原特提斯北界西段構(gòu)造演化與拼合方式
發(fā)布時間：2019-03-13 16:25
【摘要】：原特提斯洋是從Rodinia裂解到早古生代末發(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復(fù)雜大洋。原特提斯洋內(nèi)存在中祁連、柴達(dá)木、揚(yáng)子、華夏、印支、蘭坪-思茅等諸多陸塊/微陸塊，在其東亞范圍內(nèi)西北部早古生代末發(fā)育有北祁連、柴北緣等一系列蛇綠巖帶或高壓-超高壓變質(zhì)帶。這些地質(zhì)記錄表明早古生代期間原特提斯洋經(jīng)歷了復(fù)雜的洋-陸格局和聚散過程。但至今原特提斯洋的邊界、不同陸塊/微陸塊屬性和關(guān)系及其在早古生代末與北方大陸的拼合過程還存在爭論，而這是恢復(fù)重建Pangea超大陸聚合前期早古生代構(gòu)造背景的關(guān)鍵。 針對這個關(guān)鍵科學(xué)問題，本文將采用野外地質(zhì)調(diào)查、構(gòu)造、巖漿、沉積學(xué)、地球化學(xué)、構(gòu)造年代學(xué)等手段，對原特提斯域西北部進(jìn)行以下三方面的研究：（1）界定原特提斯域的北部西段邊界；（2）建立原特提斯洋北部陸塊/微陸塊的親緣性和海-陸格局；（3）厘定原特提斯北部微陸塊拼合時序與方式。通過綜合集成研究，得出以下幾點(diǎn)新認(rèn)識： 1、原特提斯洋經(jīng)歷了多島洋和微陸塊拼合的復(fù)雜構(gòu)造格局演化過程，且洋盆的打開和閉合均具有穿時性。根據(jù)蛇綠巖的對比，發(fā)現(xiàn)祁連洋向西延至北阿爾金洋，南祁連洋向西延至南阿爾金洋，具有東早西晚的剪刀式打開方式；根據(jù)榴輝巖形成時間對比，原特提斯洋具有從西向東斜向閉合的特點(diǎn)，符合“剪刀式”的拼合模式。 2、根據(jù)榴輝巖折返時間，南祁連洋早期向南俯沖，最終閉合（460~420Ma），原特提斯洋北界仍在北祁連洋；南祁連洋盆閉合后，昆南洋閉合（428Ma），最后祁連洋洋盆閉合（420~410Ma），原特提斯洋北界一直為北祁連地區(qū)。 3、原特提斯洋的演化可簡單的概括為Gondwana裂解期間，眾多地塊從Gondwana裂離并向北先后拼合的過程。震旦紀(jì)-早中寒武世期間塔里木是親揚(yáng)子的，阿拉善新元古代-早古生代親華北，總之各個微陸塊與華北陸塊和揚(yáng)子陸塊的親緣性是隨時間變化。 4、結(jié)合野外地質(zhì)、構(gòu)造變形和年代學(xué)資料以及島弧巖漿巖、沉積建造分布特點(diǎn)，本文認(rèn)為北祁連向南俯沖，南祁連洋為其弧后，裂解形成洋殼，存在時間非常短；昆南洋俯沖比北祁連稍晚，，向北俯沖形成昆中弧后盆地，發(fā)育至早古生代末轉(zhuǎn)變?yōu)槔ブ醒笈�，并開始向北俯沖，形成祁曼塔格弧后盆地。
[Abstract]:The original Tethys Ocean is a complex ocean from Rodinia cracking to the end of early Paleozoic to the north of the Yunnan-Myanmar-Thailand / Baoshan microcontinental block and to the south of the Tarim-North China continental block. In the original Tethys Ocean, there are many continental blocks / microcontinental blocks such as Qilian, Qaidam, Yangzi, Huaxia, Indosinian, Lanping-Simao and so on. North Qilian developed at the end of the early Paleozoic in the northwest of the Tethys Ocean. The northern margin of Qaidam is a series of ophiolite belt or high-pressure-ultra-high pressure metamorphic zone. These geological records indicate that the original Tethys Ocean experienced a complex ocean-land pattern and dispersion process during the early Paleozoic. But up to now, the boundary of the original Tethys Ocean, the attributes and relations of different continental blocks / microblocks and their assembling process with the northern continent at the end of the early Paleozoic are still controversial, which is the key to the restoration and reconstruction of the early Paleozoic tectonic background of the Pangea supercontinent in the early stage of aggregation. In view of this key scientific problem, this paper will adopt the methods of field geological survey, tectonics, magma, sedimentology, geochemistry, tectonic chronology and so on. The following three aspects are studied in the northwest of the original Tethys region: (1) to define the western border of the northern part of the original Tethys region; (2) to establish the affinity and sea-land pattern of the northern part of the original Tethys Ocean; (3) to determine the timing and mode of the combination of the micro-land blocks in the northern part of the original Tethys. Through the comprehensive integration study, the following new understandings are drawn: 1. The original Tethys Ocean experienced the complex tectonic framework evolution process of the multi-island ocean and the micro-continental block, and the opening and closing of the ocean basin were transitory. According to the comparison of ophiolite, it is found that the Qilian Ocean extends westward to the North Altun Ocean, and the South Qilian Ocean extends westward to the South Altun Ocean. According to the comparison of eclogite formation time, the original Tethys Ocean has the characteristics of oblique closure from west to east, which is in accordance with the "scissors" pattern. (2) according to the eclogite exhumation time, the South Qilian Ocean subducted southward and finally closed (460~420Ma) in the early stage of the South Qilian Ocean, and the original Tethys northward boundary was still in the North Qilian Ocean; After the closure of the South Qilian basin, the Kunnan Ocean closure (428Ma), and finally the Qilian Ocean Basin closure (420~410Ma), the former Tethys northward boundary has always been the North Qilian region. 3. The evolution of the original Tethys Ocean can be simply summarized as the process during the Gondwana cracking, during which many parcels split from Gondwana and coalesced northward. During the Sinian-early Middle Cambrian period, Tarim was Yangtze-friendly, and Alxa Neoproterozoic-early Paleozoic was pro-North China. In a word, the affinity between each microcontinent block, North China continent block and Yangtze continent block changed with time. 4. Combining the data of field geology, tectonic deformation and chronology as well as the distribution characteristics of island arc magmatic rocks and sedimentary formations, it is considered that the North Qilian subducted southward, and the South Qilian Ocean was its back arc, and the oceanic crust was formed by splitting and forming the oceanic crust, which existed for a very short time. The subduction of the Kunnan Ocean is a little later than that of the North Qilian. The northward subduction of the Kunnan Ocean formed a back-arc basin in Kunzhong, which developed to the end of the early Paleozoic and began to submerge northward to form a back-arc basin of Qimantag.
