發(fā)布時間：2018-06-28 05:22

  本文選題：青藏高原 + 拉薩地塊�。� 參考：《西北大學(xué)》2016年博士論文

【摘要】：青藏高原屬特提斯構(gòu)造域的東段,其形成演化過程是當(dāng)代地球科學(xué)前緣的研究課題。三疊紀(jì)是青藏高原演化過程中關(guān)鍵時期之一,高原主要地體南北向遷移、古特提斯洋逐步收縮及中(?)特提斯洋漸漸開啟等一系列重大地質(zhì)歷史事件可能就發(fā)生在這一時期。拉薩地塊與羌塘地塊位于青藏高原腹地,是組成青藏高原的主要地體,它們的運動與古特提斯洋收縮及中(?)特提斯洋開啟及閉合等地質(zhì)事件密切相關(guān)。古地磁學(xué)可以為研究塊體的運動提供定量依據(jù)。本文對青藏高原腹地羌塘塊體、拉薩塊體的三疊紀(jì)地層開展了系統(tǒng)的古地磁研究并討論其構(gòu)造意義。在拉薩地塊中部措勤地區(qū)敵布錯湖邊新發(fā)現(xiàn)的三疊紀(jì)海相碳酸鹽巖地層中布置了32個采點,采集了327塊獨立的定向樣品。巖石磁學(xué)研究顯示：樣品中主要的載磁礦物為磁鐵礦和(或)磁黃鐵礦。大部分樣品逐步退磁曲線具有明顯的三分量特征：低溫分量為現(xiàn)代地磁場的低溫粘滯剩磁；中溫分量應(yīng)為白堊紀(jì)的次生剩磁分量；高溫分量(分量C)僅可在為數(shù)不多且以磁鐵礦為主要載磁礦物的樣品中獲得。早-中三疊世的分量C可通過95%置信度的倒轉(zhuǎn)檢驗(B級)與99%置信度的褶皺檢驗；晚三疊世的分量C可通過95%置信度的褶皺檢驗。對應(yīng)的古地磁極位置：早-中三疊世(19.3°N,209.3°E,A95=4.0°,N=8)；晚三疊世(19.6°N,211.8°E,495=10.7°,N=6)；相應(yīng)的古緯度分別為16.9±4.0°S和18.4+10.7°S。對羌塘地塊北部三疊紀(jì)地層的26個采點(249塊樣品)進(jìn)行了系統(tǒng)的古地磁研究。試驗結(jié)果表明：樣品中主要載磁礦物為赤鐵礦和(或)磁鐵礦。早三疊世與晚三疊世大部分樣品的退磁曲線具有明顯的雙分量特征,中-晚三疊世圖中湖組由于后期重磁化的影響,并未獲得可靠的高溫分量。本研究揭示出了兩組高溫特征分量,早三疊世與晚三疊世樣品的高溫分量均可通過高置信度下的褶皺檢驗,獲得羌塘塊體兩個古地磁極位置：早三疊世(23.8°N,210.3°E,A95=10.9°, N=5),晚三疊世(70.6°N,275.6°E.A95=6.1,N=10)；對應(yīng)的古緯度分別為-11.4±10.9°N和14.84±6.1°N。本文結(jié)果結(jié)合前人古地磁成果推測：(1)拉薩地塊晚古生代至早中生代一直穩(wěn)定于南緯中低緯度地區(qū),可能到了白堊紀(jì)才快速北移與歐亞大陸主體碰撞拼合。(2)羌塘地塊晚古生代徘徊于南緯中低緯度地區(qū),早三疊世與拉薩塊體位置相近,早三疊世至晚三疊世期間羌塘塊體開始大規(guī)模北向移動,至晚三疊世時已移至北半球的中低緯度地區(qū)(14.8士6.1°N),三疊紀(jì)末以后持續(xù)北移,但其速度及規(guī)模已不及三疊紀(jì)這一時期。早三疊世至晚三疊世羌塘地體至少北向運動了26°,至少北向發(fā)生了2880 km的位移量,估算速度約達(dá)6.4cm/a,并伴隨55°的逆時針旋轉(zhuǎn)。(3)三疊紀(jì)時期拉薩塊體與羌塘塊體可能并不與岡瓦納大陸北緣相鄰,而是處于岡瓦納大陸與歐亞大陸之間的獨立區(qū)域。(4)夾于拉薩塊體與羌塘塊體之間的班公湖-怒江縫合帶所代表的特提斯洋盆很可能于早三疊世打開,早三疊世至晚三疊世期間快速擴張。由于班公湖-怒江-特提斯洋的迅速擴張,推動了羌塘地塊的快速北移,促使其與主體歐亞大陸的碰撞拼合以及古特提斯洋收縮閉合。
[Abstract]:The Qinghai Xizang Plateau belongs to the east section of the Tethys tectonic domain. Its formation and evolution process is a research topic in the front of the contemporary geoscience. The Triassic period is one of the key periods of the evolution of the Qinghai Tibet Plateau, the migration of the main body of the plateau, the gradual contraction of the ancient Tethys ocean and the gradual opening of the middle (?) tetitis ocean. The Lhasa and Qiangtang blocks, located in the hinterland of the Qinghai Tibet Plateau, are the main bodies of the Qinghai Tibet Plateau. Their movement is closely related to the paleoTethys ocean contraction and the opening and closing of the mid (?) Tethys ocean. The paleomagnetism can provide a quantitative basis for the movement of the research block. The Triassic paleomagnetic study of the Qiangtang block in the original hinterland and the paleomagnetic study of the Triassic in the Lhasa block were carried out and its tectonic significance was discussed. In the newly discovered Triassic marine carbonate rocks at the edge of the enemy cloth Lake in the central Cuoqin area of the Lhasa massif, 32 pieces were arranged and 327 independent directional samples were collected. The main magnetic bearing minerals are magnetite and (or) pyrrhotite. Most of the progressive demagnetization curves have obvious three component characteristics: low temperature component is low temperature viscous remanence of modern geomagnetic field; middle temperature component should be the secondary remanence component of Cretaceous; the high temperature component (component C) is only a few and magnetite is the main load. It is obtained