發(fā)布時間：2018-02-24 00:17

  本文關鍵詞： 班公湖-怒江 熱那錯 火山巖 巖石地球化學 U-Pb測年　出處：《中國地質(zhì)大學(北京)》2015年碩士論文　論文類型：學位論文

【摘要】：火山巖作為地球內(nèi)部巖漿活動的產(chǎn)物,不僅能夠反映出巖漿活動的特點,還能使我們清楚認識板塊構(gòu)造演化歷程。前人已對班公湖-怒江構(gòu)造帶進行了較為詳細的研究。由于其特殊大地構(gòu)造位置及意義,一直以來都是國內(nèi)外研究的焦點。由于近年來在班怒縫合帶上發(fā)現(xiàn)多例超大型含金斑巖銅礦,使得對該縫合帶的研究不僅具有構(gòu)造意義,同時還有較大的經(jīng)濟意義。早白堊世巖漿活動為成礦提供了物源,因此研究早白堊世巖漿活動對于總結(jié)該縫合帶的成礦規(guī)律有重要意義。研究區(qū)位于藏北高原中部,構(gòu)造位置位于班公湖-怒江縫合帶北側(cè)。通過對研究區(qū)內(nèi)熱那錯東火山巖的巖性、分布及火山機構(gòu)的詳細野外地質(zhì)調(diào)查,結(jié)合火山巖剖面、室內(nèi)巖石化學、地球化學及地質(zhì)年代測定,論文取得主要成果和認識如下:研究認為熱那錯東火山巖分布層位單一,均位于美日切錯組,巖性以玄武巖為主,并伴有安山巖、流紋巖及火山角礫巖,研究區(qū)巖漿最初時主要以基性玄武巖作為主體,伴隨著巖漿活動,從熔體中分離出斜長石等礦物,使巖漿最終轉(zhuǎn)化為酸性。熱那錯火山巖年齡值為111.7Ma左右,為早白堊世。研究區(qū)火山巖地球化學特征顯示為俯沖消減作用的鈣堿性弧火山巖。研究區(qū)內(nèi)的火山巖所具有的特征表明研究區(qū)火山巖的構(gòu)造環(huán)境為洋殼俯沖消減,無陸陸碰撞。在早白堊世,南羌塘陸塊邊緣為增生型大陸邊緣,班公湖-怒江洋盆于早白堊世末期俯沖消減。
[Abstract]:Volcanic rock, as a product of magmatic activity in the interior of the earth, can not only reflect the characteristics of magmatic activity, It can also help us to understand clearly the evolution of plate tectonics. The Bangonghu-Nujiang tectonic belt has been studied in detail by predecessors. Because of its special tectonic location and significance, It has always been the focus of research at home and abroad. Due to the discovery of a number of super-large gold porphyry copper deposits in the Bannu suture zone in recent years, the study of the suture zone is not only of tectonic significance. The study of early Cretaceous magma activity is of great significance in summarizing the metallogenic regularity of the suture zone. The study area is located in the middle of the Tibetan Plateau. The tectonic location is located on the northern side of Bangong Lake-Nujiang suture belt. Through the detailed field geological investigation of the lithology, distribution and volcanic mechanism of the volcanic rocks in the eastern part of the study area, combined with the volcanic rock profile, the interior petrochemistry, The main achievements and understandings of geochemistry and geochronology are as follows: it is considered that the volcanic rocks in the eastern part of Rinaco are all located in the United States and Japan, and the lithology is dominated by basalt and accompanied by andesite. Rhyolite and volcanic breccia, magma in the study area was mainly dominated by basalt at first, accompanied by magmatic activity, plagioclase and other minerals were separated from the melt. The magma is finally converted to acid. The age value of the Rynagh volcanic rocks is about 111.7 Ma. The geochemical characteristics of volcanic rocks in the study area show subduction subduction calc-alkaline arc volcanic rocks. The characteristics of volcanic rocks in the study area indicate that the tectonic environment of the volcanic rocks in the study area is subduction of oceanic crust. In the early Cretaceous, the margin of the southern Qiangtang block was an accretive continental margin, and the Bangong Lake-Nujiang ocean basin subducted and subducted at the end of the early Cretaceous.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P588.14;P618.41

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本文編號：1528157