Wednesday 24th September

12 — 1 pm

Rm 312.222

David Mole

CESRE, CSIRO

Komatiite volcanism controlled by the hidden architecture of early continents

David Mole

Abstract

The generation and evolution of the Earth’s continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere and led to the creation of ecological niches important for early life. In this talk we show that in the Archean, the formation and stabilisation of continents also controlled the location, geochemistry and volcanology of komatiite volcanism. This talk uses the vast database of Sm-Nd isotopic data and U-Pb geochronology from the Yilgarn Craton to unravel the complex evolution of the various internal terranes. This is brought together in a holistic model for the development of the craton, and the fundamental role crustal evolution has played in the localisation, geochemistry and prospectivity of komatiites. Results show that in the early Earth, relatively small crustal ‘blocks’ analogous to modern micro-plates progressively developed to form larger continental masses and eventually the first cratons. This cratonisation process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. Fundamentally, this study demonstrates that the dynamic evolution of the early continents directly influenced the addition of deep mantle material to the Archean crust, oceans and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits.