Discovery and significance of komatiite: 50th Anniversary

摘要

In July 1969, 50 years ago, the discovery in the Barberton area of a new type of ancient volcanic rock was announced in Pretoria at an international geological symposium.The discovery of this new rock, which was called komatiite, stemmed from extensive research carried out as part of an international cooperative programme to study the nature of the earth’s upper mantle, lying below the earth’s crust. One of the six projects identified for study was that of ultrabasic rocks (rocks with ultra-high magnesium content) approaching the composition of the earth’s upper mantle. In 1965, we were appointed to carry out PhD studies in the Department of Geology at the University of the Witwatersrand on a range of ultrabasic rocks which were known to occur in the lower part of the 3.5-billion-year-old Barberton Greenstone Belt. These rocks had previously been ascribed to a deep-seated intrusive igneous suite, similar to the well-known Bushveld Igneous Complex. At this time, no conclusive evidence had been found of ultrabasic magma extruded on the surface of the earth as lava flows.