Proterozoic-style mineralization

Abstract

Iron formations and massive or stratiform sulphide deposits are characteristic of the Proterozoic. They differ from such deposits in the Archaean in that often there is no direct association with volcanic formations, though an indirect association can be invoked with volcanic rocks in contiguous formations. They occur in large epicontinental basins close to Archaean cratons and are assumed to have a volcanic-exhalative origin, though more distal from the eruptive centres than the typical Archaean deposits. Hydrothermal uranium deposits typically occur within high-grade metasediments associated with major unconformities.