Events & Courses

Base metal deposits, providing the important strategic commodities of Cu, Pb, Zn, Ni and Sn, are developed in well defined mineral provinces that occur in relatively few parts of the world. In contrast to the ferrous and precious metals, base metals commonly occur together, but the geological processes that give rise to their ore deposits vary significantly from one district to another. Understanding ore forming processes provides geologists with fascinating insights into the workings of the Earth below its surface - they provide additional clues to the way the crust has evolved over the past 3500 million years and are vital to the proper and sustainable management of global base metal resources.

This lecture focuses on 4 very different processes, the consequences of which have produced most of the world's great base metal provinces. These processes include the circulation of sea water through oceanic crust and its exhalation as hot hydrothermal solutions at 'black smoker' vent sites, and also the formation of sedimentary rocks during the climatic catastrophes of the 'Snowball Earth' events. These are the two mechanisms that gave rise to the huge, and enormously rich, stratiform base metal deposits of the world. By contrast, the intrusion of large volumes of basaltic magma into contintental settings, with subsequent cooling and differentiation, and the emplacement of granitic magma along subducting plate margins, are two further processes by which, in the former case, most of the world's Ni (plus Cu and platinum) deposits were formed, and in the latter, the giant porphyry Cu and Sn deposits of the Andes developed.

Speaker

Laurence Robb (The Mineral Corporation, South Africa, and Department of Earth Sciences, University of Oxford, UK)

Biography

Born and raised in Rhodesia, Laurence Robb graduated with a PhD from the University of the Witwatersrand in South Africa, where he subsequently spent the next 25 years of his professional career teaching and researching many of the huge and fascinating ore deposits of the region. He spent his post-doctoral years as an Alexander von Humboldt Fellow at the University of Cologne. He returned to South Africa in 1983, eventually becoming Professor of Economic Geology in the School of Earth Sciences at Wits and also Director of its Economic Geology Research Institute. Whilst on sabbatical at Oxford during 2001-2004, he wrote the successful "Introduction to Ore Forming Processes", which is now used as an undergraduate text book around the world. He continues to teach ore forming processes at Oxford where he is presently Visiting Research Fellow in Economic Geology. Laurence is a Fellow of the Royal Society of South Africa and was President of the Geological Society of South Africa in 1999-2000. He has won that Society's senior award, the Draper Medal, and also served a term as the Society of Economic Geologist's Vice-President for Africa. He currently advises on exploration projects throughout Africa as a Senior Consultant for The Mineral Corporation.

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