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1.
《Journal of Asian Earth Sciences》2002,20(3):241-245
A comparative study of the amount of latitudinal shift of the Siberian Plate, the Lhasa Block, the Himalayan Block and the Indian Plate using palaeomagnetic data shows that the Himalayan Block belongs to the Indian Plate. The Neo-Tethys Ocean, which separated the Himalayan and Lhasa Blocks, opened to its greatest width of 31.9° in latitude in the Early Cretaceous. The extent of shortening of the latitudinal distance between the Siberian and Indian Plates amounts to 58.2° since the Early Cretaceous. It was found that after the determination of the greatest width of Neo-Tethys Ocean, the latitudinal shortening of the crust between the Indian and Siberian Plates reached 26.3°, or about 2760 km. On the basis of the palaeomagnetic data obtained from the Qaidam Block, the latitudinal shortening between the Himalayan and Qaidam Blocks reached 50.2° since the Early Cretaceous. It was concluded that over the past 50 Ma, since the Early Cretaceous, the latitudinal shift of the southern blocks or plates was larger than that of the northern ones, and that shortening between the Qaidam and Himalayan blocks was greater than the shortening between the Qaidam Block and the Siberian Plate. This differential latitudinal movement is the main cause of convergence, resulting in the compression and uplift of the Qinghai–Tibetan Plateau. 相似文献
2.
Early Cenozoic Tectonics of the Tibetan Plateau 总被引：1，自引：0，他引：1
Geological mapping at a scale of 1:250000 coupled with related researches in recent years reveal well Early Cenozoic paleo-tectonic evolution of the Tibetan Plateau. Marine deposits and foraminifera assemblages indicate that the Tethys-Himalaya Ocean and the Southwest Tarim Sea existed in the south and north of the Tibetan Plateau, respectively, in Paleocene-Eocene. The paleooceanic plate between the Indian continental plate and the Lhasa block had been as wide as 900km at beginning of the Cenozoic Era. Late Paleocene transgressions of the paleo-sea led to the formation of paleo-bays in the southern Lhasa block. Northward subduction of the Tethys-Himalaya Oceanic Plate caused magma emplacement and volcanic eruptions of the Linzizong Group in 64.5-44.3 Ma, which formed the Paleocene-Eocene Gangdise Magmatic Arc in the north of Yalung-Zangbu Suture (YZS), accompanied by intensive thrust in the Lhasa, Qiangtang, Hoh Xil and Kunlun blocks. The Paleocene-Eocene depression of basins reached to a depth of 3500-4800 m along major thrust faults and 680-850 m along the boundary normal faults in central Tibetan Plateau, and the Paleocene-Eocene depression of the Tarim and Qaidam basins without evident contractions were only as deep as 300-580 m and 600-830 m, respectively, far away from central Tibetan Plateau. Low elevation plains formed in the southern continental margin of the Tethy-Himalaya Ocean, the central Tibet and the Tarim basin in Paleocene-Early Eocene. The Tibetan Plateau and Himalaya Mts. mainly uplifted after the Indian-Eurasian continental collision in Early-Middle Eocene. 相似文献
3.
