On the gravity signature of Archaean greenstones in the Widgiemooltha-Tramways area, Eastern Goldfields, Western Australia

Abstract

A detailed gravity traverse is described along the Western Mining Corporation ? Australian Geological Survey Organisation (WMC-AGSO) Widgiemooltha-Tramways crustal seismic profile. Positive Bouguer anomalies of up to 20 mGal over the greenstone sequence imply that up to 3.5 km of mafic stratigraphy occur along the profile. Comparisons to the seismic data imply the presence of a felsic stratigraphic unit forming the base of the supracrustal greenstone succession. The 3-D structure of local successor basins (Black Flags and Merougil Beds) above the mafic stratigraphy are also constrained by the gravity data to a maximum vertical thickness in the order of 3 km. The Widgiemooltha granodiorite is modelled by the seismic and gravity data as a steep-sided intrusion underlain at depth (~ 3 km) by felsic greenstone stratigraphy.