Timing and significance of crosscourse mineralization in SW England

Abstract

Rb-Sr isotope analyses of inclusion fluids from quartz have demonstrated a Triassic age (236 ± 3 Ma) for N–S-trendmg Pb–Zn–F vein mineralization in the Tamar Valley district of the Cornubian orefield. Consideration of the stratigaphy and structure of the Permo-Triassic basins both onshore and in the English Channel suggest that this mineralization results from the formation of fractures during regional extension-driven subsidence, and the subsequent ingress of basinal brines to the Variscan basement.