Depth to the Mohorovičić discontinuity (Moho) interpreted and modelled by Geognostics with support from government and industry. The Moho surface is the boundary between the Earth's crust and the upper mantle. The depth to moho is a representation of the thickness of the Earth's Crust. This moho surface is derived from seismic, gravity and other geophysical datasets.

Please view Matthews and Sheldon (2024) for full description and instructions: Contact Sam at samuel.matthews@regional.nsw.gov.au if you have any difficulty accessing the paper.

Geothermal gradient model (2023) created by Geognostics with support from government and industry. The geothermal gradient describes how temperature increases with depth inside the Earth. It is expressed in degrees Celsius per kilometre (°C/km). The linear geothermal gradients are from the top of SEEBASE to the surface. These were calculated using the combined heat-flow contribution of multiple crustal heat sources including upper mantle, radiogenic upper crust, and sediment thickness. The highest calculated geothermal gradients are generally related to areas interpreted to be underlain by granitic intrusions in the basement. The composition and heat production characteristics of the granites are largely unconstrained by analyses

Depth to the Lithosphere–Asthenosphere Boundary (LAB) modelled by Geognostics with support from government, academia and industry. The LAB surface is the base of the ridgid lithosphere and the top of the ductile asthenosphere. In geothermal terms it marks a thermal and mechanical tranisition in the Earth at a temperature of 1330 °C. This surface is modelled using themal modelling (mantle heat flow, crustal heat production, thermal conductivity, Moho depth and lithospheric structure) seismic tomography, magnetotellurics, global and regional geodynamic models and tectonic context.

The Geological Survey of NSW developed a Seamless Geology of UTM Zone 56 during 2014 as part of a project to develop a seamless vector geology dataset of the best available geological mapping data covering the whole of NSW.The overarching aims of the Statewide Seamless Geology Project were to: (i) compile the different original scales, formats and rock unit naming conventions into a consistent, statewide format; (ii) edge-match the geology across existing map sheets; and (iii) interpret the basement geology under cover. The resulting geodatabase comprises a series of layers which include: (i) solid basement geology; (ii) cover rocks (defined as undeformed and unmetamorphosed); (iii) Mesozoic igneous rocks; and (iv) Cenozoic sedimentary and igneous rocks. The project was divided into 3 major stages corresponding to the UTM zones which divide New South Wales. This dataset includes the seamless geology layers from the NSW portion of UTM Zone 56 (ie.east of 150 degrees longitude to the coast).

In 2016, the Geological Survey of NSW (GSNSW) published a state-wide depth to basement 3D model (Robinson 2016, 2017). Since then, new geological and geophysical data have been released and used for the construction of basin-scale 3D geological models for the southern Thomson Orogen and the Sydney, Gunnedah and Bowen basins (Davidson 2019; Oliveira and Davidson 2019; Oliveira et al. 2019). The basement topography under these regions was modelled using constraints from drillholes, seismic, Seamless Geology, magnetics and gravity data. The results have now been incorporated into the updated Statewide 3D Basement Elevation Model reported herein.

Depth contours derived from the NSW Basement Elevation Model.

Gravity gradiometry data has been reported to the NSW government and released under the requirements of the NSW Mining Act 1992. Contained within this vector file is the location of surveys and acquisition parameters.

Isostatic residual Bouguer gravity image overlain on tilt-filtered total magnetic intensity reduced to the pole (Tilt TMI RTP) image. The image is a partially-transparent pseudocolour layer of Isostatic residual Bouguer gravity, with a histogram-equalised colour-stretch, overlain on a greyscale intensity layer of the Tilt TMI RTP, with a histogram-equalised stretch. Bouguer gravity compensates for variations in latitude, 'free-air' elevation and Bouguer correction (assuming a crustal density of 2.67 T/m³). The isostatic correction removes the effect of variations in the thickness of the Earth’s crust due to changes in topography. The tilt-angle filter of total magnetic intensity produces a local positive maximum over a magnetic source and is zero near the edge of the source, and is useful for tracing geological structure below variable depths of cover.

AEM curtains are a set of cross-sections generated using geophysical inversion to convert AEM data to conductivity (m/S) versus depth below surface (m). These data represent the conductivity of soil and rocks to a depth of about 400 m. A pseudocolour-stretch has been applied to the data. Blue represents low conductivity values and red represents high values. The colours vary due to; (1) natural variations in the electrical properties of soils, rocks, minerals and groundwater, (2) man-made structures, radio-transmissions and lightning strike and (3) AEM system artefacts.