Depositional and sequence stratigraphic framework of the Neoproterozoic Wonoka Formation deposited in a suprasalt minibasin and correlation to subsalt minibasin strata at Patawarta Diapir, South Australia

C. Evelyn Gannaway
The University of Texas at El Paso, Department of Geological Sciences El Paso, Texas, USA
[email protected]

The current understanding of salt tectonics is based primarily on the analysis of subsurface geophysical data combined with scaled laboratory and computer modeling. The geophysical data is primarily seismic images that are highly limited in near-diapir resolution, particularly the subsalt-sediment interface associated with allochthonous salt sheets, which images poorly but is the setting of potentially large hydrocarbon accumulations. Patawarta Diapir is a ramping allochthonous salt sheet located in the central Flinders Ranges of South Australia. Because of the oblique plane of section, both sub- and suprasalt geometries are exposed, allowing for correlation of the shelfal mixed carbonate/siliciclastic Wonoka Formation in the previously interpreted subsalt minibasin to the suprasalt counterpart. Stratigraphic sections were measured from Patawarta Diapir through the adjacent suprasalt minibasin and extensive field mapping was conducted to identify halokinetic sequence boundaries and angular unconformities. A correlation diagram will be constructed to compare depositional environments and depositional and halokinetic sequence stratigraphy laterally across the minibasin. In addition, approximately 100 samples will be cut into thin sections for detailed petrographic analysis to correlate facies and determine difference in diagenetic history between minibasins. Understanding the development of depositional and halokinetic sequences adjacent to allochthonous salt sheets facilitates the recognition and interpretation of patterns in suprasalt strata that will allow for better assessment of potential subsalt hydrocarbon accumulations in analogous modern strata.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects