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Raman-Infrared (IR) Spectroscopy Study of Natural Cordierites from Kalahandi, Odisha

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Title Raman-Infrared (IR) Spectroscopy Study of Natural Cordierites from Kalahandi, Odisha
 
Creator MAJUMDAR, AS
MATHEW, A
 
Subject HIGH-GRADE METAMORPHISM
MG-CORDIERITE
ABSORPTION SPECTRA
STRUCTURAL STATES
CRYSTAL-STRUCTURE
SOLID-SOLUTIONS
SINGLE-CRYSTAL
X-RAY
FTIR MICROSPECTROSCOPY
SYNTHETIC CORDIERITE
Cordierite
Raman spectroscopy
FTIR
volatile species
Mg-Fe exchange
Odisha
 
Description A combined Raman and IR spectroscopic study has been carried out on natural cordierite samples from Kalahandi district, Odisha to understand the effect of Mg-Fe2+ exchange on Raman peak shift and to identify the volatile species within these cordierite crystals. In the field, the cordierites are hosted by silica-saturated quartz-feldspathic rocks, mafic granulites and also by the silica-undersaturated Mg-Al granulites. X-ray Diffraction (XRD), Raman spectroscopy and microprobe analyses were initially used to characterize the samples and to obtain chemical composition respectively. XRD of the gem quality cordierite reveals perfect orthorhombic symmetry, supported by Raman analyses that deduce the extent of Al-Si ordering in this mineral. Microprobe data indicate that most cordierites are Mg-rich (X-Mg = 0.93-0.94), however, a variation in Mg/Fe concentration of cordierite from different locations is observed. The samples also show high Na content that are associated with quartzo-feldspathic rocks intruded by pegmatites, than that of the Mg-Al granulites. This result suggests temperature variance in cordierite crystallization among different host rocks. Raman spectra of these cordierites define structurally resolved Raman vibrational modes where the magnitude of peak shift of most bands towards lower wavenumber than pure Mg-cordierite is proportional with Fe concentration, and are linked with the extent of Mg-Fe exchange within cordierite structure. FTIR study confirms the presence of both type-I and type-II waters along with significant amount CO2 as channel constituents, however, type-I H2O and CO2 concentrations vary within a single crystal. The FTIR spectroscopic evidence strongly supports a H2O and CO2 bearing fluid composition during crystallization of cordierite from these localities.
 
Publisher SPRINGER INDIA
 
Date 2016-01-15T10:51:49Z
2016-01-15T10:51:49Z
2015
 
Type Article
 
Identifier JOURNAL OF THE GEOLOGICAL SOCIETY OF INDIA, 86(1)80-92
0016-7622
0974-6889
http://dspace.library.iitb.ac.in/jspui/handle/100/18393
 
Language en