本文選題：中亞造山帶 + 阿拉善北緣　； 參考：《中國(guó)地質(zhì)大學(xué)(北京)》2016年博士論文

【摘要】：阿拉善及其北緣地區(qū)位于中亞造山帶中段南緣,處于中朝板塊、塔里木板塊、西伯利亞板塊之間的匯合地帶,是天山造山帶與興蒙造山帶的交匯部位,是研究中亞造山帶構(gòu)造演化和古亞洲洋最終閉合歷史的關(guān)鍵區(qū)域。前人對(duì)阿拉善及其北緣地區(qū)的研究主要集中在構(gòu)造單元的劃分、蛇綠巖以及花崗巖的分析等方面,而對(duì)于研究區(qū)內(nèi)沉積地質(zhì)特征的研究則相對(duì)較少,并且對(duì)于阿拉善北緣地質(zhì)演化事件發(fā)生的時(shí)間也具有很大爭(zhēng)議。針對(duì)上述問(wèn)題,本文通過(guò)沉積學(xué)、古生物學(xué)、地球化學(xué)和鋯石年代學(xué)等方法,結(jié)合區(qū)域地質(zhì)調(diào)查資料和前人巖漿巖等研究成果,對(duì)阿拉善北緣地區(qū)古生代沉積地質(zhì)特征進(jìn)行分析,探討其構(gòu)造演化過(guò)程,為中亞造山帶的研究工作提供基礎(chǔ)資料。阿拉善北緣地區(qū)發(fā)育了三條重要的斷裂帶:由北至南分別為雅干斷裂帶、恩格爾烏蘇斷裂帶(蛇綠巖帶)和查干礎(chǔ)魯斷裂帶(蛇綠巖帶),以此三條斷裂帶為界可以將阿拉善北緣劃分四個(gè)構(gòu)造帶,由北至南分別為雅干構(gòu)造帶、珠斯楞-杭烏拉構(gòu)造帶、沙拉扎山構(gòu)造帶和諾爾公-狼山構(gòu)造帶。其中珠斯楞-杭烏拉構(gòu)造帶和沙拉扎山構(gòu)造帶內(nèi)保留了相對(duì)較多的沉積記錄,諾爾公-狼山構(gòu)造帶則發(fā)育有大量的巖漿巖,而雅干構(gòu)造帶處于研究區(qū)以外。在珠斯楞-杭烏拉構(gòu)造帶內(nèi)利用生物化石和碎屑鋯石年齡(420±3Ma、419.6±3.6Ma),將圓包山組時(shí)代從早志留世重新確定為早志留世-中泥盆世;利用火山巖鋯石年齡(284Ma)將方山口組的時(shí)代重新厘定為晚二疊世;利用古生物化石和碎屑鋯石年齡(最新年齡約為299Ma)確定雙堡塘組的時(shí)代為早二疊世。本帶內(nèi)發(fā)育了兩套可以反映構(gòu)造演化過(guò)程的沉積組合。第一套組合為中寒武-下奧陶統(tǒng)西雙鷹山組(∈2-O1x)、下志留統(tǒng)班定陶勒蓋組(S1b)和早志留世-中泥盆紀(jì)圓包山組(S1-D2y),此組合代表了多島洋向活動(dòng)大陸邊緣演化的過(guò)程;第二套組合為下二疊統(tǒng)雙堡塘組(P1sb)和下二疊統(tǒng)方山口組(P1f),其沉積序列可以反映出完整的弧后盆地演化過(guò)程。通過(guò)對(duì)本帶內(nèi)沉積巖、火山巖的地球化學(xué)特征分析以及前人資料,認(rèn)為杭烏拉地區(qū)在古生代經(jīng)歷了兩次大洋的開(kāi)合過(guò)程,第一次大洋閉合于晚泥盆-石炭紀(jì),第二次大洋閉合于中二疊世后。在沙拉扎山構(gòu)造帶內(nèi)利用沉積學(xué)、巖石學(xué)和地球化學(xué)等綜合研究方法,重新厘定了“阿木山組”和“本巴圖組”的地層層序。其中,“阿木山組”為查干礎(chǔ)魯弧后盆地的產(chǎn)物,其灰?guī)r段形成于晚石炭世-早二疊世早期,火山巖-砂巖段形成于早二疊世晚期,可能延續(xù)到中二疊世。通過(guò)對(duì)在查干礎(chǔ)魯蛇綠巖帶中采集的早二疊世放射蟲(chóng)化石和“阿木山組”沉積、地球化學(xué)特征的分析,并結(jié)合前人年齡研究成果(該蛇綠巖帶中輝長(zhǎng)巖年齡為275±3 Ma、烏力吉后碰撞型花崗巖年齡為250.8±2.0Ma),認(rèn)為查干礎(chǔ)魯蛇綠巖帶所代表的大洋閉合時(shí)間在275Ma和250Ma之間,即查干礎(chǔ)魯縫合帶的形成時(shí)間為晚二疊世。而“本巴圖組”層位低于“阿木山組”,形成于晚石炭世早期,其沉積序列代表了一個(gè)穩(wěn)定大陸邊緣向活動(dòng)大陸邊緣轉(zhuǎn)化的過(guò)程。在諾爾公-狼山構(gòu)造帶內(nèi)利用流紋巖中鋯石年齡數(shù)據(jù)(265.6Ma和267.2Ma),認(rèn)定蘇吉火山巖年齡為中二疊世。根據(jù)其火山巖地球化學(xué)特征和區(qū)域構(gòu)造資料,認(rèn)為蘇吉火山巖形成于大陸弧環(huán)境。通過(guò)對(duì)古生代地層和沉積地質(zhì)的詳細(xì)研究,將研究區(qū)的沉積與構(gòu)造演化劃分為五個(gè)階段:①中寒武世-早奧陶世,呼和套爾蓋洋內(nèi)弧和沙拉扎山島弧逐漸形成,此時(shí)杭烏拉地區(qū)為處于塔里木板塊和呼和套爾蓋洋內(nèi)弧之間的多島洋,大地構(gòu)造環(huán)境相對(duì)穩(wěn)定。②早志留世-中泥盆世,塔里木板塊和呼和套爾蓋洋內(nèi)弧之間的大洋向北部呼和套爾蓋洋內(nèi)弧下俯沖,杭烏拉地區(qū)結(jié)束了早古生代穩(wěn)定的大陸環(huán)境,逐漸轉(zhuǎn)變?yōu)榛顒?dòng)大陸邊緣(位于呼和套爾蓋洋內(nèi)弧南緣)。③晚泥盆世-早石炭世,杭烏拉地區(qū)的大洋在此期間閉合。④晚石炭世-早二疊世,沙拉扎山構(gòu)造帶北部活動(dòng)大陸邊緣和查干礎(chǔ)魯弧后盆地逐漸形成,構(gòu)成了典型的溝-弧-盆體系。杭烏拉地區(qū)受呼和套爾蓋北部大洋向南的俯沖作用,形成了弧后盆地。⑤中-晚二疊世,研究區(qū)內(nèi)各大洋開(kāi)始俯沖消減。中二疊世之后,杭烏拉地區(qū)的大洋閉合;晚二疊世,查干礎(chǔ)魯蛇綠巖所代表的大洋閉合;晚二疊世晚期,恩格爾烏蘇蛇綠巖所代表的大洋閉合。
[Abstract]:Alashan and its northern margin are located in the southern margin of the middle part of the Central Asian orogenic belt, which are located in the confluence zone between the Sino Korean plate, the Tarim plate and the Siberia plate. It is the intersection of the Tianshan orogenic belt and the Xingmeng orogenic belt. It is the key area for the study of the tectonic evolution of the Central Asian orogenic belt and the final closed history of the ancient Asian Ocean. The predecessors had been to Alashan and its predecessors. The northern margin of the study is mainly focused