Abstract
AbstractHigh‐quality aeromagnetic data are important in guiding new knowledge of the solid earth in frontier regions, such as Antarctica, where these data are often among the first data collected. The difficulties of data collection in remote regions often lead to less than ideal data collection, leading to data that are sparse and four‐dimensional in nature. Standard aeromagnetic data collection procedures are optimized for the (nearly) 2‐D data that are collected in industry standard surveys. In this work we define and apply a robust magnetic data correction approach that is optimized to these four‐dimensional data. Data are corrected in three phases, with phase 1 operations on point data, correcting for spatiotemporal geomagnetic conditions, then phase 2 operations on line data, adjusting for elevation differences along and between lines and in phase 3, a line‐based leveling approach to bring lines into agreement while preserving data integrity. For a large‐scale East Antarctic survey, the overall median cross‐tie error reduction error reduction is 93%, reaching a final median error of 5 nT. Error reduction is spread evenly between phases 1 and 3. Phase 2 does not reduce error directly but permits a stronger error reduction in phase 3. Residual errors are attributed to limitations in the ability to model 4‐D geomagnetic conditions and also some limitations of the inversion process used in phase 2. Data have improved utility for geological interpretation and modeling, in particular quantitative approaches, which are enabled with less bias and more confidence.
Highlights
Since the beginnings of plate tectonic theory, observations of the Earth’s magnetic field have been essential to understanding the structure and evolution of both continents and oceans [Behrendt and Wotorson, 1970; Vine and Matthews, 1963]
Further adjustment on the basis of line-intersections would reduce these errors, but we consider that, due to the incomplete data corrections applied in phase 1 and phase 2, the data remain 4D, and so it is not valuable to pursue an exact fit through levelling
Our results show that the elevation adjustment generates notable improvement to the magnetic data, with substantially stronger and more consistent definition of the anomalies beneath the thick ice of interior Antarctica
Summary
Since the beginnings of plate tectonic theory, observations of the Earth’s magnetic field have been essential to understanding the structure and evolution of both continents and oceans [Behrendt and Wotorson, 1970; Vine and Matthews, 1963]. In other parts of the world, for example in frontier regions, data like these are not widely available either due to a lack of surveying or due to data being proprietary, and the only data available are often from large-scale reconnaissance surveys These regions are where we, in general, know least about the magnetic structure of the solid earth, and so there is a need to maximise the value of these surveys. Datasets in these regions are defined, overall, by more irregular line directions and spacings, very variable flying heights and terrain separations and by much longer time-frames of data collection
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