Age of hydrothermal circulation on the Rio Grande Rise: Deep Sea Drilling Project Site 516 ( Leg 72, Atlantic Ocean).

Abstract

A well-constrained Rb/Sr isochron of secondary celadonites and carbonate from DSDP Hole 516F yields an age of 70.1+ or -1.6 Ma. This age is younger than the age of crust formation (about 82 Ma) and may provide evidence for a short-lived hydrothermal event on the Rio Grande Rise caused by a phase of off-ridge volcanism. Initial 87Sr/86Sr ratios of the celandonites and carbonate, K, Rb, and Cs contents and alkali ratios K/Rb and K/Cs of Hole 516F celadonites are also presented and discussed. -from Authors