【作者】 朱利东；

【导师】 王成善；

【作者基本信息】 成都理工大学 ， 古生物学与地层学， 2004， 博士

【摘要】 平均海拔约5000m的青藏高原有着清晰的南部边界——喜马拉雅山系，而高原的北部则存在着东西方向的差别。以阿尔金断裂为界，西部塔里木盆地与青藏高原以西昆仑山分隔，东部由高原内部向北依次发育着可可西里盆地、昆仑山系、库木库里-柴达木盆地、祁连山系和酒泉盆地(走廊盆地带)，呈现出横跨6个纬度的“盆-岭”地貌格局。青藏高原东北部的独特“盆-岭”地貌是青藏高原形成过程中长期地质作用的产物。 酒泉盆地的新生代与中生代有明显不同的构造特征，酒泉盆地的新生代以前陆盆地为主，而中生代为断陷盆地，中新生界在空间上构成了上下两个构造层，属于叠合盆地。酒泉盆地在新生代经历了4个演化阶段：(1)古新世坳陷沉降阶段(～37.7Ma)，该阶段盆地的边界不受活动断裂控制，以垂向沉降为特征。(2)渐新世早期走滑拉分阶段(37.7-30.3Ma)，该阶段盆地受阿尔金左行走滑断裂的控制。(3)渐新世晚期-中更新世前陆盆地阶段(29.5-0.13Ma)，该阶段盆地受北祁连山前断裂控制。(4)晚更新世以来山间盆地阶段(0.13Ma～)，盆地北部的宽台山和黑山的隆起导致了酒泉盆地四面环山的地貌格局。 从构造-地层关系研究、地震资料对比分析、盆地充填历史分析和盆山关系分析研究发现，柴达木盆地在中新生代之交发生了重要的构造背景变化。柴达木盆地在新生代经历了三个构造-沉积演化阶段：(1)伸展盆地阶段(65-46Ma)，东西方向的伸展构造是该阶段主要控盆构造环境；(2)前陆盆地阶段(46-2.45Ma)，近南北方向挤压和造山带逆冲是该阶段的主要控盆构造，46-30Ma期间以昆仑山的向北逆冲为主，30Ma以后形成昆仑山和祁连山向柴达木盆地的对冲构造格局；(3)山间盆地阶段(2.45-0Ma)，靠近阿尔金断裂的盆地西部发生褶皱和抬升，盆地沉积中心向东部迁移，昆仑山和祁连山的山前断裂的逆冲作用减弱或停止。 可可西里地区的中生代地层仅发育复理石沉积为主的三叠系，侏罗白垩系缺夫。可可西里盆地新生代构造演化分为三个阶段：(1)走滑拉分盆地阶段(56-53Ma)，盆地范围在金沙江缝合带内，金沙江缝合带在该阶段经历了一次左行走滑运动；(2)前陆盆地阶段(53-30.0Ma)，该阶段盆地的范围具有向北阶段性扩展的特征，金沙江缝合带的南部首先褶皱并向北逆冲，其后逆冲断裂依次向北推进：风火山坳陷的北部(53-38.2Ma)—五道梁坳陷(38.2-31.0Ma)—卓乃湖坳陷(31.0-30.0Ma)，可可西里盆地经历了约7Ma(30-23Ma之间)的沉积间断；(3)后前陆盆地阶段(23Ma-)，盆地的向北逆冲作用结束，盆地在早期夷平面之上沉积了分布广泛的碳酸盐岩，20Ma开始，可可西里-巴颜喀拉板块的西部火山活动强烈，东部发生沉降，发育了曲果组碎屑岩沉积。 高原北部新生代沉积盆地的演化具有演化序列的相似性，青藏高原北部以南北挤压为动力背景的前陆盆地在整个新生代盆地演化历史中占据了十分重要的地位：①可可西里盆地新生代的时间延限为50.7Ma(56-5.3Ma)，以五道梁群作为可可西里盆地结束的上限，前陆盆地阶段占整个新生代盆地历史的92％；②新生代柴达木盆地的发育时限为65Ma，其中46-2.45Ma为前陆盆地阶段，前陆盆地阶段在整个新生代盆地历史中所占的比例为67％；③酒泉盆地新生代底部地层尚无古地磁年龄资料，参照沉积速率推算，其底界年龄应不超过40Ma，而前陆盆地阶段就占据了其中的29.4Ma(29.5-0.13Ma)，所占比例约78％。从前陆盆地的形成序列上看，可可西里盆地的转换时间最早 (53Ma)，柴达木一库木库里盆地的转换时间次之(46Ma)，酒泉盆地最晚(29.5Ma);对应的造山带逆冲和抬升时间为:金沙江缝合带(53Ma)，昆仑山(46Ma)，祁连山(29.5Ma)，宽台山一黑山 (0.1 3Ma)。 盆地的研究显示，昆仑山向北逆冲的时间开始于46Ma，29.5Ma是北祁连前陆的逆冲推覆和酒泉前陆盆地形成的时间。但根据花岗岩体的冷却时间计算的结果显示，昆仑山和南祁连山在30Ma发生了快速的抬升和剥蚀作用。 阿尔金断裂左行走滑活动的时间可能上延至中生代甚至更早，但阿尔金断裂走滑活动的主要时期是在新生代。阿尔金断裂的走滑速率在新生代呈逐渐增大的特征，阿尔金断裂的东段(宽台山-黑山一带)汇入南东东走向逆冲断裂—黑山一龙首山一合黎山断裂。 根据盆地和造山带研究所建立的高原北部盆一山演化序列: ①65一53Ma，金沙江缝合带发生左行拉分走滑作用，形成了早期可可西里走滑拉分盆地，柴达木盆地受伸展构造控制，形成了断陷盆地; ②53一46Ma，受南部挤压作用影响，金沙江缝合带发生向北地逆冲，可可西里盆地性质发生转变，在可可西里南部开始发育前陆盆地，而柴达木盆地延续了拉张断陷的构造性质; ③46一29.5Ma，可可西里前陆盆地在这一阶段发生了向北扩展，形成北部的2个次级前陆坳陷带，柴达木盆地的南缘断裂—昆仑山北缘断裂发生向北逆冲，柴达木盆地开始前陆盆地阶段演化，酒泉盆地受阿尔金断裂的挤压走滑运动影响，发育了挤压走滑盆地; ④29.5一2.45Ma，可可西里盆地早期发生全面褶皱造山，之后在剥蚀夷平面上沉积了厚度不大的碳酸盐岩，中晚期发生大规模的火山活动，昆仑山继续向北推覆，祁连山发生向北和向南的更多还原

