Geology from aeromagnetic data

Abstract

This review aims to bridge the knowledge gap between geological and geophysical communities by elucidating the interpretation of aeromagnetic data. Aeromagnetic surveys measure the Earth's magnetic field variations and provide critical insights into subsurface geology, including basins, stratigraphy, igneous rocks and structural geology. The magnetic properties of rocks make these datasets valuable for identifying anomalies associated with various rock types and their magnetic responses. However, interpreting aeromagnetic data is complex due to the diverse geological processes that influence the formation and distribution of magnetic minerals, which must then be correlated with geological phenomena and features. Despite improved data accessibility and processing, many geoscientists still find interpreting aeromagnetic data challenging, resulting in a shortage of skilled expertise for research and industry applications. Accurate interpretation necessitates a thorough understanding of data collection and processing, recognising both the insights and limitations of the methods used and understanding how data resolution impacts the scale of interpretable geological features. This review is intended to assist those grappling with these challenges and to aid the geophysical community in interpreting complex geological features.

Data treatment is explained with a focus on the reasons for specific processing methods rather than their mathematical foundations. Emphasis is placed on rock properties and their influence on aeromagnetic data expressions. The aeromagnetic expressions of common geological elements, including sedimentary, igneous, and metamorphic rocks, and their structures, such as stratigraphy and structural geometries related to folding and faulting, are explored. The discussion covers how these responses arise and how to identify them. Our explanations aim to bolster confidence in data interpretation for geologists new to aeromagnetic data and geophysicists who may not regularly interpret geological information from such data.

Finally, we present strategies and pitfalls for interpreting aeromagnetic data, discuss automated interpretation methods, and offer practical guidance to improve interpretation skills and outcomes.