Lithostratigraphy and Chemostratigraphy of Salt Diapir Sedimentary Inclusions: Unraveling Ediacaran Salt Tectonics in the Flinders Ranges, Australia

Author(s): Rachelle Kernen (presenter) AAPG Salt Basins TIG Founder & Chair, Women's Network Co-Chair, AAPG.

Patawarta Diapir, approximately 2-6km2 located in the Central Flinders Ranges, South Australia, has been interpreted as a single allochthonous salt sheet containing Tonian-aged igneous and layered evaporite sedimentary intrasalt inclusions derived from the Callanna Group. Using detailed field mapping, petrographic analysis, and lithostratigraphic correlation within Patawarta Diapir, five primarily silty limestone inclusions (0.5-2km2) are re-interpreted as Ediacaran-aged Wonoka Formation and Patsy Hill member of the Bonney Sandstone (Wilpena Group). The Ediacaran-aged inclusions are concentrated on the diapir’s south side where they are juxtaposed against a 1-2 km2, approximately 300-million-year older Tonian-aged Curdimurka Subgroup (Callanna Group) inclusion. The Ediacaran-aged silty carbonate inclusions in the Patawarta Diapir are interpreted to represent a suprasalt condensed section forming a carapace composed of Wonoka Formation and lower beds of the Patsy Hill member (Bonney Sandstone). Based on this geometric configuration, the Patawarta Diapir is composed of two separate salt bodies that encase the suprasalt carapace at an allosuture zone. This encasement process could have been driven by any number of factors including regional shortening during the Delamerian Orogeny, high sedimentation patterns forming local depocenters, or down-dip gravity sliding on the low-angle regional shelf. By using modern concepts in salt tectonics, this study represents the first documented example of salt tectonic encasement and the diagenetic alteration of the Ediacaran Shuram Excursion in the suprasalt strata in a diapir in the Flinders Ranges, South Australia

Bios:

Rachelle Kernen - AAPG Salt Basins TIG Founder & Chair, Women's Network Co-Chair, AAPG

Rachelle Kernen holds a B.S. in Geology from the University of Wisconsin-Oshkosh and an M.S. in Geology from New Mexico State University and a Ph.D. in Geology at the University of Texas at El Paso where her focus was to integrate salt tectonic fieldwork, seismic data, physical modeling, and geochemistry to answer complex petroleum-related questions about geological processes within salt diapirs and along the salt-sediment interface (drilling hazards). She has extensive salt tectonic seismic interpretation experience in the oil industry working for Royal Dutch Shell and BP Americas. Rachelle is passionate about the Energy Transition and DEI where she is actively changing and re-shaping organizations (volunteering for non-profits at the moment). Currently, she is Co-chair of AAPG's Women's Network, Co-Founder of AAPG's Salt Basins Technical Interest Group, and an Honorary Visiting Research Fellow at Australia's School of Petroleum and Energy Resources at the University of Adelaide.