Precambrian orogenesis: was it really different?

Abstract

Identification of macro-tectonic regimes responsible for development of orogenic or mobile belts becomes increasingly difficult with age. Especially Precambrian mobile belts are difficult to interpret because of a lack of 'far-field data' such as palaeogeographic reconstructions and palaeomagnetic data from contemporaneous oceanic crust. Nevertheless, most Precambrian mobile belts can be fitted into actualistic macro-tectonic models of orogenesis involving destructive plate margins. Archaean granite-greenstone areas are an exception in that they are difficult to fit to such actualistic models. One possible explanation is that they partly developed in a setting which is different from modern macro-tectonic regimes. A granite-greenstone area in the Yilgarn Craton, Western Australia, is presented as an example of unusual geometries in such a setting.