Many airborne surveys have been acquired by the NSW government through the NSW Exploration, Discovery 2000 and New Frontiers Initiative funding. Others have been acquired jointly with Geoscience Australia (formerly AGSO). Contained within this vector file are details on each of the surveys and some acquisition parameters, which will help locate survey data stored digitally.

Depth contours derived from the NSW Basement Elevation Model.

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.

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.

Pseudocolour image of the percentage of potassium (K%) in the upper 20 centimetres of the ground. Cooler colours indicate lower abundances of potassium and warmer colours represent higher abundances. Variations in potassium values are caused by varied mineral compositions in host rocks and soils. This statewide image was generated by merging many individual airborne radiometric surveys.

Identifies Opal Prospecting Areas for the State of NSW as defined by Part 10, Division 1, Section 220 of the Mining Act 1992 No. 29.

Location of opal fields in Lightning Ridge, NSW.

In 1994 the Lightning Ridge Mining Board determined that the title ‘Preserved Fields’ would be applied to older mining areas which would not be returned to their previous land use, adopting less strict rehabilitation standards.

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

This layer shows the boundaries of each airborne gravity survey acquired by the NSW Government. Details on the spacing and age of the gravity data within each project area are in the attributes. The information contained in this publication is based on knowledge and understanding at time of writing (April 2017). Because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date. The information contained in this publication may not be or may no longer be aligned with government policy nor does the publication indicate or imply government policy.