Gilgandra, NSW, 1979 (P453), 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 Gilgandra, NSW, 1979 survey were acquired in 1979 by the NSW Government, and consisted of 13556 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）数据用于表征地壳内造岩矿物成分差异所引发的地磁场强度变化。根据岩石磁化率的差异，磁异常可分为正异常（场强高于正常背景场）与负异常（场强低于正常背景场）。本数据集通过标准处理流程开展处理，确保记录的响应仅源自地下岩石，处理后所得数据集可用于解译地下地质结构。经GA地球物理学家开展质量检查，GA发布的最终数据均符合使用要求。本次源自新南威尔士州吉尔格兰德拉（Gilgandra, NSW）1979年调查的测线数据集，由新南威尔士州政府于1979年采集，共计包含13556测线公里的数据，测线间距为1500米，地形离地高度为150米。为约束数据中的长波长信号，本次调查采用全澳航空地球物理调查（Australia-wide Airborne Geophysical Survey, AWAGS）的航空磁测数据作为独立数据集，用于校准本次调查数据的基准面，本次调查数据已基本校准至AWAGS基准。