may
comprise parts of the same plateau
sequence. Palaeomagnetic data from
both the Piñon Fm. and its sedimentary
cover rocks imply that they crystallized
at latitudes between 0 and 5S and
experienced a clockwise rotation event
during the Campanian (Luzieux et al.,
2005).
The Early Cretaceous rock sequences reported by Lapierre et al.
(2000) may represent detached fragments of the Early Cretaceous ultramafic–mafic Peltetec Unit, which
yields island arc geochemical affinities,
and accreted to the South American
continent during the Aptian (Litherland et al., 1994). This interpretation
is also supported by a negative Nb
anomaly in some of the rocks included
in the San Juan Unit (Mamberti et al.,
2004), typical for rocks formed in a
subduction zone.
Zircons from a granitic block (Pujilı́
Granite) entrained in a tectonized
zone of the Pallatanga Unit (Pujilı́
Mélange; Fig. 1) yield a weighted
mean U/Pb (SHRIMP) age of 85.5 ±
1.4 (2r) Ma. White mica from the
same granite yields an indistinguishable plateau 40Ar/39Ar age of 86 ±
1 Ma (Spikings et al., 2005). These
ages, combined with positive (juvenile) eNdi values (+6.9), high concentrations of LILE elements (Ba, Sr),
and negative Nb anomalies (Fig.
3A,B) indicate a subduction-related
origin for the granite in an intraoceanic setting. The U/Pb age of the
Pujilı́ Granite is indistinguishable
from the Pallatanga Unit, and hence
may have formed as a fractionated
intrusive fragment produced during
the initiation of westward subduction
beneath the Caribbean Plateau,
shortly after the eruption of the plateau, resulting in the formation of part
of the Great Arc of the Caribbean.
Earlier interpretations, which proposed that the Pujilı́ Granite represents fragments of Triassic plutons
that are currently exposed in the
Eastern Cordillera, and became incorporated into the mélange zone during
ocean–continent collision (Hughes
and Pilatasig, 2002; Spikings et al.,
2005) are no longer plausible. The
association of Late Cretaceous granitic rocks with island arc signatures
and Late Cretaceous mafic oceanic
plateau rocks is also described on the
Island of Aruba. White et al. (1999)
interpreted the Aruba Batholith as
being produced by partial melting of
the Caribbean Plateau above an incipient subduction zone with an anomalously hot mantle wedge. The
Aruba Batholith (c. 85 Ma, 40Ar/39Ar
hornblende; White et al., 1999) and
the Pujilı́ Granite share a similar
crystallization age (c. 85 Ma, U/Pb
zircon), and very distinctive trace
element distribution (e.g. high LILE,
high La/Yb, high Sr/Y and HREE
depletion) and isotopic geochemistry
(eNdi approximately 7), inferring that
both sequences may have formed in
the same subduction system.
The Totoras amphibolite sequence
is located in the central Western
Cordillera (Fig. 1). The amphibolites
yield an oceanic plateau geochemical
affinity (e.g. Jaillard et al., 2004;
Beaudon et al., 2005) and are juxtaposed against unmetamorphosed mafic rocks of the Pallatanga Unit.
Beaudon et al. (2005) suggested the
265
Caribbean Plateau–South American Plate collision • C. Vallejo et al.
Terra Nova, Vol 18, No. 4, 264–269
.............................................................................................................................................................
(A)
Gabbro
(B)
Granite
Hornblende, Totoras Amphibolite
Biotite, Triassic migmatite
(Figs 1 and 2B), which we interpret
as being indicative of rapid cooling
through 380–330 C during the Late
Maastrichtian.
Aspden et al. (1992) report widespread resetting of K/Ar ages acquired
from Jurassic–Lower Cretaceous
rocks in the Eastern Cordillera during
85–65 Ma. However, it is impossible
to assess whether any individual age is
partially or fully reset and consequently these data cannot be used to
distinguish between Santonian–Early
Campanian and Late Campanian–
Maastrichtian cooling. Consequently,
there is no thermochronological support from the buttressing continental
margin for reactivation by collision
during 85–80 Ma.
