TY - CHAP
T1 - Diamond-Lonsdaleite-Graphite Relations Examined by Raman Mapping of Carbon Microinclusions Inside Zircon at Kumdy Kol, Kokchetav, Kazakhstan
T2 - Evidence of the Metamictization of Diamond
AU - Smith, David C.
AU - Dobrzhinetskaya, Larissa F.
AU - Godard, Gaston
AU - Green, Harry W.
PY - 2011
Y1 - 2011
N2 - This chapter brings together an enigmatic petrogenetical problem, namely the origin of micro diamonds in the Kokchetav Massif, Kazakhstan (formed from CH4, CO2, graphite, carbonate, or CxOyHz..), and a powerful analytical method, namely Raman spectrometry. Raman mapping provides valuable information on the spatial distribution of the different mineral species or different degrees of several kinds of disorder. Precise acquisition of the three key parameters of a Raman band (wave number shift, relative intensity, and bandwidth) furnishes indications of a crystal structure that differ in some way from the ideal structure. Ideal diamond has a single T2g phonon Raman band with its wave number at 1332 cm-1. An increase in pressure (P) causes Stokes Raman bands to upshift and this has been calibrated for diamond. Whereas an increase in temperature (T) causes Raman bands to downshift for precisely the opposite reason. This chapter reports spectra and maps of two contrasting polyphase carbon inclusions inside zircon. The objectives were to map out the Raman parameters in order to clarify the geometrical and disorder interrelationships between the included diamond, the graphite (when present), and the host zircon, and also to reevaluate the two principle initial hypotheses of metamictization and/or of the possible presence of lonsdaleite, the natural 2H hexagonal polytype of sp3-bonded carbon.
AB - This chapter brings together an enigmatic petrogenetical problem, namely the origin of micro diamonds in the Kokchetav Massif, Kazakhstan (formed from CH4, CO2, graphite, carbonate, or CxOyHz..), and a powerful analytical method, namely Raman spectrometry. Raman mapping provides valuable information on the spatial distribution of the different mineral species or different degrees of several kinds of disorder. Precise acquisition of the three key parameters of a Raman band (wave number shift, relative intensity, and bandwidth) furnishes indications of a crystal structure that differ in some way from the ideal structure. Ideal diamond has a single T2g phonon Raman band with its wave number at 1332 cm-1. An increase in pressure (P) causes Stokes Raman bands to upshift and this has been calibrated for diamond. Whereas an increase in temperature (T) causes Raman bands to downshift for precisely the opposite reason. This chapter reports spectra and maps of two contrasting polyphase carbon inclusions inside zircon. The objectives were to map out the Raman parameters in order to clarify the geometrical and disorder interrelationships between the included diamond, the graphite (when present), and the host zircon, and also to reevaluate the two principle initial hypotheses of metamictization and/or of the possible presence of lonsdaleite, the natural 2H hexagonal polytype of sp3-bonded carbon.
KW - Diamond
KW - Kokchetav
KW - Lonsdaleite
KW - Mapping
KW - Metamictization
KW - Polytype
KW - Raman
UR - http://www.scopus.com/inward/record.url?scp=84872127963&partnerID=8YFLogxK
U2 - 10.1016/B978-0-12-385144-4.00001-1
DO - 10.1016/B978-0-12-385144-4.00001-1
M3 - Chapter
AN - SCOPUS:84872127963
SN - 9780123851444
SP - 43
EP - 75
BT - Ultrahigh-Pressure Metamorphism
PB - Elsevier Inc.
ER -