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Starra and trough tank : iron-formation-hosted gold-copper deposits of North-West Queensland, Australia

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Davidson, GJ (1989) Starra and trough tank : iron-formation-hosted gold-copper deposits of North-West Queensland, Australia. PhD thesis, University of Tasmania.

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Abstract

Starra and Trough Tank are stratabound Cu-Au deposits hosted by stratiform
magnetite-hematite iron formation in the Mount Isa Eastern Succession, Australia. They
are part of the rift-related Middle Proterozoic Mary Kathleen Group, deposited in a
shallow to evaporitic setting, and subsequently deformed and metamorphosed. The
location of Starra (consisting of 4 geographically separate orebodies), on the margin of a
major Greenschist facies shear zone (ore metamorphism estimated at 500 - 550° C, 3.5 -
4.5 kbar) has led to a more complex structural history than that experienced by
surrounding rocks. Both structural/metamorphic and syngenetic ore genesis models have
been proposed for the ores. Trough Tank is far less stained, but was metamorphosed to
upper Amphibolite grade (680 - 720° C, -4 kbar).
Structural events in the Starra region are identified as (1) Starra Shear
development during D1a extension, (2) peak-metamorphic D2(Main Phase) deformation,
producing upright, north-trending, isoclinal folds, (3) retrogressional left lateral strikeslip
on the Starra Shear, producing adjacent steeply-plunging medium-scale folds
(D2(Late Phase)), (4) D3 northwest-trending fold and kink domains, and (5) D4 reverse
movement on the Starra Shear and nearby Mount Dore Fault Zone.
A new stratigraphic sub-division for the base of the Staveley Formation is
proposed. Lowermost is the Harley Member, a strongly deformed chloritic unit with a
tholeiitic tuff component. This is conformably overlain by the low-Nb-Zr-Y felsic
Mariposa Creek Member, in turn conformably overlain by the Starra Iron-formation
Member, and undifferentiated calcareous metasediments. To the south and east, the
mineralised horizon strike-equivalents are massive hematitic ironstones, conglomerate-bearing
ironstone, Hamersley-style banded iron formations (BLFs), and tourmalinites, all
intercalated with shallow marine and fluvial-marine sediments. The local ore environment
is interpreted as a deeper section of the basin.

Item Type: Thesis (PhD)
Keywords: Gold ores, Copper ores, Ore deposits
Copyright Holders: The Author
Copyright Information:

Copyright 1989 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1991. Includes bibliographical references. Folded map in pocket at back of vol

Date Deposited: 09 Dec 2014 00:00
Last Modified: 11 Mar 2016 05:55
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