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1.
中国特定环境下发育的前陆盆地和冲断带在地质构造上具有许多的特殊性。在综述前人认识的基础上,笔者通过对中国前陆盆地的构造演化历程、沉积充填特征、构造成因及其空间分布规律、构造变形特征等的研究,提出了中国前陆盆地构造地质发育的5个主要特征:(1)两种不同性质的原型盆地发生正反转的叠合性,即挤压构造下作为“本体”的前陆层序与拉张构造下作为“基础”的裂谷、断陷盆地之间的叠置;(2)显生宙以来中国大陆先后发生了4期前陆冲断构造演化的多期性,它们分别是加里东晚期、海西晚期、印支期和喜马拉雅晚期;(3)基于小克拉通基底拼贴后在造山带前缘复活再生的继承性,即统一拼合大陆内部的构造变形导致古造山带的复活,在古造山带边缘发育新生代前陆盆地或前陆冲断带;(4)在空间分布上受环青藏高原巨型盆山体系控制发生陆内变形的系统性,在环青藏高原巨型盆山体系内构造变形强度、盆地沉降幅度、盆山耦合程度等从内环向外环依次降低,从古造山带向克拉通方向构造变形强度依次降低,构造变形样式逐渐简单、构造变形时间依次变新;(5)前陆冲断带的构造样式由于受边界力学条件和沉积地层介质作用而具有多变性,存在沉积盖层内脆性变形的断层相关褶皱、造山带前缘韧性变形的基底卷入构造、与走滑构造相伴生的基底卷入的断层相关褶皱、盆地内部塑性变形的盐构造。正是因为上述地质构造的特殊性,决定了油气聚集与分布特征的规律性和复杂性,由此提出了相应的一些构造地质研究与油气勘探工作的建议。 相似文献
2.
龙门山中段中生代前陆盆地的构造演化史 总被引：7，自引：0，他引：7
王道永 《成都理工学院学报》1994,21(3):20-28
依据龙门山中段中生代盆地的基底性质，沉积构造组合和构造变形，论证了川西拗陷是组合和构造变形，论证了川西拗陷是在印支期发育于扬子板块活动大陆边缘的弧背（前陆）盆地，前陆盆地的构造变形是经印支期构造变动和喜马拉雅期叠加改造形成的推覆构造，并讨论了龙门山中段中生代前陆盆地的构造演化历史。 相似文献
3.
库车前陆盆地克拉苏构造带的构造特征与油气 总被引：3，自引：0，他引：3
克拉苏构造带位于库车前陆盆地的北侧, 由浅部和深部两个层次的构造组成, 上、下不同层次的构造具有不一致性。浅部层次的构造主要为断层传播褶皱、断层传播－ 滑脱褶皱, 这些构造的突破断层发育, 不利于油气的保存; 深部层次的构造主要为被动顶板双重构造、突发构造和断层转折褶皱, 这些构造在走向上相互转变, 构成了本区最有利的构造圈闭。断裂是本区最重要的构造, 它不仅是烃源岩排烃的有效机制, 而且是油气运移的通道。 相似文献
4.
龙门山南段推覆构造与前陆盆地演化 总被引：16，自引：1，他引：15
陶晓风 《成都理工学院学报》1999,26(1):73-77
龙门山南段推覆构造带可划分为四个亚带,陇龙褶皱推覆构造带,宝头冲断推覆构造带,中林－双薄皮推覆构造带,前陆褶皱构造带,依据龙门山南段推覆构造样式,变形特征及前陆盆地的沉积特征,论述了在龙门山南段推覆构造和前陆盆地的同步演化历史。 相似文献
5.
