The breakdown of diopside to(Ca,Mg)SiO_(3)perovskite–(Mg,Ca,Fe)SiO_(3)glass–(Mg,Ca)SiO_(3)glass–(Mg,Ca)SiO_(3)majorite in a melt vein the Suizhou L6 chondrite  

作　　者：Xiande Xie Xiangping Gu 

机构地区：[1]Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China [2]School of Geosciences and Info-Physics,Central South University,Changsha 410083,China

出　　处：《Acta Geochimica》2023年第2期183-194,共12页地球化学学报（英文）

摘　　要：The Suizhou meteorite is a heavily shocked and melted vein-containing L6 chondrite.It contains a minor amount of diopside with a(Ca_(0.419)Mg_(0.466)Fe_(0.088))SiO_(3)composition,and a shock-metamorphosed diopside grain associated with ringwoodite and lingunite was found in a melt vein of this meteorite.Our electron microprobe,transmission electron microscopic and Raman spectroscopic analyses revealed four silicate phases with different compositions and structures inside this shock-metamorphosed diopside grain,termed phase A,B,C and D in this paper.Phase A is identified as orthorhombic(Ca_(0.663)-Mg_(0.314))SiO_(3)-perovskite which is closely associated with phase B,the vitrified(Mg_(0.642)Ca_(0.290)Fe_(0.098))SiO_(3)perovskite.Phase D is assigned to be(Mg_(0.578)Ca_(0.414))SiO_(3)majorite which is associated with phase C,the vetrified Carich Mg-perovskite with a(Mg_(0.853)Ca_(0.167))SiO_(3)composition.Based on high-pressure and high-temperature experiments,the diopside grain in the melt vein of the Suizhou meteorite would have experienced a P–T regime of 20–24GPa and 1800–>2000℃.Such P–T conditions are high enough for the decomposition of the diopside and the formation of four different silicate phases.The orthorhombic(Ca_(0.663)Mg_(0.314))SiO_(3)perovskite found in the Suizhou L6 chondrite might be considered as the third lower-mantle silicate mineral after bridgmanite and davemaoite after the detailed analyses of its crystal structure and physical properties being completed.

关 键 词：Suizhou chondrite DIOPSIDE Shock metamorphism (Ca Mg)SiO_(3)-perovskite (Mg Ca Fe)SiO_(3)glass (Mg Ca)SiO_(3)glass (Mg Ca)SiO_(3)majorite 

分 类 号：P185.83[天文地球—天文学] P612