西藏加多捕勒矽卡岩型铁铜矿床成矿岩体识别及地球化学特征

发布时间：2018-04-30 04:35

本文选题：矽卡岩Fe-Cu + 岩石地球化学　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：加多捕勒矽卡岩铁铜矿床位于西藏谢通门县春哲乡以北约8km,处于拉萨地体中部隆格尔-工布江达弧背断隆带南缘。矿床研究程度较低,仅有侵入岩成岩时代和岩石成因的报到,黑云母二长花岗岩与成矿关系比较密切,但其与成矿相关研究较弱。本文主要在详细矿床地质特征研究的基础上,厘定了成矿岩体,并对其展开详细的岩石地球化学和年代学研究,确定成矿岩体时代,探讨成岩成矿背景和岩石成因。加多捕勒矽卡岩铁铜矿床矿石矿物主要以磁铁矿、黄铜矿和斑铜矿为主,次为赤铁矿,其中铁矿主要位于矿区南部、铁矿和铜矿位于中部,而铜矿则位于矿区北部。脉石矿物主要为石榴石(包括钙铁榴石、钙铝榴石)、辉石(包括透辉石、钙铁辉石)、阳起石、绿帘石、绿泥石、金云母、石英和方解石。从矿区南部往北部石榴石的颜色由深变浅,成分从钙铝榴石逐渐减少钙铁榴石逐渐增多过渡。这些特征显示与成矿相关的侵入体为矿区南部的黑云母二长花岗而不是北部出露的石英二长岩。锆石U-Pb年代学研究表明黑云母二长花岗岩为53.82±0.60Ma,表明加多捕勒矽卡岩铁铜矿床形成于始新世。加多捕勒黑云母二长花岗岩具有高K钙碱性,铝饱和度A/CNK小于1.1,中等的负Eu异常,显示I型花岗岩特点。其富集Rb、Th等大离子亲石元素,明显亏损Ta、Nb、P、Ti等高场强元素,显示弧岩浆特征。全岩的Fe2O3/(FeO+Fe2O3)平均值高达0.42,指示岩浆应具有较高氧逸度。锆石Hf同位素以及全岩Pb同位素研究表明成矿岩体为幔源岩浆与古老拉萨基底的熔体二元混合的产物。结合区域构造背景,认为加多捕勒矽卡岩铁铜矿床形成于始新世,在印度-亚洲大陆碰撞造山的主碰撞期,新特提斯洋板片回卷,引发了软流圈地幔部分熔融,并与古老的下地壳熔体混合,该壳幔混源岩浆经岩浆房结晶分异后上侵而形成了黑云母二长花岗岩及相关的夕卡岩型矿化。
[Abstract]:The polysharam skarn iron and copper deposit is located in the southern margin of the Tibet Shigong gate County, Tibet, in the southern margin of the middle of the Lhasa earth body of the middle of the upland - kimu Kung Bu Jiang Da arc back uplift zone. The deposit is relatively low, only the intrusive rock age and Petrogenesis are reported, and the biotite two granites are closely related to the mineralization, but they are related to the mineralization. On the basis of the study of the geological features of the deposit, the ore-forming rock mass is determined, and the detailed geochemical and chronological studies are carried out to determine the age of the ore-forming rock mass, and the metallogenic background and petrogenesis of the diagenesis are discussed. The ore minerals of the plutarate skarn iron and copper deposits are mainly magnetite, chalcopyrite and speckles. The main copper mine is hematite, which is mainly located in the south of the mining area, iron ore and copper in the middle of the mine, and the copper mine is in the northern part of the mining area. The gangue minerals are mainly garnet (including calcite, calcite), pyroxene (including diopside, calcium Tie Huishi), Yang calcite, epidote, chlorite, gold mica, quartz and calcite. The color of the northern Garnet from the north to the north is shallower, and the composition of the calcium and aluminous garnet gradually decreases. These features show that the intrusive body associated with the mineralization is the two long black mica in the southern part of the mining area and not the northern quartz two long rock. The zircon U-Pb chronology study shows that the black mica two granites are 53.82 + 0.6. 0Ma shows that the calabarite skarn iron copper deposit was formed in Eocene. The Kabu black mica two feldspar has high K Calc alkalinity, A/CNK less than 1.1 of Al saturation, medium negative Eu anomaly and I type granite. It enriching Rb, Th and other large ionic stone elements, obviously losing Ta, Nb, P, Ti and so on, showing arc magma characteristics. The average value of Fe2O3/ (FeO+Fe2O3) is as high as 0.42, indicating that the magma should have high oxygen fugacity. The Hf isotopes of zircon and all rock Pb isotopes indicate that the ore-forming rock mass is a product of two yuan mixture of mantle derived magma and the melt of the old Lhasa basement. The main collision period of the India Asian continent collision orogenic orogeny, the new Tethys plate rewinding, caused the partial melting of the asthenosphere mantle, and mixed with the ancient lower crust melts. The crust and mantle mixed magma formed the black mica two feldspar granite and the phase of the skarn mineralization after the magma crystallization differentiation.

【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.41;P618.31

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