【作者】 田世洪； 张桂兰； 侯增谦； 丁悌平； 邹天人； 袁忠信； 白鸽； 谢玉玲；

【Author】 TIAN Shihong~1,2) ZHANG Guilan~3) HOU Zengqian~1,2) DING Tiping~1,2) ZOU Tianren~1) YUAN Zhongxin~1) BAI Ge~1) XIE Yuling~4) 1)Institute of Mineral Resources,CAGS,Beijing,100037;2)Key Laboratory of Isotope Geology,MLR,Beijing,100037;3)Academy of Information Research,Bureau of Land and Resources of Inner Mongolia,Hohhot,010020;4)Civil & Environmental Engineering School,Beijing University of Science and Technology,Beijing,100083

【机构】 中国地质科学院矿产资源研究所； 内蒙古自治区国土资源信息院； 北京科技大学土木与环境工程学院；

【摘要】 里庄稀土矿床位于四川冕宁县西南方向49 km,为侵位于碱性杂岩体中的碳酸岩脉状矿床。本文从稀土元素地球化学和同位素地球化学的角度探讨了碳酸岩与地幔过程之间的关系。研究表明,碳酸岩的∑REE 为（9236.2～5943.6）×10^-6,为LREE 富集型,与典型岩浆碳酸岩特征相似;碳酸岩的C、O 同位素组成非常稳定,其δ¹³C_V-PDB和δ¹⁸O_V-SMOW分别为-3.9‰～-5.3‰和8.7‰～11.9‰,均落在“原生碳酸岩”的C、O 同位素组成范围之内;碳酸岩的Pb、Sr 同位素组成比较均一,其⁸⁷Sr/⁸⁶Sr、²⁰⁶pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb、²⁰⁸Pb/²⁰⁴Pb 分别为0.706305～0.706997、18.197～18.220、15.601～15.604、38.401～38.434,与EM Ⅰ型地幔源区的同位素组成基本一致。所有这些特征均表明岩石来自交代富集地幔源区。更多还原

【Abstract】 The Lizhuaug REE deposit,located about 49 km southwest of Mianning County,Sichuan Province,is a carbonatite vein-type deposit hosted in alkali complex rocks.In order to find out the relationship between the carbonatites and the mantle processes,the authors made a systematic study of REE geochemistry and C,O,St,and Pb isotopes.The ∑REE contents of carbonatites rangefrom 8 393×10^-6to 8 402×10^-6,with smooth right-dipping distribution patterns that are similar to those of the well-establishedmagmatic carbonatite.The C and O isotopic compositions of the calcite samples from the carbonatite stocks in the Lizhuang REE de-posit vary in a very limited range,with the δ3¹³C_v.ODBand δ¹⁸O_v-SMOWvalues varying in the range of-3.9‰～-5.3‰and 8.7‰～11.9‰,respectively.They are fallen into the range of the“primary igneous carbonatites”.The Sr and Pb isotopic compositions ofthe calcite samples from the carbonatite in the Lizhuang REE deposit are relatively constant,with the⁸⁷Sr/⁸⁶Sr,²⁰⁶pb/²⁰⁴pb,²⁰⁷Pb/²⁰⁴Pb and²⁰⁸pb/²⁰⁴pb values varying in the range of 0.706305±0. 706997,18.197～18.220,15.601～15.604,and 38.401～38.434,respectivdy.The similarity of Sr and Pb isotopic compositions of the carbonatite with those of EMI suggests an enrichedmantle source for the mineralization of rare earth elements.All of these data suggest that the rocks were derived from the metasomaticenriched mantle.更多还原