塔里木盆地库车前陆褶皱带中段盐相关构造特征与油气聚集 总被引：24，自引：2，他引：24
塔里木盆地北部库车前陆褶皱带古新统一始新统发育盐岩层系，将库车前陆褶皱带构造变形和圈闭样式分为三层，即盐上构造、盐层(盐间)构造和盐下构造。盐上构造包括盐上背斜、盐上逆冲断层及断层相关褶皱、盐上背冲断块构造、强制褶皱、盐上逆冲断层遮挡构造和盐推覆构造等；盐层(盐间)构造主要包括盐枕构造、盐间断褶构造、盐焊接构造和外来盐席等；盐下构造主要有背冲断块构造、断层相关褶皱、叠瓦冲断带和双重构造等。库车前陆褶皱带盐构造的形成可能受挤压作用、重力滑动和重力扩展作用多重控制。笔者等讨论了盐相关构造油气成藏条件和模式，认为库车前陆褶皱带盐岩层变形与丰富的圈闭构造形成密切相关，烃源岩主要位于盐下，盐岩层作为优质盖层构成石油和天然气藏最优越的遮挡条件，断裂对盐下、盐间和盐上油气成藏都起重要控制作用，但盐下是最有利的油气聚集场所。 相似文献
6.
西昆仑甜水海地区前陆褶皱冲断带的构造样式及其演化 总被引：1，自引：0，他引：1
运用碰撞造山带大地构造朴理论,研究了西昆仑甜水海地区三叠系的沉积特征及其构造环境,晚三叠世末羌塘陆块与塔里木板块南缘的晚古生代一早中生代山弧碰撞造成的前陆褶皱冲断带的构造样式及其演化。通过对地层构造岩石组合、沉积环境及其变形强度特征的分析,得出该区三叠纪的沉积是一套典型的深水－半深水的复理石建造,形成于被动大陆边缘的沉积环境;其变形具有典型的前陆褶皱冲断带特征,并将褶皱冲断带按变形特征分５个带。提 相似文献
7.
华南鹰扬关构造带的大地构造属性与构造演化过程：基于构造解析的认识 总被引：1，自引：0，他引：1
北北东向鹰扬关构造带位于华南板块西南部,其大地构造属性尚存在蛇绿混杂岩、裂谷带与陆内构造变形带之争。笔者等在物质组成与年代学综述的基础之上开展了详细的构造解析,厘定了鹰扬关构造带的大地构造属性和构造演化过程。鹰扬关构造带主体由新元古代中—晚期岛弧型安山岩和玄武岩、裂谷型双峰式火山岩、盖帽碳酸盐岩与泥砂岩等物质组成。不同时代和不同岩性的混杂是新元古代晚期裂谷和伸展构造背景下重力作用的产物。新元古代沉积混杂岩在显生宙经历了广西期、印支晚期与燕山期造山作用的叠加,导致了不同岩块之间往往呈断层接触。广西期（450~415 Ma）造山作用使新元古代沉积混杂岩发育近E—W向紧闭褶皱和逆断层并被花岗岩侵位。印支晚期（227~220 Ma）造山作用导致NNE向鹰扬关构造带的形成,表现为NNE—SSW向褶皱、逆断层与左旋韧性剪切带。燕山期造山作用使鹰扬关构造带中NNE—SSW向断裂发生构造活化,强烈的正断作用和右行走滑控制了白垩纪上叠盆地的发育。综合物质组成、年代学和构造解析证据,鹰扬关构造带不是新元古代或早古生代蛇绿混杂岩,而是印支晚期陆内构造变形带,不具有板块缝合带的大地构造属性。 相似文献
8.
北北东向鹰扬关构造带位于华南板块西南部,其大地构造属性尚存在蛇绿混杂岩、裂谷带与陆内构造变形带之争。笔者等在物质组成与年代学综述的基础之上开展了详细的构造解析,厘定了鹰扬关构造带的大地构造属性和构造演化过程。鹰扬关构造带主体由新元古代中—晚期岛弧型安山岩和玄武岩、裂谷型双峰式火山岩、盖帽碳酸盐岩与泥砂岩等物质组成。不同时代和不同岩性的混杂是新元古代晚期裂谷和伸展构造背景下重力作用的产物。新元古代沉积混杂岩在显生宙经历了广西期、印支晚期与燕山期造山作用的叠加,导致了不同岩块之间往往呈断层接触。广西期（450~415 Ma）造山作用使新元古代沉积混杂岩发育近E—W向紧闭褶皱和逆断层并被花岗岩侵位。印支晚期（227~220 Ma）造山作用导致NNE向鹰扬关构造带的形成,表现为NNE—SSW向褶皱、逆断层与左旋韧性剪切带。燕山期造山作用使鹰扬关构造带中NNE—SSW向断裂发生构造活化,强烈的正断作用和右行走滑控制了白垩纪上叠盆地的发育。综合物质组成、年代学和构造解析证据,鹰扬关构造带不是新元古代或早古生代蛇绿混杂岩,而是印支晚期陆内构造变形带,不具有板块缝合带的大地构造属性。 相似文献
9.
