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Long structural zones in the Archaean Yilgarn Craton, Western Australia

Langsford, N 1994 , 'Long structural zones in the Archaean Yilgarn Craton, Western Australia', Coursework Master thesis, University of Tasmania.

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Eight structural zones from 250km to 800km long, traverse the granite-greenstone
terrane of the Eastern Goldfields and Murchison districts of the Yilgam Craton. The
structural zones, herein called LSZ, (long structural zones) have been traced using
1 :500,000 geological compilations and AGSO (Australian Geological Survey
Organisation) aeromagnetic and gravity data.
LSZ are complex linear deformation zones, resulting in the reactivation of structures
formed prior to a craton wide shortening episode. Some of the pre-existing structures
are interpreted as low angle extensional features, post dating the formation of much of
the supracrustals; others as still earlier structures controlling original volcanic and
sedimentary greenstone belt architecture.
The structural corridors reactivated by the shortening event are overprinted by strikeslip
faults which formed relatively narrow shear zones within the corridors.
Most of the LSZ contain or abut linear belts of relatively coarse, immature, locally
derived elastic sediments, which have been in turn overprinted by shear zones.
Carbonate and alkali metasomatism is commonly strongly developed within the local
sediment troughs.
Numerous alkalic syenitic plugs have been intruded within and adjacent to the LSZ. At I
larger scales, several LSZ are associated with K-Th-U rare metal (W-Sn-Be-Li)rich
granitoids, or alkali rich syenites in belts up to 250km long. LSZ contain a record of the youngest events related to the evolution of the greenstonegranite
terrane; the youngest sediments, the belts of elastics; the youngest shear zones;
and the youngest intrusive suites.
LSZ are direct hosts to only a few large Yilgarn gold deposits. Several major deposits ·
occur within structures directly connected to LSZ. Although major, deeply penetrating
crustal scale structures, LSZ are not a necessary or sufficient condition for the
formation of major gold deposits in the Yilgarn.

Item Type: Thesis - Coursework Master
Authors/Creators:Langsford, N
Keywords: Rock deformation, Geology, Stratigraphic, Gold ores
Copyright Holders: The Author
Copyright Information:

Copyright 1995 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 (M.Ec.Geol.)--University of Tasmania, 1995. Includes bibliographical references (p. 102-110). 5 folded sheets in pockets at back of vol

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