--> Abstract: Diagenetic Dolomite Formation in a Holocene Evaporitic Lake, by L. Coshell, M. Rosen, J. Scott, and J. V. Turner; #91004 (1991)

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Diagenetic Dolomite Formation in a Holocene Evaporitic Lake

COSHELL, LEE, National Key Centre for Resource Exploration, Perth, Western Australia, MICHAEL ROSEN, CSIRO, Floreat Park, Western Australia, J. SCOTT, National Key Centre for Resource Exploration, Perth, Western Australia, and J. V. TURNER, CSIRO, Floreat Park, Western Australia

Holocene dolomite forms in the sediment of Lake Hayward, a small, permanent, hypersaline lake in the Clifton-Preston Lakeland System, Western Australia. The Clifton-Preston Lakeland System is similar in climate, geography, and sedimentology to the Coorong Region of South Australia. However, dolomite in Lake Hayward is not a primary precipitate as in the Coorong but is of diagenetic origin. The diagenetic origin can be deduced from the combination of the following criteria: (1) the dolomite occurs only below 60-70 cm from the sediment water interface; (2) dolomite occurs as luminescing cement; and (3) dolomite has pristine well-formed rhomb-shaped crystals. The source of magnesium for dolomitization is probably from the concentration of inflowing groundwater by evaporation and the sele tive removal of calcium by aragonite/calcite precipitation.

Although the mechanisms of dolomite formation in Lake Hayward are slightly different than in the Coorong, the presence of Holocene dolomite in an almost identical setting illustrates the importance of the "Coorong model" for dolomite formation in modern coastal areas.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)