《Gondwana Research》2013,24(4):1429-1454
Different hypotheses have been proposed for the origin and pre-Cenozoic evolution of the Tibetan Plateau as a result of several collision events between a series of Gondwana-derived terranes (e.g., Qiangtang, Lhasa and India) and Asian continent since the early Paleozoic. This paper reviews and reevaluates these hypotheses in light of new data from Tibet including (1) the distribution of major tectonic boundaries and suture zones, (2) basement rocks and their sedimentary covers, (3) magmatic suites, and (4) detrital zircon constraints from Paleozoic metasedimentary rocks. The Western Qiangtang, Amdo, and Tethyan Himalaya terranes have the Indian Gondwana origin, whereas the Lhasa Terrane shows an Australian Gondwana affinity. The Cambrian magmatic record in the Lhasa Terrane resulted from the subduction of the proto-Tethyan Ocean lithosphere beneath the Australian Gondwana. The newly identified late Devonian granitoids in the southern margin of the Lhasa Terrane may represent an extensional magmatic event associated with its rifting, which ultimately resulted in the opening of the Songdo Tethyan Ocean. The Lhasa−northern Australia collision at ~ 263 Ma was likely responsible for the initiation of a southward-dipping subduction of the Bangong-Nujiang Tethyan Oceanic lithosphere. The Yarlung-Zangbo Tethyan Ocean opened as a back-arc basin in the late Triassic, leading to the separation of the Lhasa Terrane from northern Australia. The subsequent northward subduction of the Yarlung-Zangbo Tethyan Ocean lithosphere beneath the Lhasa Terrane may have been triggered by the Qiangtang–Lhasa collision in the earliest Cretaceous. The mafic dike swarms (ca. 284 Ma) in the Western Qiangtang originated from the Panjal plume activity that resulted in continental rifting and its separation from the northern Indian continent. The subsequent collision of the Western Qiangtang with the Eastern Qiangtang in the middle Triassic was followed by slab breakoff that led to the exhumation of the Qiangtang metamorphic rocks. This collision may have caused the northward subduction initiation of the Bangong-Nujiang Ocean lithosphere beneath the Western Qiangtang. Collision-related coeval igneous rocks occurring on both sides of the suture zone and the within-plate basalt affinity of associated mafic lithologies suggest slab breakoff-induced magmatism in a continent−continent collision zone. This zone may be the site of net continental crust growth, as exemplified by the Tibetan Plateau. 相似文献
4.
西藏羌塘盆地白垩纪中期构造事件的磷灰石裂变径迹证据 总被引：4，自引：1，他引：3
拉萨与羌塘地块于白垩纪中期的碰撞造山对羌塘原型盆地的热体制和构造演化有着重要影响.运用磷灰石裂变径迹方法,对羌塘盆地隆鄂尼夏里组和托纳木雪山组砂岩分析表明,裂变径迹年龄集中在120～ 80Ma之间,表明在白垩纪中期,羌塘盆地普遍发生了一次构造抬升事件,该期构造事件的年龄与盆地内早白垩世的岩浆热事件、主要构造变形作用发生在晚白垩世以及雪山组和阿布山组角度不整合的时代(125～75Ma)较一致,是拉萨与羌塘地块碰撞造山事件的记录.热历史模拟表明,白垩纪中期构造事件对羌塘盆地南部和北部的热演化历史有着差异影响,羌塘盆地南部降温速率相对不大,抬升剥蚀厚度约1500m,而北部古地温迅速降温到近地表温度,抬升剥蚀厚度近4000m.这种差异抬升剥蚀可能与班公湖-怒江洋壳向南俯冲使得因拉萨地块构造负载而导致羌塘地块的挠曲有关. 相似文献
5.
国内外不少地质学家大都将雅鲁藏布江蛇绿岩带视为印度板块与亚洲板块之间的缝合带。但是,笔者等在喜玛拉雅造山带的东段即仁布-康马一线以东地区的研究却发现,在雅鲁藏布江蛇绿岩带的南侧发育着一个宽大的增生杂岩体,它与雅江蛇绿岩是同一大洋即特提斯喜玛拉雅洋俯冲消减的产物,前者代表着特提斯喜玛拉雅洋消亡遗迹的主体,是印度板块与拉萨地块之间缝合带的主要组成部分;而后者代表的是俯冲带与拉萨地块之间的残余洋壳,它由北向南仰冲,构成日喀则-桑日弧前盆地前缘脊和南部基底,因而其不代表主缝合带。北喜玛拉雅增生杂岩体的发现改变了以Gansser(1964)为代表提出的喜玛拉雅造山带的构造模式,为重新审视印度板块与拉萨地块缝合作用过程提供了一个重要的地质制约和新的研究途径。 相似文献
6.