in the samples of magnetic minerals. The component C of the early middle three fold can be tested by the 95% confidence reversal test (B grade) and 99% confidence fold; the late three fold component C can be tested by the 95% confidence fold. The corresponding paleomagnetic pole position: the early mid three world (19.3 N, 209.3 degree E, A95=4.0, N=8); and the late three (19.6 / 19.6, 211.8 E,) 495=10.7, N=6); the corresponding paleo weft is 16.9 + 4 degree S and 18.4+10.7 degree S. respectively. The paleomagnetic study of the Triassic strata of the northern Qiangtang block (249 samples) was systematically studied. The results showed that the main magnetic minerals in the samples were hematite and (or) magnetite. Most of the early three and late three world samples were retreated. The magnetic curve has obvious double component features. The lake group in the middle late three fold world map has not obtained a reliable high temperature component because of the influence of later re magnetization. This study revealed two groups of high temperature characteristic components. The high temperature components of the early three fold and late three fold world samples can be tested by the high confidence fold, and two ancient Qiangtang blocks were obtained. The position of geomagnetic pole: early three fold (23.8 N, 210.3 E, A95=10.9, N=5), late three fold (70.6 degree N, 275.6 E.A95=6.1, N=10), the corresponding palaeoglatities were -11.4 + 10.9 and 14.84 + 6.1 = N., respectively, combined with the previous PALEOMAGNETIC RESULTS: (1) the Lhasa block was stable in the middle and low latitudes of the south latitude from Late Palaeozoic to early Mesozoic. In the Cretaceous, it was possible to move rapidly north to the main collision of Eurasian subjects. (2) the late Paleozoic in the Qiangtang block hovered in the middle and low latitudes of the south latitude, and the early three fold and Lhasa block positions were similar. The Qiangtang block began to move on a large scale during the early period of the three fold to the late three, and was moved to the middle and low latitudes of the northern hemisphere at the end of the three fold. The region (14.8 SL 6.1 N) has been moving steadily North after the Late Triassic, but its speed and scale are less than the period of the Triassic. At least 26 degrees in the north direction of the Qiangtang, at least 26 degrees in the late three fold, at least 2880 km of the north, and the estimated speed of up to 6.4cm/a and with the counter clockwise rotation of 55 degrees. (3) the Lhasa block of the Triassic period and the period of the Triassic period. The Qiangtang block may not be adjacent to the northern margin of the Gondwana continent, but in an independent region between the Gondwana continent and the Eurasia continent. (4) the Tethys basin, represented by the Lhasa block and the Qiangtang block, is likely to be opened in the early three fold period and rapidly expanded during the early period of the three fold and the late three fold. The rapid expansion of the ban Gong Lake - the Nu River - Tethys ocean has promoted the rapid northward movement of the Qiangtang block, prompting its collision with the main Eurasian continent and closing the ancient Tethys ocean.
【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：P534.51;P318.44

