The Extent of Upper Mesozoic Igneous Activity in relation to Lamprophyric Intrusions in Tasmania

Abstract

Recent mapping and petrological work, associated with some dating, demonstrates a wider range of Upper Mesozoic intrusives and post-lower Devonian Lamprophyres than Previously recognized in Tasmania. Their distribution suggests significant igneous activity across the State, but knowledge of its full extent is dependent on detailed Separation of some lamprophyres from those of older igneous episodes. All the rocks, so far assigned to the Upper Mesozoic magmatic episode in Tasmania, are potassic in nature with shoshonitic affinities. They form the southern extension of similar magmatism around Bass Strait and in eastern Australia.