Salt, sediments and weathering environments in Bunger Hills

Abstract

Terrestrial environments at Bunger Hills, East Antarctica, vary from vegetation-rich, little-weathered rock surfaces retaining glacial polish and striations near the glacier and ice-sheet margins to salty, vegetation-poor, extensively weathered regions near to and downwind of marine bays and inlets. Weathering forms include tafoni and orientated pits, which record former wind directions. Although salts are found all over Bunger Hills, the strongly weathered area is coincident with the distribution of halite (NaCl) and thenardite (Na2SO4), both of which are derived from seawater and marine salt spray. Salts elsewhere in Bunger Hills are either subglacial calcium carbonates or rock weathering products including gypsum (CaSO4·2H2O) and a range of rarer minerals. These other salt minerals do not weather rocks and sediment. The distribution of halite and thenardite acts as a major control on the geomorphology, sediment geochemistry and biogeography of Bunger Hills.