Segment-Scale Melt Storage and Transport Processes at Mediumto Fast-Spreading Ridges: Case Study at the EPR, 9 Degrees 30' Norh Area

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Magma storage and transport processes below the axes of active medium to fast spreading ridges is of fundamental importance to understanding ridge segmentation and the dynamic behavior of axial volcanoes. Detailed petrologic and geochemical studies of well-studied and well-sampled ridge segments can provides strong constraints on the nature and geometry of these processes. This project will analyze trace element, mineral chemistry, and crystal size distribution data from the East Pacific Rise between 9 degree 20 minutes North and 9 degrees 53 minutes North to test models of magma transport and magma chamber processes. One model of mid-ocean ridge volcanism considers the volcanism to be the result of deep upwelling which degenerates upward into multiple diapirs and conduits. At shallow levels magmas apparently undergo fractionation with rocks crystallized from high-temperature melts forming at local ridge-crest highs and rocks crystallizing form low-temperature melts found at ridge-crest lows. This model will be tested by comparing analyses from extensive dredge hauls to calculations of rock compositions that would be expected from a fractionation of one or more parent magmas.