White mica, Triassic migmatite
Evidence from sedimentary rocks
that span the age of collision
Pyroxene, Natividad Unit
Fig. 2 (A) Tera-Wasserburg concordia diagrams for U/Pb (zircon) data yielded by
the San Juan Unit (UTM: 759961/9967463) and the Pujili Unit (UTM: 755300/
9898600) using SHRIMP analysis. Errors are given at the 2r level. (B) 40Ar/39Ar age
spectra (25W CO2-IR laser; 2r errors) from the Totoras amphibolite (UTM: 730223/
9809289), the Triassic migmatites exposed in the southern Eastern Cordillera (UTM:
758038/9669978) and basaltic lavas of the Natividad Unit (UTM: 771610/9996629).
Analytical details and data tables are stored in the data repository. UTM coordinates
are indicated in the Prov. S. Amer. 56 system.
amphibolites were formed by metamorphism of an oceanic plateau at
800–850 C and 6–9 kbar. We obtained a hornblende 40Ar/39Ar plateau age of 84.69 ± 2.23 (2r) Ma
from the amphibolite (Fig. 2B). Considering an estimated thickness of the
Caribbean Plateau of approximately
20 km (Sinton et al., 1998; Revillon
et al., 2000) and a geothermal gradient of 40 C km)1, the peak temperature and pressure conditions acquired
from the amphibolites could have
been reached at the base of the
plateau. The high geothermal gradient was probably supported by the
same mantle plume that produced
the oceanic plateau. Retrogression of
the amphibolites through approximately 500 C at 84.69 ± 2.23 Ma
is probably a consequence of thermal
relaxation of the oceanic plateau,
subsequent to drift away from the
hotspot.
266
Thermochronological constraints
from the buttressing Late
Cretaceous continental margin
(Eastern Cordillera)
Palaeozoic–Early Cretaceous metasedimentary and intrusive rocks of
the Eastern Cordillera and the Amotape Complex (Fig. 1) define the Late
Cretaceous continental margin (i.e.
prior to collision). The earliest significant cooling and exhumation event
detected along the continental margin
by 40Ar/39Ar (white mica, biotite) and
fission track (zircon, apatite) thermochronology occurred during 75–
65 Ma (Spikings et al., 2001, 2005).
This has been confirmed by new indistinguishable plateau 40Ar/39Ar ages
from Triassic migmatites (U/Pb zircon
age of 227 ± 2 Ma; Litherland et al.,
1994) of 68.5 ± 0.4 (2r; white mica)
and 68.6 ± 0.5 (2r; biotite) Ma from
the southern Eastern Cordillera
Prominent Late Cretaceous sedimentary formations to the east and west of
the developing contemporaneous Andean chain provide a further record of
the accretion of the oceanic plateau in
the forearc. During the Maastrichtian,
erosion of the Napo Group marine
sequence in the developing Amazon
Foreland Basin (Fig. 1) was followed
by deposition of continental redbeds of
the Tena Formation (Aspden and Litherland, 1992; Jaillard, 1997). Sedimentary rocks of the Tena Formation
are the oldest within the foreland basin
to host a significant assemblage of
metamorphic mineral grains derived
from the Eastern Cordillera (Ruiz
et al., 2004). Furthermore, fissiontrack ages of detrital zircons in the
same rocks are indistinguishable from
their stratigraphic age, which is indicative of extremely rapid exhumation in
the supplying Eastern Cordillera (Ruiz
et al., 2004). At the same time, detrital
supply from the Guyana Shield diminished. In the forearc, the coeval (Late
Campanian–Maastrichtian) turbiditic
Yunguilla Unit was being deposited in
a basin partly floored by the Pallatanga
Unit (e.g. Jaillard et al., 2004; Fig. 1).
The turbidites were partially sourced
from metamorphic rocks of the Eastern
Cordillera and from mafic volcanic
rocks. These sedimentary sequences
attest to the topographic growth of
the Eastern Cordillera, located proximal to the zone of ocean–continent
collision, during the Latest Campanian–Maastrichtian.
