--> Abstract: Late Cambrian to Early Ordovician Mixed Carbonate and Siliciclastic, Storm-Dominated Shelf Deposits, Eastern Warburton Basin, South Australia, by X. Sun and C. M. Griffiths; #90937 (1998).

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Abstract: Late Cambrian to Early Ordovician Mixed Carbonate and Siliciclastic, Storm-Dominated Shelf Deposits, Eastern Warburton Basin, South Australia

SUN, XIAOWEN, CEDRIC M. GRIFFITHS, NCPGG, the University of Adelaide, Australia.

Summary

A mixed carbonate and siliciclastic, storm-dominated shelf environment is interpreted from a thick subsurface carbonate-siliciclastic succession of Late Cambrian to Early Ordovician age. The environment has three components: carbonate sand shoal, storm-dominated muddy shelf, and an intermediate mixing zone. The carbonate sand shoal is recognised by oolitic, oncolitic, and bioclastic grainstone facies and also from a cylindrical gamma log signature. The muddy shelf is mainly interpreted from mudstone and shale, and laminated siltstone. A storm dominated regime is indicated by climbing ripple cross lamination in fine-grained sandstone, micro-HCS beds, and also rip-up pebbles and brecciated carbonate grainstone. Mixed carbonate and siliciclastics are believed to be of two main types. One is due to in-situ mixing either by lateral migration of carbonate sand bodies into the siliciclastic dominated shelf, or via storm transportation of carbonate grains or brecciated carbonate grainstone from the carbonate sand shoal into the muddy shelf as thin storm beds. The other is due to periodic influx of coarse quartz and feldspar sands into the carbonate shoal, forming different mixtures ranging from sandy limestone to calcareous sandstone. Recognizing and mapping the thick carbonate sand shoal complex will help locate potential carbonate reservoirs.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah