本文選題：侵入巖　切入點(diǎn)：巖石地球化學(xué)　出處：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文

【摘要】：大興安嶺戰(zhàn)備村、二中隊(duì)幅處于濱太平洋成礦域的大興安嶺成礦省中的陳巴爾虎旗—根河Cu-Mo-Pb-Zn-Ag-Au-非金屬成礦帶東部的林�！鬄跆KCu-Pb-Zn-Au-Ag成礦亞帶北部。該成礦帶普遍發(fā)育燕山期火山巖,礦床的產(chǎn)出受北西向的火山短線和斷隆控制,且均是與燕山期淺成侵入體—火山巖有關(guān)的淺成熱液型礦床及斑巖型礦床。本文選擇戰(zhàn)備村、二中隊(duì)幅侵入巖體為研究對象,以野外地質(zhì)填圖為基礎(chǔ),運(yùn)用礦物學(xué)、巖石學(xué)、鋯石U-Pb同位素測年、元素地球化學(xué)以及水系沉積物測量等方法,對研究區(qū)侵入巖巖體進(jìn)行了綜合研究。研究區(qū)內(nèi)巖漿作用十分強(qiáng)烈,大面積出露侵入巖,主要分為四種類型:粗中粒二長花崗巖、中細(xì)粒二長花崗巖、細(xì)粒石英二長巖、細(xì)粒二長花崗巖。利用鋯石U-Pb測年測得四類侵入巖年齡分別為:粗中粒二長花崗巖(216.1±1.7Ma)、中細(xì)粒二長花崗巖(150.5±1Ma)、細(xì)粒石英二長巖(142.1±1Ma)、細(xì)粒二長花崗巖(121.0±0.8Ma)。據(jù)野外工作中觀察各侵入巖巖體與地層的接觸關(guān)系,將其分別對應(yīng)于晚三疊世、中侏羅世、晚侏羅世、早白堊世。巖石地球化學(xué)數(shù)據(jù)研究表明,本區(qū)侵入巖均具有高硅、高堿特征,大部分屬高鉀鈣堿性系列,巖漿分異指數(shù)較高,顯示其經(jīng)歷了完全(充分)的結(jié)晶分異作用,相對富集大離子元素Rb、Ba、Th、U,虧損高場強(qiáng)元素Nb、Ta、Ti,顯示其源巖具有殼源特征。研究區(qū)侵入巖均具有弧巖漿特性。晚三疊世侵入巖為蒙古—鄂霍茨克板塊俯沖,脫水熔融產(chǎn)生的弧巖漿上升混染地殼物質(zhì)形成的A型花崗巖;中侏羅世侵入巖為蒙古—鄂霍茨克俯沖板片閉合過程中新生下地殼受熱部分熔融形成的I型花崗巖;晚侏羅世和早白堊世侵入巖為蒙古—鄂霍茨克洋閉合后,地殼巖石圈持續(xù)增厚失穩(wěn)拆沉,軟流圈地幔受熱熔融,產(chǎn)生鎂鐵質(zhì)巖漿,底侵熔融地殼形成I型及A型花崗巖。區(qū)內(nèi)成礦可能的4種元素是Cu、Pb、Mo、Au。主要異常分布在晚侏羅世和早白堊世侵入巖內(nèi)。綜合侵入巖地質(zhì)特征、水系沉積物測量等數(shù)據(jù),在區(qū)內(nèi)圈定2處乙2類異常,具有進(jìn)一步工作價(jià)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 鹵1.7 Mai, 150.5 鹵1MaA, 142.1 鹵1MaA and 121.0 鹵0.8Ma. respectively. The results of field work are as follows: the age of the four types of intrusive rocks is 216.1 鹵1.7 MaA, 150.5 鹵1MaA, 142.1 鹵1MaA, 121.0 鹵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.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P612;P588.12
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本文編號：1653361