云南峨山Mo矿化花岗岩U-Pb定年、地球化学特征及构造环境

发布时间：2018-03-16 14:05

本文选题：钼矿化花岗岩　切入点：锆石U-Pb定年　出处：《中国地质大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：研究区地处扬子准地台西南缘,昆阳裂谷的中下部,为绿汁江断裂和普渡河断裂所围限。峨山花岗岩位于康滇地轴南部,属于康滇地轴花岗岩的一部分。通过对峨山钼矿化花岗岩样品的岩相学、主量元素、微量元素、稀土元素、Sr-Nd同位素、LA-ICP-MS U-Pb锆石测年以及辉钼矿Re-Os成矿年代测定等研究,结论如下:(1)峨山钼矿化ZHM1和ZHM2花岗岩岩石类型分别为肉红色中粗粒花岗岩、灰白色中粗粒花岗岩;两岩体均以富硅高碱为特征,属于高钾钙碱性过铝质花岗岩,微量元素上富集Rb、U、K、Ta、Pb、Hf,亏损Nb、Ti、P、Ba、La;稀土总含量均较低,轻稀土(LREE)富集;显示中等Eu亏损;Sr-Nd同位素表明肉红色和灰白色花岗岩均属于S型花岗岩;通过成矿元素分析,峨山肉红色花岗岩(富集Bi、Sn、Cu、W、Sb、Cr、As、B、Pb)和灰白色花岗岩(富集Bi、W、Cu、Sn、Cr、Sb、B)的成矿元素种类为富集,富集强度较高,具有比较好的成矿远景(2)利用LA-ICP-MS锆石U-Pb同位素定年获得肉红色花岗岩和灰白色花岗岩结晶年龄分别为746±34Ma和732±30Ma,成岩年代为震旦纪早期。(3)对Mo矿化花岗岩中的辉钼矿的Re-Os测年表明其成矿年代为827.9-835.1Ma,为元古代青白口纪晚期(4)峨山肉红色和灰白色花岗岩成因上均属于高分异S型花岗岩,源区均是来自上地壳富粘土泥岩的部分熔融(5)R1-R2图、Rb/30-Hf-3Ta图、Y+Yb-Rb图、Yb+Ta-Rb图等,均反映出研究区构造背景为同碰撞向碰撞后伸展构造转化的区域构造环境。中元古代晚期(1200-1000Ma),全球主要大陆汇聚成Rodinia超大陆,格林威尔造山运动在中国表现为晋宁运动,促使各陆块的拼合,形成统一的扬子基底,并产生同碰撞S型花岗岩。新元古代早期在Rodinia超大陆裂解的背景下扬子地块西缘也发生裂解,因此在本区构造环境由挤压向拉张转化,由此产生一系列的岩浆活动,本区的花岗质岩浆就是其中一部分。
[Abstract]:The study area is located in the southwest margin of the Yangtze quasi platform and the middle and lower part of the Kunyang rift, which is bounded by the Luzhujiang fault and the Puduhe fault. The Eshan granite is located in the southern part of the Kangdian axis. It is a part of the Kangdian axis granite. By studying the lithology, principal elements, trace elements, rare earth elements of Sr-Nd isotope LA-ICP-MS U-Pb zircon dating and Re-Os metallogenic dating of molybdenum mineralization granite samples from Eshan, etc. Conclusion the rock types of ZHM1 and ZHM2 granites of Eshan molybdenum mineralization are meat-red medium-coarse granites and gray-white medium-coarse granites, both of which are characterized by silicon-rich and alkali-rich granites, and belong to high-potassium calc-alkaline peraluminous granites. The rare earth elements are enriched on the trace elements, and the total contents of rare earths are all low and the light rare earth elements are enriched. The results show that the meat-red and grayish-white granites belong to S-type granites with moderate EU deficiency Sr-Nd isotopes, and the ore-forming element analysis shows that both red and grayish white granites belong to S-type granites by metallogenic element analysis, and the results show that both red and grayish-white granites belong to S-type granites. The ore-forming elements of the Eshan meat-red granites (rich in Bi-Sn-Cu-Cu-SbPb) and grayish-white granites (rich in Bi-WCU Cu-Cr-Cr-SbPb) are enriched and the enrichment intensity is relatively high, and the ore-forming elements of the granites are rich and the enrichment intensity is relatively high, and the ore-forming elements of the granites are rich. Using LA-ICP-MS zircon U-Pb isotopic dating, the crystallization ages of flesh-red granite and gray-white granite are 746 卤34Ma and 732 卤30Marespectively, and the diagenetic age is early Sinian. The Re-Os dating indicates that the metallogenic age is 827.9-835.1Ma, which is the late stage of the Proterozoic Qingbakou period. The Eshan meat-red and grayish-white granites belong to highly differentiated S-type granites. The source areas are all partially melted from clay mudstone rich in the upper crust. The R1-R2 diagram shows Rb / 30-Hf-3Ta / Y Yb-Rb and Yb Ta-Rb, etc. All of them reflect that the tectonic setting of the study area is the regional tectonic environment which transformed from the same collision to the post-collision extensional tectonics. In the late Middle Proterozoic period, the main continents converged into Rodinia supercontinent, and the Greenwell orogenic movement was manifested as Jinning movement in China. In the early Neoproterozoic era, the western margin of the Yangtze block also cracked under the background of Rodinia supercontinent fragmentation. Therefore, the tectonic environment in this area is transformed from compressional to extensional, resulting in a series of magmatic activities, among which the granitic magma is a part.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P618.65;P597.3

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