岩矿测试2017，Vol.36Issue(3)：297-304,8.DOI:10.15898/j.cnki.11-2131/td.201704060050
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
摘要
Abstract
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.关键词
鲁塘/石墨矿/成因/Re-Os同位素/定年Key words
Lu tang/graphite deposit/genesis/Re-Os isotope/dating分类
天文与地球科学引用本文复制引用
李超,王登红,周利敏,赵鸿,李欣尉,屈文俊..湖南鲁塘石墨矿Re-Os同位素研究[J].岩矿测试,2017,36(3):297-304,8.基金项目
国家自然科学基金面上项目(41673060) （41673060）
中国地质调查局地质调查项目(DD20160095) （DD20160095）
