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内蒙古大苏计斑岩型钼矿赋矿岩体的锆石U-Pb年龄与地球化学特征研究
引用本文:廖曼琪,赖勇,周弋涛,舒启海.内蒙古大苏计斑岩型钼矿赋矿岩体的锆石U-Pb年龄与地球化学特征研究[J].北京大学学报(自然科学版),2018,54(4):763-780.
作者姓名:廖曼琪  赖勇  周弋涛  舒启海
作者单位:造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871;造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871;造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871;造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871
基金项目:国家重点研发计划(2017YFC0601302)和国家自然科学基金(41390443)资助
摘    要:为研究内蒙古大苏计斑岩型钼矿床赋矿岩体的形成年龄、地球化学特征及构造背景, 对3种岩体(石英斑岩、花岗斑岩和正长花岗岩)的样品进行锆石U-Pb定年和主量元素、微量元素分析。结果显示, 石英斑岩、正长花岗岩和花岗斑岩分别形成于231, 227和225 Ma, 为印支期产物。3种岩体属于高钾钙碱性−钾玄质系列, 为高分异的I型花岗岩。岩石组合特征与区域地质背景揭示, 大苏计地区在印支期处于伸展环境, 软流圈上涌导致不同深度的地壳发生部分熔融作用, 产生与大苏计斑岩型钼矿成矿相关的母岩浆。这些母岩浆向上运移过程中萃取前中生代形成的矿源层中的成矿元素, 并在结晶分异过程中不断地富集钼元素, 当岩浆挥发分达到过饱和时发生流体相与熔体相的分离, 钼进入流体相。岩浆热液沿裂隙充填, 在演化过程中发生沸腾作用, 导致大量钼和石英沉淀, 形成大苏计钼矿床。

关 键 词:大苏计斑岩型钼矿  锆石U-Pb定年  岩石地球化学
收稿时间:2017-04-23

Zircon U-Pb Dating and Geochemical Analysis of Ore-Bearing Intrusions of Dasuji Porphyry Mo Deposit
LIAO Manqi,LAI Yong,ZHOU Yitao,SHU Qihai.Zircon U-Pb Dating and Geochemical Analysis of Ore-Bearing Intrusions of Dasuji Porphyry Mo Deposit[J].Acta Scientiarum Naturalium Universitatis Pekinensis,2018,54(4):763-780.
Authors:LIAO Manqi  LAI Yong  ZHOU Yitao  SHU Qihai
Institution:The Key Laboratory of Orogenic Belts and Crustal Evolution (MOE), School of Earth and Space Sciences, Peking University, Beijing 100871
Abstract:In order to study the age, geochemical characteristics and tectonic genesis of the ore-bearing intrusions of Dasuji porphyry Mo deposit, three kinds of rock samples of quartz porphyry, syenogranite and granite porphyry that are related to molybdenum mineralization were collected from the deposit. Zircon U-Pb dating reveals that the ages of quartz porphyry, granite porphyry and syenogranite are 231, 227 and 225 Ma, respectively. Characteristics of major and trace elements indicate that they belong to high-K calc-alkaline to shoshonite series and highly fractionated I-type granite. Geochemistry of the rock associations, integrated with regional geology indicate that Dasuji area was in extension during Indosinian. The upwelling of asthenosphere triggered partial melting of crust in a wide range of depth. Magma related to this deposit was generated in this process. During ascending, the magma extracted ore elements from protore which had collected ore elements in the pre-Mesozoic during multiple geological activities and the magma became more enriched in Mo due to the extensive crystal fractionation. When volatiles in magma were supersaturated, ore-forming fluid was separated from melt with Mo. Ore minerals were mainly precipitated with quartz and filled in the fractures during the boiling process.
Keywords:Dasuji porphyry Mo deposit  zircon U-Pb dating  petrogeochemistry  
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