The tectonic significance of Cambrian allochthonous mafic‐ultramafic complexes in Tasmania

Abstract

A reassessment of the structural significance of the large Cambrian mafic‐ultramafic complexes in Tasmania indicates that existing tectonic models for the Late Proterozoic and Early Palaeozoic history of Tasmania are inadequate. Pronounced similarities exist between the Cambrian stratigraphy of Tasmania, and the less deformed allochthonous terranes of Oman and western Newfoundland. The mafic‐ultramafic complexes are allochthonous relics of a forearc terrane which collided with, and was thrust over, passive continental margin sediments in the Middle Cambrian. Extensional tectonics in the Late Cambrian, and eruption of the Mount Read Volcanics, may have resulted from post‐obduction flipping of the subduction zone. The present complex distribution of interpreted allochthonous units in Tasmania is the result of strong folding and faulting in the Devonian.