Tectonics and Topography of the Tibetan Plateau in Early Miocene 总被引：1，自引：0，他引：1
Early Miocene stratigraphy, major structural systems, magmatic emplacement, volcanic eruption, vegetation change and paleo-elevation were analyzed for the Tibetan Plateau after regional geological mapping at a scale of 1:250,000 and related researches, revealing much more information for tectonic evolution and topographic change of the high plateau caused by Indian-Asian continental collision. Lacustrine deposits of dolostone, dolomite limestone, limestone, marl, sandstone and conglomerate of weak deformation formed extensively in the central Tibetan Plateau, indicating that vast lake complexes as large as 100,000–120,000 km2 existed in the central plateau during Early Miocene. Sporopollen assemblages contained in the lacustrine strata indicate the disappearance of most tropical-subtropical broad-leaved trees since Early Miocene and the flourishing of dark needleleaved trees during Early Miocene. Such vegetation changes adjusted for latitude and global climate variations demonstrate that the central Tibetan Plateau rose to ca. 4,000–4,500 m and the northeastern plateau uplifted to ca. 3,500–4,000 m before the Early Miocene. Intensive thrust and crustal thickening occurred in the areas surrounding central Tibetan Plateau in Early Miocene, formed Gangdise Thrust System(GTS) in the southern Lhasa block, Zedong-Renbu Thrust(ZRT) in the northern Himalaya block, Main Central Thrust(MCT) and Main Boundary Thrust(MBT) in the southern Himalaya block, and regional thrust systems in the Qaidam, Qilian, West Kunlun and Songpan-Ganzi blocks. Foreland basins formed in Early Miocene along major thrust systems, e.g. the Siwalik basin along MCT, Yalung-Zangbu Basin along GTS and ZRT, southwestern Tarim depression along West Kunlun Thrust, and large foreland basins along major thrust systems in the northeastern margin of the plateau. Intensive volcanic eruptions formed in the Qiangtang, Hoh-Xil and Kunlun blocks, porphyry granites and volcanic eruptions formed in the Nainqentanglha and Gangdise Mts., and leucogranites and granites formed in the Himalaya and Longmenshan Mts. in Early Miocene. The K2O weight percentages of Early Miocene magmatic rocks in the Gangdise and Himlayan Mts. are found to increase with distance from the MBT, indicating the genetic relationship between regional magmatism and subduction of Indian continental plate in Early Miocene. 相似文献
7.
尼玛—荣玛地区位于羌塘盆地中段,发育大量的逆冲推覆构造体系。尼玛以北主要发育自北向南运动的逆冲推覆构造体系,导致中央隆起带和班公—怒江构造带的岩石地层组合、三叠系和侏罗系地层逆冲在红层之上,其中北羌塘盆地侏罗系地层越过中央隆起,在南羌塘盆地发育滑脱构造并形成薄皮逆冲推覆构造及大型逆冲岩席;尼玛以南主要发育自南向北运动的逆冲推覆构造体系,造成侏罗—白垩系、白垩系岩石组合逆冲在红层之上。逆冲推覆构造普遍控制了红层盆地的生长,并被中新世湖相沉积角度不整合覆盖。逆冲推覆构造活动时代为早白垩世晚期至古近纪,其中中央隆起和班公—怒江构造带最早经历了早白垩世晚期—晚白垩世的抬升,随后整个研究区经历了古近纪的构造抬升,分别与新特提斯洋板片的北向俯冲以及印度—拉萨地块陆陆碰撞存在动力学相关;中新世以来的东西向伸展构造则导致局部差异抬升。逆冲推覆构造破坏了早期油气成藏,但同时伴生的断褶系统也促进地层增厚和有机质成熟,为二次生烃提供了有利的构造圈闭条件,桑列勒以及尼玛一带背斜圈闭是有利的油气靶区。 相似文献
8.
