祁连山玉石沟橄榄岩中非生物成因甲烷-石墨流体包裹体及其形成条件

Abiotic Methane Inclusions in Olivine from the Yushigou Peridotite and Their Forming Conditions

研究北祁连造山带玉石沟橄榄岩中富甲烷流体包裹体。激光拉曼光谱原位分析结果显示,这些流体包裹体主要由液态或气态CH_(4)+C(石墨)组成,次要成分为N_(2),H_(2)O,C_(2)H_(6)和C3H8,代表还原性的C-H流体形式。根据石墨的拉曼特征谱峰,利用石墨化碳质拉曼光谱(RSCM)温度计计算石墨形成温度,结果指示石墨在流体中沉淀的最低温度介于430~590℃之间,表明CH_(4)+C是非生物成因的,并形成于地幔环境。

The paper presents studies of the methane-rich fluid inclusions in the fresh peridotite from the Cambrian Yushigou ophiolite,the middle part of North Qilian Orogenic Belt.In situ analysis of laser Raman spectroscopy shows that these fluid inclusions are mainly composed of liquid or gaseous CH_(4)+C(graphite)with minor components of N_(2),H_(2)O,C_(2)H_(6) and C3H8,representing the reductive C-H fluid speciation.Based on characteristic bands of graphite,the authors carry out fluid temperature estimates using the RSCM(Raman spectroscopy of carbonaceous materials).The calculated temperatures range from 430 to 590℃,which represents the minimum temperature for precipitation of graphite and indicates that CH_(4)+C is abiotic origin and formed in the mantle environment.