Polymetallic Cu-Zn-Ag-Pb, Sn-W-Mo and Cu-Au-Bi mineralisation associated with I- and A-type granites in the Chillagoe region, north Queensland, Australia

Abstract

Polymetallic mineralisation of at least three major styles (Cu-Zn-Ag-Pb, Sn-W-Mo, and Cu-Au-Bi) occurs in different types of host rocks (skarns, breccias, porphyries) in the Chillagoe region of North Queensland, Australia. Relating mineralisation to the nearest plutonic rocks can give incorrect results, as a chain of overprinting events is responsible for the polymetallic mineralisation in the Chillagoe district. Of particular interest is that the spatially related granites of the Tate Batholith are mostly I-types (one Atype), but the metallogenic association includes elements normally associated with S-type granites (especially type II). This research is testing the potential genetic links between intrusions and mineralisation. It is possible that the Sn-W-Mo associations (and perhaps others) are related to metal contributions from the country rocks, rather than fluids released from intrusions. Alternately, if all these metals are derived from the granitoids, then a revision of the metallogenic connections between magma type and mineralisation is required.