藏北改则新生代早期逆冲推覆构造系统 总被引：2，自引：0，他引：2
藏北改则及邻区新生代早期发育大型逆冲推覆构造系统,由不同方向的逆冲断层、不同时代的构造岩片、不同规模的飞来峰和构造窗、不同类型的褶皱构造组成。羌塘中部发育羌中薄皮推覆构造,石炭系板岩和二叠系白云质灰岩自北向南逆冲推覆于上白垩统与古近系红层之上,形成大型逆冲岩席和弧形逆冲断层,原地系统古近纪红层下伏三叠系—侏罗系海相烃源岩。羌塘南部发育南羌塘薄皮推覆构造,导致班公—怒江蛇绿岩、三叠系—侏罗系海相地层及侏罗纪混杂岩自北向南逆冲推覆于古近纪红层与下白垩统海相沉积岩层之上,形成三条蛇绿岩片带、大量飞来峰和厚度较大的构造片岩。中新世早期火山岩层和湖相沉积呈角度不整合覆盖逆冲断层、褶皱构造和逆冲岩席,不整合面上覆火山岩年龄为23.7～19.1Ma,指示中新世早期改则及邻区基本结束了强烈逆冲推覆构造运动。估算羌中逆冲推覆构造的推覆距离约100～115km,南羌塘逆冲推覆构造的推覆距离约82～110km;新生代早期改则逆冲推覆构造系统近南北方向逆冲推覆总距离为182～225km,对应地壳缩短率为(50.3±2.7)%。 相似文献
9.
青藏高原北部古近纪晚期大面积发育唢呐湖组湖相沉积,主要为砖红色、棕色、灰白色泥灰岩、泥岩、粉砂岩互层,夹石膏层和灰岩,广泛出露于羌塘中部、可可西里、东昆仑南部,形成时代为41.1±0.8~32.5!0.3Ma,向可可西里东部过渡为雅西错群。对双湖采坑唢呐湖组上部湖相沉积地层进行详细观测和系统取样,对泥灰岩和粘土岩样品选碎屑锆石作LA-MC-ICP-MS U-Pb同位素测年,对不同层位泥灰岩、粘土岩、灰岩样品作碳、氧同位素分析,结合区域地质相关资料,良好揭示了碎屑锆石来源、沉积地貌环境及古海拔高度。双湖采坑唢呐湖组碎屑锆石绝大部分为岩浆锆石,统计分析碎屑锆石U-Pb年龄,发现存在4期峰值,分别为280~200Ma、780~830Ma、1920~1790Ma、2600~2360Ma;对比区域地质和岩浆岩测年资料,推断晚二叠世—三叠纪(280~200Ma)碎屑锆石主要来自于羌中隆起岩浆岩,新元古代中期(~800Ma)、古元古代晚期(~1800Ma)、太古宙末期—古元古代初期(~2500Ma)碎屑锆石主要来自于东昆仑造山带。双湖采坑碎屑锆石部分测点U-Pb同位素呈线性分布,交点年龄及谐和年龄为1883!51~1837!12Ma、2483!24~2520!37Ma,对应东昆仑造山带早前寒武纪2期岩浆热事件年龄。根据唢呐湖组湖相沉积空间分布和碎屑锆石U-Pb年龄统计分布,推断青藏高原北部古近纪晚期发育自北向南流动的古水系,古洪流将东昆仑造山带出露地表的前寒武纪基底岩浆锆石自北向南长距离搬运,汇聚于双湖古湖盆并沉积于唢呐湖组。根据双湖采坑唢呐湖组湖相沉积碳同位素和氧同位素,估算双湖古湖盆35~34Ma古海拔高度为3427~3510m,这与应用Airy均衡模式根据地壳厚度和密度变化估算的古海拔高度在误差范围内基本吻合。 相似文献
10.
《International Geology Review》2012,54(2):228-245
AbstractThis article reports the depositional environment and provenance for the Tianquanshan Formation in the Longmuco–Shuanghu–Lancangjiang suture zone, and uses these to better understand the tectonic evolution of this region. Zircons in the andesite of the Tianquanshan Formation yielded concordia ages of 246, 247, and 254 Ma, indicating that the Tianquanshan Formation formed during the late Permian–Early Triassic. The Tianquanshan Formation consists of flysch and ocean island rock assemblages, indicating that the Longmuco–Shuanghu–Lancangjiang Palaeo-Tethys Ocean continued to exist as a mature ocean in the late Permian–Early Triassic. The detrital zircons in the greywackes of the Tianquanshan Formation yielded peak ages of 470–620, 710–830, 910–1080, 1450–1660, and 2400–2650 Ma, indicating the provenance of the Tianquanshan Formation was either Indian Gondwana or terranes that have an affinity with Indian Gondwana in the Tibetan Plateau (i.e. the Southern Qiangtang, Lhasa, and Himalayan terranes). The Ordovician quartzites, Carboniferous sandstones, Carboniferous–Permian diamictites, and the Upper Permian–Lower Triassic greywackes in the Southern Qiangtang, Lhasa, and Himalayan terranes all contain detrital zircons with youngest ages of ca. 470 Ma, indicating their source areas have been in a stable tectonic environment since the Ordovician, and this inference is supported by the continuous deposition in a littoral–neritic passive margin in these regions from the Ordovician to the lower Permian. Combining the present results with regional geological data, we infer that the Southern Qiangtang, Lhasa, and Himalayan terranes were all in a stable passive continental margin along the northern part of Indian Gondwana during the long period from the Ordovician to the early Permian. At early Permian, because of the opening of the Neo-Tethys Ocean, the tectonic framework of this region underwent a marked change to a rifting and active environment. 相似文献
11.
