Swain Reefs (Rockhampton), QLD, 1964 (P282), magnetic line data, AWAGS levelled

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. These line dataset from the Swain Reefs (Rockhampton), QLD, 1964 survey were acquired in 1964 by the QLD Government, and consisted of 29810 line-kilometres of data at 4800m line spacing and 150m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.

总磁场强度（Total Magnetic Intensity, TMI）数据用于量化地壳内造岩矿物成分差异所引发的地球磁场强度变化。磁异常可分为正异常（磁场强度高于正常基准水平）与负异常（磁场强度低于正常基准水平），具体取决于岩石的磁化率。该数据集通过标准化流程开展处理，以确保记录的磁场响应仅源自地下岩石。经处理后得到的数据集可通过地质解译揭示地下地质构造。GA地球物理学家会对处理后的数据进行质量核查，以确保GA发布的最终数据符合使用要求。本次数据集源自昆士兰州罗克汉普顿附近斯温暗沙1964年航磁调查，由昆士兰州政府于1964年采集，涵盖29810测线千米的数据，测线间距为4800米，飞行离地高度为150米。为压制数据中的长波长分量，研究人员采用独立数据集——全澳航空地球物理调查（Australia-wide Airborne Geophysical Survey, AWAGS）航空磁测数据——对本次航磁调查数据的基准面进行校正。本次调查数据实质上已基于AWAGS数据完成平差处理。