Micro-Gravity for Mineral Exploration

Abstract

High definition microgravity surveys have been conducted at Fosterville in an attempt to delineate major fault structures associated with gold mineralisation in Central Victoria. More specific local gravity anomalies were also anticipated for highly prospective zones of sulphide mineralisation along the margins of the fault. Long wavelength features in the resulting data appear to be associated with the Fosterville fault but there are no obvious anomalies associated with the high level oxidezones. This result is consistent with the disseminated nature of the mineralisation within the host material and the subtle nature of any density contrasts close to the surface. However two distinct gravity anomalies have been detected to the east of the fault-line. These are associated with sulphide zones and estimates of excess mass are consistent with the geological constraints. In addition to the gravity surveys, high density magnetic images have been obtained to provide complementary data over the same area. These indicate several linear contacts identified as possible splay faults. However there is no apparent correlation with the previously identified gravity anomalies.