Further evidence for two metamorphic events in the Mawson Continent

Abstract

In this study,in situand erratic samples from George V Coast (East Antarctica) and southern Eyre Peninsula (Australia) have been used to characterize the microstructural, pressure–temperature and geochronological record of upper amphibolite and granulite facies polymetamorphism in the Mawson Continent to provide insight into the spatial distribution of reworking and the subice geology of the Mawson Continent. Monazite U-Pb data shows thatin situsamples from the George V Coast record exclusively 2450–2400 Ma ages, whereas most erratic samples from glacial moraines at Cape Denison and the Red Banks Charnockite record only 1720–1690 Ma ages, consistent with known ages of the Sleaford and Kimban events, respectively. Phase equilibria forward modelling reveals considerable overlap of the thermal character of these two events. Samples with unimodal 1720–1690 Ma Kimban ages reflect either formation after the Sleaford event or complete metamorphic overprinting. Rocks recording only 2450–2400 Ma ages were unaffected by the younger Kimban event, perhaps as a result of unreactive rock compositions inherited from the Sleaford event. Our results suggest the subice geology of the Mawson Continent is a pre-Sleaford-aged terrane with a cover sequence reworked during the Kimban event.

Predicting Geothermal Heat Flow in Antarctica With a Machine Learning Approach

“…The alternative lithospheric model (combination of AN1 and Shen18) exhibits lower values in George V Land and Terre Adélie. Specifically, this area represents the Antarctic tectonic counterpart of the Australian Gawler Craton (Payne et al., 2009; Williams et al., 2018). The high heat flow region in southeast Australia fits well to the warm region in George V Land in our presented map (Section 4.3), which supports our decision.…”

“…The alternative lithospheric model (combination of AN1 and Shen18) exhibits lower values in George V Land and Terre Adélie. Specifically, this area represents the Antarctic tectonic counterpart of the Australian Gawler Craton(Payne et al, 2009;Williams et al, 2018). The…”

Heat Flow in Southern Australia and Connections With East Antarctica

“…Further east, the Gawler Craton (Figure ) contains crystalline basement that has experienced a complex tectonic history from the Archean to Mesoproterozoic (Daly et al, ; Hand et al, ), but has remained tectonically quiescent for the past billion years. It has a long‐lived connection to the Archean‐Paleoproterozoic rocks of the Mawson Craton of Terre Adélie in East Antarctica (Payne et al, ; Williams et al, ).…”

The Antarctic Crust and Upper Mantle: A Flexible 3D Model and Software Framework for Interdisciplinary Research

“…Those interpretations are, to a large extent, still valid, although more recent field geological studies have expanded the number of outcrops visited. Geochronology and geochemistry have added insights to refine our understanding by constraining event chronologies, derive likely tectonic environments, and, in conjunction with geophysics, also allows geological correlation (regional and local studies include, e.g., (geographically) clockwise around the Antarctic continent: Halpin et al, 2005Halpin et al, , 2012Corvino et al, 2008;Williams et al, 2018;Daczko et al, 2018;Tucker et al, 2017;Morrissey et al, 2017;Maritati et al, 2019;Di Vincenzo et al, 2007;Goodge et al, 1992;Siddoway et al, 2004;Yakymchuk et al, 2015;Burton-Johnson and Riley, 2015;Will et al, 2009;Jacobs et al, 1998;Marschall et al, 2010).…”