Magnetic fields reduction to pseudo-gravity anomalies using multi-scale windows in the condition of non-uniform property and its application to searching for DSO

The Direct-Shipping Ore (DSO) is a kind of high-grade iron-rich ore. The Sokoman iron formation with low iron content is of high density and strong magnetism, causing high gravity and magnetic anomalies in the Schefferville mining district, central Labrador Trough in Canada. While the leached enrichment of hematite and goethite (also called DSO) with high iron content is featured by high density and weak magnetism, causing only high gravity anomalies. Conventional filter algorithms cannot extract the magnetic and gravity anomalies arising from DSO. Based on the Poisson equation, we propose a magnetic reduction to the pseudo-gravity anomaly. It transforms magnetic fields into gravity anomalies, then compares the results with gravity observations. The residual gravity anomalies arising from only high-density and non-magnetic DSO are derived. The residual anomalies are interpreted by density inversion and 2. 5D interactive inversion. Although the Poisson formula was proposed for a long time, it is used only in qualitative analysis of gravity and magnetic data so far. This paper derives classical Poisson formula in the condition of non-uniform density and magnetic properties, then realizes its process, and presents magnetic field reduction to the gravity field using multi-scale linear regression analysis by moving-windows. The principles of mathematics in this formula can quantify the magnetic and gravity inversion and interpretation. Finally, the pseudo-gravity reduction using multi-scale linear regression analysis by moving-windows is adopted to successfully delineate the DSO with high-density and low magnetism from the Sokoman iron formation in the Schefferville mining district, central Labrador Trough in Canada.