A SAND SEA IN SVALBARD: MICROTEXTURAL EVIDENCE FOR SYN-GLACIAL AEOLIAN DEPOSITION IN THE CRYOGENIAN BRÅVIKA MEMBER

The Cryogenian Bråvika Member is a northward-thickening and coarsening-upward wedge of quartz arenite that crops out in northeastern Svalbard. It is situated between two units that are interpreted to represent different Cryogenian climate states: the underlying upper Elbobreen Formation correlated with the warm Cryogenian interglacial, and the overlying Wilsonbreen Formation correlated with the Marinoan “Snowball Earth” glaciation. The Bråvika Member’s depositional history is ambiguous: the unit may represent a glaciofluvial environment associated with the Marinoan glaciation; a tropical non-glacial fluvial environment associated with the warm Cryogenian interglacial; or an aeolian environment associated with either climate state. The Bråvika Member’s ambiguous depositional history makes it a compelling candidate for quartz microtextural analysis, which can reveal the transport histories of modern and ancient sediments. We use scanning electron microscopy (SEM) and principal component analysis (PCA) to compare two samples of the Bråvika Member from Buldrevågen (northeastern Spitsbergen) with aeolian, fluvial, and glacial samples from modern and ancient depositional environments. Integrating PCA with field observations, we find evidence that the Bråvika Member facies in outcrop at Buldrevågen includes syn-glacial aeolian deposition and may be analogous to syn-glacial Marinoan aeolian units including the Bakoye Formation in Mali and the Whyalla Sandstone in South Australia.