摘要
本文描述了在大别山高压变质杂岩中新近发现的石榴硬玉石英岩的岩石学特征。对高压指示性矿物硬玉的物理性质、光学性质、化学成分及结构进行了精确测定和研究,认为石榴硬玉石英岩与柯石英榴辉岩形成于同一高温超高压物理化学条件,硬玉的出现主要受控于原岩特定的化学成分。
Garnet-jadeite quartzite was discovered in high-pressure metamorphic complexes in theDabie Mountain region.Quartz pseudomorph after coesite exists as inclusions in jadeite andgarnet in the rocks.The jadeite analyzed accounts for 84mol% with a few augite and acmitemolecules.Main physical and optical properties are:Mohs' hardnss=6.962,specific gravity =3.395,indices of refraction α= 1.6664,β= 1.6547,γ= 1.6534,and (+)2V= 74°.The cell para-meters obtained by X-ray powder diffraction analysis are a=9.4699nm b=8.5988nm,c= 5.2159nm,β= 107°21′and V=405.4048nm^3.The infrared spectrum of jadeite is consis-tent with that of standard jadeite.Petrological work indicates that both garnet-jadeite quart-zite and coesite eclogite have undergone the same high-temperature and ultrahigh-pressuremetamorphism at 647-755℃ and 2.8-3.5 GPa.The formation of jadeiteis controlled by the specific chemical composition of the protolith.
出处
《矿物学报》
CAS
CSCD
北大核心
1993年第4期341-345,共5页
Acta Mineralogica Sinica
基金
国家自然科学基金
关键词
变质岩
杂岩
硬玉
大别山
jadeite,garnet-jadeite
quartzite
ultrahigh-pressure
Dabie Mountain
