本文關(guān)鍵詞：拉薩地體與特提斯喜馬拉雅白堊紀(jì)古地磁學(xué)和年代學(xué)研究　出處：《中國地質(zhì)大學(xué)(北京)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 青藏高原 古地磁學(xué) 印度-亞洲碰撞 拉薩地體 特提斯喜馬拉雅

【摘要】：印度?亞洲的碰撞過程及其造成的陸內(nèi)變形一直是國內(nèi)外地學(xué)工作者研究的前沿和熱點(diǎn)課題,雅魯藏布江縫合帶兩側(cè)的特提斯喜馬拉雅和拉薩地體自白堊紀(jì)以來分別是印度板塊與亞洲大陸的最前緣,其白堊紀(jì)以來的古地理演化對理解上述課題至關(guān)重要。本論文通過對雅魯藏布江縫合帶兩側(cè)地體開展白堊紀(jì)古地磁學(xué)及U-Pb鋯石年代學(xué)等的綜合研究,并結(jié)合已有的地質(zhì)及地球物理數(shù)據(jù),獲得如下幾點(diǎn)新成果及認(rèn)識:(1)拉薩地體西部措勤地區(qū)和獅泉河地區(qū)所采火山巖的U-Pb鋯石年齡分別為早白堊世(?117 121 Ma)和晚白堊世(?67.7 Ma),而特提斯喜馬拉雅浪卡子縣工布學(xué)鄉(xiāng)地區(qū)桑秀組火山巖的U-Pb鋯石年齡為?124 135 Ma;(2)在拉薩地體西部地區(qū)獲得3個(gè)白堊紀(jì)古地磁極,表明亞洲大陸南緣(29.8°N,84.0°E)在白堊紀(jì)期間一直位于北緯?16.8°,且近于目前的東西向排列;(3)在特提斯喜馬拉雅山南地區(qū)新獲得2個(gè)早白堊世火山巖古地磁極證實(shí)了山南地區(qū)(28.5°N,92.0°E)在?130 Ma位于南緯50.5°左右,支持特提斯喜馬拉雅是印度次大陸的延伸部分;(4)確定早白堊世(?135-125 Ma)期間,寬約幾千公里的新特提斯大洋位于拉薩地體和特提斯喜馬拉雅之間;(5)推斷印度克拉通北緣與特提斯喜馬拉雅南緣之間在晚白堊世很可能存在一個(gè)小的洋盆伸展;(6)推斷印度-亞洲碰撞過程很可能是復(fù)雜的“雙陸-陸碰撞模式”,并提出特提斯喜馬拉雅北緣首先沿現(xiàn)今的雅魯藏布江縫合帶在?54.8 Ma與亞洲大陸(拉薩地體)南緣發(fā)生碰撞,而印度克拉通北緣在?41.7 Ma與特提斯喜馬拉雅南緣發(fā)生碰撞;(7)約束印度-亞洲的碰撞及隨后的持續(xù)擠壓導(dǎo)致拉薩地體和河西走廊之間發(fā)生了近800 1000 km的南北向地殼縮短。
[Abstract]:India? The collision process in Asia and the intracontinental deformation caused by it have always been the frontier and hot topic of geoscientists at home and abroad. The Tethys Himalayan and Lhasa terrains on both sides of the Brahmaputra suture belt have been the leading edge between the Indian plate and the Asian continent since the Cretaceous. The paleogeographic evolution since Cretaceous is very important to understand the above problems. In this paper, the paleomagnetism and U-Pb zircon geochronology of the Cretaceous are studied comprehensively on the two sides of the Yalu Zangbo River suture belt. Combined with existing geological and geophysical data. The U-Pb zircon ages of volcanic rocks in the western Lhasa terrane and Shiquanhe area are early Cretaceous? 117 ~ 121 Ma) and late Cretaceous? 67.7 Mahe, and U-Pb zircon age of the Sangxiu formation volcanic rocks in Gongbuxue Xiang area, Langkazi County, Himalayas, Tethys? 124 + 135 Ma; (2) three Cretaceous paleomagnetic poles were obtained in the western Lhasa terrane, indicating that the southern margin of the Asian continent is 29.8 擄Nu 84.0 擄E) and has been located in the northern latitude during the Cretaceous. 16.8 擄, and close to the current east-west alignment; 3) two new early Cretaceous volcanic rock paleomagnetic poles obtained in the southern part of the Tethys Himalayas confirm the presence of 28.5 擄Nu 92.0 擄E in Shannan area. 130Ma is located at about 50.5 擄south latitude, supporting the Tethys Himalaya as an extension of the Indian subcontinent. During 135-125 Ma, the Neo-Tethys Ocean, some several thousand kilometres wide, was located between the Lhasa terrane and the Tethys Himalayas; It is inferred that between the northern margin of the Indian craton and the southern margin of the Tethys Himalayas there may be a small ocean basin extension in the late Cretaceous. We infer that the India-Asia collision process is probably a complex "double continent collision model", and suggest that the northern margin of the Tethys Himalayas was first located along the present-day Brahmaputra suture zone? 54.8 Ma collided with the southern margin of the Asian continent (Lhasa terrace), while the northern margin of the Indian craton lies in? 41.7 Ma collided with the southern edge of the Tethys Himalayas; The collision between Lhasa and Hexi Corridor resulted in the shortening of the crust from the south to the north of the Lhasa area and between the Hexi Corridor and the collision between India and Asia.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：P597.3;P318.44

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