Gawler Craton Airborne Survey Merge Magnetics - TMI pseudocolor image (AWAGS)

Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data 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 Gawler Craton Airborne Survey Merge Magnetics - TMI pseudocolor image (AWAGS) is a pseudocolour image of the TMI grid of the Gawler Craton Airborne Survey Magnetic Radiometric and DEM Merge, SA, 2017-2019 survey. The grid used to produce this image has a cell size of 0.0004 degrees (approximately 41m). The data used to produce the TMI 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. 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. This survey grid is essentially levelled to AWAGS. This pseudocolour image shows the magnetic response of subsurface features with contrasting magnetic susceptibilities. The image can also be used to locate structural features such as dykes.

总磁场强度（Total Magnetic Intensity, TMI）数据可量化由地壳内造岩矿物成分差异引发的地球磁场强度变化。根据岩石磁化率的不同，磁异常可分为正异常（磁场强度高于正常背景值）与负异常（磁场强度低于正常背景值）两类。该数据已通过标准流程处理，确保记录的响应仅源于地下岩石。处理所得数据集可用于解译地下地质结构。经GA地球物理学家质检，GA发布的最终数据均符合使用要求。
本次发布的高勒克拉通航空测量合并磁法-TMI伪彩色图像（全澳航空地球物理调查，Australia-wide Airborne Geophysical Survey, AWAGS），是2017-2019年南澳大利亚州高勒克拉通航空测量磁法、放射性测量与数字高程模型（DEM）合并数据的TMI网格伪彩色图像。用于生成该图像的网格单元尺寸为0.0004度（约41米）。生成TMI网格所用数据由南澳州政府于2017-2019年采集，包含166万测线公里的实测数据，测线间距为200米，地形离地高度为60米。
为约束网格中的长波长信号，研究团队采用独立数据集——全澳航空地球物理调查（AWAGS）航空磁测数据，对本次测量网格的基准面进行校正，该网格已基本校准至AWAGS基准。
本伪彩色图像可直观展示具有不同磁化率的地下地质体的磁响应，亦可用于识别岩脉等构造特征。