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1.
Abstract The geotraverse from Yecheng to Shiquanhe, on the western Qinghai – Tibet Plateau, totalling 1056 km in length, passes the western Kunlun Mountains and the eastern end of the Karakorum Mountains. The Chinese and French scientists made a joint investigation along the line from July to August, 1989. Based on the outcropped ophiolites, palaeontology, sedimentary facies, magmatism, tectonic deformation and metamorphism, the region involved may be divided from north to south into five terranes and four ophiolitic suture zones. The ages of these terranes have a tendency to become increasingly younger from north to south. 相似文献
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摘要：天山两侧山前新生代构造变形强烈,是研究盆山耦合动力学机制的理想场所。文中在综合分析前人资料基础上,结合作者的野外观测和分析,综述了天山两侧盆山转换部位不同段的新生代构造变形特征,并进行对比分析。结果显示,新生代构造变形在天山南北山前相似性和差异性共存:变形由山体向盆地扩展,时间逐渐变新;但是南侧比北侧变形起始时间早,地壳缩短量和缩短率大。在东西方向上新生代构造变形也存在明显的分段相似性特征,整体上显示出斜方对称的变形图像:东天山博格达山前为基底式逆冲推覆,南侧为走滑变形;中天山南北两侧为多排子的褶皱 逆冲推覆构造,西天山南侧也为基底式的逆冲推覆,北侧为走滑变形。综合前人研究,认为印度和亚洲大陆的碰撞及其随后陆陆汇聚作用的远程效应,是形成天山两侧山前新生代构造变形在南北方向上相似性和差异性的主要原因;而天山山体内部先存的相对刚性地块和大型断裂,则导致了新生代构造变形的东西向分段差异性和斜方对称的特征。 相似文献
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造山带和盆地是在时空发展和形成机制上具有密切联系的构造系统。青藏高原内部晚三叠世古特提斯造山带的形成,对北缘的塔里木盆地产生了重要的影响,导致了盆地内部西昆仑山前地区发生了强烈的冲断构造变形,而这一冲断构造变形所形成的古构造-古地貌对后期侏罗-白垩纪的沉积具有重要的控制作用,同时也决定了该地区的油气分布。本文基于对西昆仑山前露头区中生代地层分布详细的野外考察和盆地覆盖区钻井资料的整理,结合对盆-山结合带清晰地震剖面的详细解释,开展西昆仑山前的晚三叠世古构造特征及侏罗-白垩纪沉积充填过程研究,以期揭示晚三叠世的古构造-古地貌特征及对沉积的控制作用。通过研究发现,西昆仑山前地区发育晚三叠世前陆褶皱冲断带,冲断带根部发育基底卷入构造,锋带发育叠瓦状构造;古生界受逆冲断裂控制,形成一系列的北陡南缓的背斜隆起,冲断带前锋位置与新生代构造前锋位置相近。三叠纪末古地貌形态由于特提斯造山带的强烈隆升,总体呈南高北低的地貌形态,但是褶皱冲断构造带受地表风化剥蚀作用,背斜核部形成南缓北陡的古隆起,而断层破碎带形成南陡北缓的洼地,是侏罗系发育前的基本地貌格架。早侏罗世受特提斯造山带造山后伸展的影响,西昆仑山前发育4个箕状断陷,控陷断层发育于古造山带一侧;受大型控陷断层的影响,在断陷内部呈北高南低的地形特点,断陷内侏罗系逐渐向北部斜坡超覆。晚三叠世形成的古构造-古地貌与早侏罗世断陷叠加形成的古地理格架一直控制了侏罗纪-早白垩世的沉积,直到晚白垩世沉积时才没有起到控制作用。 相似文献
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The Crustal Structure and Assembly of Terranes in the Qaidam-Qilian-Beishan Area, Western China 总被引：2，自引：0，他引：2
LIU Xun GAO RuiInstitute of Geology Chinese Academy of Geological Sciences Baiwanzhuang Rd. Beijing 《《地质学报》英文版》1998,72(3):243-255
Through a study of the geotransect from Golmud to Ejin Qi published recently, the tectonics of the crust beneath the area from the northern Qinghai-Tibet plateau (Qaidam and the Qilian Mountains) to the border between China and Mongolia and its structure, composition and tectonic evolution have been revealed, and abundant information about the deep structures has been provided. Based on the research into the geotransect, it is suggested that the crust in this area was formed by the assembly of the terranes in different geological stages. Following the formation of the Palaeo-Asian continent, the north part of the corridor of the transect became a part of the huge unifying continent by the end of the Early Permian. In the Mesozoic and Cenozoic, as a result of the compression mainly by the push of the Qinghai-Tibet plateau on the south, the unique crustal structure and geomorphologic features on the northern Qinghai-Tibet plateau were formed. This geotransect together with the Yadong-Golmud geotransect co 相似文献
