Late cainozoic environments of part of Northeastern South Australia

Abstract In the Lake Frome area of South Australia there is a sedimentary sequence of non‐marine (or possibly distant marginal marine) pale‐green to grey, fine elastics and carbonates (Namba Formation). The base of these deposits is Medial Miocene in age and they are overlain unconformably by Pleistocene (and ? Pliocene) sediments. The Miocene sequence is equivalent to the Etadunna Formation of the Lake Eyre Basin, and the clay mineralogy is similar. Combining evidence from mineralogy, palynology, and vertebrate palaeontology, a warm high‐rainfall climate operating on a subdued topography is indicated for the lower part of the Miocene Lake Frome sequence. This caused the illite‐chlorite‐kaolinite suite of the largely Precambrian provenance to be transformed to smectite and randomly‐interstratified clay. A palygorskite‐dolomite assemblage accumulated in alkaline lakes of extreme marginal marine situation during periods of seasonal dry intervals superposed on the previous climate. A change to illite‐dominat...