A Simple Model for the Caribbean

1
Geology of the Caribbean PlateauKeith
JamesInstitute of Geography Earth Sciences,
Aberystwyth, Wales, UK,khj_at_aber.ac.uk
This model the plate formed in place, between N
and S America.
Paradigm -the Caribbean Plate is oceanic and
came from the Pacific. -the Plateau formed over
a mantle plume.
-it is mostly extended continental crust.
-the plateau consists of NE trending continental
blocks, Palaeozoic and older, flanked by
Triassic-Jurassic seaward-dipping wedges and
overlain by Cretaceous basalts.
K. H. James 07
2
Middle America
Atlantic Plate
3
5

Gulf of Mexico
2
0

U
Venezuela Basin
L
Colombia Basin
5

Pacific Plate
-
8
5

-
7
0

-
5
5

K. H. James 07
3
Problems with Caribbean geology
Geology is spread over many different countries.
Some areas are poorly mapped (access, vegetation,
weathering).
There are no spreading ridges or magnetic
anomalies in the whole of middle America, save
for the central 300 km of the Cayman Trough
(Miocene - Recent).
Most data are collected/interpreted under the
assumption that the Caribbean Plate is oceanic
and came from the Pacific.
K. H. James 07
4
The Caribbean Plateau
Caribbean Plate crust in the western Venezuela
Basin-Beata Ridge area is up to 20 km thick.
This is the original Caribbean Plateau. Five
ODP/DSDP sites have penetrated Cretaceous
basalts, dated 88 - 90 Ma, at the very top of the
thick, uncalibrated section. Overlying sediments
are shallow marine carbonates.
Peripheral to thick Caribbean crust, supposed
original oceanic crust is thin, 3 km, not
drilled, not dated.
Other parts of the Caribbean Plate interior (in
the Colombia, Grenada and Yucatán basins) also
are thick. Together with the original plateau
and accreted rocks around the Caribbean and in
Colombia, they are seen to comprise an oceanic
plateau or large igneous province. Some of the
accreted sections include palaeosols.
Several oceanic plateaux (Ontong-Java, Iceland,
Kerguelen, Vøring, Rockall) are known to have
continental roots. Is this true of the Caribbean
Plateau?
5
Popular model The Caribbean Plate is oceanic and
migrated from the Pacific (successive arc
locations).
Arc volcano
Extinct
MEoc
2
0

Mas
LA
Tur
Brm
MMio
5

CAP
-
8
5

-
7
0

K. H. James 07
6
Caribbean
Banda
ATLANTIC OCEAN
Plate boundary
SOUTHEAST ASIA
Continent margin
30
Shoreline
Volcanic arc
Gulf of Mexico
Bahamas
15
Philippines
Hispaniola
Yucatán
Puerto Rico
PACIFIC OCEAN
Maya
Basin
BR
Lesser
AR
15
Sulawesi
Chortis
Borneo
Antilles
0
Sumatra
Papua-
New Guinea
Java
PACIFIC OCEAN
INDIAN OCEAN
Timor
AUSTRALIA
-70
-85
-100
Scotia
120
135
105
The plates are strikingly similar.
Scotia and Banda formed in-place by back-arc
spreading.
PACIFIC
OCEAN
Scotia and Banda carry marginal and interior
continental fragments.
Is there continental material in the Caribbean?
K. H. James 07
7
Indications of continent in the Caribbean
3
5

-carry Precambrian, Palaeozoic zircons,
-continental grantitoids, red beds, greywackes,
arkose.
2
0

-crustal thickness 20 km,
-crustal thickness 40 - 45 km,
-flysch from N.NE contains gneiss, schist,
quartzite, slate, marble
-gravity continental density,
-high silica ignimbrites, granulite xenoliths
5

-Albian and Miocene quartz sandstones.
-
8
5

-
7
0

-
5
5

K. H. James 07
8
Indications of continent in the Caribbean
3
5

-crustal thickness 30 km
-gravity continental density
-continental rocks on Hispaniola, Puerto Rico
Trough, Cretaceous stratigraphic continuity with
Bahamas
-Silica content up to 76
2
0

-conglomerates with abundant quartz, fragments
of schist and quartzite
-underlain by granitic rocks
5

-
8
5

-
7
0

-
5
5

K. H. James 07
9
The Caribbean plateau
shelf edge
plate boundary
NORTH AMERICA
3
5

thick crust
"accreted plateau"
DSDP locations
ridge
ATLANTIC
2
0

has NE structural grain (not the radial pattern
expected of a plume)
5

.
PACIFIC
SOUTH AMERICA
-
5
5

-
1
0
0

K. H. James 07
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It conforms with the regional tectonic pattern
.
3
5

5

-
1
0
0

K. H. James 07
11
Seismic line 1293 (after Diebold Driscoll, 1999)
Wedge
Seamount
Ridge
K. H. James 07
12
Seaward-dipping wedges are commonfeatures of
continental margins (e.g. N. Atlantic, after
Parson et al.)
Jan Mayan
Greenland
Jan Mayan and Icelandcontinental roots.
Iceland
Rockall and Vøring subaerial-shallow marine
basalts.
Faroe
Vøring andesite-dacite at (ODP Site 642) shows
continental input.
RockallPlateau
Wales, etc.

