Sulfide precipitates at 21°N on the East Pacific Rise: ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po

Abstract

Sulfide samples collected by the deep submersible ALVIN from hydrothermal vents at 21°N on the East Pacific Rise have extremely variable contents of uranium series nuclides. In samples we have analyzed, ²¹⁰Pb and ²¹⁰Po activities vary by more than an order of magnitude within the same vent. In two out of three samples measured ²¹⁰Po activities are higher than the parent ²¹⁰Pb activities. Consideration of ²¹⁰Pb/Pb in particulate sulfide filtered from hot vent water indicates that the lead in these deposits has a basalt as opposed to a seawater origin. Comparison of ²¹⁰Po and ²¹⁰Pb contents of active and inactive vent particulates suggests that the cycle of buildup, cessation and decay by oxidation of these sulfide chimneys is measured in tens to a few hundreds of years.