b'AEGC 2021Short abstractsBryah and Yerrida Basins provide an opportunity to evaluate thewhich host the deposit were looked at more in depth as well. electromagnetic responses from the near surface and deeperPreviously collected geophysical surveys, surficial mapping sedimentary basin packages. In this research we produce new 3Defforts, borehole logs, petrophysics, and local perspective MT and 1D AEM inversions of these survey responses and jointlywere all considered in the modelling process. Using this interpret the two inversion types in conjunction with recentinformation, 2D cross sections were created of the survey area. geological interpretations of the Bryah and Yerrida Basins. TheThese sections were employed to match geophysics first and new MT and AEM inversions resolve detailed local-scale faultingelucidate what could be modellable. These sections were then and folding of the Yerrida Basin sediments, and the northernused to derive a 3D geological model that was supported by contact of the Bryah and Yerrida Basins with the Archean Marymiageophysical data rather than derived from it. This model was Inlier as a resistor where previous regional-scale MT results haveinverted to investigate the optimized subsurface structure. The recovered this contact as a conductive linear feature. However,final model and inversion had mixed results. While a regional inversions over potentially conductive shales and siltstonesmodel could not be derived, BPAB fault and the Archibald within the Bryah Basin are inconclusive due the geological andSettlement formation were discerned to a reasonable degree. electrical complexity of the deformed Bryah Basin sediments,The Archibald Settlement formation had a distinct contrast which are poorly resolved in the new 3D MT inversions. with the surrounding units which was clear in the inverted data. BPAB fault was found to have a steep (70-80) westward 69: A method for the downward continuation of gravitydip, unlike previous research which suggested a near vertical data using Pad approximation or eastward dip. It is recommended that a more extensive survey be conducted with the express purpose of constraining Dr Chong Zhang, Prof Qingtian L, Dr Wenna Zhou and Profthe fault. An E-W seismic survey would provide both Jiayong Yan overburden thickness and fault structure over Nash Creek.Downward continuation which can enhance weak information of the data is useful to process gravity anomaly data. Because of78: Vertically integrated geoscientific data at the its inherent instability, methods that are performed directly inGeological Survey of New South Walesthe wavenumber or the space domain are not popular anymore. We present a stable and accurate downward continuationDr Ned Stolz 1method of gravity anomaly data using Pad approximation1 ASEGexpansion with the derivatives calculated by the ISVD method in the wavenumber and space domains. Because the PadThe Geological Survey of New South Wales (GSNSW) has a approximation is a sum of polynomials in the formation of avertically integrated structure for geophysics data and products. rational function, whose possible degree is infinite, we limitRaw geophysics data are directly acquired through regional scale the highest degree for downward continuation. Apart fromsurveys such as the Cobar AEM; statewide and national surveys the Pad method with the derivatives calculated by the ISVDsuch as AusLAMP; laboratory measurement of petrophysics method, the Taylor method with the derivatives calculated byproperties; and harvesting of industry geophysical data the FFT and the Taylor method with the derivatives calculatedsubmitted with annual exploration licence reporting. These data by the ISVD are also used for comparison in our article. Testedare compiled, quality assured and catalogued in a repository for on the synthetic model, the Pad method is more accurate thandelivery to clients via the GSNSW MinView web-based search the other two methods with the same summation degrees.and delivery tool. GSNSW geoscientists subsequently synthesise Besides, the proposed method is applied to a real examplethe data into a range of products including statewide merges, with airborne gravity data and we obtain reliable results. Itstructural interpretations, 2D and 3D models of geophysical demonstrated that the Pad approximation can be used todata and ultimately 3D geological models. This presentation will downward continue precise and stable results, which might beexplain the high-level strategy for pre-competitive geophysical used to identify geological structures of mineral systems. data delivery at GSNSW and give some examples of the latest innovative datasets, tools and products.72: 3D Modelling and synthesis of geophysical data in79: Results from the largest Airborne Electromagnetic Nash Creek, New Brunswick, Canada (AEM) survey ever flown in NSWMr Alexander Furlan 1, Mr Hernan Ugalde2,1, Mrs AlzbetaMiss Astrid Carlton 1Ondercova3 and Prof Bernd Milkereit31 ASEG1 Brock University2 Dip Geosciences In 2019 the Geological Survey of New South Wales (GSNSW) 3 University of Toronto and Geoscience Australia (GA) conducted an AEM surveyover the greater Cobar Basin. This survey was part of NSWs Hotspot geophysical exploration has passed its zenith. Incontribution to the National Drilling Initiative (NDI) of areas like New Brunswick, where this exploration style hasthe MinEx Cooperative Research Centre.The NDI aims to been successful, deposits with a more complex signatureimprove geological knowledge and define the potential for have been left behind. Using improved computationalmineral systems in five areas across NSW that are undercover power and geophysical modelling, deposits like those foundextensions of known mineralised terranes. The Cobar survey at Nash Creek can be reinvestigated. Nash Creek hosts ais the largest AEM survey ever flown in NSW, covering an area Zn-Pb-Ag deposit on the western limb of the Jacquet Riverof 19,000 km2, equivalent to two and a half times the Greater Syncline and is truncated by the N-S trending Black PointSydney area. Under the guidance of experts from GA, an team Arleau Brook (BPAB) Fault. While regional mapping was theof GSNSW geoscientists has interpreted these data. They have goal, the Archibald Settlement and Sunnyside formationsmapped conductive saprolite, faults, aquifers, groundwater, 73 PREVIEW AUGUST 2021'