本文選題：西藏改則熱那錯(cuò) + 班怒帶　； 參考：《中國(guó)地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：西藏地區(qū)歷來(lái)都是全球地質(zhì)工作者的熱點(diǎn)研究區(qū)域,本論文研究區(qū)大地構(gòu)造位置位于班公湖-怒江縫合帶與龍木錯(cuò)-雙湖逢合帶之間。研究區(qū)內(nèi)的構(gòu)造演化受到班公湖-怒江縫合帶的控制。但在大地構(gòu)造背景上還存在許多爭(zhēng)議。有的學(xué)者認(rèn)為班怒洋殼向北俯沖至羌塘陸塊之下;有的學(xué)者認(rèn)為是班怒洋殼向南俯沖至拉薩地塊之下;還有學(xué)者認(rèn)為班公湖中特提斯洋殼向北、向南作雙向俯沖。研究區(qū)內(nèi)出露一套侵入巖,其巖性組合為云英閃長(zhǎng)巖,石英二長(zhǎng)閃長(zhǎng)巖,石英閃長(zhǎng)巖,花崗閃長(zhǎng)巖。主量元素特征顯示為一套中酸性侵入巖,為高鉀鈣堿性準(zhǔn)鋁質(zhì)I型花崗巖,Harker圖解顯示有很好線性相關(guān)性。稀土配分曲線向右傾斜,具有弱的負(fù)銪異常,是LREE相對(duì)富集,而HREE相對(duì)虧損,都屬輕稀土富集類型。微量元素原始地幔標(biāo)準(zhǔn)化蜘蛛圖表現(xiàn)為整體上向右傾斜,強(qiáng)不相容的元素較為富集,高場(chǎng)強(qiáng)的元素Ta、Nb、Ti負(fù)異常明顯。鋯石U-Pb的SHRIMP測(cè)年結(jié)果為:石英二長(zhǎng)閃長(zhǎng)巖為139±4Ma,MSWD=1.6;石英閃長(zhǎng)巖為147.3±3.3Ma,MSWD=0.45,花崗閃長(zhǎng)巖為134±4Ma,MSWD=5.6,形成時(shí)代均為晚侏羅世-早白堊世早期。結(jié)合研究區(qū)的大地構(gòu)造位置,與采集樣品的地球化學(xué)分與年齡分析結(jié)果,認(rèn)為改則縣北的侵入巖為班公湖-怒江洋向北俯沖時(shí)期形成的火山弧花崗巖,其特征為高鉀的準(zhǔn)鋁質(zhì)鈣堿性I型花崗巖,是同源演化的產(chǎn)物,其物質(zhì)來(lái)源為殼�；旌蟻�(lái)源,且源區(qū)受到來(lái)自俯沖板塊的沉積物熔體的交代。根據(jù)本次測(cè)年結(jié)果,結(jié)合研究區(qū)內(nèi)的沉積及構(gòu)造特征,判斷班怒洋洋殼于晚侏羅世向北俯沖。
[Abstract]:Tibet has always been a hot research area for geologists all over the world. The tectonic location of the study area lies between the Bangong Lake-Nujiang suture zone and the Longmu-Shuanghu-Shuanghu suture zone.The tectonic evolution in the study area is controlled by the Bangong Lake-Nujiang suture zone.However, there are still many controversies in the tectonic background.Some scholars think that the Banrou oceanic crust subducts to the north under the Qiangtang block; some scholars think that the Banrou oceanic crust subducts south to the Lhasa block; others believe that the Tethys oceanic crust in Bangong Lake subducts north and makes a two-way subduction south.A set of intrusive rocks are exposed in the study area. Their lithologic assemblages are Yunying diorite, quartz diorite, quartz diorite and granodiorite.The principal element features are a set of intermediate-acid intrusive rocks, and the Harker diagram of high-potassium calc-alkaline quasi-alumintic I-type granite shows a good linear correlation.The rare earth partition curve inclines to the right and has weak negative europium anomaly, which is relatively enriched in LREE, and HREE is relatively depleted, which all belong to the type of light rare earth enrichment.The trace element primitive mantle-standardized spider map shows that the whole is inclined to the right, the strongly incompatible elements are more enriched, and the high field strength element Taan NbCTi is negative anomaly obviously.The SHRIMP dating results of zircon U-Pb are as follows: the quartz diorite is 139 鹵4 Ma-MSWD1.6, the quartz diorite is 147.3 鹵3.3 Ma-MSWDU 0.45, and the granodiorite is 134 鹵4 Ma-MSWD5. 6. The age of formation is from late Jurassic to early Cretaceous.In combination with the geotectonic location of the study area and the geochemical score and age analysis of the collected samples, it is considered that the intrusive rocks in the north of the county are volcanic arc granites formed during the northward subduction of the Bangonghu Lake and the Nujiang Ocean.It is characterized by a high-potassium quasi-aluminous calc-alkaline I-type granite, which is the product of homologous evolution. Its material source is a mixture of crust and mantle, and the source region is metasomatized by the sediment melt from subduction plate.According to the results of this dating, combined with the sedimentary and structural characteristics of the study area, it is concluded that the Banrou oceanic crust subducted northward in the late Jurassic.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P588.121

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 和鐘鏵;楊德明;王天武;;岡底斯帶谷露區(qū)中新世花崗巖地球化學(xué)特征及構(gòu)造環(huán)境[J];吉林大學(xué)學(xué)報(bào)(地球科學(xué)版);2007年01期

2 潘桂棠,朱弟成,王立全,廖忠禮,耿全如,江新勝;班公湖—怒江縫合帶作為岡瓦納大陸北界的地質(zhì)地球物理證據(jù)[J];地學(xué)前緣;2004年04期

3 廖六根,曹圣華,肖業(yè)斌,歐陽(yáng)克貴,胡肇榮,馮國(guó)勝;班公湖-怒江結(jié)合帶北側(cè)陸緣火山-巖漿弧帶的厘定及其意義[J];沉積與特提斯地質(zhì);2005年Z1期

相關(guān)博士學(xué)位論文 前1條

1 張玉修;班公湖—怒江縫合帶中西段構(gòu)造演化[D];中國(guó)科學(xué)院研究生院（廣州地球化學(xué)研究所）;2007年

，

本文編號(hào)：1769697