2006 Blackwell Publishing Ltd
C. Vallejo et al. • Caribbean Plateau–South American Plate collision
Terra Nova, Vol 18, No. 4, 264–269
.............................................................................................................................................................
Rock/primitive mantle
(A)
(B)
Fig. 3 (A) Primitive mantle normalized (Sun and McDonough, 1989) multi-element
diagram for the Pallatanga Unit and the Rio Cala Arc sequence. The subduction
nature from the Rio Cala Arc sequence is evident by the relative enrichment in LILE
elements and the Nb anomaly, the latter not observed in rocks from the Pallatanga
Unit (i.e. whole-rock data shown in grey field; Hughes and Pilatasig, 2002). (B) eNdi–
eSri correlation diagram for the Rio Cala Arc sequence (Rio Cala, Pilatón, Mulaute
and Natividad units), including data from Cosma et al. (1998) and Mamberti et al.
(2004). The eNdi ratios of these rocks (+6 to +9) imply an intra-oceanic setting and
may be a continuation of the Great Arc of the Caribbean (e.g. Burke, 1988). The shift
towards higher eSri values in the Pujilı́ Granite can be accounted for by hydrothermal
alteration, possibly associated with serpentinization of the host mafic rocks.
The lifespan of the Rio Cala Arc
sequence
The Rio Cala Arc sequence, exposed
in the northern Western Cordillera
(Fig. 1), is defined here as a series of
volcanoclastic turbidites (Natividad,
Pilatón and Mulaute units), with
intercalated and juxtaposing, faultbounded sequences of basaltic lavas
(e.g. the Rio Cala and La Portada
units). Primitive mantle-normalized
multielement plots of these volcanic
rock sequences (Fig. 3A) indicate high
concentrations of LILE elements (Sr
and Ba) and distinctive negative Nb
anomalies, typical of rocks formed via
subduction. High eNdi values of (+6
to +9) have been obtained from the
Rio Cala Arc sequence, which overlap
with those acquired from basalts in
the present-day Caribbean region (e.g.
Thompson et al., 2003). The chemical
composition of clinopyroxenes extracted from both basalts and sandstones
in the Rio Cala arc sequence indicates
a tholeiitic island arc setting (data
repository item).
2006 Blackwell Publishing Ltd
Kerr et al. (2002) proposed that
volcanic rocks of the Rio Cala Unit
were produced by eastward subduction below an already accreted oceanic
plateau in a continental arc setting.
This interpretation was based on the
more evolved nature of rocks from the
Rio Cala Unit, as shown by an
enrichment of LREE concentrations,
despite relatively high MgO contents
(approximately 8%). However, geochemical evidence led Allibon et al.
(2005) to suggest that the lavas of the
Rio Cala Unit originated from subduction beneath thickened oceanic
crust in an intra-oceanic arc. The
LREE enrichments are accounted for
by the assimilation of oceanic plateau
rocks. Similarly, initial Nd and Pb
isotope ratios indicate that the rocks
of the Rio Cala Unit result from the
mixing of Pacific MORB mantle, subducted pelagic sediments and an oceanic plateau component (Allibon et al.,
2005), which is consistent with an
intra-oceanic island arc setting. Furthermore, heavy mineral assemblages
(Vallejo et al., 2003) within turbidites
intercalated with volcanic rocks of the
Rio Cala Unit, indicate they were
derived exclusively from a mafic volcanic source region. Collectively, these
data support the hypothesis that the
Rio Cala Arc developed in an intraoceanic setting, and has a pre-accretionary origin.
Sedimentary rocks intercalated
within boninitic pillow basalts of the
La Portada Unit (Van Thournout
et al., 1992; Kerr et al., 2002) yield a
Santonian–Campanian
biostratigraphic age (Boland et al., 2000). A
prevailing interpretation for boninitic
rocks is that they define the early stage
of an island arc (Pearce et al., 1992;
Stern and Bloomer, 1992), formed
beneath very young and hot oceanic
crust (Stern et al., 1991).
