Flow rates and reaction rates in the Galapagos Rise spreading center hydrothermal system as inferred from Ra/Ra in vesicomyid clam shells.
The (228)Ra/(226)Ra ratios in a previously dated vesicomyid clam shell were used to determine that seawater was in contact with mid-oceanic-ridge basalt glass for 22-45 years prior to arrival to the surface at 350 degrees C at the Galapagos Rise Spreading Center. The minimum rate of reaction for the 45-year sojourn time, based on a water/rock ratio of 2.8 derived from (226)Ra concentrations, is 8 g of basalt altered per kg of seawater per year.
Department of Geology and Geophysics, Yale University, Box 6666, New Haven, CT 06511.
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Turekian
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Cochran