| 藏北美多锑矿带地质地球化学特征及其地球动力学背景探讨 |
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| 引用本文：闫升好,余金杰,赵以辛,徐志忠,王安建,滕荣丽.2004.藏北美多锑矿带地质地球化学特征及其地球动力学背景探讨[J].地球学报,25(5):541-548. |
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| 基金项目:国家重点基础研究规划973项目(编号:2001CB409807)，国土资源部定向基金 |
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| 中文摘要:藏北美多锑矿带位于小唐古拉山南麓，东西长200km、南北宽40km，已发现锑矿床(点)10多处，其中以美多矿床规模最大。锑矿产于上三叠统土门格拉群的硅质岩组，受NW向和NE向断裂联合控制。矿石矿物主要为辉锑矿，脉石矿物有石英、蛋白石和方解石等。矿石类型有浸染状硅质岩型、辉锑矿一石英脉型、角砾状硅质岩型、辉锑矿一方解石脉型等4种。矿石硫、铅、氦、氩同位素研究表明，成矿流体为大气降水，成矿物质不可能主要由围岩地层提供，地幔物质参入成矿明显。成矿年龄为20Ma，处于青藏高原新生代大陆碰撞造山带形成演化的后碰撞构造阶段。成矿作用在时间与空间上与藏北大规模富碱中性熔岩所对应的构造热事件(30-10Ma)相耦合以及地幔物质参入成矿的事实表明，藏北锑矿带的形成可能与中新世以来造山带增厚岩石圈底部拆沉作用引起的软流圈上升和地幔底辟作用有关。 |
| 中文关键词:藏北 锑矿 氦氩同位素 碰撞造山带 后碰撞阶段 |
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| Geology and Geochemistry of the Meiduo Antimony Ore Belt in Northern Tibet: Its Origin and Geodynamic Setting |
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| Abstract:The EW-trending Meiduo antimony ore-forming belt,200 km in length and 40 km in width, is distributed along the sou- thern edge of the TanggulaMountains in the northern part of Tibet. More than ten deposits have been founded in this area, of which Meiduo is the largest one. The antimony orebody is hosted in the siliceous rocks of the Tumengela Group and controlled jointly by the NW-andNE-striking faults. The antimony ores are mainly composed of such minerals as stibnite, quartz, opal and calcite. Four types of ores could be identified, namelydisseminated siliceous rocks, stibnite-quartz veins, brecciated siliceous rocks, and stibnite-calcite veins. Isotopic compositions of the sulfur, lead, heliumand argon indicate that the ore-forming fluids were mainly meteoric water, theore metals seemed unlikely to be provided mainly by the wall rocks, and some mantle-derived materials obviously participated in the ore-forming process. The metallogenic age is about 20.2 m.y., suggesting the post-collision stage of the Qinghai-Tibet Cenozoic continent collision orogen. The time-space coupling of theore-forming event with the tectonic-thermal event corresponding to the extensivealkali-rich lavas (30～10 m.y.) and the obvious participation of the mantle-derived materials in the ore-forming process suggest that the formation of the Meiduoantimony ore belt was most probably connected with the upwelling of the rheosphere or mantle diapir and the delaminating of the bottom part of the thickened lithosphere within the orogen since Miocene. |
| keywords:northern Tibet plateau antimony deposit helium and argon isotope collisional orogen post-collision stage |
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