Rubidium and Strontium chemistry of oceanic crust

Results from drilling sites 105, 332B and 418A, Atlantic Ocean, which have basement formation ages of 155 m.y., 3.5 m.y., and 110 m.y., respectively, show that vein deposition is essenrially complete within 5-10 m.y. after formation of the basaltic crust.

This provids direct evidence that hydrothermal circulation of sea-water through the oceanic crust is an important process for only 5-10 m.y. after crust formation.