Southern Thomson Orogen VTEM Airborne Electromagnetic Survey - Inversion Products

The Southern Thomson Orogen VTEMplus� Airborne Electromagnetic Survey was conducted by Geoscience Australia as part of a collaborative project with its partners the Geological Survey of New South Wales and the Geological Survey of Queensland. The Survey contributes to the Australian Academy of Science�s UNCOVER Initiative and Geoscience Australia�s response to this as part of the National Mineral Exploration Strategy. Geoscience Australia contracted Geotech Airborne Ltd to acquire VTEMplus� airborne electromagnetic (AEM) data over part of the Southern Thomson Orogen in Queensland and New South Wales in April and May 2014. The data were also processed by Geotech Airborne Ltd using its FullWaveForm� processing techniques. The survey is designed to assess the under-cover geology and prospectivity of the Southern Thomson Orogen around Hungerford and Eulo and straddles the New South Wales-Queensland border. The survey comprises two parts: 1. A regular regional survey on 5000 m spaced east-west flight lines totalling 3352 line km and covering an area of 16 261 km2. 2. Two regional traverses adjacent to roads totalling 915 line km. The Southern Thomson Orogen is a priority area for mineral systems research. Much of the area lies underneath cover of sedimentary basins and is a poorly-understood element of Australia�s geology. The Orogen contains Cambro-Ordovician rocks that have potential for Iron Oxide Copper-Gold (IOCG) resources, porphyry copper-gold and Volcanic-Hosted Massive Sulphide (VHMS) deposits. Survey data will add to knowledge of cover thickness and character and will inform future geological mapping in the region. Previously Released Data (Phase 1) In August 2014 the processed data from the Southern Thomson Orogen VTEMplus� AEM Survey were released in the Phase 1 data release package that is available free of charge from Geoscience Australia�s web site (see http://www.ga.gov.au/metadata-gateway/metadata/record/gcat_81852). The Phase 1 package includes the final processed electromagnetic data, waveform files, multiplots, conductivity estimates from the EM Flow� conductivity depth imaging algorithm, and an operations and processing report, all produced by the contractor Geotech Airborne Ltd. Current Release (Phase 2) This Phase 2 data release package contains results from the electromagnetic inversion of the data in the Phase 1 release. The inversion results were generated using two different types of algorithm, a deterministic regularized gradient based algorithm, which we call GALEISBS (Roach, 2010), and a reversible-jump Markov chain Monte Carlo algorithm, which we call GArjMcMC (Brodie and Sambridge, 2012; Brodie and Reid, 2013). Both algorithms assume a layered earth or 1D conductivity structure. Each airborne electromagnetic sounding is inverted independently and the results are then stitched into combined sections. The deterministic GALEISBS inversion products are available for download in four logical parts based on the type of derived product. These are zipped into the following four files: 1. galeisbs_point_located_data.zip 2. galeisbs_sections.zip 3. galeisbs_georeferenced_sections.zip 4. galeisbs_gocad_sgrids.zip The stochastic GArjMcMC inversion products are available for download in five logical parts based on the type of derived product. These are zipped into the following five files; 1. rjmcmc_point_located_data.zip 2. rjmcmc_sections.zip 3. rjmcmc_georeferenced_sections.zip 4. rjmcmc_gocad_sgrids.zip 5. rjmcmc_probability_map_plots.zip南汤姆逊造山带VTEMplus®航空电磁测量由澳大利亚地球科学局（Geoscience Australia）联合新南威尔士州地质调查局、昆士兰州地质调查局的合作项目共同实施。该测量项目隶属于澳大利亚科学院UNCOVER计划，同时作为澳大利亚地球科学局落实《国家矿产勘探战略》的组成部分。澳大利亚地球科学局委托吉泰克航空有限公司（Geotech Airborne Ltd）于2014年4月至5月间，在昆士兰州与新南威尔士州境内的南汤姆逊造山带部分区域采集VTEMplus®航空电磁（Airborne Electromagnetic, AEM）数据，并由该承包商采用全波形（FullWaveForm®）处理技术完成数据处理。 本测量旨在评估亨格福德与尤洛周边区域南汤姆逊造山带的盖层下地质特征与成矿潜力，测区横跨新南威尔士州与昆士兰州州界。本次测量包含两部分：1. 常规区域测量：采用间距5000米的东西向测线，总测线长度3352线公里，覆盖面积16261平方公里；2. 沿道路区域测线：共两条道路旁区域测线，总测线长度915线公里。 南汤姆逊造山带是矿产系统研究的优先区域，该区域大部分被沉积盆地盖层覆盖，是澳大利亚地质认知程度较低的构造单元。造山带内发育寒武-奥陶纪地层，具备氧化铁铜金（Iron Oxide Copper-Gold, IOCG）资源、斑岩型铜金矿床以及火山成因块状硫化物（Volcanic-Hosted Massive Sulphide, VHMS）矿床的成矿潜力。本次测量数据将增进对区域盖层厚度与特征的认知，为该区域未来地质填图工作提供支撑。 已发布数据（第一阶段） 2014年8月，南汤姆逊造山带VTEMplus®航空电磁测量的处理数据以第一阶段数据包形式对外发布，可从澳大利亚地球科学局官网免费获取（详见http://www.ga.gov.au/metadata-gateway/metadata/record/gcat_81852）。第一阶段数据包包含由承包商吉泰克航空有限公司生成的最终处理电磁数据、波形文件、多图件、基于EM Flow®电导率深度成像算法的电导率估算结果，以及作业与处理报告。 当前发布版本（第二阶段） 本第二阶段数据包包含第一阶段发布数据的电磁反演结果。反演结果采用两种不同算法生成：一种为确定性正则化梯度类算法，命名为GALEISBS（Roach, 2010）；另一种为可逆跳跃马尔可夫链蒙特卡洛算法，命名为GArjMcMC（Brodie and Sambridge, 2012; Brodie and Reid, 2013）。两种算法均假设地层为层状地球或一维电导率结构。每个航空电磁测深点均独立完成反演，随后将反演结果拼接为综合剖面。 确定性GALEISBS反演产品按衍生产品类型分为四个逻辑部分，打包为以下四个压缩文件： 1. galeisbs_point_located_data.zip 2. galeisbs_sections.zip 3. galeisbs_georeferenced_sections.zip 4. galeisbs_gocad_sgrids.zip 随机型GArjMcMC反演产品按衍生产品类型分为五个逻辑部分，打包为以下五个压缩文件： 1. rjmcmc_point_located_data.zip 2. rjmcmc_sections.zip 3. rjmcmc_georeferenced_sections.zip 4. rjmcmc_gocad_sgrids.zip 5. rjmcmc_probability_map_plots.zip