發(fā)布時間：2018-06-02 08:44

  本文選題：內(nèi)蒙古 + 花崗巖�。� 參考：《長安大學(xué)》2015年碩士論文

【摘要】：內(nèi)蒙古額濟(jì)納旗位于華北板塊西部,花崗巖廣泛分布,近年來在阿拉善北緣發(fā)現(xiàn)了一些花崗巖多形成于晚古生代,這與以往的認(rèn)識有所不同。本論文在野外地質(zhì)填圖的基礎(chǔ)上對阿拉善拐子湖地區(qū)大扎干敖包花崗巖類開展了詳細(xì)的巖石學(xué)、年代學(xué)、地球化學(xué)等綜合研究,并探討了其巖石成因與構(gòu)造環(huán)境。本區(qū)花崗質(zhì)巖石形成年齡在270Ma之間,為二疊紀(jì)侵入體,巖性主要為深灰色細(xì)粒閃長巖,淺肉紅色-灰白色中粒二長花崗巖,灰白色似斑狀黑云母花崗巖,肉紅色細(xì)粒鉀長花崗巖。巖體全部為準(zhǔn)鋁質(zhì)-弱過鋁質(zhì),鈣堿性-高鉀鈣堿性系列,不含白云母、堇青石等礦物,暗色礦物主要以黑云母為主,有極其少量的角閃石,表明本區(qū)花崗巖主要為I型深熔成因花崗巖,物質(zhì)來源于地殼物質(zhì)的熔融,閃長巖物質(zhì)來源于地幔物質(zhì)。本區(qū)花崗巖類巖漿演化順序從早到晚依次為926高地淺肉紅色中粒二長花崗巖-927.1高地灰白色似斑狀黑云母花崗巖-946高地肉紅色細(xì)粒鉀長花崗巖,巖體表現(xiàn)為輕稀土元素、大離子親石元素(Rb、Th等)富集,重稀土元素、高場強(qiáng)元素(Nb、Ta、Ti、P等)虧損。本區(qū)花崗巖類是具有火山弧地球化學(xué)特征的后碰撞花崗巖質(zhì)巖石,在早二疊世,以恩格爾烏蘇蛇綠巖為代表的古亞洲洋向南俯沖形成的溝弧盆體系和本區(qū)的弧后盆地已經(jīng)閉合,形成了具有島弧特征的新增陸殼,在早二疊世,已經(jīng)進(jìn)入了后碰撞造山階段。
[Abstract]:Ejina Banner of Inner Mongolia is located in the western part of North China plate, and granite is widely distributed. In recent years, some granites were found in the northern margin of Alashan, most of which were formed in the late Paleozoic, which is different from previous understanding. On the basis of field geological mapping, detailed petrology, geochronology and geochemistry have been carried out on the granitoids of Dazhagan Aobo in Guizi Lake area, Alashan. The petrogenesis and tectonic environment of the granites have also been discussed. The granitic rocks are mainly dark gray fine-grained diorite, grayish reddish grayish-gray-white monzonitic granites and gray-white porphyry biotite granites, and the granitic rocks are formed at the age of 270Ma and are Permian intrusive bodies, and their lithology is mainly dark gray fine-grained diorite. Meat-red fine-grained potassium feldspar granite. All the rock bodies are quasi-aluminum-weakly peraluminous, calc-alkaline-high-potassium calc-alkaline series, do not contain Muscovite, cordierite and other minerals, dark minerals are mainly biotite, with a very small amount of hornblende, The results show that the granites in this area are mainly type I deep-melt granites with materials derived from the melting of crustal materials and diorite materials from mantle materials. The magmatic evolution sequence of granitic magma in this area is from early to late in the order of grayish white porphyry biotite granitic potash feldspar granitic granites of highlands 926 highlands with light rare earth elements. The heavy rare earth elements and high field strength elements are depleted. Granitoids in this area are post-collisional granite rocks with volcanic arc geochemical characteristics. In the early Permian, the trench arc basin system formed by the subduction of the ancient Asian oceanic ophiolite, represented by the Englesu ophiolite, and the back-arc basin in this area have been closed. The new continental crust with the characteristics of island arc has entered the post-collision orogenic stage in the early Permian.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P588.121

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本文編號：1968148