GSNSW Exploration NSW Area S Braidwood magnetic first vd grid geodetic

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 GSNSW Exploration NSW Area S Braidwood magnetic first vd grid geodetic is a first vertical derivative of the Total Magnetic Intensity grid for the NSW DMR, Discovery 2000, Area S, Braidwood, NSW 2001.This grid has a cell size of 0.00049 degrees (approximately 50m). The grid has units of nanoTesla per km (or nT/km). The data used to produce the TMI grid was acquired in 2001 by the NSW Government, and consisted of 25736 line-kilometres of data at 250m line spacing and 60m terrain clearance. A Fast Fourier Transform (FFT) process was applied to the original grid to calculate the first vertical derivative grid.

总磁场强度（Total Magnetic Intensity，TMI）数据用于表征由地壳中成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（磁场强度高于正常值）与负异常（磁场强度低于正常值）两类，其分类取决于岩石的磁化率。该数据已通过标准流程进行处理，以确保所记录的响应仅源自地下岩石。经处理后得到的数据集可通过解译，揭示地下地质构造。经处理的数据已由GA地球物理学家开展质量核查，以确保GA发布的最终数据符合使用要求。本GSNSW勘探项目新南威尔士州（New South Wales, NSW）S区域布雷德伍德磁异常一阶垂直导数大地测量网格，是针对新南威尔士州矿产资源部（NSW DMR）"Discovery 2000"计划、S区域、布雷德伍德地区的总磁场强度网格计算得到的一阶垂直导数网格。该网格的单元尺寸为0.00049度（约合50米）。该网格的单位为纳特斯拉每千米（亦可记作nT/km）。用于生成该总磁场强度网格的数据由新南威尔士州政府于2001年采集，数据总测线长度达25736测线公里，测线间距为250米，航高为60米。已通过快速傅里叶变换（Fast Fourier Transform, FFT）算法对原始网格进行处理，以计算得到该一阶垂直导数网格。