Legacy product - no abstract available

Legacy product - no abstract available

Speculation is increasing that Proterozoic eastern Australia and western Laurentia represent conjugate rift margins formed during breakup of the NUNA supercontinent and thus share a common history of rift-related basin formation and magmatism. In Australia, this history is preserved within three stacked superbasins formed over 200 Myr in the Mount Isa region (1800-1750 Ma Leichhardt, 1730-1670 Ma Calvert and 1670-1575 Ma Isa), elements of which extend as far east as Georgetown. The Mount Isa basins developed on crystalline basement of comparable (~1840 Ma) age to that underlying the Paleoproterozoic Wernecke Supergroup and Hornby Bay Basin in NW Canada which share a similar tripartite sequence stratigraphy. Sedimentation in both regions was accompanied by magmatism at 1710 Ma, further supporting the notion of a common history. Basin formation in NW Canada and Mount Isa both concluded with contractional orogenesis at ~1600 Ma. Basins along the eastern edge of Proterozoic Australia are characterised by a major influx of sediment derived from juvenile volcanic rocks at ~1655 Ma and a significant Archean input, as indicated by Nd isotopic and detrital zircon data. A source for both these modes is currently not known in Australia although similar detrital zircon populations are documented in the Hornby Bay Basin, and in the Wernecke Supergroup, and juvenile 1660-1620 Ma volcanism occurs within Hornby Bay basin NW Canada. These new data are most consistent with a northern SWEAT-like tectonic reconstruction in a NUNA assembly thus giving an important constraint on continental reconstructions that predate Rodinia.

The Ord Valley Airborne Electromagnetics (AEM) Interpretation Project was undertaken to provide information in relation to salinity and groundwater management in the Ord River Irrigation Area (ORIA), and to guide its future expansion. The project included the acquisition of 5,936 line km of AEM data acquired using the SKYTEM time domain system, the acquisition of a Light Ranging and Detection (LiDAR) survey, and complementary drilling, borehole geophysics, laboratory analysis and interpretation services. Within the limits of available bore data and the scales of airborne data acquisition, this study provided greater spatial detail on critical elements of the hydrostratigraphy in the sedimentary alluvial aquifer systems. This included the indicative 3D extent and thickness of gravel, sand, silt, clay units as well as salt stores and groundwater quality. It also produced first generation of salinity hazard maps. The AEM mapping identified discrete palaeochannels, interpreted as elements of the palaeo-Ord drainage system. Overall, the amount and extent of gravel and sand aquifers present in the study area was significantly less than previously thought, with gravel aquifers present in laterally confined palaeochannel systems. There was also several buried bedrock ridges and shallow pediments that were interpreted to reduce aquifer storage and throughflow. In the Mantinea Plain-Carlton Hill-Parry's Lagoon area, the presence of a marine sand aquifer containing very saline groundwater was confirmed. The 3D mapping provided an important framework for hydrodynamic analysis and hydrogeochemical process studies. In summary, the project demonstrated the potential for 'calibrated' AEM systems and iTEM Fast Approximate Inversion software to shorten project timelines for studies that involve the analysis and interpretation of AEM data.

The Early Cretaceous Gage Sandstone and South Perth Shale formations are a prospective reservoir-seal pair in the Vlaming Sub-basin. Plays include post-breakup pinch-outs in the Gage Sandstone with the South Perth Shale forming top seal. The Gage reservoir has porosities of 18-25% and permeabilities of 1-1340 mD. It was deposited in palaeotopographic lows of the Valanginian breakup unconformity and is the lowstand component of the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic reconstructions for the SP Supersequence were derived from mapping higher-order prograding packages and establishing changes in sea level and sediment supply. Higher resolution Gage reservoir reconstructions were based on seismic facies mapping. The Gage reservoir forms part of a sand-rich submarine fan system similar to model proposed by Richards et al (1998). It ranges from canyon confined inner fan deposits to middle fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach is applicable for detailed studies of other sedimentary basins. APPEA

Poster describing how GA made the WASANT palaeovalley map (GEOCAT #73980).

Legacy product - no abstract available

The Early Cretaceous Gage Sandstone and South Perth Shale formations are one of the most prospective reservoir-seal pairs in the Vlaming Sub-basin. Plays include post-breakup pinch-outs with the South Perth Shale forming a top seal. The Gage reservoir has porosities of 23-30% and permeabilities of 200-1800 mD and was deposited in palaeotopographic lows of the Valanginian breakup unconformity. This is overlain by the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. The palaeogeographic reconstructions for the Gage reservoir are based predominantly on the seismic facies mapping, whereas SP Sequence reconstructions are derived from mapping higher-order prograding sequences and establishing changes in sea level and sediment supply. The Gage reservoir forms part of a sand-rich submarine fan system and was deposited in water depths of > 400 m. It ranges from confined canyon fill to fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Seven palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach could be applicable for detailed studies of other sedimentary basins

New 2D seismic data acquired in the Mentelle Basin by Geoscience Australia in 2008-09 has been used for a seismic facies study of the post-rift succession. The Mentelle Basin is a large deep to ultra deep-water, frontier basin located on Australia's southwestern margin about 200 km southwest of Perth. The study focused on the post-rift sequences deposited following the breakup between Australia and Greater India. Stratigraphic wells DSDP 258 and DSDP 264 provide age and lithological constraints on the upper portion of the post-rift succession down to mid-Albian strata. The depositional environment and lithology of the older sequences are based on analysis of the seismic facies, stratal geometries and comparisons to the age equivalent units in the south Perth Basin. Fourteen seismic facies were identified based on reflection continuity, amplitude and frequency, internal reflection configuration and external geometries. They range from high continuity, high amplitude, parallel sheet facies to low continuity, low amplitude, parallel, subparallel and chaotic sheet, wedge and basin fill facies. Channel and channel fill features are common in several facies along with a mounded facies (probably contourite) and its associated ponded turbidite fill. A progradational sigmoidal to oblique wedge facies occurs at several stratigraphic levels in the section. A chaotic mound facies, probably comprising debrite deposits, has a localised distribution.

No product available. Removed from website 25/01/2019