Gympie, QLD, 1987 (P542), 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 Gympie, QLD, 1987 survey were acquired in 1987 by the QLD Government, and consisted of 13720 line-kilometres of data at 1500m 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引发的地球磁场强度变化。磁异常可依据岩石磁化率特性分为正异常（场强高于正常背景场）与负异常（场强低于正常背景场）两类。本数据集通过标准处理流程完成预处理，确保所记录的磁场响应仅源于地下岩石。经处理后的数据集可用于解译地下地质构造。GA地球物理学家已对预处理后的数据开展质量核查，确保GA发布的最终数据适配实际使用需求。本次测线数据集源自1987年昆士兰州（QLD）金皮地区的航空磁测项目，由昆士兰州政府于1987年采集完成，测线总长13720千米，测线间距1500米，地形离地高度150米。为约束数据中的长波长分量，研究团队采用澳大利亚全国航空地球物理调查（Australia-wide Airborne Geophysical Survey, AWAGS）航空磁测数据作为独立参考数据集，对本次测数据的基准水平进行校正。本次测数据已基本校准至AWAGS基准。