Neoproterozoic-Paleozoic Convergent Margins in Northeast Queensland, Australia - New Ideas from the Discovery of Metamorphic Diamonds and Ophiolites.

Abstract

<p>The Tasmanides of eastern Australia record a complex geological history. The central, and southern Tasmanides have been widely interpreted to reflect long-lived, accretionary-style convergent tectonics. The northernmost Tasmanides, which extend into north Queensland, are more poorly understood, but considered highly prospective for numerous styles of mineralization. The region contains several slices of mafic-ultramafic rocks, situated along major regional structures. The mafic-ultramafic complexes record strong, oceanic geochemical signatures, and are structurally interleaved within high grade, strongly deformed, Paleozoic basement metamorphic assemblages. Along the Clarke River Fault, the Running River Metamorphics, which host ophiolitic mafic-ultramafic rocks, also record evidence of diamond facies, ultra-high pressure (UHP) metamorphism. The discovery of diamond facies metamorphism, in conjunction with convergent margin ophiolites, suggests that the Clarke River Fault may represent a continental suture zone. This is the first indication of continent suturing in the Tasmanides, and challenges the idea that the Tasmanides, and greater Terra Australis Orogen, represent a simple accretionary system.</p>