Post-eruptive processes in kimberlites—implications for diamond exploration

Abstract

Deposits of primary diamond ore—kimberlite and, less commonly, lamproite and lamprophyre volcanics and intrusives—are scarce, and even in highly prospective terranes geochemical and geophysical methods are needed to facilitate location of the tiny volcanic targets. The environment at the time of eruption and, more importantly, the environments to which the diamond-bearing volcanic material has been subjected since eruption condition how targets will respond to these survey methods. Post-eruption processes within the crater, such as serpentinization, and beyond the crater—in particular, the effects of erosion—are outlined and illustrated by reference to the Fort à la Corne kimberlite field in western Canada. The consequences for exploration of such factors as groundwater and seawater levels, uplift and climate are indicated.