Gairdner - Th equivalent concentration grid (AWAGS, no nasvd)

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. The Geological Survey of South Australia commissioned the Gawler Craton Airborne Survey (GCAS) as part of the PACE Copper initiative. The airborne geophysical survey was flown over parts of the Gawler Craton in South Australia. The program was designed to capture new baseline geoscientific data to provide further information on the geological context and setting of the area for mineral systems (http://energymining.sa.gov.au/minerals/geoscience/pace_copper/gawler_craton_airborne_survey). This radiometric thorium grid has a cell size of 0.0004 degrees (approximately 41m) and shows thorium element concentration of the Gairdner Airborne Magnetic Radiometric and DEM survey, SA, 2018 in units of parts per million (or ppm). The data used to produce this grid was acquired in 2018 by the SA Government, and consisted of 104788 line-kilometres of data at 200m line spacing and 60m terrain clearance. To constrain long wavelengths in the grid, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey grid.

放射性测量法（radiometric method），或称伽马射线能谱法（gamma-ray spectrometric method），通过探测地球表面附近因钾（K）、铀（U）和钍（Th）的自然放射性衰变所产生的伽马射线，测量其天然变化。采集所得的数据需通过标准流程处理，以确保记录的响应仅源于地下岩石。经处理得到的数据集可通过解译，揭示地下地质构造。
处理后的数据将由GA地质物理学家开展质量校验，确保GA发布的最终数据满足实际使用需求。南澳大利亚地质调查局（Geological Survey of South Australia）作为PACE铜矿倡议（PACE Copper initiative）的一部分，委托开展了高勒克拉通航空测量（Gawler Craton Airborne Survey, GCAS）项目。本次航空地球物理测量飞行覆盖了南澳大利亚境内高勒克拉通的部分区域，旨在获取全新的基础地球科学数据，为该区域成矿系统的地质背景与成矿环境提供更多参考信息（http://energymining.sa.gov.au/minerals/geoscience/pace_copper/gawler_craton_airborne_survey）。
本次发布的放射性钍网格（radiometric thorium grid）像元分辨率为0.0004度（约合41米），展示了2018年南澳大利亚盖尔德纳航空磁测、放射能谱与数字高程模型（DEM）调查中的钍元素浓度，单位为百万分率（parts per million, ppm）。用于生成该网格的数据由南澳政府于2018年采集，涵盖总长度达104788测线公里的观测数据，测线间距为200米，飞行地形离地高度为60米。为约束网格中的长波长信号，本次研究采用了全澳航空地球物理测量（Australia-wide Airborne Geophysical Survey, AWAGS）的航空磁测数据作为测量网格的基准面控制数据源。