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西藏冈底斯南缘火山—岩浆弧演化与不同类型夕卡岩矿床的研究

A Research on Evolution and Different Types for the Skarn Deposits on Southern Margin of Gangdisi Volcanic-magmatic Arc, Tibet

【作者】 姚鹏

【导师】 顾雪祥;

【作者基本信息】 成都理工大学 , 矿物学、岩石学、矿床学, 2006, 博士

【摘要】 青臧高原冈底斯南缘火山-岩浆弧带曾经历了非常复杂的演化过程,特别是洋—陆转换历史。按照板块构造观点,将该弧的演化历程划分为五个阶段:①早期(J2)洋壳俯冲—普通火山弧形成阶段;②晚期(J3-K1)洋壳俯冲—特殊火山弧(adakite)发育阶段;③弧后扩张与盆地沉积阶段(J3-K);④俯冲洋壳最终消减完毕(洋消失)—陆-陆开始碰撞阶段(70-50Ma);⑤碰撞造山-快速隆升-山根拆沉阶段(20-10Ma)。 通过各演化阶段所产生的不同地质背景以及与不同类型夕卡岩矿床的研究,发现除④阶段外,其余每一个构造阶段所产生的不同地质背景均产有各具特色的夕卡岩矿床类型。如早期(J2)新特提斯主洋壳俯冲阶段所形成的普通火山弧,产有火山熔(流)型夕卡岩铜多金属矿床;晚期(J3-K1)与新特提斯主洋盆有关的小洋盆俯冲阶段所形成的特殊火山弧(adakite),产有与adakite有关的火山热液型夕卡岩铜(金)矿床;晚期俯冲所产生的弧后扩张沉积盆地,产有层控热(卤)水交代型夕卡岩铜多金属矿床;高原隆升-山根拆沉阶段所形成的含矿斑岩带,产有与斑岩有关的岩浆热液接触交代型夕卡岩铜矿床。这充分表明,冈底斯南缘火山-岩浆弧带的夕卡岩矿床具有多成因的特点,属多成因矿床的范畴。 上述不同类型夕卡岩矿床在空间上的展布明显可分为两大成矿带:一为与adakite有关的火山热液型夕卡岩铜(金)成矿带;二为由多种类型夕卡岩矿床所组成的铜多金属复合成矿带(除与adakite有关的火山热液型夕卡岩成矿带外,余者三种夕卡岩矿床类型)。不同类型夕卡岩矿床在空间上的展布格局明显受控于冈底斯南缘火山-岩浆弧的演化。冈底斯南缘火山-岩浆弧夕卡岩矿床的这一分布规律特征,可为我们确定找矿方向以及部署普查找矿地区提供重要依据。

【Abstract】 The volcanic-magma arc belts on southern margin of Gangdisi had ever gone through greatly complicated course of evolvement, especially history of ocean-continent conversion. According to plate tectonics, the course of evolvement of the volcanic-magma arc are divided into fivestages as followed: (1) Early ocean crust subduction (J2)--commonvolcanic - arc stage; (2) Late ocean crust subduction (J3-K1)--peculiarvolcanic - arc(adakite) stage; (3) Post-arc spreading basin stage(J3-K); (4)Ocean crust subduction completed--begining collision of platestage(70-50Ma); (5) Collision orogenic - quickly uplift - root of mountain delamination stage(20-10Ma).Based on the research of the different geological backgrounds in the course of evolvement on southern margin of Gangdisi volcanic-magmatic arc and different types of the skarn deposit, we find several characteristic types for the skarn deposits on southern margin of Gangdisi volcanic-magmatic arc. For example, there is the volcanic magmatic-hydrothermal transitional type of skarn Cu polymetallic deposit, located in common volcanic-arc which New-Tethys main ocean crust had subducted; a volcanic-hydrothermal type of skarn Cu(Au) deposit related to adakite locates in peculiar volcanic-arc which small ocean basin assocated with New-Tethys main ocean subducted; the strata-bound hot brine metasomatic type of skarn Cu polymetallic deposit exists in post-arc spreading basin, and there is also a magmatic-hydrothermal contact metasomatic type of skarn copper deposit concerned with porphyry. It is clearly show that the skarn deposit within volcanic-magma arc on southern margin of Gangdisi is characteristics of polygenetic, and belongs to category of polygenesis ore deposits.According to time - space distribution of different types for the skarn deposits, they can be divided into two metallogenic belts: the Cu-Au

  • 【分类号】P542
  • 【被引频次】10
  • 【下载频次】558
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