b'Geophysics in the surveysNewsGeological Survey of South Australia: The GCAS reaches another major milestoneall survey data and value-added data packages delivered!The 1.6 million line-kilometre Gawlertotal magnetic intensity (TMI) datahas worked closely with four survey Craton Airborne Survey (GCAS) began(Figure1), but it is on enhancementacquisition contractors engaged in 2017, and has been systematicallyof that TMI data that the advantagesduring the life of the acquisition and delivering new high quality magnetic,are more noticeably articulated. Manyprocessing to ensure that rigorous data radiometric and elevation data from itsof the image enhancements thatstandards established nationally through 16 survey regions as data acquisitionare routinely performed to enhanceGeoscience Australia and Australian state and processing were completed over thegeological interpretation are ofgeological surveys were achieved. A past two years. February 2020 markedlimited application to the previousnumber of survey specifications updated a significant milestone in the life of theTMI data across the area because offor GCAS have become the new standard, program with the release of the finalinsufficiencies and imperfectionsin line with technological improvements survey data package (Region 5, Streakyin that data together with abruptin acquisition equipment and platforms.Bay) and on 2 March 2020 the final value- contrasts on passing between surveys addeddata packages and magneticof different line spacing, flyingThe Gawler Craton Airborne Survey source depth models were released. height or flight-line orientation. The advantage of consistency and closeCommunity Information webpageGCAS data were captured using 200 mline spacing also supports higher line spacing; half the line spacing of theresolution and more confident sourceThe GCAS Community Information previous 400 m regional data coverage.depth mapping from the magnetic fieldwebpage is a dedicated resource The 200 m line spacing ensures griddeddata (Foss et al, 2018). The result is andeveloped to provide near-real-data products offer a higher resolutioninternally consistent set of geophysicaltime information to landholders and (four times the resolution of thedatasets, creating image products thatstakeholders. It has been a valuable previous 400 m line spaced regionalwill merge seamlessly to provide highresource using an embedded GIS map geophysical data) and more consistentquality geological information overservice to show where aircraft were mapping of the radiometric andthe Gawler Craton, South Australiasworking during the acquisition phase of magnetic field than is available frompremier mineral producing region. the survey; provide answers to frequently the previous multi-survey coverage.asked questions and act as a one-stop-The advantages of the new surveyThe Geological Survey of SA andshop for the GCAS data. The webpage data are clear on examination of theGeoscience Australia GCAS teamcontinues in its capacity to deliver the Figure 1.A preliminary total magnetic intensity (TMI) grid merge from the 16 GCAS regions, all now available online, via SARIG and the GCAS web page.19 PREVIEW APRIL 2020'