龙门山前陆褶皱冲断带构造解析与川西前陆盆地的发育 总被引：57，自引：2，他引：55
通过详细的野外地质调查和精细的地震剖面构造解析。揭示了龙门山前陆褶皱冲断带的基本构造特征。对比分析了龙门山北段与南段构造变形几何学和运动学的差异。提出龙门山北段主要表现为一系列复杂的逆冲推覆构造,晚三叠纪变形强于新生代;龙门山南段则以基底卷入的叠瓦状冲断为特点,晚白垩纪-早第三纪变形尤为突出。与前陆褶皱冲断带相对应的是,川西晚三叠纪时期的周缘前陆盆地主要表现在整个龙门山褶皱冲断带的前渊地区;而晚白垩纪-早第三纪再生前陆盆地却局限在川西盆地的南部,并且印-藏碰撞的持续挤压作用使得晚新生代构造变形不断向东扩展进入川西盆地南部。 相似文献
10.
钦防褶皱带的形成及其地质影响 总被引：4，自引：0，他引：4
位于广西壮族自治区东南，钦州—防城一带的钦防褶皱带，是中国南方唯一的海西褶皱带，它的形成和发展有三个阶段。晚加里东阶段，扬子陆块与华夏陆块的不完整拼合，造成具有地槽型沉积特点的钦防线余海槽，与泥盆系为整合关系。海西期，它成为华南海侵的主要通道，随着寰牢山洋盆的打开与华南大陆边缘北西向裂谷系的形成，与右江盆地融为一体，成为它们的东部边界。东吴运动后，在滨太平洋构造影响下，钦防海柄褶皱成山，西侧形成上思前陆盆地并逐渐向西迁移，造成迭置的沉积棱柱体，从而使前期的右江盆地解体为构造性质不同的东西两部份。印支期后，右江盆地和上思前陆盆地同时消失。 相似文献
11.
龙门山断裂带印支期左旋走滑运动及其大地构造成因 总被引：60，自引：6，他引：60
位于青藏高原东缘的龙门山构造呈北东—南西向将松潘—甘孜褶皱带和华南地块分割开。前者主要是由一套巨厚的三叠纪复理石沉积组成 ,分布在古特提斯海的东缘。后者由前寒武纪基底和上覆的古生代和中生代沉积盖层组成。位于汶川—茂汶断裂以东的前龙门山存在一系列倾向北西的逆掩断层 ,它们将许多由元古宙和古生代岩层组成的断片向南东置于四川盆地的中生代红层之上 ,构成典型的薄皮构造。许多研究由此断定松潘—甘孜褶皱带和四川盆地之间在中生代发生过大规模的北西—南东向挤压。然而 ,汶川—茂汶断裂西侧的松潘—甘孜褶皱带内部的挤压构造线大多是垂直于而不是平形于龙门山断裂带 ,这表明当时的挤压应力不是北西—南东向而是北东—南西向。近年来在龙门山构造带内发现 ,在三叠纪时龙门山断裂带在发生推覆的同时还经历过大规模的北东—南西向的左旋走滑运动 ,协调走滑运动的主要构造为汶川—茂汶断裂。走滑运动的成因与松潘—甘孜褶皱带北东—南西向缩短有关。汶川—茂汶断裂的左旋走滑在龙门山的北东端被古特提斯海沿勉略俯冲带的消减和发生在大巴山的古生代 /中生代岩层的褶皱和冲断作用所吸收 ,在龙门山的南西端被古特提斯海沿甘孜—理塘俯冲带的消减和松潘—甘孜三叠纪复理石的褶皱和冲断作用所吸? 相似文献
12.
