High-T, low-P metamorphism in the Palaeoproterozoic Halls Creek Orogen, Northern Australia: The middle crustal response to a mantle-related transient thermal pulse

Abstract

High-T, low -P metamorphic rocks of the Palaeoproterozoic central Halls Creek Orogen in northern Australia are characterised by low radiogenic heat production, high upper crustal thermal gradients (locally exceeding 40 °C km-1) sustained for over 30 Myr, and a large number of layered mafic-ultramafic intrusions with mantle-related geochemical signatures. In order to account for this combination of geological and thermal characteristics, we model the middle crustal response to a transient mantle-related heat pulse resulting from a temporary reduction in the thickness of the mantle lithosphere. This mechanism has the potential to raise mid-crustal temperatures by 150-400 °C within 10-20 Myr fo..