Mantle Control of a Dynamically Evolving Spreading Center: Temporal Aspects

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OCE-9314483 In this project, the P.I.s will carry out a combined field (geochemical) and modelling study on two segments of the slow- intermediate spreading MAR at 31-35S. The P.I.s wish to capitalize on a possible window of opportunity of Ewing being in this part of the Atlantic around the proposed time. They will focus on two along axis geochemical anomalies near 33S: the first is a 206Pb/204Pb spike at segment 4, and the second is high Na8.0/low Fe8.0 anomaly at segment 3. The P.I.s contend that in the latter area they can obtain best constraints on the temporal component of a transform fault effect (TFE). Zero-age and off-axis sampling (to 8 Ma old crust) of these two anomalies will allow them to decipher the extent of mantle geochemical heterogeneities and melting processes. Using such constraints the P.I.s ultimately wish to develop satisfactory models of upper mantle heterogeneities and convection. Michael & Hanan will be co-chiefs. Michael will perform electron probe analysis of glasses at Tulsa and trace elements with Ion Probe (WHOI), DCP (Lamont) or ICP-MS (Cornell). Hanan will be responsible for isotopic work.