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The Union Reefs prospect, N.T.: Structure and geochemistry of a turbidite hosted gold deposit

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Donaldson, J (1992) The Union Reefs prospect, N.T.: Structure and geochemistry of a turbidite hosted gold deposit. Honours thesis, University of Tasmania.

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Abstract

The Union Reefs gold prospect is located approximately 15.5 km north-west of Pine
Creek, in the Northern Territory. It is hosted within the Burrell Creek Formation, a
Palaeoproterozoic turbidite sequence of the Pine Creek Geosyncline.
Two deformations have been recognised at the prospect. The first deformation
produced tight folds and a continuous slaty cleavage. The second deformation
produced long wavelength folds, mesoscopic folds, a discontinuous spaced and
crenulation cleavage, and conjugate kinks. A domal structure was produced from fold
interference.
The mineralisation event occurred during the second deformation. It is associated
with breccia zones and quartz sulphide veins, and crosscuts buck quartz veins and
sheeted quartz veins. Mineralisation consists of pyrrhotite, arsenopyrite, marcasite,
pyrite, chalcopyrite, sphalerite, galena, gold, bismuth, bismuthinite and an unidentified
phase.
Based on data derived from field observations, petrographic studies and sulphur
isotope analyses, a genetic model for gold mineralisation at the prospect is proposed.
The genetic model suggests that sulphur was derived from a mixed igneous and
sedimentary source. Gold was sourced from the sedimentary pile by fluids
convecting under elevated temperature in response to emplacement of the Allamber
Springs Granite. The convecting fluids were focussed into dilatant structures within
uplifted, fault bounded blocks and corridors. Deposition of gold is thought to be a
result of a decrease in the oxygen fugacity of the gold bearing fluid.

Item Type: Thesis (Honours)
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Date Deposited: 02 May 2012 05:52
Last Modified: 11 Mar 2016 05:55
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