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大别山前寒武纪变质地体基本组成 总被引：5，自引：0，他引：5
本文以新城－圻春断裂为界将大别山前寒武纪变质地体划分为华北陆块南缘和场子陆块北缘两个次级变质地体，两个次级地体不仅在地球物理，构造变形方面明显不同，而且在物质成分上有显著差异，它们有各自独立的变质地层系统，遭受了不同类型的变质作用，有完全不同的岩浆活动图象，上述差异均可指示华北，扬子两古陆碰掸对接时扬子陆块北缘向北俯冲至华北陆块南缘之下，这可能包括两次合作用，从元古代开始至中生代最终结束的长期复杂 相似文献
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本文基于沉积建造及岩浆岩的研究，确定龙首山是阿拉善地块南缘的古裂谷带。裂谷型建造以中—晚元古带的墩子沟群和韩母山群为代表；岩浆岩组合则是富含Bi-Cu矿产的超镁铁岩及镁铁岩．河西走廊可分为东西两段；东段是阿拉善南缘的造山带，由永昌—武威冒地斜和冷龙岭—古浪优地斜2个单元构成；西段是祁连造山带北祁连优地斜的一部分。二者分别属于2个古板块，其间的缝合线位于高台至民乐一带．笔者在该区〔包括祁连山〕共识别出7个构造—地层地体，其中1个具外来属性，其余均为增生地体。 相似文献
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本文基于沉积建造及岩浆岩的研究,确定龙首山是阿拉善地块南缘的古裂谷带。裂谷型建造以中-晚元古带的墩子沟群和韩母山群为代表;岩浆岩组合则是富含Bi—Cu矿产的超镁铁岩及镁铁岩。河西走廊可分为东西两段;东段是阿拉善南缘的造山带,由永昌—武威冒地斜和冷龙岭—古浪优地斜2个单元构成;西段是祁连造山带北祁连优地斜的一部分。二者分别属于2个古板块,其间的缝合线位于高台至民乐一带。笔者在该区(包括祁连山)共识别出7个构造—地层地体,其中1个具外来属性,其余均为增生地体。 相似文献
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在前人研究成果和野外地质调查的基础上,系统研究了东天山南北两侧（准噶尔东缘和吐哈北缘）早二叠世沉积序列、岩相组合、古流向及盆地演化。研究表明,早二叠世准噶尔盆地东缘石人子沟组和塔什库拉组发育枕状玄武岩、流纹岩等双峰式火山岩建造和海相砂、泥质及碳酸盐岩复理石相沉积,并含有大量的海相生物化石,指示了海相裂谷盆地环境。吐哈北缘发育依尔希土组,以安山岩、流纹质火山岩及火山碎屑岩夹陆相碎屑岩为主,表现为陆相裂谷盆地环境。东天山南北两侧古流向及物源显示,东天山北侧,早二叠世古水流指向东南方向,在其南侧古水流指向西北部凹陷区,并且物源主要来自下伏前二叠纪岩石建造,表明早二叠世时期东天山博格达地区为汇水沉积区,且由东至西分别发育陆相和海相裂谷盆地,至早二叠世末期整体演化为陆相坳陷盆地。而导致东天山南北两侧早二叠世沉积环境迥异的原因是,石炭纪博格达裂谷东段祁家沟-天池地区和西段吐哈北缘地区演化的差异,造成随后的闭合阶段中东段早闭合、沉积环境“突变”,西段晚闭合和沉积环境“渐变”的不同过程。 相似文献
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D. Koehn K. Link T. Sachau C. W. Passchier K. Aanyu A. Spikings R. Harbinson 《International Journal of Earth Sciences》2016,105(6):1693-1705
This contribution discusses the development of the Palaeoproterozoic Buganda-Toro belt in the Rwenzori Mountains and its influence on the western part of the East African Rift System in Uganda. The Buganda-Toro belt is composed of several thick-skinned nappes consisting of Archaean Gneisses and Palaeoproterozoic cover units that are thrusted northwards. The high Rwenzori Mountains are located in the frontal unit of this belt with retrograde greenschist facies gneisses towards the north, which are unconformably overlain by metasediments and amphibolites. Towards the south, the metasediments are overthrust by the next migmatitic gneiss unit that belongs to a crustal-scale nappe. The southwards dipping metasedimentary and volcanic sequence in the high Rwenzori Mountains shows an inverse metamorphic grade with greenschist facies conditions in the north and amphibolite facies conditions in the south. Early D1 deformation structures are overgrown by cordierite, which in turn grows into D2 deformation, representing the major northwards directed thrusting event. We argue that the inverse metamorphic gradient develops because higher grade rocks are exhumed in the footwall of a crustal-scale nappe, whereas the exhumation decreases towards the north away from the nappe leading to a decrease in metamorphic grade. The D2 deformation event is followed by a D3 E-W compression, a D4 with the development of steep shear zones with a NNE-SSW and SSE-NNW trend including the large Nyamwamba shear followed by a local D5 retrograde event and D6 brittle reverse faulting. The Palaeoproterozoic Buganda-Toro belt