岩石矿物学杂志2012，Vol.31Issue(4)：479-496,18.
西藏班戈县多巴区矽卡岩型铁多金属矿床含矿花岗岩LA-ICP-MS锆石U-Pb定年、地球化学及意义
LA-ICP-MS zircon U-Pb dating and geochemical characteristics of ore-bearing granite in skarn-type iron polymetallic deposits of Duoba area,Baingoin County, Tibet, and their significance
摘要
Abstract
Located in northwestern Baingoin County of Tibet, Duoba area is near the middle of Bangong Co-Nujiang River metallogenic belt with the distribution of a large number of skarn iron-copper polymetallic deposits (mineralization spots) characterized by good prospecting potential. Due to high elevations, traffic inconvenience and less mining, only a small amount of work has been carried out. This research is based on the systematic field geological survey, indoor petrographic and ore microscopic studies, zircon LA-ICP-MS U-Pb dating and analysis of major and trace elements. The authors chose Sousha skarn mineralization spot and Zai' a skarn iron polymetal-lic deposit to conduct researches on the relationship between the petrogenesis and the mineralization. There are mainly fine grained porphyritic granodiorites in Sousha area and fine grained granodiorites in Zai' a. Zircon' s LA-ICP-MS dating indicates that the age of the fine grained porphyritic granodiorite is 77.37 ± 0.55 Ma, whereas that of the fine grained granodiorite is 79.78 ± 0.99 Ma, suggesting products of late Cretaceous magma-tism. Their A/CNK values change between 0.78 and 1.29, and A/NK values change in the range of 0.88～ 1.51. The rocks belong to weakly peraluminous. They are enriched in big ion incompatible elements Rb, Th, U and K, and depleted in Nb, identical overall with the same period granite in Bangong Co-Nujiang River metallo-genicbelt. ∑ REE range from 199.82× 10-6 to 274.64× 10-6, LREE/HREE = 3.552～7.199, δEu=0.20 ～0.82, with medium negative Eu anomalies. These data indicate that the separation of plagioclase crystallization might have occurred in magmatic evolution processes. The ore-forming processes of Sousha and Zai'a rock bodies might have had something to do with the southward subduction of the Bangong Co-Nujiang Ocean Basin and acted as the products of magmatic activity after closing. With favorable iron and bismuth polymetallic ore-forming geological and geochemical conditions, this area deserves more attention in further prospecting and evaluation work.关键词
LA-ICP-MS/班公湖-怒江成矿带/矽卡岩型铁多金属矿床/梭沙/再阿/西藏班戈县Key words
LA-ICP-MS/ Bangong Co-Nujiang River metallogenic belt/ skarn-type iron polymetallic deposit/ Sousha/ Zai'a/ Baingoin County, Tibet分类
天文与地球科学引用本文复制引用
定立,赵元艺,杨永强,崔玉斌,吕立娜..西藏班戈县多巴区矽卡岩型铁多金属矿床含矿花岗岩LA-ICP-MS锆石U-Pb定年、地球化学及意义[J].岩石矿物学杂志,2012,31(4):479-496,18.基金项目
国家973项目(2011CB403103) （2011CB403103）
国家科技支撑课题(2006BAB01A05) （2006BAB01A05）
中国地质调查局青藏专项(1212010818097) （1212010818097）
国家自然科学基金资助项目(41072070) （41072070）
