Facies Analysis, Petrology and Sediment Provenance of The Neoproterozoic to Late Cambrian Amadeus Basin
Geoscience Masters Degree, 2012
University of Adelaide
This study aims to fill research gaps that show a deficiency of geological studies in sedimentology by presenting a sedimentologic study for better understanding the Neoproterozoic to late Cambrian northeastern section of the Amadeus Basin. The study focus aims to improve the current understanding of the source of sediments by the inclusion of lithofacies and petrographic analysis which assists in clarifying depositional environments interpretation and provenance in the northeast of the Amadeus Basin.
The provenance study is important because it integrates knowledge of the principle source sediment generation, transportation, deposition and early diagenesis. The interactions between texture, sediment composition and grain size provide clues to the initial state of the sediment quality before significant burial in subsurface. The provenance investigation also provides information about tectonic setting, mapping depositional systems and paleogeography reconstruction. This provenance study is also important for enabling better comprehension of the exploration possibilities within the northeast Amadeus Basin.
New data used in this project included seven thin sections, zircon age data from five samples, a sedimentologic log data and thin section descriptions from existing wells. The sedimentologic log and samples were provided by Dr. Amos. The zircon age dating and initial interpretation was carried out by Mann et al. (2012). Thin section descriptions from well completion reports were available from Santos Ltd (1988). All of these data are from the focus area in the Eastern MacDonnell, to the east of Alice Springs, northeastern area of the Amadeus Basin.
This study recognised six lithofacies types (Cm, St, Sh, Sw, Sm, Sr) from the sedimentologic log data. A repeated general coarsening-upward was very clear through combining the vertical succession of the facies associations identified in the sedimentologic log. These were interpreted as deltaic settings in the Arumbera Sandstone and Shannon Formation. The Todd River Dolomite and Giles Creek Dolomite is possibly transitional marine to deltaic-peritidal settings. Petrographic analysis in this study classified the Heavitree Quartzite as a quartz arenite, the Arumbera Sandstone and Todd River as arkoses and the Shannon Formation as dolostone. Both petrographic interpretation and QFR ternary diagrams data in this study proposed the source of these depositional units were possibly derived from the same continental block (stable craton) due to continental interior. The interpretation of zircon age data in this study from (Mann et al., 2012) and previous data by (Maidment et al., 2007) suggested that the Musgrave Province, Arunta Region and Gawler Craton were uplifted, eroded and provided sediments for Neoproterozoic to late Cambrian units in the Amadeus Basin and Centralian Superbasin.