Mechanisms of geochemical and geophysical variations along the western Galápagos Spreading Center

摘要: (1) Improved insights into the processes of hot spot-ridge interaction along Galapagos Spreading Center (GSC) are revealed by geochemical data between � 91Wand 98W. Principal components analysis reveals that >87% total isotopic variability can be explained with only two mantle source components. The ''depleted'' component has lower ratios highly to moderately incompatible elements, higher Nd ratios, and Sr Pb ratios. second is relatively enriched in more radiogenic less Nd, comparable C or ''common'' observed at many locations Pacific. component's signature strongest nearest spot 92W diminishes distance from 95.5W. Near 95.5W, lava compositions change sharply, becoming dominated depleted remaining so farther west, Thus, most clearly influences composition GSC 91W 98W differs evident Archipelago, east 91W, East Pacific Rise. This suggests some form compositional zoning regional mantle. If materials intrinsic plume, then plume bilaterally zoned feeds a 91W-98W distinct material elsewhere region. possibility supported melting models which uniform mixture matrix fine-scale veins. expression fusible veins predicted enhanced (� 92W), where plume-like upwelling drives rapid flow deeper zone (where melting). With increasing westward spot, deep, plume-driven decrease, as does compositions. model therefore adequately explains crustal variations average this region not differ significantly ambient beneath other ridges influenced spots.