Mineral exploration

High-density minerals and associated material often cause positive gravity anomalies.

Gravity measurements have been used for prospect-scale mapping of shallow mineable deposits for several decades. Dense minerals such as gold, lead, porphyry copper, iron or metal sulfides can cause local increase in gravity at the surface. The method has been successfully used is many cases, often together with other geophysical methods and geological insight. Good examples have been described in Dentith and Mudge (2014).

Gravity surveys are relatively inexpensive compared to other exploration methods. Most such surveys are done traditionally with measurements on the ground and typically 50 – 200 m station spacing. Due to improvements in gravimeters like Scintrex CG-6, in positioning (GNSS) and in data processing, more precise gravity maps can be aquired with a smaller crew having lower cost than in the past. Airborne gravity and gravity gradiometry surveys are possible to carry out, but these are less precise for detailed mapping and therefore more suitable at a regional scale.

We expect increasing activity of gravity mapping in the search for the minerals, which society will need. Quad Geometrics has recently carried out a large survey in the Norwegian mountains using state-of-the art instruments and data processing.