Mid-Late Holocene Development of the Mixed Carbonate Clastic System of the Faure Channel-Bank Complex and Wooramel Delta (Shark Bay, Australia)

Abstract

Registered as a World Heritage Property in 1991, Shark Bay is located on the westernmost coast of Australia, approximately 800 km north of Perth. Shark Bay has an area of around 22000 sq km, of which about two-thirds are occupied by the marine environment. Seagrass is one of the most important features that has contributed to the evolution of the marine ecosystem of Shark Bay, and in particular to the growth of the Faure Sill and juxtaposed Wooramel Delta. The presence of well-developed barrier banks, associated with a semi-arid to arid climate and a restricted water exchange produced and preserves the metahaline and the hypersaline conditions in the southern embayments of Hamelin Pool and L'Haridon Bight, providing a basis for the development of a variety of biogenic and physical structures such as microbial communities (stromatolites) and oolitic shoals. To investigate the Holocene development of the Faure Sill, remote sensing imagery analysis, shallow acoustic stratigraphy and sedimentological information (core logging, X-Ray diffraction and radiocarbon dating) were combined, in order to correlate internal architecture, sediment body morphologies and lithofacies. The analyses have revealed that the system is a channel-bank complex which consists of mixed bioclastic and quartz sediments. Bioclastic particles are mainly calcareous seagrass epiphytes, including foraminifera, coralline algae, bivalves and other constituents. The source of most quartz is from erosion of the Peron Sandstone, which forms topographic highs such as Faure and Pelican Islands, with minor amounts of terrigenous input (clay minerals) from the Wooramel Delta. Dating values, obtained with the accelerator mass spectrometer method (AMS), were used to estimate the age of the bank onset and to calculate accumulation rates in the bank and delta areas. The results indicate that the development of the bank, during Mid-Late Holocene time, has been controlled by pre-Holocene topography, seagrass and sea level fluctuations. The Faure complex is an example of a mixed clastic carbonate system that provides an opportunity to study behaviour, architecture, interaction and facies distribution for potential comparison with partial ancient analogues of hydrocarbon reservoirs in the Browse Basin, Western Australia.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015