Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Weinberg, R. F. Articles by Groves, D. I. Search for Related Content GeoRef GeoRef Citation

Kinematic History of the Boulder-Lefroy Shear Zone System and Controls on Associated Gold Mineralization, Yilgarn Craton, Western Australia

R. F. Weinberg^1,, P. Van der Borgh², R. J. Bateman³ and D. I. Groves⁴

¹ Centre for Global Metallogeny, University of Western Australia, Crawley, Western Australia 6009, Australia, and School of Geosciences, Monash University, Clayton, Victoria 3800, Australia
² Centre for Global Metallogeny, University of Western Australia, Crawley, Western Australia 6009, Australia
³ Mineral Exploration Research Centre, Willet Green Miller Centre, Laurentian University, Sudbury, Ontario, Canada P3E 6B5
⁴ Centre for Global Metallogeny, University of Western Australia, Crawley, Western Australia 6009, Australia

Corresponding author: e-mail, roberto.weinberg{at}sci.monash.edu.au

The Boulder-Lefroy shear zone, developed in the ca. 2.7 to 2.65 Ga Archean greenstone sequence of the Kalgoorlie terrane in the Yilgarn craton, is remarkable for the number and importance of gold deposits it hosts. These include, from south to north, the following gold districts (with tons of contained Au): St Ives (253 t), Hampton-Boulder-Jubilee (123 t), Golden Mile (1,821 t) plus Mount Charlotte (219 t), and Paddington-Broad Arrow (112 t). Detailed structural studies reveal that the shear zone system developed in two main stages, the first related to a phase of north-northwest–south-southeast–trending folding and thrusting (regional D₂) and the second related to sinistral shearing (regional D₃) that reactivated and linked the preexisting north-north-west–south-southeast–trending network of thrust planes. Sinistral movement resulted in only limited displacement (less than 12 km) and evolved from a ductile shearing in broad zone toward semibrittle shearing along narrow planes (regional D₄). The structures suggest a temporal evolution from crustal thickening during D₂ through lateral escape during D₃ to the development of brittle structures during D₄.

The Fimiston and Oroya lodes at the Golden Mile in Kalgoorlie are also exceptional in their gold endowment and associated alteration and were most likely developed during D₂. All other deposits along the shear zone system were formed within 25 m.y. of the Fimiston and Oroya lodes, late in the tectonic history of the terrane, either during D₃ or D₄. Intense mineralization within and around the shear zone resulted from multiscale focusing of mineralizing fluids. At a regional scale, fluids were focused into the shear zone system and its large anticlines which expose deeper mafic and ultramafic rocks. At a local scale, fluids were further focused into structural pathways resulting from strain-induced permeability in rocks with contrasting rheology.

This article has been cited by other articles:

				N. J. McNaughton, A. G. Mueller, and D. I. Groves The Age of the Giant Golden Mile Deposit, Kalgoorlie, Western Australia: Ion-Microprobe Zircon and Monazite U-Pb Geochronology of a Synmineralization Lamprophyre Dike Economic Geology, October 1, 2005; 100(7): 1427 - 1440. [Abstract] [Full Text] [PDF]