Ann: SER Business Review 2011 , page-17

No worries 10,

Mineralium Deposita
Volume 19, Number 4, 266-273, DOI: 10.1007/BF00204379

Ian B. Lambert, Janice Knutson,Terrence H. Donnelly,Hashem Etminan and Malcolm G. Mason



http://www.springerlink.com/content/x6836270254p618w/



The Myall Creek copper prospect is in unmetamorphosed carbonaceous dolosiltstone and sandstone at the base of the late Proterozoic (Adelaidean) Tapley Hill Formation. It contains disseminated, fine-grained chalcopyrite, zincian tennanite, bornite, chalcocite, pyrite, sphalerite and galena, and irregular to straight chalcopyrite-rich veinlets. Some ore minerals rim and/or partially replace pyrite or clastic grains. There is no evidence of hydrothermal activity. The delta34SCDT values of pyrite and the other sulfides fall in the wide range –3.6 to +44.2permil. Dolomite in both mineralised and unmineralised samples has delta13CPDB values concentrated around –3permil, and delta18OSMOW values around +25permil. It is concluded that the mineralising fluids were near-neutral brines which leached metals from the basement and early Adelaidean rocks. They entered the Tapley Hill sediments at moderately low temperatures via permeable strata and faults. The metals were precipitated by biogenic H2S, and also fixed by reaction with iron sulfides and, possibly, organic matter. Continuing ascent of brines into the mineralised strata caused breakdown of detrital feldspars and Fe-Ti oxides, and some solution-remobilisation of early-formed sulfides.

Raider