on the division of structural units, the analysis of the ophiolite and the granite, while the study on the sedimentary geological characteristics in the study area is relatively small, and the time of the geological evolution events in the northern margin of Alashan is also very controversial. The study, geochemistry and zircon chronology, combined with the research results of regional geological survey and previous magmatic rocks, analyzed the Paleozoic sedimentary geological characteristics of the northern margin of Alashan and explored its tectonic evolution process, providing basic information for the research work of the Central Asian mountain zone. Three important developments in the northern margin of Alashan have been developed. The fault zone: from north to south, respectively, the jakan fault zone, the Engel Wusu fault zone (ophiolite belt) and Chagan chadu fault zone (ophiolitic belt). By this three fault zones, the northern margin of Alashan can be divided into four tectonic zones, from north to south, respectively, the jakan tectonic belt, the zhusleng hang URA structural belt, the salad Zhan mountain structural belt and Norway. In the Langshan tectonic belt, there are relatively large deposits of sedimentary records in the Pearl - Leng - hang - URA structural belt and the Sarah Zhishan tectonic belt, while the Norman Langshan tectonic belt is developed with a large number of magmatic rocks, while the JYA Jigan tectonic belt is outside the study area. The age of the fossil and detrital zircons in the Pearl - Leng hang tectonic belt (420 +. 419.6) The era of the Yuan Baoshan formation was redefined from Early Silurian to Early Silurian Middle Devonian, and the age of the volcanic zircon age (284Ma) was redefined to the Late Permian, and the age of the paleontological fossils and detrital zircon ages (the latest age of 299Ma) was determined to be the early Permian. The development of this zone was in the development of the early Permian. Two sets of sedimentary assemblages that can reflect the tectonic evolution process, the first set of assemblages are the Middle Cambrian and the lower Ordovician Double Eagle mountain group (2-O1x), the Lower Silurian class Dingtao Le Gu group (S1b) and the Early Silurian - Mian Baoshan Group (S1-D2y). This assemblage represents the evolution of the multi island ocean to the active continental margin; the second sets are the lower two. The sedimentary sequence of the double Fort pond formation (P1sb) and the lower two series of the square Yamaguchi formation (P1f) can reflect the complete evolution process of the back arc basin. Through the analysis of the geochemical characteristics of the sedimentary rocks and volcanic rocks in the present belt and the previous data, it is believed that the region of Hangzhou has experienced two oceanic opening and closing processes in the Palaeozoic, and the first Ocean was closed in the late mud. In the Basin Carboniferous period, the second ocean was closed after the Middle Permian. In the salzhashan tectonic belt, the stratigraphic sequence of the "A Mu mountain formation" and the "Ben