The Tectonic Setting of Sulphide Nickel Deposits in the Western Australian Shield as shown by Major Gravity Lineaments
published: Jan 1, 1989
ArtNo. ESP136000302006, Price: 19.00 €
Conventional descriptions of the tectonic setting of the sulphide nickel deposits of the Western Australian Shield rely heavily on stratigraphic and petrographic data for their substance, in which they accordingly invoke the more easily seen lithologic, fold-axial and strike-fault trends as being the most significant ore controls. Of comparable, if not greater importance, are systematic transcurrent structural trends in the regional geological pattern which are much more subtle, and which therefore frequently escape the attention of an unprepared observer. They appear as cross-cutting linear features which are clearly related to centres of maximum incidence of sulphide nickel mineralization. There are various techniques for bringing these structural features into clearer synoptic view, and confirming them as expressions of the corresponding geophysical lineaments based on gravimetric and magnetic data. The Western Australian Shield is a stimulating subject for such a study because it explicitly demonstrates the relationship of clusters of sulphide nickel deposits to regional gravity lineaments and their intersections. Some regional lineaments lie "conformably" in the strike-fault direction (generally NNW) whilst others cross transcurrently in WNW, ENE and NNE directions. In these divergent roles they control the NNW trend of the Wiluna-Norseman nickel belt, as well as the positions of nickel deposits within the belt which are associated with the transcurrent lineaments crossing through it. The major gravity lineaments which characterize sulphide nickel deposits in Western Australia are considered to represent the traces of deep fundamental fracture zones exercising an environmental structural control over the formation of syngenetic and epigenetic ore deposits and their host rocks. They are considered to be systematic and part of a continental tectonic pattern reflecting the directions of a fundamental global pattern.