Geochemical and stratigraphic evidence against an oceanic crust interpretation for the Tumut ‘greenstone’ occurrence

Abstract

Evidence is presented to show that the Tumut ‘greenstone’ occurrence is unlikely to be an example of Palaeozoic oceanic crust. First, new rare‐earth element analyses are unlike those obtained from oceanic tholeiites. Second, the published major‐ and trace‐element analyses of the metabasalts are not definitive of an oceanic magma type. Third, the juxtaposition of mafic volcanic rocks and ultramafic intrusives is not considered to be diagnostic of an oceanic crustal section. Fourth, the sulphide mineralization is not similar to that found in typical ophiolites such as those at Troodos in Cyprus. In the light of the presently available data the basalts could have formed in a variety of environments including island‐arc, continental‐marginal or continental.