The Sedimentary Facies and Paleogeography of the Birkhead Formation, Western Flank, Eromanga Basin
Christabel Antenero - 2014
Honours Degree of Bachelor of Science (Petroleum Geology & Geophysics)
Australian School of Petroleum
The University of Adelaide
This study focuses on the development of a depositional model for the western flank of the Birkhead Formation. Thirteen lithofacies were identified from analysing core from across the region leading to the interpretation of eight facies. Five facies associations were then able to be established based on the core results and wireline data. The five facies associations that were established are: pro-delta, delta front, delta or alluvial plain, main fluvial channels and distributary channels. The facies analysis of the Birkhead deposits was able to envisage the general distribution of the different depositional settings and its evolution through time in a series of paleogeographic maps. These maps revealed that the paleo-environment of the region comprised of an alluvial plain that was traversed by fluvial channels, and a number of extensive prograding lacustrine delta systems. The lacustrine delta systems were formed from the flooding of distributary channel banks. Eventually these lakes inundated resulting in thick shale-siltstone units to be deposited on top of the formation.
Overall, the sediments of the western flank of the Birkhead Formation were deposited in a fluvial-lacustrine-deltaic environment. This study has successfully gained a greater understanding of the depositional environments and could facilitate in predicting the distribution of reservoir and source rocks.