Speakers: Peter Downes and David Tilley

Abstract

The Nymagee mineral system study in central NSW is the recently completed Geological Survey of New South Wales project to update the geological, geochronological, geochemical and mineral system framework for the Nymagee 250 000 map sheet and adjacent areas.
As part of the project a comprehensive program of dating of granites, volcanic units and mineralisation was undertaken together with the collection of new S-isotope and Pb-isotope data. In addition, the volcanic setting of the Mount Hope Group was reassessed in the light of recent advances in the understanding of volcanic rocks and the palaeontological controls to the stratigraphy were reviewed.
Other studies undertaken as part of the project include the systematic mapping of alteration in drill core from 15 prospects using the GSNSW HyLogger spectral scanner based at our Londonderry core facility.

The preliminary results from the project include the highlighting of a major magmatic event between 427 and 420 Ma, that major deformation in the area occurred during the Middle Devonian, the identification of magmatic-, reduced seawater sulfate (basinal)- and mixed-sulfur isotope reservoirs contributing to mineralisation, a revised basement interpretation and the identification of distinct coherent rhyolites units (flows and/or high level intrusions/domes) within the Mount Halfway Volcanics with a number of possible volcanic centres also being identified and the reinterpretation of the metallogenic potential of the Devonian units along the western edge of the study area.
These and other results will be presented during the evening.
March 2015

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