【Abstract】 Qinghai-Tibet Plateau with 5000m in average altitude has the distinct south boundary-Himalaya Mountain. However, there are different characters from east to west in the north of the Plateau. Divided by Altyn Fault, Tarim Basin is separated from the Qinghai-Tibet Plateau by West Kunlun Mountain to the west, and a series of basin-ridge geomophical systems exist to the east, which cross over six latitude zone and respectively are Hoh Xil Basin, Kunlun Mountains, Kumkool and Qaidam Basin, Qilian Mountains and Jiuquan Basin (Hexi Corridor Basin) from south to north. This unique basin-ridge geomophy in the north-east of the Qinghai-Tibet Plateau is the result of tectonic action during forming of the Qinghai-Tibet Plateau.There are different tectonic character of Jiuquan Basin in Cenozoic and Mesozoic: it was a foreland basin in Cenozoic and was a downfaulted basin in Mesozoic. So it is a superimposed basin and there are two tectonic units from Mesozoic to Cenozoic. The evolution of Jiuquan Basin in Cenozoic can be divided into the following four stages: l)subsiding and depressing stage in Paleocene (~37.7Ma). Boundary of the basin of this stage was not controlled by fault and movement of the basin was mainly vertical subsiding; 2) strike-slip and pull-apart stage in Oligocene (37.7-30.3Ma). The basin was controlled by the Alytn sinistral strike-slip Fault; 3) foreland stage from Oligocene to middle Pleistocene (29.5-0.13Ma). The basin was controlled by piedmont fault of Qilan Mountain; 4) intramontane basin stage from latter Pleistocene to present (0.13Ma~). Uplift of Kuantai Mountain and Heshan Mountain lead to the basin surrounded by mountains.Based on the research of tectonics-strata relationship, contrast and analysis of seismic data, infilling history and relationship between basins and mountains, we can find that Qaidam Basin had an important change of tectonic background between Mesozoic and Cenozoic. In Cenozoic, Qaidam Basin experienced three stages of tectonic and sedimentary evolution: 1) stretched basin stage (65-46 Ma). In this stage, east-westward stretch structure was the essential control-basin structure; 2) foreland basin stage (46-2.45Ma). Approximate south-northward extruding and orogenic zone thrusting was the main control-basin tectonic background. The tectonic evolution sequence was: Kunlun Mountain thrusted northward from 46 to 30Ma; Kunlun Mountain and Qilian Mountain thrusted against Qaidam Bsain after 30Ma; 3) piedmont basin stage (2.45-0Ma). Near the Altyn fault, the west part of basin folded and lift up, and sedimentary centre removes to the east of the basin. Thrusting of piedmont fault of Kunlun Mountain and Qilian Mountain decreased or stopped.Mesozoic strata in Hoh Xil basin only have Triassic sediments, which are mainly about flysch sediments, but are lack of Jurassic-Cretaceous sediments. Hoh Xil basin experienced three stages of tectonics-sediment evolution in Cenozoic: 1) strike-slip and pull-apart basin stage (56-53Ma). The basin was in the Jinsha River suture zone, and Jinsha River suture zone expericed a sinistral strike-slipmovement; 2) foreland basin stage (53-30.0Ma), The basin had a character of northward phasic extension. The south of Jinsha River suture zone firstly folded and thrust northward, then thrust faults propelled northward progressivly. north of Fenghuoshan depression (53-38.2Ma), Wudaoliang depression (38.2-31.0Ma), Zhuonaihu depression (31.0- 30.0 Ma). Hoh Xil basin experienced about 7Ma (30-23Ma) sedimentary discontinuity; 4) post-foreland basin stage (23Ma-). Northward thrust of basin ended up, and carbonate rock deposited broadly on the planation surface. Since 20Ma, intense volcanicity took place in the west of Hoh Xil Basin-Bayan Har plate and depressing occurred in the east, which led to depositing of clastic rock of Quguo Formation.Cenozoic sedimentary basins in the north of the Qinghai-Tibet Plateau have similar evolution process, and foreland basins formed on the north-south extrusing background are very important in the evolution history of enti更多还原