The use of quartz grain microtextures in the study of the origin of sand terrains in Western Australia

The origin of extensive sand terrains which lie inland from the coastal margin of Western Australia is contentious, with the debate centering around an in situ vs. an aeolian origin. To resolve this debate the shape and surface features of sand grains are reported for sandplains, sand dunes and bedrock for the Victoria Plateau sandplain, which lies in the central west coastal region of Western Australia. All three components of the Victoria Plateau are similar in grain shape and microtexture. Quartz grains show a combination of chemical dissolution and precipitation micromorphology. Characteristics of dissolution include etch patterning, triangular shaped etch pits and solution features. Precipitation forms include edge rounding, silica veneers and plate- and sheet-like structures. Features such as peeling plates, complex precipitation forms projecting from grain surfaces, adhering particles and preserved grain contact faces indicate stability rather than a transport dominated environmental history. The combination of preserved dissolution and precipitation forms, a dearth of mechanically derived features and a correspondence between grains in rock and overlying sands points to local siliceous sedimentary rocks as the source of the sands.