| 中蒙边境沙麦-玉古兹尔地区钨和钨(钼)矿床地质特征, 形成时代和成因机理 |
| |
| 关键词:tungsten and tungsten (molybdenum) deposit geological feature ore-forming process Yuguzer Shamai Sino-Mongolian border |
| 基金项目:国家科技支撑项目(编号: 2007BAB25B02)；地质调查项目(编号: 1212010911029) |
|
| 摘要点击次数: 4564 |
| 全文下载次数: 5746 |
| 摘要: |
| Geological Features, Geochronology and Origin of the Tungsten and Tungsten (Molybdenum) Deposits in the Shamai-Yuguzer Mineralization Concentrated Camp along the Sino-Mongolian Border |
| Located on the western side of the southernmost part of the Mesozoic Da Hinggan Ling tectono-magmatic belt along the Sino-Mongolian border, the Shamai-Yuguzer area is the largest tungsten and molybdenum concentrated camp along the Sino-Mongolian border. During the Mesozoic Indosinian orogeny, intensive tectonic and igneous activities resulted in the large-scale granitoid magmatism in the Shamai-Yuguzer tungsten and molybdenum concentrated camp and its neighboring areas. The Shamai-Yuguzer granitoid batholith was emplaced in the Paleozoic and Mesozoic volcano-sedimentary sequences, controlled by NE- and NNE-trending fault zones. It has an outcrop area of 2700 km2, and consists mainly of porphyritic biotite granite and fine-grained biotite granite that have no difference in mineral assemblage. Rock-forming minerals are mainly quartz, microcline, microperthite and plagioclase associated with minor biotite and sericite. Accessory minerals are magnetite, apatite, zircon, sphene and allanite. The granitoid batholith is petrochemically characterized by relatively high SiO2, K2O, Rb, U and Th, and obviously low CaO, Fe2O3 + FeO, MgO, Sr, Ba, Ti, P and Eu, thus belonging to silicon-high and po-tassium-rich rocks of calc-alkaline series. Tungsten and tungsten (molybdenum) mineralization occurs within the Shanmai-Yuguzer granitoid batholith or along its contact with wall rocks in the forms of veins, veinlets and dis-seminated blocks. Ores consist of pyrite, chalcopyrite, molybdenite, scheelite, wolframite, K-feldspar, quartz, sericite, chlorite and epidote. As the most important economic minerals, molybdenite and wolframite occur in the forms of impregnation, radioflakes, thin films, aggregated flakes and veinlets in the veins. Re-Os isotopic data of six molybdenite separates defined a correlation line corresponding to an age of 224 ? 6.2 Ma, which is similar to the zircon SHRIMP U-Pb age (225.9±2.1 Ma) of the porphyritic biotite granite. Hydrothermal alterations in Shamai-Yuguzer show gross zonation of K feldspathization, greisenization, silicification, and propylitization from the porphyritic biotite granite outwards. Of these alterations, silicification and greisenization are well developed and have an intimate relationship with tungsten and molybdenum mineralization. Fluid inclusion studies yield homogeneous temperatures from 180℃ to 400℃, with the temperature of the main ore-forming stage ranging from 280℃ to 320℃. Gaseous inclusions are frequently co-existent with multiphase inclusions containing daughter minerals such as halite, sylvite, molybdenite and K feldspar. Intensive boiling of ore-forming fluid resulted in the deposition of a great volume of molybdenite, scheelite and wolframite under the circumstances of medium to high temperature, relatively low fO2 and fS2 as well as weak acidity. Sulfur and oxygen isotopic data of the molybde-num ore indicate that the ore-forming fluid was dominated by magmatic water at the early metallogenic stage, and was characterized by the mixture with magmatic water as the major source at the main metallogenic stage. By contrast, the ore-bearing fluid was mainly heated meteoric water. Therefore, it is conceivable that ore-forming materials were mostly derived from the magmatic source. The combined geochemical data, field geological ob-servations and petrological evidence indicate that the tungsten and tungsten (molybdenum) deposits or ore spots within the Shamai-Yuguzer mineralization concentrated camp are of hydrothermal vein type deposits or ore spots related to Mesozoic granitoid intrusions. It is believed that they are products of the Late Triassic intra-plate grani-toid magmatism along the NE-trending fault belt. Meanwhile, the genetic model and mineral exploration criteria of the Shamai and Yuguzer deposits can also be employed as useful tools during the comprehensive evaluation of concealed tungsten and tungsten (molybdenum) deposits on the western side of the southernmost segment of the Da Hinggan Ling tectono-magmatic belt along the Sino-Mongolian border. |
| NIE Feng-jun,HU Peng,JIANG Si-hong,LIU Yi-fei.2010.Geological Features, Geochronology and Origin of the Tungsten and Tungsten (Molybdenum) Deposits in the Shamai-Yuguzer Mineralization Concentrated Camp along the Sino-Mongolian Border[J].Acta Geoscientica Sinica,31(3):383-394. |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|