What geophysical technique is most suitable for investigating a skarn?

The most suitable geophysical technique for investigating a skarn is magnetics. Skarns are typically formed through the metamorphism of carbonate-rich rocks in the presence of fluid enrichment from intruding igneous bodies, which often alters their mineral composition. This alteration can result in the concentration of magnetic minerals, making magnetics particularly effective for detecting these geological formations.

The magnetic method takes advantage of anomalies associated with the magnetic susceptibility of different rock types and can help delineate the extent and boundaries of skarn deposits. Since skarns often have a complex mineralogy, variations in magnetic properties can indicate the presence of sulfide minerals that are often associated with ore deposits.

In contrast, the other techniques have limitations in this context. Gravity primarily detects density variations, which may not be as effective in differentiating skarn from surrounding rock types if the density contrast is minimal. Seismic reflection and refraction methods are better suited to mapping larger-scale structures and stratigraphy rather than localized, small-scale alterations typical of skarns. Therefore, magnetic surveys provide the best insight into locating and characterizing skarn deposits due to their sensitivity to the magnetic properties of altered rocks.