Chris J.L. Wilson Brenton A. Worley Shefa Chen Mathew J. Harrowfield Liu Shugen Luo Zhili WT ”BX 《地学前缘》2000,(Z1)
DEFORMATIONAL AND METAMORPHIC HISTORY OF THE CENTRAL LONGMEN MOUNTAINS, SICHUAN CHINA1 ArneDC ,WorleyBA ,WilsonCJL ,etal.Differentialexhumationinresponsetoepisodicthrustingalongtheeasternmar ginoftheTibetanPlateau[J] .Tectonophysics,1997,2 80 :2 39～ 2 56 .
2 ChenSF ,WilsonCJL ,WorleyBA .TectonictransitionfromtheSongpan GarzeFoldBelttotheSichuanBasin,south westernChina[J] .BasinResearch ,1995,7:2 35～ 2 53.
3 ChenSF ,WilsonCJL .Emplaceme… 相似文献
13.
《International Geology Review》2012,54(8):661-735
The Longmen Shan region includes, from west to east, the northeastern part of the Tibetan Plateau, the Sichuan Basin, and the eastern part of the eastern Sichuan fold-and-thrust belt. In the northeast, it merges with the Micang Shan, a part of the Qinling Mountains. The Longmen Shan region can be divided into two major tectonic elements: (1) an autochthon/parautochthon, which underlies the easternmost part of the Tibetan Plateau, the Sichuan Basin, and the eastern Sichuan fold-and-thrust belt; and (2) a complex allochthon, which underlies the eastern part of the Tibetan Plateau. The allochthon was emplaced toward the southeast during Late Triassic time, and it and the western part of the autochthon/parautochthon were modified by Cenozoic deformation. The autochthon/parautochthon was formed from the western part of the Yangtze platform and consists of a Proterozoic basement covered by a thin, incomplete succession of Late Proterozoic to Middle Triassic shallow-marine and nonmarine sedimentary rocks interrupted by Permian extension and basic magmatism in the southwest. The platform is bounded by continental margins that formed in Silurian time to the west and in Late Proterozoic time to the north. Within the southwestern part of the platform is the narrow N-trending Kungdian high, a paleogeographic unit that was positive during part of Paleozoic time and whose crest is characterized by nonmarine Upper Triassic rocks unconformably overlying Proterozoic basement. In the western part of the Longmen Shan region, the allochthon is composed mainly of a very thick succession of strongly folded Middle and Upper Triassic Songpan Ganzi flysch. Along the eastern side and at the base of the allochthon, pre-Upper Triassic rocks crop out, forming the only exposures of the western margin of the Yangtze platform. Here, Upper Proterozoic to Ordovician, mainly shallow-marine rocks unconformably overlie Yangtze-type Proterozic basement rocks, but in Silurian time a thick section of fine-grained clastic and carbonate rocks were deposited, marking the initial subsidence of the western Yangtze platform and formation of a continental margin. Similar deep-water rocks were deposited throughout Devonian to Middle Triassic time, when Songpan Ganzi flysch deposition began. Permian conglomerate and basic volcanic rocks in the southeastern part of the allochthon indicate a second period of extension along the continental margin. Evidence suggests that the deep-water region along and west of the Yangtze continental margin was underlain mostly by thin continental crust, but its westernmost part may have contained areas underlain by oceanic crust. In the northern part of the Longmen Shan allochthon, thick Devonian to Upper Triassic shallow-water deposits of the Xue Shan platform are flanked by deep-marine rocks and the platform is interpreted to be a fragment of the Qinling continental margin transported westward during early Mesozoic transpressive tectonism. In the Longmen Shan region, the allochthon, carrying the western part of the Yangtze continental margin and Songpan Ganzi flysch, was emplaced to the southeast above rocks of the Yangtze platform autochthon. The eastern margin of the allochthon in the northern Longmen Shan is unconformably overlapped by both Lower and Middle Jurassic strata that are continuous with rocks of the autochthon. Folded rocks of the allochthon are unconformably overlapped by Lower and Middle