b'Geophysics in the surveysNewsGeological Survey of New South Wales: New state-wide geophysical images for New South WalesDuring 2019 the Geological Survey ofusing the Intrepid software package.downloaded from MinView, either New South Wales (GSNSW) undertook aThis allowed grids to be levelled to thefor the whole of New South Wales or refresh of publicly available geophysicsAWAGS (https://www.ga.gov.au/about/ for a selected area, and in a variety by collating, cataloguing and quality- projects/resources/awags) Australia-wideof projections most appropriate to assuring all the company data acquiredmagnetic traverses, which accuratelydifferent areas of the state. Grids are across New South Wales. All companysample the long spatial wavelengths.available with either 25 m or 50 m cell and government airborne geophysicalWherever possible, smaller surveys weresizes, depending on the resolution surveys from the past 60 years can nowinserted into larger surveys so regionalneeded and allowing for the large file be discovered and searched throughmagnetic variations are retained. Thesize of the higher resolution grids.the GSNSW MinView web-basedinclusion of high-resolution data has mapping application, and can usuallyenabled the new state-wide images toAs part of the refresh, the state-be immediately downloaded. be gridded with a 25 m cell size ratherwide gravity grid was also updated than the previous 50 m. This providesfollowing the removal of 50 000 After completion of the refresh, over 150excellent resolution of complex anomalyolder, poor quality data points from high-quality company airborne magneticpatterns, especially when zooming intothe original grid. No company data datasets were flagged as providingcamp and prospect scales. has been incorporated into the significantly higher resolution data thangravity grid, however a new MatLab-the existing state-wide magnetic image,The new images are delivered throughbased imaging algorithm has greatly which mainly comprises regional-scalethe MinView portal, where they canimproved the presentation of the government surveys. A new merge hasbe displayed and integrated withdata. A new image of the state-wide now been created which includes open- other GSNSW datasets. Images of theisostatically corrected gravity based on file company, GSNSW and Geosciencetotal magnetic intensity (reduced tothe new grid is available on MinView. Australia surveys, and surveys flownthe pole), first vertical derivative andThe GSNSW will commence work on an by the NSW Government for the coaltilt-angle filter can be viewed online.update of the state-wide radiometrics industry (Figure 1). Magnetic grids fromImages and grids of an extendedimage in early 2021.individual surveys were merged togetherset of enhancements can be directly The new total magnetic intensity image of state-wide magnetics is shown in Figure 2. We invite all geologists and geophysicists to inspect the new images on MinView (https://minview.geoscience.nsw.gov.au/#/?lon=148.9143&lat=-32.65607&z=6&bm=bm1&l=) and download the data for incorporation into their New South Wales GIS and modelling projects.Under the NSW Mining Regulation (2016), a large amount of currently confidential company geophysical data collected before June 2016 will become open file on 1 June 2021. This will initiate another major update of the state-wide magnetic grids by adding over 100 high-quality company surveys. GSNSW will continue to update the merge in future years as more recent data becomes available.Ned Stolz Geological Survey of New South Wales Figure 1.Composition of the updated magnetic merge of NSW, coloured by survey type. ned.stolz@planning.nsw.gov.au21 PREVIEW AUGUST 2020'