Magnetic signatures of lithologic variation, fault structures and hydrothermal mineralization: an example from the Baguio Mineral District, Luzon, Philippines

A reconnaissance ground magnetic survey was conducted in the Baguio Mineral District in northern Luzon to investigate the geophysical signatures of the different lithologic units and areas of mineralization. The magnetic-intensity contours match the varying rock types. Magnetic lows were found to correspond to the sedimentary rocks. Magnetic highs coincide with presence of intrusive bodies and the skarn/porphyry-copper deposits. This is to be expected since igneous rocks are more magnetic than sedimentary rocks. Futhermore, the skarn/porphyry copper deposits consist of an ore assemblage of which magnetite is a component. An anomalouos zone, coincident with the sedimentary and igneous rock boundary, was defined from the magnetic survey results. This sedimentary and igneous rock boundary, inferred to be a zone of high permeability, is the probable host to mineable mineral deposits. The geophysically defined anomalous area, characterized by magnetic lows, is consistent with a previously defined prospective zone of mineralization.