原特提斯北界東段構(gòu)造演化與拼合方式
發(fā)布時間：2018-11-29 08:34
【摘要】：原特提斯洋是從Rodinia超大陸裂解到加里東末期發(fā)育于滇緬泰/保山微陸塊以北、塔里木-華北陸塊以南的一個近東西向古大洋，洋內(nèi)存在華北、揚(yáng)子、華夏、柴達(dá)木、中祁連、印支、北秦嶺等諸多陸塊/微陸塊。但是對原特提斯洋的邊界、不同陸塊/微陸塊的屬性及洋-陸格局等尚不清楚。因此，本文主要以北秦嶺-桐柏造山帶北緣為研究對象，利用精細(xì)的野外構(gòu)造幾何學(xué)和運動學(xué)解析及LA-ICPMS、40Ar/39Ar測年等方法，結(jié)合已有的火成巖大地構(gòu)造、沉積巖大地構(gòu)造、巖石地球化學(xué)、同位素年代學(xué)、巖相古地理等諸多研究資料，進(jìn)行集成創(chuàng)新，以厘定原特提斯洋的北界東段；確定原特提斯北部東段陸塊/微陸塊的屬性、拼合時序及方式，建立洋-陸格局；探討其構(gòu)造演化過程，為Pangea超大陸的全球陸塊重建打下堅實基礎(chǔ)。 1.通過對古洛南-欒川斷裂帶兩側(cè)的沉積地層、碎屑鋯石年齡譜、巖漿活動、構(gòu)造變形變質(zhì)等方面進(jìn)行大地構(gòu)造對比，得到作為被動陸緣的華北地塊南緣和早古生代作為活動陸緣的北秦嶺兩者的地質(zhì)特征具有天壤之別，厘定原特提斯北界東段邊界為古洛南-欒川斷裂。 2.構(gòu)造變形幕次及特征：基于詳細(xì)的構(gòu)造解析及地質(zhì)年代學(xué)資料，本文將早古生代研究區(qū)的構(gòu)造變形劃分為三幕。第一幕變形以發(fā)育區(qū)域上透入性的片理及向南傾的逆沖斷層為主；第二幕變形主要表現(xiàn)為以近北西向的緊閉褶皺為主；第三幕變形以近北西西向的寬緩褶皺為主要特征。 3．拼合時序及方式：540Ma，寬坪洋向南俯沖，之后俯沖極性發(fā)生反轉(zhuǎn)，460Ma，商丹洋開始向北俯沖，450Ma，北秦嶺島弧與華北地塊南緣發(fā)生弧陸碰撞。 4.北秦嶺-桐柏造山帶北緣及其鄰區(qū)的構(gòu)造單元可劃分為如下的大地構(gòu)造分區(qū)及演化歷程，自北向南依次是華北地塊南緣新元古代-早古生代為被動大陸邊緣；寬坪群為近島架的火山裂谷-大洋盆地，碎屑物質(zhì)主要來源于北秦嶺；二郎坪群為寬坪大洋向南俯沖的弧前盆地，后期轉(zhuǎn)變成為島弧或弧后盆地；秦嶺群為一古老的獨立微陸塊，于早古生代轉(zhuǎn)變?yōu)榇箨憤u弧，且末期向北與華北地塊碰撞拼貼為一體；商丹洋為獨立的大洋盆地或者可能是寬坪大洋向南俯沖形成的弧后盆地；龜山雜巖和南灣復(fù)理石屬晚古生代商丹洋向北發(fā)生俯沖產(chǎn)生的弧前增生楔體系及構(gòu)造混雜巖帶，但南秦嶺及揚(yáng)子北緣早古生代均為被動陸緣。
[Abstract]:The original Tethys ocean developed from the Rodinia supercontinent to the end of Caledonian, north of Yunnan, Myanmar, Thailand / Baoshan microcontinent, and south of Tarim to North China block. There are North China, Yangtze, Cathaysia, Chaidamu and Middle Qilian in the ocean. Indosinian, North Qinling and many other land blocks / microcontinental blocks. However, it is not clear about the boundary of the original Tethys ocean, the attributes of different land blocks / microblocks and the ocean-land pattern. Therefore, in this paper, the northern margin of Qinling to Tongbai orogenic belt is taken as the research object, and the detailed methods of structural geometry, kinematics and LA-ICPMS,40Ar/39Ar dating are used to combine with the existing igneous geotectonics. Sedimentary geotectonics, geochemistry, isotopic geochronology, lithofacies and paleogeography, and so on, have been integrated and innovated to determine the eastern segment of the northern boundary of the original Tethys Ocean. The attributes of the continental blocks / microblocks in the eastern segment of the northern part of the former Tethys are determined, the sequence and pattern of the assemblage are combined, the ocean-continental pattern is established, and the tectonic evolution process is discussed, which lays a solid foundation for the reconstruction of the global land blocks of the Pangea supercontinent. 1. The geotectonic correlation of sedimentary strata, zircon age spectrum, magmatic activity, tectonic deformation and metamorphism on both sides of the Paleo-Luonan-Luanchuan fault zone is carried out. The geological characteristics of the southern margin of the North China block as a passive continental margin and the North Qinling Mountains as the active margin of the early Paleozoic are different from each other, and the eastern boundary of the northern boundary of the original Tethys is determined to be the Palonan-Luanchuan fault. 2. Tectonic deformation episodes and characteristics: based on detailed tectonic analysis and geochronological data, the tectonic deformation of the early Paleozoic study area is divided into three acts in this paper. The deformation of the first act is mainly characterized by the permeable lithology of the developing region and the thrusting fault trending to the south, the deformation of the second act is mainly characterized by the closed fold near the north-west direction, and the deformation of the third act is characterized by the wide and gentle fold in the near NW direction. 3.The sequence and mode of assemblage are as follows: 540Ma. the Kuanping Ocean subducts south, then the subduction polarity reverses, 460Ma. the Shangdan Ocean subducts northward, 450 Ma. the arc-land collision occurs between the northern Qinling island arc and the southern margin of the North China block. 4. The tectonic units in the northern margin of the North Qinling-Tongbai orogenic belt and its adjacent areas can be divided into the following tectonic divisions and evolution processes. The southern margin of the North China Block is the Neoproterozoic to the early Paleozoic as the passive continental margin from north to south. The Kuanping Group is a volcanic rift oceanic basin near the island frame, and the clastic material is mainly derived from the North Qinling Mountains, while the Erlangping Group is a front arc basin of the Kuanping Ocean subducting to the south, and is transformed into an island arc or a back-arc basin in the latter stage. The Qinling Group is an ancient independent microcontinental block, which was transformed into a continental island arc in the early Paleozoic and collided with the North China block in the late stage, and the Shangdan Ocean is an independent oceanic basin or possibly a back-arc basin formed by the subduction of the Kuanping Ocean to the south. The Qiushan complex and the Nanwan flysch belong to the late Paleozoic Shangdan Ocean subduction northward system of accretive wedge system and tectonic melange belt, but the South Qinling Mountains and the northern margin of Yangtze are all passive continental margin in early Paleozoic.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：P736.22