Jurassic rocks in rare outcrops in the northern part of the region. They also are extensively intruded by a poorly dated, generally undeformed belt, of plutons whose ages (mostly K/Ar ages) range from Late Triassic to early Cenozoic, but most of the reliable ages are early Mesozoic. All evidence indicates that the major deformation within the allochthon is Late Triassic/Early Jurassic in age (Indosinian). The eastern front of the allochthon trends southwest across the present mountain front, so it lies along the mountain front in the northeast, but is located well to the west of the present mountain front on the south. The Late Triassic deformation is characterized by upright to overturned folded and refolded Triassic flysch, with generally NW-trending axial traces in the western part of the region. Folds and thrust faults curve to the north when traced to the east, so that along the eastern front of the allochthon structures trend northeast, involve pre-Triassic rocks, and parallel the eastern boundary of the allochthon. The curvature of structural trends is interpreted as forming part of a left-lateral transpressive boundary developed during emplacement of the allochthon. Regionally, the Longmen Shan lies along a NE-trending transpressive margin of the Yangtze platform within a broad zone of generally N-S shortening. North of the Longmen Shan region, northward subduction led to collision of the South and North China continental fragments along the Qinling Mountains, but northwest of the Longmen Shan region, subduction led to shortening within the Songpan Ganzi flysch basin, forming a detached fold-and-thrust belt. South of the Longmen Shan region, the flysch basin is bounded by the Shaluli Shan/Chola Shan arc—an originally Sfacing arc that reversed polarity in Late Triassic time, leading to shortening along the southern margin of the Songpan Ganzi flysch belt. Shortening within the flysch belt was oblique to the Yangtze continental margin such that the allochthon in the Longmen Shan region was emplaced within a left-lateral transpressive environment. Possible clockwise rotation of the Yangtze platform (part of the South China continental fragment) also may have contributed to left-lateral transpression with SE-directed shortening. During left-lateral transpression, the Xue Shan platform was displaced southwestward from the Qinling orogen and incorporated into the Longmen Shan allochthon. Westward movement of the platform caused complex refolding in the northern part of the Longmen Shan region. Emplacement of the allochthon flexurally loaded the western part of the Yangtze platform autochthon, forming a Late Triassic foredeep. Foredeep deposition, often involving thick conglomerate units derived from the west, continued from Middle Jurassic into Cretaceous time, although evidence for deformation of this age in the allochthon is generally lacking. Folding in the eastern Sichuan fold-and-thrust belt along the eastern side of the Sichuan Basin can be dated as Late Jurassic or Early Cretaceous in age, but only in areas 100 km east of the westernmost folds. Folding and thrusting was related to convergent activity far to the east along the eastern margin of South China. The westernmost folds trend southwest and merge to the south with folds and locally form refolded folds that involve Upper Cretaceous and lower Cenozoic rocks. The boundary between Cenozoic and late Mesozoic folding on the eastern and southern margins of the Sichuan Basin remains poorly determined. The present mountainous eastern margin of the Tibetan Plateau in the Longmen Shan region is a consequence of Cenozoic deformation. It rises within 100 km from 500–600 m in the Sichuan Basin to peaks in the west reaching 5500 m and 7500 m in the north and south, respectively. West of these high peaks is the eastern part of the Tibetan Plateau, an area of low relief at an elevations of about 4000 m. Cenozoic deformation can be demonstrated in the autochthon of the southern Longmen Shan, where the stratigraphic sequence is without an angular