AAPG Foundation 2019 Grants-in-Aid Projects

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Stratigraphy and paleo-environmental evolution of the Permo-Triassic Sydney Basin, New South Wales, Australia

Abstract

The onshore Sydney Basin is a Permo-Triassic sedimentary basin in New South Wales, Australia. The basin is a major coal producer and the Late Permian coal beds are predominantly prospective for coal bed methane (Herbert and Helby, 1980; Ward and Kelly, 2013). The database utilized for this project comprises coastal outcrops and a continuous 1251-metre core (Pacific Power Hawkesbury Bunnerong DDH-1), drilled through most of the Middle Permian to Middle Triassic succession. The succeeding integration of core logging and outcrop examination offers a unique opportunity to examine the entire Permian-Triassic basin fill in detail. We aim to detail the depositional history of the basin with an emphasis on the controlling factors of tectonics and paleoclimatic variations through time, with a specific focus on the sequences hosting the coal bed methane resources. Using sequence stratigraphic specific to both Late Permian and Middle Triassic successions, as well as burial history models, this study delineates the paleoenvironment and allocyclic controls on sedimentation of the basin fill over 60 million years. Of particular interest is the understanding of the interaction between glacial, eustatic and tectonic controls on the deposition of the Lower Permian strata. Besides, tidal influence on the paleo-depositional setting and seismic controls are recognized by the sedimentary facies development and injectite study of the Middle Triassic Hawkesbury Sandstone. Novel insights are provided into the reservoir potential of the central Sydney Basin and the evolution of analogous basins in Australia.