东昆仑西段阿克苏河岩体年代学及地球化学特征

发布时间：2018-03-28 05:12

  本文选题：东昆仑西段　切入点：阿克苏河　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：研究区位于新疆且末县阿克苏河地区,大地构造位置上处于东昆中断裂带西段,昆北(祁漫塔格)弧后盆地与昆南增生楔杂岩接壤处,本文依托东昆仑西段祁漫塔格地区古生代构造变形特征及动力学机制研究项目,对阿克苏河岩体的岩石学、年代学及地球化学特征进行研究,并讨论其构造意义:1.通过野外地质和岩石学研究,系统的厘定了阿克苏河岩体的岩石类型及空间分布方式。认为阿克苏河岩体由北至南依次为糜棱岩化中细粒英云闪长岩、糜棱岩化中细粒花岗闪长岩、花岗闪长斑岩、细中粒含二云二长花岗岩和细中粒含白云母二长花岗岩。2.基于侵位关系及锆石U-Pb测年数据结果可知,阿克苏河岩体形成于晚泥盆世-早石炭世时期,由老至新依次为糜棱岩化中细粒英云闪长岩(355±5.0Ma)、糜棱岩化中细粒花岗闪长岩(354±4.3Ma)、花岗闪长斑岩(362±2.3Ma)、细中粒含二云二长花岗岩(339.7±3.9Ma)和细中粒含白云母二长花岗岩(331±5.0Ma)。3.阿克苏河岩体地球化学特征揭示,该岩体属于强过铝质、高钾钙碱性S型花岗岩:富铝、硅和碱(SiO_2:69.2%-77.77%、Al_2O_3:12.00%-14.78%),全碱含量、Na_2O及K_2O相对富集分别为:4.27%-7.98%、2.95%-4.39%、1.70%-4.23%,贫铁(0.73%-3.78%)、镁(0.11%-1.37%)、钙(0.87%-1.16%)、钛(0.03%-0.51%)、磷(0.02%-0.16%)等。分异程度相对较高(DI:74.49-95.64),CaO、Al_2O_3、TFeO、MgO、P_2O_5、TiO_2与SiO_2呈负相关;稀土总量∑REE:77.78-161.68×10~(-6),轻稀土相对富集(LREE/HREE:2.71-11.19、(La/Yb)N:1.99-14.26),轻重稀土元素分馏明显,铕负异常(δEu:0.05-0.75)显著;Rb、Th、U、Zr、Hf元素相对富集,P、Ti、Ta、Nb相对亏损;锆饱和温度为TZr:705-835℃、锆石Ti温度为T:524-756℃、成岩环境压力较低;Nb/Ta、CaO/Na_2O、Zr/Hf及各源区判别图解均具有陆壳特征。反映岩体大致分为两期,且随着岩性、年龄、含硅量、铕亏损等因素的变化,岩浆表现出良好的分异演化趋势。4.本文认为研究区是在早泥盆世-早石炭世由于古特提斯洋壳俯冲作用形成的活动大陆边缘弧。
[Abstract]:The study area is located in Aksu River area, Qiemai County, Xinjiang. The geotectonic position is located in the west section of the middle fault zone of East Kunming, and the back arc basin in the north of Kunming (Qimantage) is bordered by the accretive wedge complex in the south of Kunming. In this paper, the petrology, chronology and geochemistry of the Aksu River rock body are studied on the basis of the Paleozoic tectonic deformation characteristics and the dynamic mechanism of the Qimantag area in the western part of East Kunlun. Through field geological and petrological studies, the rock types and spatial distribution patterns of the Aksu River rock body are systematically determined. It is considered that the Aksu River rock body is mylonized in order of fine quartz diorite from north to south. Mylonized medium granodiorite, granodiorite, fine-grained Eryun monzogranite and fine-grained Muscovite monzogranite. 2. Based on emplacement relationship and zircon U-Pb dating data, it can be seen that, The Aksu River rock body was formed during the late Devonian to early Carboniferous. The order from old to new is mylonitization with medium fine quartz diorite (355 卤5.0 Ma), mylonization with fine granodiorite (354 卤4.3 Ma), granodiorite with porphyry (362 卤2.3 Ma), fine granodiorite with Eryun monzogranite (339.7 卤3.9 Maa) and fine-grained Muscovite diorite with 331 卤5.0 Mai. 3Acke River. Geochemical characteristics of rock mass reveal, The rock body belongs to strong peraluminous, high-potassium calc-alkaline S-type granite: aluminum-rich, silicon and alkali SiO269.2- 77.7777 and Al2O312.00-14.78. the total alkali content is: Na2O and K2O are relatively enriched in: 4.27-7.982.95-4.3923C, 0.73-3.78m, 0.11-1.37m, 0.11-1.37m, 0.87-1.16kg, 0.03- 0.51N, 0.02- 0.16C, respectively. The differentiation degree is relatively high and the difference is relatively high. The relationship between the two groups is 74.495.CaOAl2O3-CaOMgO2O5O _ 2O _ 5O _ 2O _ 5O _ 2O _ 5 and SiO_2 _ 2O _ 5O _ 2O _ 5, etc. The relative degree of differentiation is 74.495.CaOO _ 2O _ 3O _ 2O _ 5O _ 2O _ 5O _ 2 SiO_2 _ 2 and so _ 2 _ 2 _ _ _. The total amount of rare earth is 鈭，

本文编号：1674893