發(fā)布時間：2018-01-26 02:19

  本文關鍵詞： 內(nèi)蒙古阿拉善北部 雙堡塘組 早二疊世 構造背景　出處：《中國地質大學(北京)》2017年碩士論文　論文類型：學位論文

【摘要】：研究區(qū)位于銀根—額濟納旗盆地,為華北板塊、塔里木板塊、西伯利亞板塊以及哈薩克斯坦板塊交匯部位,屬古亞洲洋中段南緣,是研究古亞洲洋構造域構造演化的重要區(qū)域。本文通過沉積學、古生物學、巖石學和地球化學等方法,結合區(qū)域地質調(diào)查資料和前人研究成果,對阿拉善北緣下二疊統(tǒng)雙堡塘組進行了深入研究。研究區(qū)古生界以恩格爾烏蘇縫合帶為界,分為西北部的塔里木—南疆大區(qū)和東南部的華北地層大區(qū),下二疊統(tǒng)雙堡塘組(P1sb)位于塔里木—南疆大區(qū),主要呈帶狀分別出露在南部杭烏拉—蒙根烏拉一帶和北部哈日敖日布格靠近中蒙邊境一帶,均為北東東向展布。根據(jù)在杭烏拉南部雙堡塘組中采集到的大量古生物化石和碎屑鋯石U-Pb年齡確定研究區(qū)南部雙堡塘組時代為早二疊世早期,北部哈日敖日布格一帶雙堡塘組由于缺少古生物化石證據(jù)和年齡數(shù)據(jù),本文暫時將其歸入雙堡塘組。野外研究發(fā)現(xiàn),南北兩處雙堡塘組在空間展布、巖石組合特征和變質變形程度等方面均存在較大差異,通過對比分析MG和HR兩處剖面實測和采樣數(shù)據(jù),結合室內(nèi)外研究工作,對兩處雙堡塘組沉積特征進行了總結和對比,結合砂巖碎屑成分物源分析和地球化學特征對比,認為阿拉善北緣南北兩處雙堡塘組的物源可能來自于不同大地構造環(huán)境。綜合巖石組合、沉積構造、古生物化石等證據(jù),認為MG剖面下部為淺海碳酸鹽巖臺地相向無障壁陸源碎屑海岸相過渡的環(huán)境,上部以濱淺海相為主,HR剖面整體表現(xiàn)為濱淺海相為主,逐漸向碳酸鹽巖臺地過渡的沉積環(huán)境。晚石炭—早二疊世,受呼和套爾蓋洋內(nèi)弧北部大洋向南俯沖的影響,研究區(qū)南部逐漸形成了完整的溝-弧-盆體系,連續(xù)沉積的雙堡塘組和方山口組代表了弧后盆地沉積的演化過程;呼和套爾蓋洋內(nèi)弧于早古生代晚期完成洋殼—陸殼的轉變,哈日敖日布格一帶地層形成于呼和套爾蓋洋內(nèi)弧的北緣。
[Abstract]:The study area is located in Yingen-Ejinaqi basin, which is the intersection of North China plate, Tarim plate, Siberian plate and Kazakstan plate. It is an important area to study the tectonic evolution of the Paleo-Asian oceanic tectonic domain. This paper combines regional geological survey data with previous research results by means of sedimentology, paleontology, petrology and geochemistry. The Lower Permian Shuangboutang formation in the northern margin of Alashan is studied in depth. The Paleozoic in the study area is divided into the northwestern Tarim-South Xinjiang region and the southeastern North China stratigraphic region with the Engelwusu suture belt as the boundary. The lower Permian Shuangboutang formation (P1sb) is located in the Tarim-South Xinjiang area, mainly showing in the southern part of the Hangula-Mongengwula area and in the northern part of Hari Ojbuge near the border between China and Mongolia. According to a large number of paleontological fossils and detrital zircon U-Pb ages collected in the Shuangboutang formation in the southern part of Hangwula, the early early Permian age of the Shuangboutang formation in the southern part of the study area was determined. Due to the lack of paleontological fossil evidence and age data, the Shuangbaotang formation in the northern area of Haribuge area is temporarily classified into the Shuangbaotang formation in this paper. Field studies show that the Shuangbaotang formation in the north and south is distributed in space. There are great differences in rock assemblage characteristics and metamorphic deformation degree. By comparing and analyzing the measured and sampled data of MG and HR sections, combined with indoor and outdoor research work. The sedimentary characteristics of the Shuangbaotang formation are summarized and compared, combined with the source analysis and geochemical characteristics of the sandstone clastic components. It is considered that the provenance of the Shuangboutang formation in the north and south of the northern margin of Alashan may come from different geotectonic environments, comprehensive rock assemblages, sedimentary structures, paleontological fossils, and so on. It is considered that the lower part of MG section is a transition environment from shallow carbonate platform to continental clastic coastal facies without barrier, and the upper section is dominated by shoreline and shallow sea facies. During the late Carboniferous and early Permian, the southern part of the study area gradually formed a complete trench-arc basin system due to the subduction of the northern ocean in the northern arc of Huhu and the Thuergai ocean toward the south. The continuous deposition of Shuangbaotang formation and Fangshankou formation represent the evolution process of back-arc basin. The transition of oceanic crust to continental crust was completed in the late early Paleozoic, and the stratigraphic formation in the area of Hariozibuge was formed in the northern margin of the Huhe Arc.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P534.46;P548
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本文編號：1464376