本文編號：2364511
[Abstract]:The original Tethys ocean developed from the Rodinia supercontinent to the end of Caledonian, north of Yunnan, Myanmar, Thailand / Baoshan microcontinent, and south of Tarim to North China block. There are North China, Yangtze, Cathaysia, Chaidamu and Middle Qilian in the ocean. Indosinian, North Qinling and many other land blocks / microcontinental blocks. However, it is not clear about the boundary of the original Tethys ocean, the attributes of different land blocks / microblocks and the ocean-land pattern. Therefore, in this paper, the northern margin of Qinling to Tongbai orogenic belt is taken as the research object, and the detailed methods of structural geometry, kinematics and LA-ICPMS,40Ar/39Ar dating are used to combine with the existing igneous geotectonics. Sedimentary geotectonics, geochemistry, isotopic geochronology, lithofacies and paleogeography, and so on, have been integrated and innovated to determine the eastern segment of the northern boundary of the original Tethys Ocean. The attributes of the continental blocks / microblocks in the eastern segment of the northern part of the former Tethys are determined, the sequence and pattern of the assemblage are combined, the ocean-continental pattern is established, and the tectonic evolution process is discussed, which lays a solid foundation for the reconstruction of the global land blocks of the Pangea supercontinent. 1. The geotectonic correlation of sedimentary strata, zircon age spectrum, magmatic activity, tectonic deformation and metamorphism on both sides of the Paleo-Luonan-Luanchuan fault zone is carried out. The geological characteristics of the southern margin of the North China block as a passive continental margin and the North Qinling Mountains as the active margin of the early Paleozoic are different from each other, and the eastern boundary of the northern boundary of the original Tethys is determined to be the Palonan-Luanchuan fault. 2. Tectonic deformation episodes and characteristics: based on detailed tectonic analysis and geochronological data, the tectonic deformation of the early Paleozoic study area is divided into three acts in this paper. The deformation of the first act is mainly characterized by the permeable lithology of the developing region and the thrusting fault trending to the south, the deformation of the second act is mainly characterized by the closed fold near the north-west direction, and the deformation of the third act is characterized by the wide and gentle fold in the near NW direction. 3.The sequence and mode of assemblage are as follows: 540Ma. the Kuanping Ocean subducts south, then the subduction polarity reverses, 460Ma. the Shangdan Ocean subducts northward, 450 Ma. the arc-land collision occurs between the northern Qinling island arc and the southern margin of the North China block. 4. The tectonic units in the northern margin of the North Qinling-Tongbai orogenic belt and its adjacent areas can be divided into the following tectonic divisions and evolution processes. The southern margin of the North China Block is the Neoproterozoic to the early Paleozoic as the passive continental margin from north to south. The Kuanping Group is a volcanic rift oceanic basin near the island frame, and the clastic material is mainly derived from the North Qinling Mountains, while the Erlangping Group is a front arc basin of the Kuanping Ocean subducting to the south, and is transformed into an island arc or a back-arc basin in the latter stage. The Qinling Group is an ancient independent microcontinental block, which was transformed into a continental island arc in the early Paleozoic and collided with the North China block in the late stage, and the Shangdan Ocean is an independent oceanic basin or possibly a back-arc basin formed by the subduction of the Kuanping Ocean to the south. The Qiushan complex and the Nanwan flysch belong to the late Paleozoic Shangdan Ocean subduction northward system of accretive wedge system and tectonic melange belt, but the South Qinling Mountains and the northern margin of Yangtze are all passive continental margin in early Paleozoic.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：P736.22
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