Lavas intercalated in the Natividad
Unit yield a plateau 40Ar/39Ar (clinopyroxene) age of 64.3 ± 0.4 Ma (2r;
Fig. 2B) and volcanoclastic strata of
the Natividad Unit yield Campanian
to Maastrichtian microfossils (Boland
et al., 2000).
We interpret the Rio Cala Arc
sequence to have originated by west
dipping subduction of the protoCaribbean oceanic crust beneath the
relatively buoyant Caribbean Plateau
(e.g. Burke, 1988) during the Santonian–Early Campanian (Fig. 4). The
termination of the arc in the Maastrichtian–Danian period corresponds
to clogging of the subduction zone by
collision between the Caribbean Plateau and the South American Plate.
The absence of regional igneous
activity on the continental margin
during 85–65 Ma may be attributable
to a cessation of subduction beneath
the continental margin as a consequence of ocean basin closure being
solely accommodated by westward
subduction beneath the Caribbean
Plateau.
A significant quantity of material
derived from the Eastern Cordillera
occurs in the uppermost Mulaute Unit
(Spikings et al., 2005), which conformably overlies Maastrichtian to
Palaeocene volcanic-derived turbidites
of the Pilatón Unit. This data suggest
that the island arc system was close to
the continent during the Palaeocene.
Summary and conclusions
A new zircon U/Pb (SHRIMP) age
of 87.10 ± 1.66 Ma from basement
267
Caribbean Plateau–South American Plate collision • C. Vallejo et al.
Terra Nova, Vol 18, No. 4, 264–269
.............................................................................................................................................................
Hughes, regarding accretionary events in
western Ecuador and the Caribbean region. John Aspden and Andrew Kerr
provided constructive reviews of the manuscript. Field sampling benefited from the
assistance and knowledge of Peter Hochuli,
Friedrich Heller, Efraı́n Montenegro, William Lugo and Diego Villagomez. This
work was supported by the Swiss National
Science Foundation (projects 2-77193-02
and 2-77504-04).
Fig. 4 Reconstruction of the Caribbean Plateau during the Santonian–Maastrichtian
(modified and simplified from Ross and Scotese, 1988). Schematic postulated
extensions to the Great Arc of the Caribbean have been made to include the Rio Cala
Arc sequence. The Pallatanga Terrane is shown as a fragment of the Caribbean
Plateau. GHS: Galápagos hot spot.
mafic rocks of the previously mapped
Early Cretaceous San Juan Unit,
within the eastern Western Cordillera, suggests that the San Juan Unit
is inaccurately mapped and the Early
Cretaceous rocks may only exist as
small-scale (e.g. several metres wide),
fault-bounded slivers. Our new Late
Cretaceous U/Pb age is the first
radiometric age from mafic basement
rocks of the Pallatanga Unit, which,
when combined with its geochemical
characteristics, supports a derivation
from the coeval Caribbean Plateau.
The U/Pb age is consistent with
volcanism associated with the Caribbean Plateau during 92–88 Ma (Sinton et al., 1998; Kerr et al., 2003) and
an 40Ar/39Ar age of 88 ± 1.6 Ma
from oceanic plateau rocks of the
Piñón Fm., located along present-day
coastal Ecuador (Luzieux et al.,
2005). Palaeomagnetic analyses of
the Piñón Fm. (Luzieux et al., 2005)
strongly indicate that these oceanic
plateau remnants were derived from
an oceanic plateau formed at equatorial palaeolatitude, which is consistent with a Galapagos hotspot origin
(Fig. 4).
The initiation of west-dipping subduction at the leading edge of the
plateau, was probably responsible for
the generation of the ocean island-arc
related Pujilı́ Granite at c. 85.5 Ma, via
partial melting of the plateau, similar
to what has been proposed by White
et al. (1999) for the Aruba Batholith.
Furthermore, Santonian–Campanian
boninites of the La Portada Unit
(Rio Cala Arc sequence) were also
produced during the early stages of arc
magmatism via subduction beneath
268
the Caribbean Plateau, and may be
partly coeval with the Pujilı́ Granite.
