A revised stratigraphy for the precambrian in North-West Tasmania

Abstract

Within the Proterozoic rocks of the Rocky CapeGeanticline in north-west Tasmania, three contrastingsedimentary assemblages are recognised.The Rocky Cape Group, which has been previouslyused very broadly, is redefined to include only oneof these assemblages. The revised definitionincludes the orthoquartzite, siltstone and shalewhich form a continuous sequence in the RockyCape area. Some new formations are defined.The Smithton Dolomite, and related rocks, unconformablyoverlie the Rocky Cape Group to the westat Black River. The Burnie Formation is a thicksequence flanking the Rocky Cape Group to theeast. The Rocky Cape Group and the BurnieFormation are separated by the Keith Metamorphics,which is a belt of low grade regional metamorphicgreenschist, amphibolite and pelitic schist.