Discovery of moissanite in retrogressive eclogite from the Pre-pilot Hole of the Chinese Continental Scientific Drilling Project (CCSD-PP2) and its geological implication.
2007; Science Press; Linguagem: Inglês
ISSN
2095-8927
Autores Tópico(s)Methane Hydrates and Related Phenomena
ResumoThe thin-sections for retrogressive eclogite are observed by Microscope and analyzed by Raman spectrum from the Pre- pilot Hole of the Chinese Continental Scientific Drilling Project(CCSD-PP2).A series of the inclusions within garnet are recognized including moissanit,omphacite,apatite,zircon,rutile,coesite,quartz,magnesite,and magnetite,among which the moissanit is firstly found in retrogressive eclogite,and is of important implication to temperature and pressure.The Raman shifts of moissanites are typical and stable,the main shifts,secondary ones,and another two weaker ones are 786～789cm~(-1),966～977cm~(-1),and 769～781cm~(-1)and 915～918cm~(-1),respectively.The compositional zoning and mineral assemblages in garnets show that the retrogressive eclogite in CCSD-PF2 were from retrogressive metamorphism of rutile eclogite which formed in ultrahigh pressure and temperature,and the moissanite formed at the peak stage metamormism.According to the formed conditions of moissanite,that is extremely low redox state and T1000℃,P6.0GPa,and the temperature and pressure condition for eclogite calculated by mineralogical thermometer and barometer,speculate that a few eclogite in the Sulu ultrahigh pressure metamorphic belt was the result of subduction of Yangzi plate and rapid exhumation after captured moissanite,and the depth of subduction is deeper than 200 km,which equivalents to the low part of the upper mantle.
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