Hydrologic Setting, Occurrence, and Significance of Gypsum in Late Quaternary Salt Lakes, South Australia: ABSTRACT

Abstract

Well-exposed, commonly laminated gypsum sequences occur in many Quaternary salt lakes in southern South Australia. The gypsum in the salt lakes is classified by increasing grain size into gypsite, gypsarenite, and selenite. The salt lakes are classified by age and hydrologic setting into (1) coastal salinas which are Holocene seawater-fed ground water lakes, and (2) continental playas which are late Pleistocene endorheic basins. A study of the relations between coastal salina hydrology and the associated gypsum deposition has shown that different types of gypsum form under distinct hydrologic regimes. As the hydrology above a coastal salina depositional surface changes through time, so does the type of gypsum deposited. Application of a gypsum depositional model derived f om a study of the coastal salina gypsum to those parts of a continental-playa gypsum unit where deposition is no longer occurring confirms the applicability of the model to non-salina gypsum deposits. End_of_Article - Last_Page 640------------