Permo‐Carboniferous gold epoch of northeast Queensland∗

Tables 3 and 4 [indicated by an asterisk (∗) in the text and listed at the end of the paper] are Supplementary Papers lodged with the National Library of Australia (Manuscript Section); copies may be obtained from the Business Manager, Geological Society of Australia.

Abstract

The ⁴⁰Ar/³⁹Ar and U‐Pb methods of isotopic dating have been used to determine the age of alteration minerals and host rocks from a number of Permo‐Carboniferous Au deposits in the Tasman Fold Belt system of northeast Queensland. There was a continuum in porphyry‐style Au mineralisation from ca 330 to 290 Ma, which post‐dates epithermal Au in the Eastern Basin sequence of the Drummond Basin. Porphyry‐style Au at Kidston, and the Buck Reef, Ravenswood, formed at ca 330 Ma. The Red Dome and Mungana skarns were deposited at ca 320–310 Ma and ca 310 Ma, respectively. The Au mineralisation at Mt Wright, and in the quartz‐sulfide veins, Ravenswood, was emplaced at ca 310–305 Ma. The youngest porphyry‐style Au deposit is Mt Leyshon, which probably formed at ca 290 Ma. Where high‐level intrusions are associated with Au, magmatism and mineralisation are, in general, essentially coeval. The age of the host rocks to the Permo‐Carboniferous Au deposits is variable, and may be more than 150 million years older than the mineralisation. The plutonic‐style Au deposit at Charters Towers is significantly older than the porphyry systems, and formed at ca 414Ma.

Key words:

• argon‐argon dating
• gold deposits
• mineralisation
• uranium‐thorium‐lead dating

Notes

Tables 3 and 4 [indicated by an asterisk (∗) in the text and listed at the end of the paper] are Supplementary Papers lodged with the National Library of Australia (Manuscript Section); copies may be obtained from the Business Manager, Geological Society of Australia.

Present address: Coal and Mineral Industries Division, Department of Primary Industries and Energy, GPO Box 858, Canberra, ACT 2601, Australia.