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Modelling Fluid Evolution in Ore-Forming Systems

Detailed PIXE analysis, using the CSIRO-GEMOC Nuclear Microprobe, of brine fluid inclusions which trap the more primitive fluids exsolved from crystallising intrusives provides starting compositions for modelling the formation of ore deposits in the surrounding area.

Modelling of progressive cooling of the brine composition, given by PIXE analysis of brine fluid inclusions in the Yankee Lode quartz, with addition of meteoric water, predicts the sequence of ore deposition (right to left) from cassiterite, through arsenopyrite, chalcopyrite, galena and sphalerite, to pyrite in the country rock.

This trend is in general agreement with the regional distribution of Sn, As and base metal deposits away from the centre of the intrusion, and helps to explain the detailed zonation of ore deposits in the Mole Granite of the New England district of eastern Australia (Heinrich and Ryan, 1992).

For further information contact: Dr. Chris Ryan via email: (

+61-2-9490 8673
+61-2-9490 8909

CSIRO Exploration and Mining
PO Box 136
North Ryde NSW 2113

CSIRO-GEMOC Nuclear Microprobe
CSIRO Exploration and Mining


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