Rigsby 9400751 In this project the PIs will determine the O, C, Sr, and Pb-isotopic composition of carbonates recovered from the Middle Valley of the northern JdF at ODP Leg 139. They will also perform whole-core radiography to determine textural variations downhole. The objective is to obtain past and existing thermal profiles, fluid advection, and sources of metals in sediments of past and present hydrothermal system. They also wish to investigate the sulfide ore deposition in these sediments. The PIs' and their collaborators' ultimate goal is to develop models of hydrothermal fluid circulation and chemical exchange between fluids and sediments through time. A second Leg is now being planned (along with USGS collaborators) to drill the Middle Valley sediments to specifically examine the problem of sulfide mineralization.
