發(fā)布時間：2018-02-26 02:19

  本文關鍵詞： 中國東北東部 虎林地區(qū) 花崗巖 早白堊世 伸展 鋯石年齡 地球化學　出處：《吉林大學》2017年碩士論文　論文類型：學位論文

【摘要】：對興凱地塊北部虎林地區(qū)花崗質(zhì)巖石進行了詳細的野外調(diào)查、巖石學、巖相學、LA-ICP-MS鋯石U-Pb同位素年代學和全巖主微量元素地球化學研究,明確了花崗質(zhì)巖石的分布范圍和巖石組合特征,確定了花崗質(zhì)巖石的形成時代,揭示了花崗質(zhì)巖石的巖石成因、巖漿源區(qū)和構(gòu)造環(huán)境。結(jié)合區(qū)域研究資料,探討了虎林花崗質(zhì)巖石所屬的區(qū)域花崗質(zhì)巖漿活動期次及其與郯廬斷裂、虎林盆地、虎林片巖和東北東部早白堊世NE向巖漿巖-火山巖-變質(zhì)巖的構(gòu)造耦合關系。最后,確定了虎林花崗質(zhì)巖石形成的地球動力學背景。LA-ICP-MS鋯石U-Pb同位素年代學研究表明,虎林花崗質(zhì)巖石的形成時代分別為太和村北花崗閃長斑巖巖脈127.8±2.8Ma、天盛花崗閃長巖巖體114.1±1.4Ma、西山黑云母二長花崗巖巖體115.2±1.4Ma和慶豐村北花崗閃長斑巖巖脈114.9±1.4Ma。他們形成于東北東部早白堊世NE向花崗質(zhì)巖漿活動的早期(131~118Ma)和中期(116~111Ma),屬于區(qū)域巖漿活動的一部分。全巖主微量元素地球化學研究表明,樣品具有低TiO_2、Fe_2O_3、P_2O_5和高Na_2O等特征,屬于準鋁質(zhì)-弱過鋁質(zhì)中鉀鈣堿性系列,具有富集輕稀土和大離子親石元素(Rb、Ba和K),虧損重稀土和高場強元素(Nb、P和Ti)的特征�；⒘只◢徺|(zhì)巖石野外特征、礦物組成、主微量元素特征、巖石成因判別圖、巖漿源區(qū)判別圖、構(gòu)造環(huán)境判別圖和元素協(xié)變關系的綜合研究表明,虎林花崗質(zhì)巖石為I型花崗巖類;原始巖漿為殼�；旌显�,主要來自加厚下地殼基性巖石部分熔融,并受俯沖帶流體交代作用形成的富集地幔部分熔融作用的影響;形成于大陸弧引張環(huán)境。結(jié)合區(qū)域研究資料,虎林花崗質(zhì)巖石與鄰區(qū)郯廬斷裂系、虎林盆地、虎林片巖和東北東部NE向早白堊世巖漿-火山-變質(zhì)事件均存在構(gòu)造耦合關系,他們形成于早白堊世NW-SE向伸展環(huán)境,且該伸展環(huán)境具有早強晚弱的特征。花崗質(zhì)巖石形成過程和早白堊世伸展活動與中國東北東部前白堊紀增厚巖石圈發(fā)生重力失穩(wěn)和早白堊世太平洋板塊俯沖誘發(fā)巖石圈拆沉減薄的地球動力學背景相關。
[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 鹵2.8 Ma in the northern granodiorite porphyry, 114.1 鹵1.4 Main in Tiansheng granodiorite, 115.2 鹵1.4 Ma in the Xishan biotite monzogranite and 114.9 鹵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.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P588.1

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