PESA SA/NT September Technical Luncheon – Thursday, September 30th: Dryland Deltas of Western Australia – from wave- to tide-dominated, ephemeral flood-prone fluvial depositional systems

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 reservoir analogue study examining the influence of increasing tidal range and wave power on the facies distribution of the arid to semi-arid coast of Western Australia,. Focus is on the role of channel avulsions, and the architecture of larger distributary fluvial systems and floodplains, their associated subaqueous distributary mouth bars and oolitic tidal-bars, and subaerial or inter-tidal terminal splays.
The main Quaternary sedimentary facies and depositional processes will be summarised (main focus on the Gascoyne delta), based on satellite image- and drone-derived bathymetry, recent flooding, LIDAR digital elevation models, ground penetrating radar, auger holes and river-bank outcrops.
Ideas will be presented on how these deltas 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). These delta systems have already been useful for understanding aspects of the Early Triassic Caley Formation at Dorado Field, many aspects of the outboard Late Triassic Mungaroo, and Early Jurassic Plover reservoirs for exploration, development & production on the North West Shelf of Australia. Key concepts can be deployed (with caveats) to many other fluvial-deltaic reservoir systems, including training images for guiding AI based modelling approaches. 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 the impact climate-change.

Event Details:

Technical Luncheon, Ayers House at 12:00pm, for a 12:30pm start. Includes a 2-course lunch and drinks.

Bookings close Monday , 27th September at 1pm. Any late bookings will incur an additional $10 fee. Strictly no walk-ins