No abstract available

Geoscience Australia conducted an absolute gravity survey during April and May 2015 in order to maintain and update the Australian Fundamental Gravity Network (AFGN). During the 2015 AFGN field campaign 35 absolute gravity readings were taken with an A10 gravity meter out of which 29 were new additions to the network. Six of the readings were taken over older AFGN stations in order to update and validate existing values. The re-measures found the previous gravity values agreed with the new A10 measurements within their stated uncertainties. Two ties were made with the CG5 gravity meter from a newly established station in order to resolve discrepancies with existing gravity values. 30 pre-existing stations were checked for their condition during this survey and 5 stations were found to be destroyed. GPS readings were taken at existing stations and their locations updated in the database as many of the old stations had poorly defined locations.

This gravity anomaly image has been generated from the Bouguer Gravity Anomaly Grid of Australia 2016. The Bouguer grid has been image enhanced and displayed as a hue-saturation-intensity (HSI) image with sun shading from the northeast. The product has been derived from observations stored in the Australian National Gravity Database (ANGD) as at February 2016 together with the 2013 New South Wales Riverina gravity survey. Out of the almost 1.8 million records in the ANGD approximately 1.4 million stations were used to generate this image. The image shows spherical cap Bouguer anomalies over onshore continental Australia. The data used in this image has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. The spherical cap Bouguer anomalies in this image are the combination of Bullard A and B corrections to the Free Air anomaly values using a density of 2670 kg/m^3.

A 3D map of the Cooper Basin region has been produced over an area of 300 x 450 km to a depth of 20 km (Figure 1). The map was constructed from 3D inversions of gravity data using geological data to constrain the inversions. It delineates regions of low density within the basement of the Cooper / Eromanga Basins that are inferred to be granitic bodies. This interpretation is supported by a spatial correlation between the modelled bodies and known granite occurrences. The map, which also delineates the 3D geometries of the Cooper and Eromanga Basins, therefore incorporates both potential heat sources and thermally insulating cover, key elements in locating a geothermal play. A smaller region of the Cooper Basin 3D map (Figure 1) has been used as a test-bed for GeoModeller's 3D thermal modelling capability. The thermal modelling described herein is a work in progress and is being carried out to test the capability of the thermal modelling component of 3D GeoModeller, as well as to test our understanding of the thermal properties of the Cooper Basin region.

No abstract available

This paper presents new interpretations of the distribution of magmatic and pre-rift rock packages in the Exmouth-Gascoyne margin, based on the integrated interpretation of two deep crustal transects with existing seismic reflection, refraction, gravity and magnetic data. Interpretations are constrained by data from sparse ODP and petroleum drilling, and dredging. There is evidence for significant accumulation of magmatic rocks and their clastic derivatives infilling extensional fault-controlled basins developed in a broad volcanic margin transition (VMT) zone between the outer Exmouth Plateau and true oceanic crust. These rocks have distinctive seismic facies in the form of Seaward Dipping Reflector Sequences (SDRS), and are dense and magnetised. Most significantly, these packages give rise to potential field anomalies that have previously been interpreted as due to seafloor spreading. Recognition of these packages in a VMT zone has implications for the recognition of the inboard edge of unequivocal oceanic crust, the Oceanic Volcanic Margin Boundary (OVMB). Notably, in the volcanic margin transition zone off the Exmouth Plateau, the main locus of igneous activity is spatially offset from a previously recognised high velocity zone, suggesting that these two phenomena may not be temporally related. Seismically imaged differences in total thinning and partitioning of thinning between upper and lower crust provide support for models of depth dependent thinning previously proposed for this margin.

No abstract available