unconformity from Paleozoic to Eocene or Oligocene time. During Cenozoic deformation, the western part of the Yangtze platform (part of the autochthon for Late Triassic deformation) was deformed into a N- to NE-trending foldandthrust belt. In its eastern part the fold-thrust belt is detached near the base of the platform succession and affects rocks within and along the western and southern margin of the Sichuan Basin, but to the west and south the detachment is within Proterozoic basement rocks. The westernmost structures of the fold-thrust belt form a belt of exposed basement massifs. During the middle and later part of the Cenozoic deformation, strike-slip faulting became important; the fold-thrust belt became partly right-lateral transpressive in the central and northeastern Longmen Shan. The southern part of the fold-thrust belt has a more complex evolution. Early Nto NE-trending folds and thrust faults are deformed by NW-trending basementinvolved folds and thrust faults that intersect with the NE-trending right-lateral strike-slip faults. Youngest structures in this southern area are dominated by left-lateral transpression related to movement on the Xianshuihe fault system. The extent of Cenozoic deformation within the area underlain by the early Mesozoic allochthon remains unknown, because of the absence of rocks of the appropriate age to date Cenozoic deformation. Klippen of the allochthon were emplaced above the Cenozoic fold-andthrust belt in the central part of the eastern Longmen Shan, indicating that the allochthon was at least partly reactivated during Cenozoic time. Only in the Min Shan in the northern part of the allochthon is Cenozoic deformation demonstrated along two active zones of E-W shortening and associated left-slip. These structures trend obliquely across early Mesozoic structures and are probably related to shortening transferred from a major zone of active left-slip faulting that trends through the western Qinling Mountains. Active deformation is along the left-slip transpressive NW-trending Xianshuihe fault zone in the south, right-slip transpression along several major NE-trending faults in the central and northeastern Longmen Shan, and E-W shortening with minor left-slip movement along the Min Jiang and Huya fault zones in the north. Our estimates of Cenozoic shortening along the eastern margin of the Tibetan Plateau appear to be inadequate to account for the thick crust and high elevation of the plateau. We suggest here that the thick crust and high elevation is caused by lateral flow of the middle and lower crust eastward from the central part of the plateau and only minor crustal shortening in the upper crust. Upper crustal structure is largely controlled in the Longmen Shan region by older crustal anisotropics; thus shortening and eastward movement of upper crustal material is characterized by irregular deformation localized along older structural boundaries. 相似文献
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本文在综合解译地质图、遥感影像及数字高程模型的基础上,沿着青衣江河谷对龙门山南段多条断裂进行了详细调查。将前第四纪大规模不整合边界作为断裂的分布范围,同时通过构造地貌标志确定最新的活动断裂位置,如断错山脊、断层槽谷、河道形态变化等。解译过程中也参考了前人研究成果,如开挖探槽位置信息,浅层地震剖面资料。调查结果显示,松潘—甘孜褶皱带与龙门山接触地带发育了中岗断裂、永富断裂,晚第四纪活动特征不明显。龙门山后山、中央、前山3条主干断裂在南段依次对应耿达—陇东断裂、岩井—五龙断裂、与双石—大川断裂,与北段具有相似的断块构造。3条断裂都有断错地貌特征但断裂分支较多,其中盐井—五龙断裂有一条分支为宝兴断裂,双石—大川断裂有小关子断裂一条分支。在前陆地区,基底滑脱带延伸至浅部盖层,断坡处发育了始阳断裂、新开店断裂等浅部分支断裂。通过这些断裂分布样式、断错地貌特征、与实测地质剖面发现,龙门山南段具有纯挤压特征,最新构造活动已经开始改造前陆地区,是扩展的边界。而龙门山北段具有和逆冲相当的走滑分量,表明青藏高原在推挤龙门山的过程中,龙门山北缘向西秦岭方向发生走滑逃逸,龙门山南段由于同时受川滇块体向东推挤作用而呈现纯挤压特征。高原推挤作用集中于松潘—甘孜褶皱带东缘的小金弧形构造,控制了龙门山断裂带南北构造差异。 相似文献
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环青藏高原盆山体系东段新构造变形特征——以川西为例 总被引：3，自引：0，他引：3
介于扬子板块与青藏高原之间的川西前陆冲断带是环青藏高原盆山体系东段的重要组成部分,它是研究喜马拉雅构造运动对青藏高原东缘沉积盆地构造作用的重要场所。本文分别选取川西南段、川西北段和川北西段米仓山前的区域构造地质剖面来研究沉积地层在喜马拉雅运动中发生的构造变形特征。通过前陆冲断构造变形带的宽度、水平缩短量,山体隆升、盆地沉降,新构造对早期古构造的叠加与改造关系的研究,揭示出在环青藏高原盆山体系内,造山带与盆地边缘的冲断构造变形从造山带向克拉通盆地内扩展的同时受欧亚大陆与印度板块碰撞及其远程效应的空间位置限制,靠近青藏高原的川西南段到远离它的川北西段,新构造变形强度、新构造变形范围、盆山耦合程度具有依次降低等特征。这种受环青藏高原盆山体系控制的前陆冲断带构造变形具有明显的资环效应,特别是对油气资源的聚集与分布有重要的影响,控制了川西南段晚期次生气藏发育,川西北段和川北西段的早期原生气藏的发育。 相似文献
17.
