湖南鲁塘石墨矿Re-Os同位素研究

doi:10.15898/j.cnki.11-2131/td.201704060050

CORC > 北京大学 > 地球与空间科学学院

	湖南鲁塘石墨矿Re-Os同位素研究; Study on the Re-Os Isotope Composition of Graphite from the Lutang Graphite Deposit in Hunan Province
	李超 ; 王登红 ; 周利敏 ; 赵鸿 ; 李欣尉 ; 屈文俊
刊名	岩矿测试
	2017
关键词	鲁塘石墨矿成因 Re-Os同位素定年 Lu tang graphite deposit genesis Re-Os isotope dating
DOI	10.15898/j.cnki.11-2131/td.201704060050
英文摘要	石墨具有较高的Re、Os含量,可望成为理想的Re-Os同位素测年对象,但迄今国内外研究较少,尤其在煤层经变质作用形成石墨过程中,其中Re-Os同位素体系的变化还有待研究.湖南鲁塘石墨矿是我国典型的隐晶质石墨矿床之一,矿体产于二叠系龙潭组煤系地层中.本文采用Carius管逆王水溶解样品,直接蒸馏、微蒸馏分离纯化Os,丙酮萃取法分离富集Re,热表面电离质谱法对鲁塘矿区石墨样品以及外围原煤进行了Re-Os同位素分析.结果表明:鲁塘石墨的Re含量为0.901 ～9.794 ng/g,Os含量为7.3～189.5 pg/g,Re-Os同位素等时线年龄为155.6±3.6 Ma,该年龄与鲁塘石墨矿东侧骑田岭岩体第二阶段中粒黑云母花岗岩锆石U-Pb年龄153 ～157 Ma一一致,表明了龙潭组煤层受到骑田岭岩体“烘烤”作用,发生热接触变质作用,使得靠近骑田岭岩体原煤变质为石墨,形成石墨矿床.通过对比石墨、原煤和骑田岭岩体Re、Os含量及比值,发现石墨中的Re、Os主要来源于原煤,并根据石墨Re-Os等时线初始(187 Os/188 Os)i值(0.686±0.032),推测骑田岭岩体在侵入煤系地层过程中,有少量具有较低187 Os/188 Os值的Os被碳质吸附.; Graphite has relatively high Re and Os contents and is an ideal mineral for Re-Os isotope dating.However,there are few studies on Re-Os dating of graphite.Particularly for the graphite which was formed by deformation of coal beds,the variation in Re-Os isotope system needs further study.The Lutang graphite deposit in Hunan is one of the typical cryptocrystalline graphite deposits in China.The orebodies are hosted in coals of the Permian Longtan Formation.In this study,the Re-Os isotopic compositions of the graphite samples from Lutang deposit and the raw coal samples from the peripheral area were analyzed by digesting sample in the Carius tube,direct distilling Os from the Carius tube,extracting Re by acetone and determining Re and Os isotopes by Negtive Thermal Ionization Mass Spectrometry.The results indicate that the Re and Os contents are 0.901-9.794 ng/g and 7.3-189.5 pg/g,respectively.The Re-Os isotope isochron age is 155.6 ±3.6 Ma,which is consistent with the zircon U-Pb age (153-157 Ma) of Stage Ⅱ medium-grained biotite granite of the Qitianling pluton on the east side of the deposit.It also indicates that the coal seam of the Longtan Formation is subjected to ‘baking’ by the Qitianling pluton,inducing the hot contact metamorphism and changing the raw coal near the Qitianling pluton to graphite to form a graphite deposit.The comparison of Re and Os content and Os isotopic composition between the graphite,coal and Qitianlign pluton demonstrates that the Re and Os in the graphite are mainly derived from raw coal.According to the initial Os isotope ratio of 0.686 ± 0.032,it can be concluded that minor Os with low 187Os/188Os value was absorbed by carbonaceous material during the intrusion of coal seam by the Qitianling pluton.; 国家自然科学基金面上项目; 中国地质调查局地质调查项目; 3; 297-304; 36
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/465661]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	李超,王登红,周利敏,等. 湖南鲁塘石墨矿Re-Os同位素研究, Study on the Re-Os Isotope Composition of Graphite from the Lutang Graphite Deposit in Hunan Province[J]. 岩矿测试,2017.
APA	李超,王登红,周利敏,赵鸿,李欣尉,&屈文俊.(2017).湖南鲁塘石墨矿Re-Os同位素研究.岩矿测试.
MLA	李超,et al."湖南鲁塘石墨矿Re-Os同位素研究".岩矿测试 (2017).