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Variations in composition and abundance of white mica in the hydrothermal alteration system at Hellyer, Tasmania, as revealed by infrared reflectance spectroscopy

Citation

Yang, K and Huntington, JF and Gemmell, JB and Scott, KM, Variations in composition and abundance of white mica in the hydrothermal alteration system at Hellyer, Tasmania, as revealed by infrared reflectance spectroscopy, Journal of Geochemical Exploration, 108, (2) pp. 143-156. ISSN 0375-6742 (2011) [Refereed Article]


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DOI: doi:10.1016/j.gexplo.2011.01.001

Abstract

Short-wave infrared (SWIR) spectral reflectance of hydrothermally altered volcanic rocks in the footwall of the Hellyer massive sulfide deposit was measured with a portable PIMA-II infrared spectrometer. The Al–OH band was used to derive information on the octahedral Al content and the abundance of white mica (sericite) in the hydrothermal alteration and mineralization system. The range of the Al–OH band wavelength from 2192 nm to 2222 nm corresponds to the number of octahedral Al (Alvi) in white mica approximately from 3.9 to 3.0 (based on 4 octahedral cations per formula). This Alvi range represents a significant compositional variation, covering most of the compositional region between muscovite (Alvi = 4.0) and phengite (Alvi = 3.0). Furthermore, the spectral reflectance data show that the compositional variation of white mica is spatially related to hydrothermal alteration zoning, such that phengitic white mica tends to occur in 1) main upflow fluid channel, 2) intensely altered volcanic rocks, and 3) Pb–Zn mineralization, whereas muscovitic white mica was formed preferentially distal to massive sulfide mineralization on the margin of the footwall alteration system. The results suggest that the Al–OH band wavelength, and therefore the octahedral Al content, of white mica can be used as vectors to mineralization to map the hydrothermal system at Hellyer.

Item Details

Item Type:Refereed Article
Keywords:SWIR white mica hydrothermal alteration Hellyer VHMS
Research Division:Earth Sciences
Research Group:Geology
Research Field:Ore Deposit Petrology
Objective Division:Mineral Resources (excl. Energy Resources)
Objective Group:Mineral Exploration
Objective Field:Copper Ore Exploration
Author:Gemmell, JB (Professor Bruce Gemmell)
ID Code:74880
Year Published:2011
Web of Science® Times Cited:16
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2011-12-14
Last Modified:2012-04-19
Downloads:1 View Download Statistics

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