PESA WA : Evening talk – Sedimentology of the Gascoyne river. An analogy for the Mungaroo.
Thursday, 22 April @ 6:00 pm - 8:15 pm (Australia/Perth time)Free – $30
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The Gascoyne Delta, Western Australia – a wave-dominated, tide-influenced, ephemeral flood-prone fluvial system along a dryland coast; a useful partial-analogue for facies juxtaposition in ancient deltaic reservoirs of the North West Shelf.
Simon C. Lang1 & Robert Seggie2
1 Centre for Energy Geoscience, School of Earth Science, University of Western Australia, Perth, Australia. firstname.lastname@example.org
- Robert Seggie, SeggieGeoscience, Nedlands, Perth, Australia. email@example.com
Marine deltas are shaped by the dominance of fluvial outflow (F) relative to the influence of waves (W) and tides (T) that in turn control facies distribution. However, in dryland fluvio-deltaic systems, the rivers typically flow only following ephemeral or seasonal flooding events (i.e., a few weeks of the year either following cyclones or winter storms), but replenish sands and mud to the delta front.
The Gascoyne, Ashburton, and de Grey river deltas are the subject of a long-term project to study the influence of increasing tidal range and wave power on the facies distribution of the arid to semi-arid coast of Western Australia, especially the role of distributary channel avulsion and how they build larger distributary fluvial systems and the associated spread of subaqueous distributary mouth bars and in some cases subaerial or inter-tidal terminal splays.
This presentation will focus on the Gascoyne delta (prior to the planned PESA field trip). It will summarise the main patterns of Quaternary sedimentary facies and depositional processes, based on satellite image-derived bathymetry and recent major flooding, LIDAR derived digital elevation models, ground penetrating radar, auger holes and river-bank outcrops.
Ideas will be presented on how the Gascoyne delta can be used as a training dataset for teaching the next generation of geoscientists on how to generate conceptual geological models for reservoir/aquifer & seal modelling, the potential ranges of uncertainty, and compensating for the wide array of local differences (in this case specifically dryland processes). The Gascoyne system has already been useful for understanding aspects of the Late Triassic Mungaroo and Early Jurassic Plover reservoirs for exploration, development & production on the North West Shelf of Australia. It can be deployed (with caveats) to many other fluvial-deltaic reservoir systems. It can also be useful for modelling SEDEX copper mineralization plays in redbed delta settings.
Furthermore, this study improves understanding of geological-scale coastal changes during the Icehouse conditions of the Quaternary, and offers lessons for predicting climate-change impact.
Thursday 22nd April March 6pm (for talk start at 6.45pm)
PESA Members: $15.00 (Members must Log on to the PESA website to see the member prices)
PESA Students Members: Free (registration is essential)
Bookings close 12 noon for venue and catering purposes.
Catering supported by Business Events Perth