Mapping a coastal transition in braided systems: an example from the Precipice Sandstone,Surat Basin |
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Authors: | V Bianchi F Zhou D Pistellato M Martin S Boccardo J Esterle |
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Institution: | 1. School of Earth and Environmental Sciences, University of Queensland, Brisbane, 4072 QLD, Australia;2. WestSide Corporation, 300 Queen Street, Brisbane, 4000 QLD, Australia;3. Department of Geosciences, University of Padua, Padua 35121, Italy |
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Abstract: | The Precipice Sandstone is traditionally interpreted as a braided fluvial deposit that transitions upwards into meandering channel deposits responding to a rise in base level that eventually deposits the overlying alluvial to lacustrine Evergreen Formation. This study found sedimentary evidence of tidal to marine influence within the Precipice Sandstone coincident with avulsion and diversion of the system from southward to northward-flowing channels as the system was transgressed. The north-flowing channels are interpreted to debouch into a shallow restricted marine embayment with tide and wave influence, which provides an alternative insight into this unit and suggests a Lower Jurassic north or northeasterly marine connection. The Precipice Sandstone is a regional aquifer, in places hosts hydrocarbons and has been considered as a storage unit for CO2 geosequestration. Outcrop analogues can provide geometries to accompany facies interpreted from sedimentary structures that are observable in core, to assist in characterising reservoir heterogeneity. |
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Keywords: | Lower Jurassic Precipice Sandstone facies analysis paleogeography coastal transition braided |
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