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Raman mapping of coesite inclusions in garnet from the Kokchetav Massif (Northern Kazakhstan)


Korsakov, AV and Hutsebaut, D and Theunissen, K and Vandenabeele, P and Stepanov, AS, Raman mapping of coesite inclusions in garnet from the Kokchetav Massif (Northern Kazakhstan), Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 68, (4) pp. 1046-1052. ISSN 1386-1425 (2007) [Refereed Article]

Copyright Statement

Copyright 2007 Elsevier

DOI: doi:10.1016/j.saa.2007.04.005


Coesite inclusions occur in a wide range of lithologies and coesite is therefore a powerful ultrahigh-pressure (UHP) indicator. The transformation of coesite to quartz is evidenced by three optically well identifiable characteristics (e.g. palisade textures, radial crack patterns, polycrystalline quartz pseudomorphs). Under overpressure monomineralic coesite (on an optical basis), lacking the above transformation characteristics may survive. Raman micro-spectroscopy was applied on monomineralic coesite inclusions in garnet porphyroblasts from diamond-bearing garnet–clinozoisite–biotite gneisses of the Barchi-Kol area (Kokchetav Massif, Northern Kazakhstan). These coesite inclusions are euhedral and display a characteristic anisotropic hallo. However, Raman maps and separate spectra of these inclusions display shifted bands for coesite and quartz. Microscopically undetectable, quartz shows on the Raman map as a thin shell around coesite inclusion. Shift of the main coesite band allows to estimate their overpressure: coesite inclusions record 0–2.4 GPa in garnet and zircon. The quartz shell remains under lower pressure 0–1.6 GPa. The possible application of coesite and quartz Raman geobarometers for UHP metamorphic rocks is discussed.

Item Details

Item Type:Refereed Article
Keywords:coesite, Raman spectroscopy, Raman mapping, Raman geobarometer, UHP metamorphism, Kokchetav Massif
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Inorganic geochemistry
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Mineral exploration
Objective Field:Diamond exploration
UTAS Author:Stepanov, AS (Mr Sasha Stepanov)
ID Code:95758
Year Published:2007
Web of Science® Times Cited:28
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2014-10-08
Last Modified:2014-11-11

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