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Does tungsten availability control the presence of tungsten in turbidite-hosted orogenic gold mineralization? Evidence from the meguma and Bendigo-Ballarat Terranes

Citation

Cave, BJ and Large, RR and White, CE and McKnight, S, Does tungsten availability control the presence of tungsten in turbidite-hosted orogenic gold mineralization? Evidence from the meguma and Bendigo-Ballarat Terranes, Canadian Mineralogist, 55, (6) pp. 973-999. ISSN 0008-4476 (2017) [Refereed Article]


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Copyright Statement

Copyright 2017 Mineralogical Association of Canada

DOI: doi:10.3749/canmin.1600088

Abstract

Turbidite-hosted orogenic Au deposits are commonly enriched in W, along with a variety of other trace elements. A mineralogical source for W has recently been shown in the Otago Schist of southern New Zealand (Cave et al. 2016), with detrital rutile in the metasedimentary rocks recrystallizing to metamorphic titanite and making W available to be mobilized from the rock mass. In this study, we investigate the availability of W through prograde metamorphic mineral recrystallization in two additional turbidite-hosted orogenic Au provinces, one containing orogenic Au mineralization with associated subordinate W (Meguma Terrane, Canada), and the other containing orogenic Au mineralization without associated W (Bendigo-Ballarat Terrane, Australia). This was undertaken to assess whether W availability during prograde metamorphism is a key process in controlling the presence of W in turbidite-hosted orogenic Au mineralization. Like the Otago Schist, in both terranes detrital rutile is identified as being the most important host mineral for W in the lowest metamorphic grade rocks, and its prograde metamorphic recrystallization (to ilmenite) makes significant amounts of W available for mobilization (0.65 and 1.85 g of W per tonne of rock from the Goldenville and Halifax groups of the Meguma Terrane, respectively, and 0.16 g of W per tonne of rock from the Castlemaine Group of the Bendigo-Ballarat Terrane). This release of W in the Meguma Terrane is likely the source of W in these orogenic Au deposits. The lack of W in the orogenic Au deposits of the Bendigo-Ballarat Terrane suggests that W availability is not the only process controlling the presence of W minerals in turbidite-hosted orogenic Au mineralization. Alternatively, it might reflect a lower greenschist facies metasedimentary (Castlemaine Group) source for these deposits (i.e., a lower metamorphic grade source than the rutile to ilmenite conversion), as has been previously suggested.

Item Details

Item Type:Refereed Article
Keywords:Bendigo-Ballarat Terrane, coupled dissolution-re-precipitation processes, ilmenite, Meguma Terrane, metal availability, metals source, mineral recrystallization, orogenic gold, rutile, tungsten
Research Division:Earth Sciences
Research Group:Geology
Research Field:Volcanology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Cave, BJ (Mr Ben Cave)
Author:Large, RR (Professor Ross Large)
ID Code:126655
Year Published:2017
Deposited By:CODES ARC
Deposited On:2018-06-20
Last Modified:2018-09-18
Downloads:0

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