Gawler Craton Airborne Survey Merge Radiometrics

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 total dose rate is due to natural sources of radiation and is computed by adding estimates of cosmic dose at ground level to the terrestrial dose. The terrestrial dose rate grid is derived as a linear combination of the filtered K, U and Th grids. A low pass filter is applied to this grid to generate the filtered total dose rate grid.This Gawler Craton Airborne Survey Merge Radiometrics has a cell size of 0.0004 degrees (approximately 41m) and shows the total dose rate of the Gawler Craton Airborne Survey Magnetic Radiometric and DEM Merge, SA, 2017-2019 survey. The data used to produce this grid was acquired in 2017-2019 by the SA Government, and consisted of 1660000 line-kilometres of data at 200m line spacing and 60m terrain clearance.

放射性测量法（radiometric method），亦称伽马能谱法（gamma-ray spectrometric method），通过探测地球表面附近的伽马射线自然变化，量化钾（K）、铀（U）及钍（Th）天然放射性衰变所产生的辐射响应。所采集的数据将通过标准流程进行预处理，以确保记录到的辐射响应仅源自地下岩石的放射性衰变。经处理得到的数据集可通过解译，揭示地下地质构造特征。经预处理的数据将由GA地球物理学家开展质量核验，以确保GA发布的最终数据符合应用需求。总剂量率源自天然辐射源，其计算方式为将地面宇宙射线剂量估算值与陆地剂量求和得到。陆地剂量率格网通过滤波后的钾、铀、钍格网的线性组合构建得到。对该格网施加低通滤波处理，即可得到滤波后的总剂量率格网。本高勒克拉通航空测量融合放射性测量数据集的格网单元尺寸为0.0004度（约41米），展示了2017-2019年南澳州（South Australia, SA）高勒克拉通航空测量磁法-放射性测量与数字高程模型（DEM）融合项目的总剂量率分布。本格网所用数据由南澳州政府于2017-2019年间采集，总测线长度达166万公里，测线间距为200米，飞行离地高度为60米。