Deep Background of Wenchuan Earthquake and the Upper Crust Structure beneath the Longmen Shan and Adjacent Areas 总被引：5，自引：0，他引：5
LI Qiusheng GAO Rui WANG Haiyan ZHANG Jisheng LU Zhanwu LI Pengwu GUAN Ye HE Rizheng 《《地质学报》英文版》2009,83(4):733-739
Abstract: By analyzing the deep seismic sounding profiles across the Longmen Shan, this paper focuses on the study of the relationship between the upper crust structure of the Longmen Shan area and the Wenchuan earthquake. The Longmen Shan thrust belt marks not only the topographical change, but also the lateral velocity variation between the eastern Tibetan Plateau and the Sichuan Basin. A low-velocity layer has consistently been found in the crust beneath the eastern edge of the Tibetan Plateau, and ends beneath the western Sichuan Basin. The low-velocity layer at a depth of ~20 km beneath the eastern edge of the Tibetan Plateau has been considered as the deep condition for favoring energy accumulation that formed the great Wenchuan earthquake. 相似文献
18.
By analyzing the deep seismic sounding profiles across the Longmen Shan,this paper focuses on the study of the relationship between the upper crust structure of the Longmen Shan area and the Wenchuan earthquake.The Longmen Shan thrust belt marks not only the topographical change,but also the lateral velocity variation between the eastern Tibetan Plateau and the Sichuan Basin.A lowvelocity layer has consistently been found in the crust beneath the eastern edge of the Tibetan Plateau, and ends beneath the ... 相似文献
19.
应用多级平衡恢复原则,对浙西北地区褶皱-冲断构造样式及其组合进行缩短量计算与分析,同时,对前陆褶皱冲断带的变形缩短量和前陆盆地的缩短量及其二者关系进行了探讨,表明后者包容于前者之中.平衡缩短量与构造样式空间展布关系的研究表明前陆褶皱冲断带蕴含了递进变形的复杂过程,记录了造山作用及其挤压变形从初始→发展→顶峰→尾声的连续过程.综合分析表明缩短量自南东向北西呈递减趋势,即向前陆方向缩短量减少,与应变状态向前陆方向减弱是协调一致的.构造平衡及其综合分析是浙西北前陆褶皱冲断带向北西的构造极性的主要制约因素之一. 相似文献
20.
青藏高原东缘龙门山前陆逆冲带复合结构与生长 总被引：1，自引：1，他引：0
位于青藏高原东缘的北东向龙门山逆冲带,研究已经证明是中生代与新生代前陆复合扩展和生长的结果。然而,2008年5·12汶川地震地表破裂、余震和滑坡等的单向和分段迁移现象,对龙门山复合逆冲带的结构认识提出了挑战。文章在已有研究成果基础上,针对龙门山复合生长下构建的特殊结构进行了野外调查和构造解析。结果表明,以中生代与新生代两期前陆逆冲带复合生长为基础,龙门山复合逆冲带具有特殊的、主要由前陆逆冲楔叠加后形成的复合结构,而且这种复合逆冲楔具有分级和时序特征;中生代前陆逆冲楔是以逆冲断层-褶皱为特征,并分别组合形成碧口厚皮逆冲推覆体、唐王寨薄皮逆冲推覆体和龙王庙逆冲推覆体,总体从晚三叠世以前开始,至~160 Ma向南递进扩展生长;新生代前陆逆冲楔由逆冲断层和逆冲岩片组成,分为约35~10 Ma和10 Ma以来两个阶段,向南东向递进扩展生长,并可能与川西盆地东侧龙泉山构造相连通。因此,龙门山逆冲带具有前陆逆冲带和生长过程的双重复合结构。 相似文献