The time-span between the eruption of
oceanic plateau basalts and the islandarc related Pujilı́ Granite and boninites
of the Rio Cala Arc sequence suggests
that migration of the Caribbean Plateau and subsequent initiation of westward subduction below the plateau
occurred c. 2 Myr after the eruption of
the plateau.
The oceanic plateau and overlying
island arc subsequently drifted to the
northeast and collided with the South
American continental margin during
the Campanian, although subductionrelated magmatism terminated at the
Maastrichtian–Danian
transition,
suggesting that the collision may have
been oblique. It is likely that the
collision between the South American
Plate and the Caribbean Plateau resulted in rapid surface uplift in the
Eastern Cordillera, with erosion and
deposition in the fore- and backarc.
Furthermore, the onset of rapid exhumation throughout the Late Cretaceous continental margin at 75–65 Ma
temporally corroborates the onset of
clastic sedimentation derived from the
continental margin during the Late
Campanian–Maastrichtian.
Collectively, this evidence strongly
favours the hypothesis that the collision between the Caribbean Plateau
and the Ecuadorian margin occurred
in the Late Campanian–Maastrichtian
(75–65 Ma).
Acknowledgements
The authors would like to express their
thanks to Arturo Egüez and Richard
References
Allibon, J., Monjoie, P., Lapierre, H.,
Jaillard, E., Bussy, F., Bosch, D., 2005.
High Mg-basalts in the Western Cordillera of Ecuador: evidence of plateau
root melting during Late Cretaceous arcmagmatism. In: Proceedings of the Sixth
International Symposium on Andean
Geodynamics, Program and Abstracts,
Barcelona, Spain, pp. 33–35.
Aspden, J.A. and Litherland, M., 1992.
The geology and Mesozoic collisional
history of the Cordillera Real, Ecuador.
Tectonophysics, 205, 187–204.
Aspden, J.R., Harrison, S.H. and Rundle,
C.C., 1992. New geochronological control for the tectono-magmatic evolution
of the metamorphic basement, Cordillera Real and El Oro Province of Ecuador. J. S. Am. Earth Sci., 6, 77–96.
Beaudon, E., Martelat, J.E., Amórtegui,
A., Lapierre, H., Jaillard, E., 2005.
Métabasites de la cordillère occidentale
dÕÉquateur, témoins du soubassement
océanique des Andes dÕÉquateur. CR
Geosci, 337, 625–634.
Boland, M.L., Pilatasig, L.F., Ibadango,
C.E., McCourt, W.J., Aspden, J.A.,
Hughes, R.A. and Beate, B., 2000.
Geology of the Cordillera Occidental of
Ecuador between 0 and 1 N. Proyecto
de Desarrollo Minero y Control Ambiental, programa de Informacion Cartográfica y Geológica, CODIGEM-BGS,
Quito, Informe 10.
Burke, K., 1988. Tectonic evolution of the
Caribbean. Annu. Rev. Earth Planet.
Sci., 16, 201–230.
Cosma, L., Lapierre, H., Jaillard, E.,
Laubacher, G., Bosch, D., Desmet, A.,
Mamberti, M. and Gabriele, P., 1998.
Pétrographie et géochimie des unités
magmatiques de la Cordillere occidentale d’Equateur (030¢S): implications
tectoniques. Bull. Soc. Ge´ol. Fr., 169,
739–751.
Duncan, R.A., Hargraves, R.B., 1984.
Plate tectonic evolution of the Caribbean
region in the mantle reference frame. In:
The Caribbean–South America Plate
Boundary and Regional Tectonics (W.E.
Bonini, R.B. Hargraves and R. Shagam,
eds). Geol. Soc. Am. Mem., 162, 81–93.
Harrison, T.M. and McDougall, I., 1981.
Excess 40Ar in metamorphic rocks from
2006 Blackwell Publishing Ltd
Terra Nova, Vol 18, No. 4, 264–269
C. Vallejo et al. • Caribbean Plateau–South American Plate collision
.............................................................................................................................................................
Broken Hill, New South Wales: implications for 40Ar/39Ar age spectra and the
thermal history of the region. Earth
Planet. Sci. Lett., 55, 123–149.
