Magnetic Anomaly Map of Australia, Seventh Edition, 2019 TMI RTP Greyscale Image

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 2019 Total magnetic Intensity (TMI) grid of Australia has a grid cell size of ~3 seconds of arc (approximately 80 m). This grid only includes airborne-derived TMI data for onshore and near-offshore continental areas. Since the sixth edition was released in 2015, data from 234 new surveys have been added to the database, acquired mainly by the State and Territory Geological Surveys. The new grid was derived from a re-levelling of the national magnetic grid database. The survey grids were levelled to each other, and to the Australia Wide Airborne Geophysical Survey (AWAGS), which serves as a baseline to constrain long wavelengths in the final grid. It is estimated that 33 500 000 line-kilometres of survey data were acquired to produce the 2019 grid data, about 2 000 000 line-kilometres more than for the previous edition. 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 Magnetic Anomaly Map of Australia, Seventh Edition, 2019 TMI RTP Greyscale Image is a greyscale image of the TMI grid of the Magnetic Anomaly Map of Australia, Seventh Edition, 2019.This grid in this image has a cell size of 0.00083 degrees (approximately 80m). This greyscale 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）数据用于表征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（Magnetic Anomaly）可分为正异常（磁场强度高于正常背景水平）与负异常（磁场强度低于正常背景水平），其类型取决于岩石的磁化率。2019年澳大利亚总磁场强度（TMI）网格数据的网格单元尺寸约为3角秒（近似80米）。该网格仅涵盖陆上及近岸大陆区域的航空采集TMI数据。自2015年第六版发布以来，数据库新增了234项新测量数据，此类数据主要由澳大利亚各州及领地地质调查局采集。新版网格通过对国家磁场网格数据库进行重新平差处理生成。各测量网格之间以及与作为基准的澳大利亚全域航空地球物理调查（Australia Wide Airborne Geophysical Survey, AWAGS）数据集进行平差匹配，以约束最终网格中的长波长信号。据估算，为生成2019版网格数据，共采集了3350万测线公里的测量数据，较上一版本多出约200万测线公里。数据采用标准流程进行处理，以确保记录的磁场响应仅由地下岩石引起。处理后得到的数据集可用于解译，以揭示地下地质结构。GA的地球物理学家会对处理后的数据进行质量检查，以确保GA发布的最终数据符合使用要求。《澳大利亚磁异常图（Magnetic Anomaly Map）第七版（2019年TMI极化归算（Reduction to the Pole, RTP）灰度图像）》为基于2019年第七版《澳大利亚磁异常图》TMI网格数据生成的灰度图像。该图像中的网格单元尺寸为0.00083度（近似80米）。该灰度图像展示了具有不同磁化率的地下地质体的磁响应特征，还可用于识别岩墙等构造特征。

搜集汇总

背景与挑战

背景概述

该数据集是2019年澳大利亚第七版磁异常图的灰度图像，基于总磁强度（TMI）数据，网格单元大小为约80米。数据经过处理和质控，可用于揭示地下地质结构和特征，如岩脉等。