A Tentative Discussion on the Genesis of Ni-Bearing Carbonatites in Bangong
详细信息
- 责任者：Chen Hua (Institute of Mineral Resources ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Qu Xiaoming
- 刊名：Mineral Deposits
- 出版年：2010
- 卷期：29(6)
- 关键词：碳酸岩 ; carbonatites ; 西藏 ; Tibet
- 页码：p.1029-1042
- 图表：8 illus., 2 tables, 49 refs.
- 分类号：0801
- issnNo：ISSN0258-7106
- isbnNo：CN11-1965/P
摘要
Numerous carbonatite bodies, associated intimately with ultrabasic rocks in the ophiolite zone, have been discovered through field survey. The characteristics suggest that calciocarbonatite firstly differentiated from mantle in late Proterozoic, then went through eruption,sedimentation and metamorphism successively, and lastly remelted in Mesozoic as a result of being heated by the intrusion of mafic magma. Magnesiocarbonatite differs from either typical mantle-sourced or crust-sourced carbonatites in geochemical characteristics, but its REE pattern is the same as the REE pattern of associated Ni-bearing ultrabasic rocks, with their Pb isotopes also indicating the same material source. All these phenomena prove that magnesiocarbonatite is the product of metasomatism of ultrabasic rocks metasomatized by deep-seated CO2-rich fluid in the middle-lower crust.