Hoernle, K., Hauff, F., Van den Bogaard,
P., 2004. 70 m.y. history (139–69 Ma)
for the Caribbean Large Igneous Province. Geology, 32, 697–700.
Hughes, R.A. and Pilatasig, L.F., 2002.
Cretaceous and Tertiary terrane accretion in the Cordillera Occidental of the
Ecuadorian Andes. Tectonophysics, 345,
29–48.
Jaillard, E., 1997. Sintesis estratigrafica del
Cretaceo y Paleogeno de la cuenca oriental del Ecuador. Convenio ORSTOMPetroproduccion, Quito, 164 p.
Jaillard, E., Ordoñez, M., Suárez, J.,
Toro, J., Iza, D. and Lugo, W., 2004.
Stratigraphy of the Late Cretaceous–
Paleogene deposits of the Cordillera
Occidental of central Ecuador: geodynamic implications. J. S. Am. Earth
Sci., 17, 49–58.
Kerr, A.C. and Tarney, J., 2005. Tectonic
evolution of the Caribbean and northwestern South America: the case for
accretion of two Late Cretaceous
oceanic plateaus. Geology, 33, 269–272.
Kerr, A.C., Aspden, J.A., Tarney, J. and
Pilatasig, L.F., 2002. The nature and
provenance of accreted terranes in
western Ecuador: geochemical and
tectonic constraints. J. Geol. Soc.
London, 159, 577–594.
Kerr, A.C., White, R.V., Thompson, P.M.,
Tarney, J., Saunders, A. 2003. No
oceanic plateau–no Caribbean Plate?
The seminal role of an oceanic plateau
in Caribbean Plate evolution. In: The
Circum-Gulf of Mexico and the Caribbean: Hydrocarbon Habitats, Basin Formation, and Plate Tectonics (C. Bartolini,
R.T. Buffler and J. Blickwede, eds).
AAPG Mem., 79, 126–168.
Lapierre, H., Bosch, D., Dupuis, V., Polvé,
M., Maury, R.C., Hernandez, J., Monié,
P., Yéghicheyan, D., Jaillard, E., Tardy,
M., Mercier de Lépinay, B., Mamberti,
M., Desmet, A., Keller, F. and Sénebier,
F., 2000. Multiple plume events in the
genesis of the peri-Caribbean Cretaceous
oceanic plateau province. J. Geophys.
Res., 105, 8403–8421.
Lebrat, M., Megard, F., Dupuy, C. and
Dostal, J., 1987. Geochemistry and tectonic setting of pre-collisional Cretaceous
and Paleogene volcanic rocks of Ecuador.
Geol. Soc. Am. Bull., 99, 469–578.
Litherland, M., Aspden, J. and Jemielita,
R.A., 1994. The metamorphic belts of
2006 Blackwell Publishing Ltd
Ecuador. Br. Geol. Surv. Overseas Mem.,
11, 147.
Luzieux, L.D., Heller, F., Spikings, R.,
Winkler, W. and Vallejo, C., 2005. Cretaceous block rotations in the coastal
forearc of Ecuador: paleomagnetic,
chronostratigraphic evidences, and
implications for the origin and accretion
of the blocks. In: Proceedings of the
Third Swiss Geoscience Meeting, Program and Abstracts, Zürich, Switzerland,
pp. 95–96.
Mamberti, M., Lapierre, H., Bosch, D.,
Ethien, R., Jaillard, E., Hernandez, J.
and Polve, M., 2003. Accreted fragments
of the Late Cretaceous Caribbean–
Colombian Plateau in Ecuador. Lithos,
66, 173–199.
Mamberti, M., Lapierre, H., Bosch, D.,
Jaillard, E., Hernandez, J. and Polve,
M., 2004. The Early Cretaceous San
Juan Plutonic Suite, Ecuador: a magma
chamber in an oceanic plateau? Can. J.
Earth Sci., 41, 1237–1258.
Pearce, J.A., van der Laan, S., Arculus,
R.J., Murton, B.J., Ishii, T. and Peate,
D.W., 1992. Boninite and Harzburgite
from Leg 125 (Bonin–Mariana Forearc): a case study of magma genesis
during the initial stage of subduction.
