苏北榴辉岩中水晶的形成时代及其对超高压变质岩折返的示踪意义  

Dating on the Ecl ogite-hosted Quartz Crystal and Its Significance for Tracing the Exhumation History of the UHP Belt in North Jiangsu Province

作　　者：王登红[1] 徐珏[1] 陈毓川[2] 李华芹[3] 余金杰[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质科学院,北京100037 [3]中国地质调查局宜昌地质矿产研究所,443003

出　　处：《地质学报》2003年第4期544-548,共5页Acta Geologica Sinica

基　　金：中国大陆科学钻探工程综合研究项目"超高压变质带的成矿作用及其动力学背景";国家"973项目"(编号 G19990432)的成果

摘　　要：江苏东海水晶以其晶体粒大和产量巨大而闻名,在地质上也因其产于高压超高压变质带而独具特色。在对大别—苏鲁超高压变质带的区域成矿作用进行研究和对中国大陆科学钻探工程(CCSD)主孔岩心进行编录的过程中,认识到超高压带存在着超低压成矿现象,包括中国最主要的水晶矿床成矿带在内的许多矿床都可能是在超高压变质之后退变质结束阶段的超低压环境中形成的,对水晶进行流体包裹体的Rb-Sr等时线年代学研究,获得208 Ma的等时线年龄,表明成矿时代为印支期。该年代可视为超高压变质带折返并经历了退变质之后而“稳定”下来的时间。The quartz crystals mined from Donghai, Jiangsu Province, are famous for its large size of crystal, large amount of production, which occupy half of the total production in China. It is also unique for its occurrence within ultra-high pressure metamorphic belt. Based on the logging for the Chinese Continental Scientific Drilling cores and the comparison study on the regional metallogenic regularity, this paper suggests that there exists ultra-low pressure mineralization in the Sulu-Dabie high-ultrahigh pressure metamorphic belt. The existing of vugh within eclogite, quartz vein infilling tension fissures, and the leaking of slurry during the drilling process indicate that there exists ultra-low pressure condition for mineralization. Geochronological study on fluid-inclusions within quartz from eclogites by Rb-Sr method gives a 208±22 Ma isochron age, favoring for the idea that most of the famous quartz crystals in Donghai, China, were formed at Triassic and under the ultra-low pressure condition after the UHP metamorphic belt forming and exhumation.

关 键 词：榴辉岩 水晶矿床 同位素定年 大别-苏鲁变质带 CCSD 

分 类 号：P588.3[天文地球—岩石学]