地质通报2012，Vol.31Issue(2)：277-286,10.
滇西龙陵地区勐冒奥陶纪二长花岗岩LA-ICP-MS锆石U-Pb定年及其构造环境
LA-ICP-MS zircon U-Pb dating of Ordovician Mengmao monzogranite in Longling area of western Yunnan Province and its tectonic setting
摘要
Abstract
Mengmao monzogranite, exposed in Longling area of western Yunnan, was geochemically analyzed and discussed to probe into its genesis, ore-forming material source and tectonic setting. The results show that Mengmao granite has high SiO2 (72.17%~ 76.45%) and AI2O3, with A/CNK ratios ranging between 0.86 and 1.45 (1.12 on average). These data suggest that Mengmao granite belongs to typical peraluminous granite, with over-saturated Si and Al . The ZREE values range from 138.17X10"6 to 383.68x10"*, and the REE patterns show right oblique feature and obvious negative Eu anomaly. Trace elements show enrichment of LILE (large-ion lithophile elements) such as K, Sr, R-b and Ba and depletion of HFSE (high field strength elements) such as Zr, Ta, Nb and Th. Magmatic source was typical of crustal genesis and was probably formed by rising and emplacement of granitic magma, which had been partially melted by greywacke. LA-ICP-MS U-Pb dating of zircons indicates that Mengmao granite was emplaced during the Middle Ordovician (454.7±1.5Ma), with post-collisions] magmatic activity features. Mengmao granite, as post-collisional granite and a product of magmatism by late Gondwana land orogenic movement, was formed in the tectonic transition stage from syn-collision (extrusion environment) to post-collision (stretching environment). The result of the researches on Mengmao monzogranite has significance in revealing tectonic attributes of Nujiang fault belt in western Yunnan.关键词
滇西/龙陵地区/花岗岩/地球化学/构造环境/后碰撞/怒江断裂带Key words
western Yunnan/ Longling area/ granite/ geochemistry/ tectonic setting/ post-collision/ Nujiang tectonic belt分类
天文与地球科学引用本文复制引用
熊昌利,贾小川,杨学俊,罗改,白宪洲,黄柏鑫..滇西龙陵地区勐冒奥陶纪二长花岗岩LA-ICP-MS锆石U-Pb定年及其构造环境[J].地质通报,2012,31(2):277-286,10.基金项目
中国地质调查局地调项目《云南1∶5万清河街幅、镇安街幅、龙陵县幅、龙新幅调查地质调查》(编号:1212010784006) （编号:1212010784006）