In: Proceedings for the Ocean Drilling
Program (P. Fryer, J.A. Pearce and
L.B. Stokking, eds). Sci. Results, 125,
623–659.
Revillon, S., Hallot, E., Arndt, N.T.,
Chauvel, C. and Duncan, R.A., 2000. A
complex history for the Caribbean Plateau: petrology, geochemistry, and geochronology of the Beata Ridge, South
Hispaniola. J. Geol., 108, 641–661.
Reynaud, C., Jaillard, E., Lapierre, H.,
Mamberti, M. and Mascle, G.H., 1999.
Oceanic plateau and island arcs of
southwestern Ecuador: their place in the
geodynamic evolution of northwestern
South America. Tectonophysics, 307,
235–254.
Ross, M.I. and Scotese, C.R., 1988. A hierarchical tectonic model of the Gulf of
Mexico and Caribbean region. Tectonophysics, 155, 139–168.
Ruiz, G.M.H., Seward, D. and Winkler, W.,
2004. Detrital thermochronology – a new
perspective on hinterland tectonics, an
example from the Andean Amazon Basin,
Ecuador. Basin Res., 16, 413–430.
Sinton, C.W., Duncan, R.A., Storey, M.,
Lewis, J. and Estrada, J.J., 1998. An
oceanic flood basalt province within the
Caribbean plate. Earth Planet. Sci. Lett.,
155, 221–235.
Spikings, R.A., Winkler, W., Seward, D.
and Handler, R., 2001. Along-strike
variations in the thermal and tectonic
response of the continental Ecuadorian
Andes to the collision with heterogeneous oceanic crust. Earth Planet. Sci.
Lett. 186, 57–73.
Spikings, R.A., Winkler, W., Hughes, R.A.
and Handler, R., 2005. Thermochronology of Allochthonous Terranes in
Ecuador: unraveling the accretionary
and post-accretionary history of the
Northern Andes. Tectonophysics, 399,
195–220.
Stern, R.J. and Bloomer, S.H., 1992. Subduction zone infancy: examples from the
Eocene Izu-Bonin-Mariana and Jurassic
California arcs. Geol. Soc. Am. Bull.,
104, 1621–1636.
Stern, R.J., Morris, J., Bloomer, S.H. and
Hawkins, J.W., 1991. The source of the
subduction component in convergent
margin magmas: trace element and
radiogenic evidence from Eocene boninites, Mariana fore arc. Geochim.
Cosmochim. Acta, 55, 1467–1481.
Sun, S-S. and McDonough, W.F., 1989.
Chemical and isotopic systematics of
ocean basalts. Implications for mantle
composition and processes. In: Magmatism in the Ocean Basins (A.D. Saunders
and M.J. Norry, eds). Spec. Publ. Geol.
Soc. London, 42, 313–346.
Thompson, P., Kempton, P., White, R.,
Kerr, A., Tarney, A., Saunders, A., Fitton, J. and McBirney, A., 2003. Hf–Nd
isotope constraints on the origin of the
Cretaceous Caribbean plateau and its
relationship to the Galápagos Plume.
Earth Planet. Sci. Lett., 217, 59–75.
Vallejo, C., Winkler, W., Spikings, R.,
Luzieux, L. Hochuli, P. and Heller, F.,
2003. Provenance analysis of accreted
units in the Western Cordillera of the
Ecuadorian Andes, preliminary results.
In: Proceedings of the First Swiss Geocience Meeting, Basel, Switzerland,
p.118.
Van Thournout, F., Hertogen, J. and
Quevedo, L., 1992. Allochthonous
terranes in northern Ecuador. Tectonophysics, 205, 205–222.
White, R., Tarney, J., Kerr, A., Saunders,
A., Kempton, P., Pringle, M. and Klaver,
G., 1999. Modification of an oceanic
plateau, Aruba, Dutch Caribbean: implications for the generation of continental
crust. Lithos, 46, 43–68.
Received 15 March 2006; revised version
accepted 17 May 2006
269