is relatively stiff and crosses the NNE-SSW running rift system exactly at the node where the highest peaks of the Rwenzori Mountains are situated and where the Lake George rift terminates towards the north. Orientation of brittle and ductile fabrics show some similarities indicating that the cross-cutting Buganda-Toro belt influenced rift propagation and brittle fault development within the Rwenzori Mountains and that this stiff belt may form part of the reason why the Rwenzori Mountains are relatively high within the rift. 相似文献
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龙门山构造变形始于印支期,经历燕山期和喜山期多次递进变形,构造变形时期具有由北向南、由西向东逐渐变晚和构造变形强度西侧强、东侧弱的特点。龙门山冲断带具有南北分段、东西分带和纵向分层的差异变形特征。龙门山逆冲推覆带构造变形强烈,油气保存条件差。山前断褶带主要发育断弯背斜、断展背斜和断挡背斜等,变形适中,油气保存条件好,龙门山山前断褶皱带有利于油气富集,形成构造油气藏。 相似文献
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中国西北和东北地区发育中生代河湖相沉积的陆相盆地,其中赋存丰富的脊椎动物化石群,包括天山北部准噶尔盆地的乌尔禾翼龙动物群、天山南部吐哈盆地的哈密翼龙动物群和辽西热河生物群富含翼龙化石。乌尔禾和哈密翼龙动物群都发现于下白垩统吐谷鲁群中,两者的繁盛时间大致相当,这两个动物群的翼龙个体数量巨大,但是物种多样性很低。乌尔禾翼龙动物群的化石多保存在半深湖环境沉积的细砂岩和粉砂岩中,化石保存较为完整,主要为正常死亡;哈密翼龙动物群的化石富集保存在滨浅湖环境事件沉积的风暴岩中,大都经过了大型风暴的短距离搬运和快速埋藏,骨架分散,但几乎所有单个骨骼完整。东北地区的热河生物群翼龙种类众多,共生包括鱼类、两栖类、恐龙等其他爬行类、鸟类和哺乳类等脊椎动物,生物多样性极为丰富,大多保存在半深湖-深湖环境形成的页岩中,骨架多为完整保存,是火山爆发事件导致其集群死亡,并被火山灰快速埋藏,与新疆的动物群面貌明显不同。根据天山南北的翼龙动物群初步对比,乌尔禾翼龙动物群的主要优势类群准噶尔翼龙类,在天山北部的准噶尔盆地及相邻的蒙古西部地区都有分布,与天山南部的哈密翼龙动物群中已知唯一翼龙类群哈密翼龙完全不同,两者亲缘关系很远。因此认为在中生代,天山的隆升就已经达到了一定的高度,并对翼龙的南北迁徙交流形成了有效的地理阻隔。依据中国东北和西北地区早白垩世翼龙动物群对比,认为辽西及相邻周边地区由于华北克拉通破坏,导致大量火山活动,造成了生态环境的多样性和生物种类的快速更替,从而形成了热河生物群独有的极高的生物多样性,而缺少火山活动、环境相对单一的西北陆相盆地,虽然翼龙类具有数以千万计的庞大居群,但是物种多样性很低。华北克拉通破坏导致的辽西地区频繁而强烈的火山活动,是形成中国西北和东北早白垩世生物多样性差异的重要原因。 相似文献
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Accelerated Exhumation During the Cenozoic in the Dabie Mountains: Evidence from Fission-Track Ages 总被引：3，自引：0，他引：3
WANG Guocan YANG Weiran Faculty of Earth Science China University ofGeosciences Wuhan Hubei 《《地质学报》英文版》1998,72(4):409-419
Zircon and apatite fission-track dating indicates that the exhumation of the Dabie Mountains tended to be accelerated in the Cenozoic and that the exhumation of the eastern Dabie Mountains was more and more intense from south to north, which is in accordance with the more and more intense dissection from south to north, as is reflected by the modern geomorphologic features of the Dabie Mountains. The accelerated exhumation during the Cenozoic was related to the high elevation of the Dabie Mountains resulting from Late Cretaceous-Palaeogene detachment faulting and subsequent fault-block uplift and subsidence. The average elevation at that time was at least about 660 m higher than that at the present. The intense exhumation lagged behind intense uplift. 相似文献
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格尔木——额济纳旗地学断面综合研究 总被引：17，自引：0，他引：17
格尔木－额济纳旗地学断面从南到北穿过昆仑、祁连和北山３个构造带;在断面中划分出北昆仑－柴达木、中南祁连、北祁连、北山南部和北山北部５个构造地层地体;以及昆仑中央、北宗务隆、中祁连北缘、宽滩山及石板井－小黄山５条地体边界断裂带。断面内地壳厚度约５０￣７０ｋｍ,中南祁连地体地壳厚度最大,显示有山根存在;岩石圈厚度约１４０￣１５０ｋｍ。根据地球卫星及地震反射剖面结构表明：青藏高原为一个单独的岩石圈构造单 相似文献
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桐柏－大别山自早更新世晚期以来,不断发生着自北向南的掀斜隆升,从而对长江中游的环境,尤其是水系的演化产生了严重影响。主要表现在：鄂西各东西向河流的阶地高差自北向南逐渐降低;江汉平原水系同步向南发生异常弯曲,长江主河道不断南移,湖相沉积范围也由北向南收缩和迁移;鄂东长江两岸水系和河谷地貌发育不对称,长江主河道紧逼南岸丘陵区。现代地壳形变资料表明：桐柏－大别山的掀升作用仍在继续,由此引起的环境问题还将 相似文献
