Isotope ratios and trace element concentrations of basalts from DSDP Leg 15 sites (Appendix 1)

• Main Authors: Thompson, Patricia M E, Kempton, Pamela D, White, Rosalind V, Kerr, Andrew C, Tarney, J, Saunders, Andrew D, Fitton, J Godfrey, McBirney, A
• Format: Dataset
• Language: English
• Published: PANGAEA 2003
• Subjects: 15-146; 15-151; 15-152; AGE; Caribbean Sea/BASIN; Caribbean Sea/CONT RISE; Caribbean Sea/RIDGE; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Event label; Glomar Challenger; Hafnium; Inductively coupled plasma - mass spectrometry (ICP-MS); Leg15; Lutetium; Lutetium-176/Hafnium-177; Mass spectrometer Finnigan MAT 262; Neodymium; Neodymium-143/Neodymium-144 ratio; Samarium; Samarium-147/Neodymium-144 ratio; Sample code/label; ε-Hafnium; ε-Neodymium (T); Reykjanes; Iceland
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.725469; https://doi.org/10.1594/PANGAEA.725469

Formation of the Cretaceous Caribbean plateau, including the komatiites of Gorgona, has been linked to the currently active Galápagos hotspot. We use Hf-Nd isotopes and trace element data to characterise both the Caribbean plateau and the Galápagos hotspot, and to investigate the relationship between them. Four geochemical components are identified in the Galápagos mantle plume: two 'enriched' components with epsilon-Hf and epsilon-Nd 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 Galápagos. Likewise, the depleted end member of the array is geochemically indistinguishable from MORB and corresponds to the depleted component of the Galápagos system. Enriched basalts from Gorgona partially overlap with the Caribbean plateau array in epsilon-Hf vs. epsilon-Nd, whereas depleted basalts, picrites and komatiites from Gorgona have a high epsilon-Hf for a given epsilon-Nd, defining a high-epsilon-Hf 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 Galápagos 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 ...