發(fā)布時(shí)間：2018-03-22 10:41

  本文選題：滇西北　切入點(diǎn)：麗江　出處：《成都理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：麗江盆地位于滇西北地區(qū)麗江市,是一個(gè)新生代的斷陷盆地。其西側(cè)緊鄰滇西名山”玉龍雪山”,玉龍雪山發(fā)育著北半球緯度最低的山岳冰川。金沙江從盆地北部大具盆地穿過。盆地呈近南北走向,長約31km,北部寬約3-6km,南部寬約11km。麗江盆地在構(gòu)造位置上處于川滇菱形地塊中部,活動斷裂發(fā)育。本文主要以滇西北地區(qū)麗江盆地為研究對象,進(jìn)行詳細(xì)的野外地質(zhì)調(diào)查,對盆地第四紀(jì)沉積物的分布范圍、沉積物類型、相互關(guān)系等進(jìn)行詳細(xì)的路線地質(zhì)調(diào)查及關(guān)鍵地質(zhì)點(diǎn)調(diào)查,對關(guān)鍵的沉積物出露地進(jìn)行剖面測制。結(jié)合對斷裂的野外觀測,分析了盆地的發(fā)展演化過程。取得如下主要認(rèn)識:通過對盆地沉積物的巖性、結(jié)構(gòu)、構(gòu)造以及沉積環(huán)境等分析,確定了麗江盆地的沉積類型以及分布范圍。冰前期蛇山組主要分布在盆地南部蛇山公園一帶,是一套以粘土夾細(xì)砂和礫石層的河湖相沉積。玉龍雪山產(chǎn)生的兩期冰磧物分布在盆地北部,均為山岳冰川類型,主要為一套混雜堆積的礫石,夾有巨大的漂礫,礫石成分以玄武巖為主�，F(xiàn)代湖相沉積分布在盆地西南部,其更早時(shí)候的分布范圍達(dá)到了麗江城西部及東部山麓地區(qū),主要為一套湖沼沉積�，F(xiàn)代河流相沉積分布在盆地中部以及偏北地區(qū),分布范圍正在不斷向南擴(kuò)張,主要為一套河流相礫石層。通過對盆地周邊斷裂的野外調(diào)查,發(fā)現(xiàn)玉龍山東麓斷裂并不是單一的正斷層性質(zhì),野外擦痕表明其并存著逆沖和走滑性質(zhì)。在拉市海東南部和麗江城北黑龍?zhí)豆珗@新發(fā)現(xiàn)北西-南東向構(gòu)造,該方向構(gòu)造在蛇山組中有明顯的反映。拉市海蛇山組發(fā)育傾向北東的正斷層,在蛇山組沉積時(shí)期也有該方向正斷層的影響,發(fā)育同沉積正斷層。蛇山組受該方向構(gòu)造作用影響發(fā)生褶皺作用,軸面向下北西。很可能是北西-南東向構(gòu)造作用導(dǎo)致蛇山組沉積中斷,發(fā)生構(gòu)造抬升,接受剝蝕作用。綜合麗江盆地周邊斷裂性質(zhì)及斷裂組合樣式、沉積物形態(tài)、沉積速率,麗江盆地的性質(zhì)為走滑-拉分盆地。
[Abstract]:Lijiang Basin is located in Lijiang City, Northwest Yunnan. It is a Cenozoic faulted basin. The west side of the basin is next to the famous mountain Yulong Snow Mountain in western Yunnan. The Yulong Snow Mountain has the lowest latitude in the Northern Hemisphere. The Jinsha River passes through the basin from the northern part of the basin. The basin is nearly north-south strike. The Lijiang basin is about 31km in length, 3-6km in the north and 11km in the south. The Lijiang basin is located in the middle of the Sichuan-Yunnan rhombic block and the active faults are developed. Detailed route geological survey and key geological site survey are carried out on the distribution range, type and interrelation of the Quaternary sediments in the basin, and the key sediment outcrops are profiled, combined with the field observation of the faults. The development and evolution of the basin are analyzed. The main conclusions are as follows: through the analysis of the lithology, structure, structure and sedimentary environment of the sediments in the basin, The sedimentary types and distribution range of Lijiang basin are determined. It is a set of fluvial and lacustrine facies deposited in clay with fine sand and gravel. The two periods of moraine produced by the Yulong Snow Mountain are distributed in the northern part of the basin, both of them are of mountain glacier type, mainly a set of mixed and accumulated gravel with huge drift gravel. The gravels are mainly basalts. The modern lacustrine deposits are distributed in the southwest of the basin, and their earlier distribution ranges to the western and eastern foothills of Lijiang City. The modern fluvial facies deposits are distributed in the central and northward regions of the basin, and the distribution range is continuously spreading southward, mainly a set of fluvial gravel beds. Through field investigation of the faults around the basin, It is found that the Yulong Shandong foot fault is not a single normal fault, and the field scratches indicate that the faults coexist with thrust and strike-slip properties. NW-SE trending structures were newly discovered in the southeast of Lashi Hai and the northern Heilongjiang Lake Park of Lijiang City. This direction structure is obviously reflected in the Shishan formation. The normal fault of the Lashi Haishishan formation tends to be northeastward, and it also has the influence of this direction normal fault during the sedimentary period of the Sheshan formation. A synsedimentary normal fault is developed. The Shishan formation is affected by this direction of tectonism, and the axis faces to the lower north west. It is very likely that the NW-SE tectonic process caused the sedimentary interruption and tectonic uplift of the Seshan formation. The characteristics of faults and fault assemblages, sediment morphology, sedimentation rate, and strike-slip pull-apart basin are synthesised in Lijiang Basin.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P56

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本文編號：1648298