黑龙江虎林地区花岗质岩石年代学、地球化学特征及构造背景

发布时间：2018-02-26 02:19

本文关键词： 中国东北东部虎林地区花岗岩早白垩世伸展锆石年龄地球化学　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：对兴凯地块北部虎林地区花岗质岩石进行了详细的野外调查、岩石学、岩相学、LA-ICP-MS锆石U-Pb同位素年代学和全岩主微量元素地球化学研究,明确了花岗质岩石的分布范围和岩石组合特征,确定了花岗质岩石的形成时代,揭示了花岗质岩石的岩石成因、岩浆源区和构造环境。结合区域研究资料,探讨了虎林花岗质岩石所属的区域花岗质岩浆活动期次及其与郯庐断裂、虎林盆地、虎林片岩和东北东部早白垩世NE向岩浆岩-火山岩-变质岩的构造耦合关系。最后,确定了虎林花岗质岩石形成的地球动力学背景。LA-ICP-MS锆石U-Pb同位素年代学研究表明,虎林花岗质岩石的形成时代分别为太和村北花岗闪长斑岩岩脉127.8±2.8Ma、天盛花岗闪长岩岩体114.1±1.4Ma、西山黑云母二长花岗岩岩体115.2±1.4Ma和庆丰村北花岗闪长斑岩岩脉114.9±1.4Ma。他们形成于东北东部早白垩世NE向花岗质岩浆活动的早期(131~118Ma)和中期(116~111Ma),属于区域岩浆活动的一部分。全岩主微量元素地球化学研究表明,样品具有低TiO_2、Fe_2O_3、P_2O_5和高Na_2O等特征,属于准铝质-弱过铝质中钾钙碱性系列,具有富集轻稀土和大离子亲石元素(Rb、Ba和K),亏损重稀土和高场强元素(Nb、P和Ti)的特征。虎林花岗质岩石野外特征、矿物组成、主微量元素特征、岩石成因判别图、岩浆源区判别图、构造环境判别图和元素协变关系的综合研究表明,虎林花岗质岩石为I型花岗岩类;原始岩浆为壳幔混合源,主要来自加厚下地壳基性岩石部分熔融,并受俯冲带流体交代作用形成的富集地幔部分熔融作用的影响;形成于大陆弧引张环境。结合区域研究资料,虎林花岗质岩石与邻区郯庐断裂系、虎林盆地、虎林片岩和东北东部NE向早白垩世岩浆-火山-变质事件均存在构造耦合关系,他们形成于早白垩世NW-SE向伸展环境,且该伸展环境具有早强晚弱的特征。花岗质岩石形成过程和早白垩世伸展活动与中国东北东部前白垩纪增厚岩石圈发生重力失稳和早白垩世太平洋板块俯冲诱发岩石圈拆沉减薄的地球动力学背景相关。
[Abstract]:A detailed field investigation of granitic rocks in the Hulin area in the northern part of the Xingkai block has been carried out, including petrology, petrology, zircon U-Pb isotopic geochronology of LA-ICP-MS and geochemistry of the main trace elements in the whole rock. The distribution range and rock assemblage of granitic rocks are defined, the forming age of granitic rocks is determined, and the petrogenesis, magmatic source region and tectonic environment of granitic rocks are revealed. The tectonic coupling relationship between the regional granitic magmatic activities of the Holin granitic rocks and the Tanlu fault, the Hulin basin, the Hulin schist and the early Cretaceous NE trending magma-volcanic rock-metamorphic rocks in the eastern part of Northeast China are discussed. The geodynamic background of the formation of the Holin granitic rocks has been determined. The U-Pb isotopic study of zircon from LA-ICP-MS shows that, The age of formation of the Holin granitic rocks is 127.8 卤2.8 Ma in the northern granodiorite porphyry, 114.1 卤1.4 Main in Tiansheng granodiorite, 115.2 卤1.4 Ma in the Xishan biotite monzogranite and 114.9 卤1.4 Ma. in the northern granodiorite vein of Qingfeng village. In the early Cretaceous NE granitic magmatism of the eastern part of Northeast China, the early stage of NE granitic magmatism (131C 118MaA) and the middle stage of NE-trending granitic magmatism (111MaA) belong to the regional magmatism. The geochemical study of main trace elements in the whole rock indicates that. The samples are characterized by low tio _ 2Feth _ _ _. It has the characteristics of enrichment of light rare earth elements and large ion lithophile elements such as RB, Ba and K, depletion of heavy rare earths and high field strength elements NbP- P and Ti. field characteristics of granitic rocks, mineral composition, main trace element characteristics, petrogenetic discriminant map, magma source area discriminant diagram, and so on. The Synthetical study of tectonic environment discriminant diagram and element covariation shows that the Holin granitic rocks are I-type granites, the primitive magma is a mixed source of crust and mantle, and mainly comes from the partial melting of thickened basic rocks in the lower crust. It is influenced by partial melting of enriched mantle formed by fluid metasomatism in subduction zone, formed in continental arc extensional environment, and combined with regional research data, Hulin granitic rocks and Tanlu fault system in adjacent area, Hulin basin, The Hulin schist and NE trending early Cretaceous magma volcano-metamorphic events in the eastern part of China are tectonically coupled. They were formed in the early Cretaceous NW-SE extensional environment. The extensional environment is characterized by early strong and late weak. Granitic rock formation process and early Cretaceous extensional activity and gravity instability in the thickening lithosphere of the eastern part of northeast China and early Cretaceous Pacific plate subduction. The geodynamic background of lithospheric dewatering and thinning is related.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P588.1

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