Palaeoproterozoic terrestrial sedimentation in the Beasley River Quartzite, lower Wyloo Group, Western Australia

Abstract

Pre-2.2Ga aeolianite deposits are relatively rare in the geological record, due to reworking of aeolianites either by fluvial systems, transgression or non-recognition. Here, we present high resolution sedimentary facies analysis of a section through the 2.2Ga Beasley River Quartzite, lower Wyloo Group, Western Australia. The unambiguous presence of terrestrial (fluvial-aeolian) deposition is documented in the form of fluvial architectural elements (channel, bar, lateral accretion and overbank deposits) and aeolian features (dune, pin-stripe lamination, wind streaks, and adhesion features). These observations contrast strongly with a previous interpretation of marine deposition, which is discounted. Our data is consistent with the dominantly terrestrial depositional mode of the rest of the lower Wyloo Group, including the basal Three Corners Conglomerate Member and the subaerial Cheela Springs Basalt. We conclude that the lower Wyloo succession formed in a terrestrial regime during continental rifting.