黑龙江大兴安岭战备村、二中队幅侵入岩岩石地球化学及成矿预测

发布时间：2018-03-23 11:56

  本文选题：侵入岩　切入点：岩石地球化学　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：大兴安岭战备村、二中队幅处于滨太平洋成矿域的大兴安岭成矿省中的陈巴尔虎旗—根河Cu-Mo-Pb-Zn-Ag-Au-非金属成矿带东部的林海—大乌苏Cu-Pb-Zn-Au-Ag成矿亚带北部。该成矿带普遍发育燕山期火山岩,矿床的产出受北西向的火山短线和断隆控制,且均是与燕山期浅成侵入体—火山岩有关的浅成热液型矿床及斑岩型矿床。本文选择战备村、二中队幅侵入岩体为研究对象,以野外地质填图为基础,运用矿物学、岩石学、锆石U-Pb同位素测年、元素地球化学以及水系沉积物测量等方法,对研究区侵入岩岩体进行了综合研究。研究区内岩浆作用十分强烈,大面积出露侵入岩,主要分为四种类型:粗中粒二长花岗岩、中细粒二长花岗岩、细粒石英二长岩、细粒二长花岗岩。利用锆石U-Pb测年测得四类侵入岩年龄分别为:粗中粒二长花岗岩(216.1±1.7Ma)、中细粒二长花岗岩(150.5±1Ma)、细粒石英二长岩(142.1±1Ma)、细粒二长花岗岩(121.0±0.8Ma)。据野外工作中观察各侵入岩岩体与地层的接触关系,将其分别对应于晚三叠世、中侏罗世、晚侏罗世、早白垩世。岩石地球化学数据研究表明,本区侵入岩均具有高硅、高碱特征,大部分属高钾钙碱性系列,岩浆分异指数较高,显示其经历了完全(充分)的结晶分异作用,相对富集大离子元素Rb、Ba、Th、U,亏损高场强元素Nb、Ta、Ti,显示其源岩具有壳源特征。研究区侵入岩均具有弧岩浆特性。晚三叠世侵入岩为蒙古—鄂霍茨克板块俯冲,脱水熔融产生的弧岩浆上升混染地壳物质形成的A型花岗岩;中侏罗世侵入岩为蒙古—鄂霍茨克俯冲板片闭合过程中新生下地壳受热部分熔融形成的I型花岗岩;晚侏罗世和早白垩世侵入岩为蒙古—鄂霍茨克洋闭合后,地壳岩石圈持续增厚失稳拆沉,软流圈地幔受热熔融,产生镁铁质岩浆,底侵熔融地壳形成I型及A型花岗岩。区内成矿可能的4种元素是Cu、Pb、Mo、Au。主要异常分布在晚侏罗世和早白垩世侵入岩内。综合侵入岩地质特征、水系沉积物测量等数据,在区内圈定2处乙2类异常,具有进一步工作价值。
[Abstract]:Daxing'anling war preparedness village, In the Daxing'anling metallogenic province, located in the ore-forming region of the Pacific Ocean, the second Zhongdun area is located in the northern part of the Linhai-Da Usu Cu-Pb-Zn-Au-Ag metallogenic subzone in the eastern part of the Chenbalhuqiang-Genhe Cu-Mo-Pb-Zn-Ag-Au-nonmetallic metallogenic belt. The metallogenic belt is characterized by Yanshanian volcanic rocks. The occurrence of the deposit is controlled by the short line of volcanoes and fault uplifts in the NW direction, and they are both epithermal deposits and porphyry type deposits related to the Yanshanian epigenetic intrusion-volcanic rocks. Based on field geological mapping, the methods of mineralogy, petrology, zircon U-Pb isotopic dating, element geochemistry and hydrographic sediment survey are used. A comprehensive study of intrusive rock mass in the study area has been carried out. The magmatism in the study area is very strong, and there are four main types of intrusive rocks: coarse medium-grained monzogranite, medium-fine-grained monzogranite, fine-grained quartz monzonite. The age of four types of intrusive rocks by zircon U-Pb dating are 216.1 卤1.7 Mai, 150.5 卤1MaA, 142.1 卤1MaA and 121.0 卤0.8Ma. respectively. The results of field work are as follows: the age of the four types of intrusive rocks is 216.1 卤1.7 MaA, 150.5 卤1MaA, 142.1 卤1MaA, 121.0 卤0.8Ma. respectively. Contact relationship between each intrusive rock mass and strata, The petrogeochemical data show that the intrusive rocks in this area have the characteristics of high silicon and high alkalinity, most of which belong to the high potassium calc-alkaline series, and the magma differentiation index is relatively high, and the magmatic differentiation index is higher than that in the late Triassic, the middle Jurassic, the late Jurassic and the early Cretaceous. It shows that it has experienced complete (sufficient) crystallization differentiation, The relative enrichment of the large ion element RbsBaHU Thu and the depletion of the high field strength element NbSU Ta-tii show that the source rocks have the characteristics of crust-source. The intrusive rocks in the study area all have the characteristics of arc magma. The late Triassic intrusive rocks were subducted by the Mongolian-Okhotsk plate. The arc magma caused by dehydration and melting is a type A granite formed by mixed crustal materials, and the Middle Jurassic intrusive rock is a type I granite formed by partial melting of the new lower crust during the closure of the Mongolia-Okhotsk subduction plate. After the late Jurassic and early Cretaceous intrusive rocks were closed in the Mongolia-Okhotsk Ocean, the crustal lithosphere was continuously thickened and unstable, and the asthenosphere mantle was heated and melted, resulting in magmatic magma. The submersion molten crust forms type I and A type granites. The four possible elements for mineralization in the area are Cu PbPbMo au. The main anomalies are found in late Jurassic and early Cretaceous intrusive rocks. The geological characteristics of intrusive rocks and sediment measurements of water system are synthesized. There are 2 type B and 2 anomalies in the area, which is valuable for further work.
【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】：P612;P588.12
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本文编号：1653361