Hf-Nd isotope constraints on the origin of the Cretaceous Caribbean Plateau and its relationship to the Galápagos Plume

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doi: 10.1016/S0012-821X(03)00542-9
Author(s): Thompson, P. M. E.; Kempton, P. D.; White, R. V.; Kerr, A. C.; Tarney, J.; Saunders, A. D.; Fitton, J. G.; McBirney, A.
Author Affiliation(s): Primary:
University of Leicester, Geology Department, Leicester, United Kingdom
Other:
NERC Isotope Geosciences Laboratory, United Kingdom
Cardiff University, United Kingdom
University of Edinburgh, United Kingdom
University of Oregon, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 217(1-2), p.59-75. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 77 refs.; illus., incl. 3 tables, geol. sketch map
Summary: Formation of the Cretaceous Caribbean plateau, including the komatiites of Gorgona, has been linked to the currently active Galapagos hotspot. We use Hf-Nd isotopes and trace element data to characterise both the Caribbean plateau and the Galapagos hotspot, and to investigate the relationship between them. Four geochemical components are identified in the Galapagos mantle plume: two "enriched" components with εHf and εNd similar to enriched components observed in other mantle plumes, one moderately enriched component with high Nb/Y, and a fourth component which most likely represents depleted MORB source mantle. The Caribbean plateau basalt data form a linear array in Hf-Nd isotope space, consistent with mixing between two mantle components. Combined Hf-Nd-Pb-Sr-He isotope and trace element data from this study and the literature suggest that the more enriched Caribbean end member corresponds to one or both of the enriched components identified on Galapagos. Likewise, the depleted end member of the array is geochemically indistinguishable from MORB and corresponds to the depleted component of the Galapagos system. Enriched basalts from Gorgona partially overlap with the Caribbean plateau array in εHf vs. εNd, whereas depleted basalts, picrites and komatiites from Gorgona have a high εHf for a given εNd, defining a high-εHf depleted end member that is not observed elsewhere within the Caribbean plateau sequences. This component is similar, however, in terms of Hf-Nd-Pb-He isotopes and trace elements to the depleted plume component recognised in basalts from Iceland and along the Reykjanes Ridge. We suggest that the Caribbean plateau represents the initial outpourings of the ancestral Galapagos plume. Absence of a moderately enriched, high Nb/Y component in the older Caribbean plateau (but found today on the island of Floreana) is either due to changing source compositions of the plume over its 90 Ma history, or is an artifact of limited sampling. The high-εHf depleted component sampled by the Gorgona komatiites and depleted basalts is unique to Gorgona and is not found in the Caribbean plateau. This may be an indication of the scale of heterogeneity of the Caribbean plateau system; alternatively Gorgona may represent a separate oceanic plateau derived from a completely different Pacific plume, such as the Sala y Gomez. Abstract Copyright (2004) Elsevier, B.V.
Year of Publication: 2004
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Absolute age; Alkaline earth metals; Atlantic Ocean; Basalts; Caribbean Plateau; Caribbean Sea; Caribbean region; Colombia; Cretaceous; DSDP Site 146; DSDP Site 151; DSDP Site 152; DSDP Site 504; Deep Sea Drilling Project; East Pacific; East Pacific Ocean Islands; Enrichment; Experimental studies; Galapagos Islands; Galapagos Rift; Geochemistry; Gorgona Island; Hafnium; Hf-177/Hf-176; Hot spots; Igneous rocks; Isotope ratios; Isotopes; Komatiite; Laboratory studies; Lava; Lead; Leg 15; Leg 165; Lu/Hf; Mantle; Mantle plumes; Mesozoic; Metals; Nd-144/Nd-143; Neodymium; North Atlantic; ODP Site 1001; Ocean Drilling Program; Pacific Ocean; Pb-207/Pb-204; Plate tectonics; Plateaus; Radioactive isotopes; Rare earths; South America; Sr-87/Sr-86; Stable isotopes; Strontium; Ultramafic composition; Volcanic rocks
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Record ID: 2004063222
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands