西藏山南金鲁西蛇绿岩U-Pb同位素年龄及地质意义

U-Pb dating of Chromite from Shannan Jinluxi in Tibet and Its Geological Significance

西藏山南金鲁西铬铁矿地处雅鲁藏布江缝合带东段,位于雅江铬铜金铂钯成矿带西段,紧邻国内最大的罗布莎铬铁矿区,矿床形成于地幔橄榄岩内,铬铁矿多呈豆荚状、浸染状产于超基性岩体内。金鲁西铬铁矿含矿岩体的成岩年龄为(154.9±2.0)Ma,罗布莎铬铁矿含矿岩体成岩年龄为(162.9±2.8)Ma。通过U-Pb同位素年龄测定,对金鲁西和罗布莎岩体的年龄和成矿背景进行了对比,分析显示两者具有相近的形成时代和相似的构造环境,经历了相似的演化阶段。

Shannan Jinluxi chromite in Tibet is located in zone of the eastern section of the Yarlung Zangbu Suture, located in the western Yajiang gold platinum palladium chromium copper metallogenic belt, adjacent to the largest Luobusha chromite deposits. the deposit formed in the mantle peridotite, chromite in Podiform and dissem- inated in ultrabasic rock body. The ore bearing rock Jinluxi chromite diagenetic age was （ 154.9 ± 2.0） Ma, Luobusha chromite ore rock diagenetic age was （162.9 ± 2.8） Ma. The U-Pb isotopic age determination, compared to age and metallogenic background Jinluxi and Norbusa rock, shows that they are, similar to the formation age and tectonic environment similar to that experienced a similar evolution stage.