| 内蒙古北山地区斑岩型钼矿的成岩成矿时代和形成环境探讨 |
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| 关键词:porphyry type ore-forming age zircon SHRIMP U-Pb dating ore-forming environment geochemistry Beishan area |
| 基金项目:国家科技支撑计划(编号: 2006BAB01A09) |
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| Rock-forming and Ore-forming Ages as well as Formation Environments of Porphyry Molybdenum Deposits in Beishan Area, Inner Mongolia |
| A nearly EW-trending molybdenum (copper) ore belt was found in Beishan area of Inner Mongolia. The relatively large deposits in this belt include Liushashan molybdenum deposit, Elegenwulanwula molybdenum deposit and Xiaohulishan molybdenum deposit., Re-Os isotope dating of molybdenite samples from these three deposits yielded isochron ages of (260±10) Ma (Middle Permian), 332.0 Ma (Early Carboniferous) and 220 Ma (Late Triassic) respectively. Obviously, different metallogenic epochs reflect different environments for the formation of these deposits. Based on new SHRIMP zircon U-Pb age data of the porphyry related to mineralization as well as basic rock and ore geochemical work, the authors revealed the formation environments of the three deposits from the angle of regional crustal evolution. In the Early Paleozoic, the three deposits were in Kazakhstan plate, and in the Late Paleozoic, due to the development of Hongshishan-Baiheshan-Pengboshan area from rift valley to ocean basin, the position of the Liushashan molybdenum deposit was split into the Tarim plate. Due to the difference in subduction mechanism and underlying basement, tectono-magmatic activities were somewhat different in two island arcs. In active marginal belt of north Tarim plate, magmatic activity was unusually strong and lasted from Carboniferous to the end of Permian. In the early stage, mineralization was dominated mainly by iron, and molybdenum (copper) deposits were formed in the late stage. Magmatic activity of the marginal belt in south Kazakhstan plate was a bit weaker than that in the northern marginal belt of Tarim plate, and the magmatic activity was mainly concentrated in Carboniferous; in such an environment, the Elegenwulanwula molybdenum deposit was formed. At the end of Permian, the split plate of Beishan area became a unified plate again through collage. From that time on, Beishan area entered into an environment of intra-continental crustal activity, and stretching-extrusion structure and meta-acid and meta-alkaline magmatic intrusion constituted an important style of Mesozoic crustal activity; in such an environment, the Xiaohulishan molybdenum deposit and some rare metal deposits were formed. |
| YANG Yue-qing,ZHAO Jin-hua,MENG Gui-xiang,YAN Jia-yong,LÜ Bo,WANG Shou-guang,JIA Ling-long,HAN Jian-gang.2013.Rock-forming and Ore-forming Ages as well as Formation Environments of Porphyry Molybdenum Deposits in Beishan Area, Inner Mongolia[J].Acta Geoscientica Sinica,34(4):401-412. |
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