Studies of the hydrogeochemistry of layer 2 of the oceanic crust are of primary importance for gaining a more thorough understanding of alteration reactions occurring in the crust and geochemical fluxes associated with exchange between the ocean and layer 2. In both cases the composition of the fluids trapped in layer 2 as formation waters is critical to modelling and flux calculations. Ocean drilling allows such fluids to be directly sampled. Unfortunately, the drilling process often disturbs the fluids in a hole requiring a sampling plan that involves a return to the site after the fluids have come to equilibrium. Although such return visits have been done by the drillship itself, other techniques are being perfected to allow return sampling by submersible (France) and by regular research vessels (United States). The present award will continue support to Dr. Gieskes for such studies. He has recently participated with the French in a re- entry program in the Atlantic. Funds in the this award will support analyses and publication of the results from this cruise. Additionally, he will undertake the design of a new sampler to be deployed in drillholes from a re-entry vehicle under construction at Scripps Institution. This system will deploy the samplers from a vehicle navigated on a cable from a surface vessel, eliminating the need for a costly submersible or drillship.
