Fluid circulation through the oceanic crust: The solution to geochemical mass balances?

An important problem that confronts marine geochemists today is balancing the fluxes of elements in the oceans. Thirty-two years ago Mackenzie and Garrels (1966) could not produce such a balance without invoking "reverse weathering." At the time this paper was published, seawater circulation through the oceanic crust was only a hypothesis.

Much of my research has focused on a myriad of problems associated with fluid circulation through the oceanic crust—circulation caused by the intrusion of basaltic magma; differential lithospheric cooling on mid-ocean ridge flanks; compression along zones of subduction, and differences in head gradient on continental shelves and margins. Although these geologic settings and mechanisms for fluid flow are vastly different, in each of them, the fluid in basement reacts with and changes the crust as it is transported, thus resulting in chemical, mass, and thermal fluxes to and from the oceans. By examining this range of settings, one can study the continued alteration and evolution of the crust as it passes along a continuum from the ridge axis to the flanks before it is ultimately recycled.

I will highlight some of my work that relates to global geochemical fluxes in each of the oceanic settings mentioned above, and I will provide a direction for determining these fluxes. The methods and results from this work also are applicable for studies of microbial and benthic communities, the nature and size of geologic deposits, and crustal evolution.

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