Magmatism, orogeny and the origin of high-heat-producing granites in Australian Proterozoic terranes

2016-06-21T11:34:41Z (GMT) by Sandra McLaren Roger Powell
<p>Temperature-dependent processes such as magmatism and orogeny provide key insights into the Earth’s thermal state. We propose an integrated model for the origin of voluminous Proterozoic-aged granitic rocks in northern Australia, suggesting that the observed large range of concentrations of incompatible elements (particularly U, Th and K) was established progressively as a consequence of a hot-plate orogenic style involving little crustal thickening, combined with ‘normal’ juvenile magma additions. Progressive extraction of the heat-producing elements into the mid- to upper crust, where they remain below the erosional base level, resulted in anomalous thermal conditions that modulated the continuing orogenic history. This may represent an important style in post-Archaean lithospheric behaviour. </p>