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 柏千惠;閆永剛;黃寶春;趙杰;Zaw Win;Hla Hla Aung;;緬甸撣邦地塊二疊紀(jì)-三疊紀(jì)灰?guī)r的巖石磁學(xué)初步研究結(jié)果[J];地球物理學(xué)進(jìn)展;2015年03期

2 李小波;王保弟;劉函;王立全;陳莉;;西藏達(dá)如錯地區(qū)晚侏羅世高鎂安山巖——班公湖—怒江洋殼俯沖消減的證據(jù)[J];地質(zhì)通報;2015年Z1期

3 鄧起東;程紹平;馬冀;杜鵬;;青藏高原地震活動特征及當(dāng)前地震活動形勢[J];地球物理學(xué)報;2014年07期

4 CHENG Xin;WU HanNing;DIAO ZongBao;WANG HaiJun;MA Lun;ZHANG XiaoDong;YANG Gang;HONG JingJing;JI WenHua;LI RongShe;CHEN ShouJian;ZHAO ZhenMing;;Paleomagnetic data from the Late Carboniferous-Late Permian rocks in eastern Tibet and their implications for tectonic evolution of the northern Qiangtang-Qamdo block[J];Science China(Earth Sciences);2013年07期

5 許志琴;楊經(jīng)綏;李文昌;李化啟;蔡志慧;閆臻;馬昌前;;青藏高原中的古特提斯體制與增生造山作用[J];巖石學(xué)報;2013年06期

6 唐祥德;黃寶春;楊列坤;易治宇;喬慶慶;陳力為;;拉薩地塊中部晚白堊世火山巖Ar-Ar年代學(xué)和古地磁研究結(jié)果及其構(gòu)造意義[J];地球物理學(xué)報;2013年01期

7 程鑫;吳漢寧;刁宗寶;王海軍;張曉東;馬輪;周亞楠;康偉偉;計文化;李榮社;陳守建;趙振明;;羌北地塊中—晚侏羅世雁石坪群古地磁新結(jié)果[J];地球物理學(xué)報;2012年10期

8 ;Paleomagnetic results of Late Paleozoic rocks from northern Qiangtang Block in Qinghai-Tibet Plateau, China[J];Science China(Earth Sciences);2012年01期

9 陶琰;畢獻(xiàn)武;李金高;朱飛霖;廖名揚;李玉幫;;西藏吉塘花崗巖地球化學(xué)特征及成因[J];巖石學(xué)報;2011年09期

10 李超;肖傳桃;龔文平;田海艷;王小陽;王振鴻;;班公湖-怒江縫合帶中段構(gòu)造演化再探討[J];長江大學(xué)學(xué)報(自然科學(xué)版);2011年03期

，

本文編號：2076910