Rockall 5 km sedimentary section,including 1.5
km basalt, on 13 km highly stretched
continental crust.
13
Seaward-dipping wedges, Caribbean and Vøring
plateaux
A
convex-up reflections
SE
NW
smooth B"
Caribbean plateau
C
B
C
SE
NW
Vøring margin
14
Eastern N America (after Manspeizer, 1988).
15
Seaward-dipping wedges offshore N America note
presence of salt (after Benson Doyle, 1988).
NW
SE
SW
NE
Shore line
COST
Neogene
U Cret - Pal
Km
Mid. JJ -
5
Early KK
Pre-Mesozoic
basement
10
Salt
Post rift
unconformity
15
Rift
basin
100 Km
20
Wedge
V/E x10
16
Interpretation of plateau (after Diebold
Driscoll, 1999)
A - Early volcanic thickening
volcanic mounds with dipping flanks
depleted source
Mantle
ve 25
B - Extension - final volcanics
additional depletion
K. H. James 07
17
Diapirs - Gulf of Mexico and Caribbean
NW
SE
10 km
18
Seismic line 1293 interpretation - this study
(James 2007)
11
Sea floor
SB"
A"
RB"
CVFZ
?
K. H. James 07
19
Atlantic spreading
JJ
KK
K. H. James 07
20
Middle America mostly extended continental
crust. Greatest extension produced serpentinized
mantle.
North
JJ
KK
America
CZ

South
America
K. H. James 07
21
Caribbean crustal types
Continental crust
Extended
continental crust
Oceanized crust
Accreted ocean/arc
Oceanic crust
Shelf edge
K. H. James 07
22
Restoration removal of extension
K. H. James 07
23
Pangean reconstruction
Appalachians
Florida
Cuba
Bahamas
Maya
Chortis
S. America
K. H. James 07
24
Triassic-Jurassic rift/drift
Regional tectonic fabric is inherited from
Palaeozoic and older structures (e. g.
Appalachian suture).
K. H. James 07
25
SUMMARY
The Caribbean Plate formed in place during
American drift.
It consists mainly of extended continental crust.
The Caribbean plateau is built of NE trending
Palaeozoic/older blocks, flanked by basins with
Triassic - Jurassic seaward dipping wedges,
Jurassic - Cretaceous shales/salt, covered by
Cretaceous igneous flows.
K. H. James 07
26
Last thought if Scotia, Banda and the Caribbean
are so alike, why is there an LIP in the
Caribbean alone?
K. H. James 07
27
References Diebold, J., N. Driscoll, and the
EW-9501 Science Team, 1999, New Insights on the
Formation of the Caribbean Basalt Province
Revealed by Multichannel Seismic Images of
Volcanic Structures in the Venezuela Basin IN
Mann, P. (ed.), Caribbean Sedimentary Basins,
Sedimentary Basins of the World, Elsevier, p.
561-589. Parson, L.M. the ODP Leg 104
Scientific Party Dipping reflector styles in the
NE Atlantic Ocean In Morton, A. C., and
L.M.Parson, Early Tertiary Volcanism and the
Opening of the NE Atlantic GSL Special
Publication No. 39, p. 57-68. Manspeizer, W.,
1988, Triassic-Jurassic rifting and opening of
the Atlantic An Overview In Manzpeizer, W.
(Ed.), Triassic-Jurassic Rifting, Part A,
Elsevier, p. 41-79. Benson, R. N. and R. G.
Doyle, 1988, Early Mesozoic rift basins and the
development of the United States middle Atlantic
continental margin In Manzpeizer, W. (Ed.),
Triassic-Jurassic Rifting, Part A, Elsevier, p.
99-127. Burk, C. A., M. Ewing, J. L. Worzel, A.
O. Beall, W. A. Berggren, D. Bukry, A. G. Fisher
and E. A. Pessagno, 1969, Deep-Sea Drilling into
the Challenger Knoll, Central Gulf of Mexico
AAPG Bull., v. 53, p. 1338-1347.
Diebold et al. (1999) discuss seaward-dipping
wedges, the Vøring Plateau, unusually thin
oceanic crust and serpentinization. However,
their interpretation (shown in this presentation)
of the Caribbean Plateau is that it formed by two
phases of volcanic extrusion on extended oceanic
crust. They remark that their volcanic mounds
have magnetic signature, so the diapirs discussed
in this presentation could be igneous/serpentiniti
c. However, the magnetic data could record old
intrusions and structural relief along basement
faults. Salt diapirism is often focussed along
fault zones. Diebold et al. (1999) note that
their volcanic mounds trend NE or E-W. Sigsbee
Knoll and NE Mexican salt diapirs in the Gulf of
Mexico trend NE, following the regional fabric
highlighted by this presentation.