Israelite Plain, southwestern Australia, a siliciclastic, late Quaternary Coorong analogue, without dolomite

The Israelite Plain, a narrow terrace at the western edge of the Great Australian Bight, is characterised by a series of schizohaline, ephemeral lakes leeward of a marginal marine eolianite dune complex that has many similarities to the Coorong Coastal Plain (CCP). The late Pleistocene and Holocene sediments are a mixture of dominantly quartzose sand and lesser carbonate components. Paleolagoon to shallow marine MIS 5e, mollusc-rich quartzose deposits are capped by calcrete or karst and contain a biota similar to the well-documented, coeval Glanville Formation on the CCP. Holocene sands with minor carbonate are also lagoonal and resemble many modern Coorong Lagoon deposits. Both deposits are interpreted to reflect marine accumulation during sea-level highstands. Lakes today range from dry to water-filled with most floored by calcareous quartzose sand. Microbial influenced sedimentary structures in the form of pustular to laminated mats veneer lake margin bedrock and sediment. Carbonate minerals are mostly calcite with abundant accessory magnesium-calcite, aragonite and traces of magnesite, monohydrocalcite and halite. Gypsum is minor but ubiquitous and floors one of the smaller, marginal-marine lakes. Although having a similar evaporative climate and evidence of groundwater resurgence like Coorong lakes, there is no significant synsedimentary dolomite. This aspect is interpreted to reflect the narrow width of the plain, and the Mg-poor source of groundwater from the nearby karst Nullarbor Plain to the north. The Israelite Plain, together with other coeval, young successions marginal to the Southern Ocean under a semiarid climate now illustrate the depositional variations and early diagenetic differences that can occur in similar environments adjacent to a cool ocean.