The Caribbean-Colombian Cretaceous igneous province: The internal anatomy of an oceanic plateau

Kerr, Andrew Craig ORCID: https://orcid.org/0000-0001-5569-4730, Tarney, John, Marriner, Giselle F., Nivia, Alvaro and Saunders, Andrew D. 1997. The Caribbean-Colombian Cretaceous igneous province: The internal anatomy of an oceanic plateau. Mahoney, John J. and Coffin, Millard F., eds. Large Igneous Provinces: Continental, Oceanic, and Planetary Flood Volcanism, AGU Geophysical Monograph, vol. 100. Washington, DC: American Geophysical Union, pp. 123-144. (10.1029/GM100p0123)

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Abstract

The Late Cretaceous Caribbean—Colombian igneous province is one of the world's best-exposed examples of a plume-derived oceanic plateau. The buoyancy of the plateau (resulting from residual heat and thick crust) kept it from being totally subducted as it moved eastward with the Farallon Plate from its site of generation in the eastern Pacific and encountered a destructive plate margin. In effect, the plateau makes up much of the Caribbean Plate; it is well exposed around its margins, but more so in accreted terranes in western Colombia (including the well-known Gorgona komatiites and Bolívar mafic/ultramafic cumulates). Compositionally, the lavas of the plateau form three groups: (a) basalts, picrites, and komatiites with light-rare-earth-element (LREE)-depleted chondrite-normalised patterns; (b) basalts with LREE-enriched patterns; and (c) basalts with essentially flat REE patterns (the most dominant type) similar to many of the basalts from the Ontong Java Plateau. These three types demonstrate the heterogeneous nature of the mantle plume source region. The picrites and the komatiites seem to lie nearer the base of the plateau than the more homogeneous basalts; thus, the more MgO-rich melts may have been erupted before large magma chambers had a chance to develop. A reconstructed crustal cross section through the plateau consists of dunitic and pyroxenitic cumulates near the base which are overlain by layered olivine-rich gabbros and more isotropic gabbros. The lowermost eruptive sequence comprises compositionally heterogeneous picrites/komatiites overlain by more homogeneous pillow basalts. Spectacular hornblende-plagioclase veins cut the Bolívar assemblage and these may represent local partial melts of the plateau's base as it was thrusted onto the continent. Subduction-related batholiths and extrusive rocks found around the margin of the province are of two distinct ages; one suite represents pre-plateau collision-related volcanism whereas the other suite, slightly younger than the plateau, may be associated with obduction.

Item Type:	Book Section
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	G Geography. Anthropology. Recreation > GC Oceanography Q Science > QE Geology
Publisher:	American Geophysical Union
ISBN:	0875900828
ISSN:	0065-8448
Last Modified:	18 Oct 2022 12:23
URI:	https://orca.cardiff.ac.uk/id/eprint/9607

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