Sm-Nd Isochron Age of Carbonatite from the Maoniuping REE Deposit, Sichuan Province and Their Geological Implications
详细信息
- 责任者：Hu Wenjie (East China Institute of Technology ; Fuzhou 344000 ; China) ; Tian Shihong
- 刊名：Mineral Resources and Geology
- 出版年：2012
- 卷期：26(3)
- 关键词：稀土矿床 ; rare earth deposit ; 钐—钕计时 ; Sm-Nd dating ; 四川 ; Sichuan Province
- 页码：p.237-241
- 图表：2 illus., 1 table, 29 refs.
- 分类号：1001
- issnNo：ISSN1001-5663
- isbnNo：CN45-1174/TD
摘要
The Mianning-Dechang REE belt in western Sichuan, SW China is one of the most significant REE belt in China, including one giant （Maoniuping）, one large （Dalucao）, one intermediate （Muluozhai）, one small （Lizhuang） and so on. The REE mineralization is associated with the carbonatite-alkalic complexes, controlled by a series of Cenozoic strike-slip faults in the eastern Indo-Asian collision zone. These complexes consist of carbonatitic sill or dyke and associated alkalic syenite stocks, which intruded Proterozoic basement and Devonian-Cretaceous sedimentary sequence. Main phase of host carbonatites are calcite carbonatites and associated alkalic syenites are predominated by nordmarkites. They show similar abundance patterns of trace elements normalized by primitive mantle and Sr-Nd isotopic signatures, suggesting an immiscibility origin, which implys their diagenetic ages should be consistent. However, the formers＇ results indicate that diagenetic ages of carbonatite and syenite from Maoniuping are 31.7 Ma （K-At method for arfvedsonite） and 40. 8 Ma （K-Ar method for whole rock）, respectively, with the difference between 10 Ma. In addition, the formers results indicate that diagenetic ages of carbonatite-alkalic complex from Dalucao, Muluozhai and Lizhuang are consistent with their corresponding metallogenic ages, while the ages of carhonatite and syenite from Maoniuping are markedly different from its metallogenic ages. In this work, we present Sm-Nd isochron dating for the carbonatite carbonatite and metallogenic from Maoniuping. Together with age from Maoniuping REE deposit other data, we confirm the diagenetic age of are 29.9 Ma and 26~27 Ma, respectively, within analytical uncertainty.