Borehole observatories record driving forces for hydrotheraial circulation in young oceanic crust



A greatly improved understanding of the mechanisms of hydrothermal circulation seems within reach, based on preliminary interpretation of long-term monitoring data from borehole observatories installed during two recent legs of the Ocean Drilling Program (ODP). These new data should be especially helpful in refining circulation models to resolve the vigor and scale of hydrothermal phenomena in the oceanic crust.

Substantial progress already has been made toward quantifying average thermal and chemical fluxes associated with hydrothermal circulation, but progress toward understanding the mechanisms of circulation has been modest. Measurements of temperatures, pressures, and permeabilities at depth are rare; hence, models for circulation are little more than conceptual, relying to a large degree on inferences from data gathered at the seafloor rather than on in situ observational constraints.