【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
[Abstract]:The original Tethys Ocean is a complex ocean from Rodinia cracking to the end of early Paleozoic to the north of the Yunnan-Myanmar-Thailand / Baoshan microcontinental block and to the south of the Tarim-North China continental block. In the original Tethys Ocean, there are many continental blocks / microcontinental blocks such as Qilian, Qaidam, Yangzi, Huaxia, Indosinian, Lanping-Simao and so on. North Qilian developed at the end of the early Paleozoic in the northwest of the Tethys Ocean. The northern margin of Qaidam is a series of ophiolite belt or high-pressure-ultra-high pressure metamorphic zone. These geological records indicate that the original Tethys Ocean experienced a complex ocean-land pattern and dispersion process during the early Paleozoic. But up to now, the boundary of the original Tethys Ocean, the attributes and relations of different continental blocks / microblocks and their assembling process with the northern continent at the end of the early Paleozoic are still controversial, which is the key to the restoration and reconstruction of the early Paleozoic tectonic background of the Pangea supercontinent in the early stage of aggregation. In view of this key scientific problem, this paper will adopt the methods of field geological survey, tectonics, magma, sedimentology, geochemistry, tectonic chronology and so on. The following three aspects are studied in the northwest of the original Tethys region: (1) to define the western border of the northern part of the original Tethys region; (2) to establish the affinity and sea-land pattern of the northern part of the original Tethys Ocean; (3) to determine the timing and mode of the combination of the micro-land blocks in the northern part of the original Tethys. Through the comprehensive integration study, the following new understandings are drawn: 1. The original Tethys Ocean experienced the complex tectonic framework evolution process of the multi-island ocean and the micro-continental block, and the opening and closing of the ocean basin were transitory. According to the comparison of ophiolite, it is found that the Qilian Ocean extends westward to the North Altun Ocean, and the South Qilian Ocean extends westward to the South Altun Ocean. According to the comparison of eclogite formation time, the original Tethys Ocean has the characteristics of oblique closure from west to east, which is in accordance with the "scissors" pattern. (2) according to the eclogite exhumation time, the South Qilian Ocean subducted southward and finally closed (460~420Ma) in the early stage of the South Qilian Ocean, and the original Tethys northward boundary was still in the North Qilian Ocean; After the closure of the South Qilian basin, the Kunnan Ocean closure (428Ma), and finally the Qilian Ocean Basin closure (420~410Ma), the former Tethys northward boundary has always been the North Qilian region. 3. The evolution of the original Tethys Ocean can be simply summarized as the process during the Gondwana cracking, during which many parcels split from Gondwana and coalesced northward. During the Sinian-early Middle Cambrian period, Tarim was Yangtze-friendly, and Alxa Neoproterozoic-early Paleozoic was pro-North China. In a word, the affinity between each microcontinent block, North China continent block and Yangtze continent block changed with time. 4. Combining the data of field geology, tectonic deformation and chronology as well as the distribution characteristics of island arc magmatic rocks and sedimentary formations, it is considered that the North Qilian subducted southward, and the South Qilian Ocean was its back arc, and the oceanic crust was formed by splitting and forming the oceanic crust, which existed for a very short time. The subduction of the Kunnan Ocean is a little later than that of the North Qilian. The northward subduction of the Kunnan Ocean formed a back-arc basin in Kunzhong, which developed to the end of the early Paleozoic and began to submerge northward to form a back-arc basin of Qimantag.
【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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