A study of the nature, timing, and processes in the Mount Isa lead-zinc orebodies; their relationship to adjacent copper ore-bodies and the lead-zinc systems at McArthur River, Hilton, and Mount Novit

Perkins, William George (1996) A study of the nature, timing, and processes in the Mount Isa lead-zinc orebodies; their relationship to adjacent copper ore-bodies and the lead-zinc systems at McArthur River, Hilton, and Mount Novit. PhD thesis, James Cook University of North Queensland.

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Abstract

This thesis is written in four parts, the first three of which either have been, or are intended to be submitted to joumals for publication and hence have their own individual abstracts. Part A presents the results of work on the Mount Isa lead-zinc orebodies themselves. Part B addresses the formation of the major development of fme-grained pyrite bodies at Mount Isa, incorporating some of the evidence and argument from the HYC deposit at McArthur River. Part C combines investigations of similar aspects of the mineralisation at the HYC deposit, Hilton deposit, and the non-commercial Mount Novit prospect, and attempts to draw comparisons between these systems and Mount Isa. Part D presents geochemical data for Mount Isa and Hilton deposits and discusses some of the constraints on processes of ore formation.

The central thesis is that the Mount Isa lead-zinc lodes have not formed by synsedimentary processes, as almost universally believed, but are the result of shear controlled replacement along bedding, following lithification, peak metamorphism, and the bulk of the ductile deformation. Fine-grained stratiform pyrite forms a major part of many sediment-hosted lead-zinc systems, and is universally regarded as forming in early diagenesis as a result of biogenic sulfate reduction. Stratiform pyrite at Mount Isa has characteristics suggesting it did not form early in diagenesis, but was deposited probably by abiogenic sulfate reduction, after development of both a bedding-parallel and a crosscutting cleavage. This proposed late origin of the Mount Isa fme-grained pyrite is consistent with reinterpretation of existing sulphur isotopic data that suggests that the two generations of fine-grained pyrite at HYC are hydrothermal rather than biogenic.

Timing relationships for HYC, Hilton and Mount Novit are not as diagnostic as those at Mount Isa. However, Hilton and Mount Novit appear very similar to Mount Isa in terms of timing and ore controls. HYC sulphide relationships are significantly different in that the bulk of the sulphides appear to have replaced bituminous material, rather than metasomatic carbonates and silicates as at the other three deposits. Many features suggest that the HYC sulphides are post-compaction, are younger than ubiquitous microthrust structures, and form at some stage during a post-McArthur Group compressive deformation.

Item ID: 38407
Item Type: Thesis (PhD)
Keywords: copper deposits; Cu; Hilton; lead deposits; McArthur River; Mount Isa Mine; Mount Novit; ores; Pb; zinc deposits; Zn
Additional Information:

Publications arising from this thesis are available from the Related URLs field. The publications are:

Part A: Perkins, W.G. (1997) Mount Isa lead-zinc orebodies: replacement lodes in a zoned syndeformational copper-lead-zinc system? Ore Geology Reviews, 12 (2). pp. 61-110.

Part B: Perkins, W.G. (1998) Timing of formation of Proterozoic stratiform fine-grained pyrite; post-diagenetic cleavage replacement at Mount Isa? Economic Geology, 93 (8). pp. 1153-1164.

Part C: Perkins, W.G., and Bell, T.H. (1998) Stratiform replacement lead-zinc deposits: a comparison between Mount Isa, Hilton, and McArthur River. Economic Geology, 93 (8). pp. 1190-1212.

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Date Deposited: 22 Apr 2015 01:21
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040307 Ore Deposit Petrology @ 34%
04 EARTH SCIENCES > 0403 Geology > 040311 Stratigraphy (incl Biostratigraphy and Sequence Stratigraphy) @ 33%
04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 33%
SEO Codes: 84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840102 Copper Ore Exploration @ 50%
84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840108 Zinc Ore Exploration @ 50%
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