Tanami EW 5ZA - Th equivalent concentration grid (AWAGS)

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.This radiometric thorium grid has a cell size of 0.00018 degrees (approximately 20m) and shows thorium element concentration of the NTGS Tanami EW 5ZA Region Detailed Airborne Magnetic Radiometric and Digital Elevation Survey, NT, 2018 in units of parts per million (or ppm). The data used to produce this grid was acquired in 2018 by the NT Government, and consisted of 1547 line-kilometres of data at 100m 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），又称伽马射线能谱法（gamma-ray spectrometric method），通过检测地表附近的伽马射线自然变化量，反映钾（K）、铀（U）与钍（Th）的天然放射性衰变所产生的辐射信号。所采集的数据将经标准化流程处理，确保记录的响应信号仅来源于地下岩石。经处理得到的数据集可通过解译以揭示地下地质构造特征。经处理的数据将由GA地球物理学家开展质量核验，确保GA发布的最终数据满足应用要求。本次发布的钍元素放射性测量网格单元尺寸为0.00018度（约20米），展示了2018年北领地（Northern Territory，NT）NTGS塔纳米（Tanami）EW 5ZA区域详细航空磁测与放射性测量及数字高程调查项目中的钍元素浓度，单位为百万分率（ppm）。本网格所用数据由北领地政府于2018年采集，总测线长度达1547线公里，测线间距为100米，飞行离地高度为60米。为约束网格中的长波长信号，本次处理引入了独立数据集——全澳航空地球物理调查（Australia-wide Airborne Geophysical Survey，AWAGS）航空磁测数据，以校准本次测量网格的基准水平。