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TECTONIC FEATURES AND HYDROCARBON POTENTIAL OF THE EASTERN QAIDAM BASIN 相似文献
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Metamorphic evidence for an inverted crustal section, with constraints on the Main Karakorum Thrust, Baltistan, northern Pakistan 总被引：1，自引：0，他引：1
Abstract The Shyok Suture Zone separates rocks in the Asian plate from rocks in the Kohistan-Ladakh island arc. In Baltistan, this suture has been reactivated by the late 'break-back'Main Karakorum Thrust (MKT). The P-T histories of metamorphic rocks both north and south of the MKT have been determined in an effort to place constraints on the tectonic history of this zone. The terranes north and south of the MKT have different, unrelated metamorphic histories. Rocks from the Kohistan-Ladakh island arc south of the MKT have undergone a static low- P (2–4 kbar, c. 500° C) thermal metamorphism. The P-T paths and metamorphic textures of these rocks are consistent with metamorphism due to emplacement of plutonic rocks into the island arc. This metamorphism pre-dates folding and deformation of these rocks. Rocks in the Karakorum Metamorphic Complex, north of the MKT, have experienced a complex deformational and metamorphic history. Prograde metamorphic isograds have been deformed by subsequent south-verging folding and by gneiss dome emplacement. However, decompression metamorphic reactions occurred during nappe emplacement. Higher pressure rocks are associated with higher level nappes, creating an inverted pressure metamorphic sequence (8–9-kbar rocks over 5–6-kbar rocks). There is little variation in temperature with structural level (550–625° C). These two different terranes have been juxtaposed after metamorphism by the late south-directed MKT. 相似文献
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《Gondwana Research》2002,5(1):109-122
A new statistical method is proposed to compare crustal terranes and to cluster terranes into crustal provinces, regions and realms. Geochronological data on mafic igneous rocks, felsic igneous rocks, deformation history and Nd model age were collected from the recent literature for over 100 terranes.The 54 selected Laurentian terranes cluster into 9 provinces including a previously well recognized very distinctive SW USA province, region and realm. The 38 selected Australian terranes cluster into six provinces including a distinctive Gawler Province. A combined dendrogram of the 100 terranes from Laurentia, Australia and Antarctica results in 8 superprovinces and 11 provinces. Five of the superprovinces contain both Laurentian and Australian terranes.The inclusion of the Nevada-Californian Mojave and the San Gabriel terranes in an otherwise Australian superprovince that includes Broken Hill and Mt Isa terranes, strongly supports the AUSWUS Laurentia-Australia reconstruction rather than the SWEAT reconstruction. Low statistical similarities between western Laurentia and eastern Antarctica fail to support the SWEAT hypothesis whilst high similarities between Canadian and north Australian terranes provides weak support for AUSWUS. 相似文献