Reports

Plate Tectonics 2.5 Billion Years Ago: Evidence at Kolar, South India

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Science  10 Mar 1989:
Vol. 243, Issue 4896, pp. 1337-1340
DOI: 10.1126/science.243.4896.1337

Abstract

The Archean Kolar Schist Belt, south India, is a suture zone where two gneiss terranes and at least two amphibolite terranes with distinct histories were accrted. Amphibolites from the eastern and western sides of the schist belt have distinct incompatible element and isotopic characteristics sugesting that their volcanic protoliths were derived from dint mantle sources. The amphibolite and gneiss terranes were juxtaposed by horizontal compression and shearing between 2530 and 2420 million years ago (Ma) along a zone marked by the Kolar Schist Belt. This history of accretion of discrete crustal terranes resembles those of Phanerozoic convergent margins and thus suggests that plate tectonics operated on Earth by 2500 Ma.