Bartle group" was redefined by the comprehensive research methods of sedimentology, petrology and geochemistry. Among them, the "A Mu mountain formation" was the product of the chashanlu back arc basin, and the limestone section was formed late in the late period. Early Permian in the Carboniferous - Early Permian, volcanic rock sandstone segments were formed in the Late Permian Early Permian, possibly extending to the Middle Permian. The geochemical characteristics of the early Permian radiolarian and the "A Mu mountain formation" collected in Chagan chchic ophiolitic belt were analyzed and combined with the research results of the age of the former (the age of gabbro in the ophiolite belt. The age of age is 275 + 3 Ma, and the age of post Uligi collision type granite is 250.8 + 2.0Ma. It is considered that the ocean closure time of the chchinacinu ophiolite belt is between 275Ma and 250Ma, that is, the formation time of chchacinu suture zone is late Permian. The "Ben Bartle group" layer is lower than the "A Mu mountain" formation and formed in the Early Carboniferous. The column represents a process of transformation from a stable continental margin to the active continental margin. In the Norway Langshan tectonic belt, using zircon age data in rhyolite (265.6Ma and 267.2Ma), the Suji volcanic rocks are identified as the Middle Permian. According to their geochemical characteristics and regional tectonic data, the Suji volcanic rocks are considered to be formed in the continent. Arc environment. Through the detailed study of Paleozoic strata and sedimentary geology, the sedimentary and tectonic evolution of the study area are divided into five stages: (1) the Middle Cambrian Early Ordovician, the Huhe and shigai ocean inner arc and the Sarah Zhan island arc gradually formed, and the hang URA region is a multi island between the Tarim plate and the inner arc of the call and the shigai ocean. The tectonic environment of the ocean is relatively stable. (2) the Early Silurian Middle Devonian, the Tarim plate and the inner arc of the inner arc of the inner arc of the Huhh and shigigai ocean, and the subduction of the inner arc of the neigen ocean. The early Paleozoic continental environment was finished in the hang URA region, and gradually transformed into the active continental margin (located in the southern margin of the Huhe and shigai ocean inner arc). In the late Devonian Early Carboniferous period, the ocean in the hang URA region closed during this period. (4) the Late Carboniferous Early Permian, the northern active continental margin of the shagzhan tectonic belt and the Chagan chchidu back basin gradually formed, forming a typical trench arc basin system. After the middle and Late Permian, the ocean in the study area began to subduction. After the Middle Permian, the ocean was closed in the hang URA region; the Late Permian was closed by the Chagan chchidu ophiolite, and the oceanic closure represented by the Engel URU ophiolite in the Late Permian.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：P534.4;P548

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