GNG researchers are using magnetics, as one of our geophysics tools, to help delineate Aotearoa New Zealand’s supercritical geothermal resources.

There is an abundance of magnetic data available for the upper North Island, collected between 1949 and 2020. But since these data were collected using different platforms, observation heights and resolutions, our team started by collating the data and assembling this puzzle. The result is the first integrated total magnetic intensity (TMI) grid and magnetic database for this region.

A recent publicly-accessible report is a user’s guide that describes a semi-automated procedure for merging processed airborne and shipborne magnetic data. This process used three datasets which covered large areas to make a regional drape grid, and added another 37 micro-survey datasets. The report describes the data preparation, input, processing, gridding and software used to produce an integrated TMI grid of the upper North Island, New Zealand.

The processing sequence can be applied to create magnetic grids from any geographic area and is also adaptable for other potential field datasets. In GNG, we will use the magnetic information to investigate the deep crustal structure, identify magnetisation variations related to deep magmatic bodies, and to estimate the depth-to-the-bottom of a magnetic layer (i.e. the Curie point depth).