新疆东天山多头山铁-铜矿区花岗岩类的年代学、地球化学、岩石成因及意义

发布时间：2018-06-27 03:40

本文选题：岩石成因 + Ⅰ型花岗岩　；参考：《大地构造与成矿学》2017年06期

【摘要】：多头山矿床是东天山阿奇山?雅满苏成矿带铁铜矿床的典型代表,矿床成因与区内岩浆岩有紧密联系。矿区出露的侵入岩主要有花岗斑岩、二长花岗岩、钾长花岗岩及英安玢岩。LA-ICP-MS锆石U-Pb年代学研究获得花岗斑岩、二长花岗岩及英安玢岩的年龄分别为316.3±8.1 Ma、318.3±3.0 Ma和197.2±3.5 Ma。花岗斑岩A/CNK介于0.82~1.01之间,显示偏铝质特征,为Ⅰ型花岗岩;同时样品富集大离子亲石元素Th、U、Pb,亏损高场强元素Nb、Ta、Ti,显示弧岩浆特征。钠质蚀变导致了花岗斑岩显示出富Na、贫K、Rb、Ca、Sr的特征。钠化花岗斑岩Nb/Ta为12.4~16.0,具有较高的ε_(Nd)(t)(5.76~6.24)值和较低的I_(Sr)值(0.70353~0.70532),与安第斯中生代岩基地球化学特征相似,结合样品中出现古老锆石的捕掳晶,表明其源区为新生的下地壳,混合有少量幔源物质,并伴随有地壳混染。二长花岗岩与钠化花岗斑岩具有相近的形成年龄和相似的地球化学特征,如Nb/Ta比值(14.2),亏损高场强元素、富集大离子亲石元素,同为准铝质(A/CNK=0.97)弧岩浆,暗示它们可能具有相似的源区。而早侏罗世的英安玢岩具有高Sr(552×10~(-6))含量和较高的Sr/Y(73.6)比值,显示出钙碱性埃达克岩的特征,同时样品具有较高的K_2O(3.27%)含量、Mg~#指数(55),表明其来源于拆沉下地壳的熔融并混有少量幔源岩浆。综合区域研究资料、年代学、地球化学及同位素特征,我们认为多头山所在的阿奇山?雅满苏成矿带可能是晚古生代洋壳向南俯冲至中天山地块之下形成的大陆边缘弧。
[Abstract]:Duotoushan deposit is the East Tianshan Aqi Mountain? Typical representative of iron and copper deposits in the Yamansu metallogenic belt, the genesis of the deposits is closely related to magmatic rocks in the area. Granitic porphyry, monzogranite, kalium feldspar and Yingan porphyrite. LA-ICP-MS zircon U-Pb chronological study obtained the granitic porphyry, the ages of the monzogranite and Yingan porphyrite are 316.3 卤8.1 Ma-318.3 卤3.0 Ma and 197.2 卤3.5 Ma, respectively. The A / CNK of granitic porphyry is between 0.82 ~ 1.01, which shows metaluminite and is type I granite, and the sample is rich in large ion lithophile element Thu UU Pb, and depleted in high field strength element NbPU TaTi3, which shows the characteristics of arc magma. Sodium alteration causes granitic porphyry to show the characteristics of rich in Na and poor in K ~ (2 +) Rb ~ (2 +) Ca ~ (2 +) Sr. The sodium granitic porphyry NB / Ta is 12.4 ~ 16.0, which has higher 蔚 _ (ND) (t) (5.766.24) and lower I _ (Sr) values (0.70353 ~ 0.70532), which is similar to the geochemical characteristics of the Andes Mesozoic rocks. The occurrence of the ancient zircon in the samples indicates that the source area is a new lower crust. There is a small amount of mantle material mixed with the crust. The bifeldite and sodium granitic porphyry have similar age of formation and similar geochemical characteristics, such as NB / Ta ratio (14.2), depletion of high field strength elements, enrichment of large ion lithophile elements, and similar arc magma with A / CNK _ (0.97) arc magma. It suggests that they may have similar sources. The early Jurassic porphyrite has a high Sr (552 脳 10 ~ (-6) content and a high Sr / Y (73.6) ratio, indicating the characteristics of calc-alkaline adakite. At the same time, the sample has a high K _ 2O (3.27%) content and a MgN ~ # index (55), which indicates that it originated from the melting of the lower crust and mixed with a small amount of mantle magma. Synthesizing regional data, geochronology, geochemistry, and isotopic characteristics, we think that the Akiyama where the Duotou Mountains are located? The Yamansu metallogenic belt may be a continental margin arc formed by the late Paleozoic oceanic crust subducting south to the middle Tianshan massif.
【作者单位】：中国科学院广州地球化学研究所矿物学与成矿学重点实验室;中国科学院大学;新疆地质矿产勘查局第一地质大队;
【基金】：重点基础研究计划“973”项目“新疆北部古弧盆体系成矿机理”(2014CB440802)资助
【分类号】：P588.121;P618.2

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