羌塘盆地是我国陆域上面积最大的海相盆地,前人对该盆地构造演化过程及其油气远景存在截然不同的观点。以最近完成的1︰ 5万地质调查为基础,本文再次讨论了南羌塘盆地构造演化过程及其油气远景。羌塘盆地中央近东西向的羌中隆起山脉将羌塘盆地分为南、北两部分。最近的研究表明,在寒武-奥陶纪之交,南、北羌塘块体被古大洋分隔开。北羌塘盆地南缘形成的晚三叠-早侏罗世的那底岗日组火山岩,其上部为流纹岩,表明晚三叠世南羌塘块体北向俯冲于北羌塘块体之下,在南羌塘块体北部形成了富含有机质的前陆盆地。南羌塘盆地南缘发育一套代表成熟海盆的侏罗纪复理石建造,表明南羌塘南部地区在早侏罗世具有被动大陆边缘的特点,随着南部班公-怒江洋的扩张,在南、北羌塘块体内分别沉积了侏罗纪-早白垩世的浅海相地层,以富含有机质礁灰岩为特征。盆地内部孕育了巨厚的晚白垩-古新世陆源碎屑岩,不整合覆盖于早期海相沉积岩之上,表明在该时期南羌塘块体逐渐从被动大陆边缘海相盆地转变为陆相盆地。新生代时期,印度与亚洲大陆持续汇聚,南羌塘盆地南向逆冲于拉萨块体之上,盆地内发育了多条大型逆冲断裂带,再次将盆地内部的上三叠统、侏罗系、白垩系富含有机质的海相礁灰岩深埋,这有利于油气资源的生成与保存。横跨南羌塘盆地的构造剖面显示盆地内部主要大型逆冲断裂带之间,构造变形较弱,发育宽缓的向斜构造,向斜核部发育新生代陆相地层,推测该新生代陆相地层之下保存有深埋的富含有机质的海相地层,因此,南羌塘盆地逆冲断裂带下盘和宽缓向斜核部区域可能具有良好的油气资源前景。 相似文献
12.
冈底斯弧弧后早白垩世裂谷作用的沉积学证据 总被引：9，自引：0，他引：9
冈底斯弧弧后地区早白垩世地层的一个显著特点是 ,由下而上普遍从陆相 -海陆交互相碎屑岩变化为海相碳酸盐岩。该地区在早白垩世中期开始了广泛的海侵 ,沉积范围由早期仅局限于班公湖 -怒江缝合带附近而扩展至羌塘地体南缘和拉萨地体 ,沉积了巨厚的台地相灰岩 ;与塔里木南部和思茅地区同期海平面变化非常不同 ,那里在晚白垩世才出现海侵。砂岩组分研究显示 ,早白垩世早期碎屑物源主要来自北侧的造山带 ,向上则逐步受到南侧火山弧的控制。在海侵层系的下部 ,发现了丰富的双峰型火山岩和双峰式火山岩碎屑。因而推断该区在早白垩世发生了强烈的裂谷沉降作用。与此同时的在印度和巴基斯坦境内的 L adakh- Kohistan弧后裂谷作用还形成了具有洋壳基底的Shyok边缘海。因此 ,在早中白垩世 ,欧亚大陆南缘为西太平洋型的活动大陆边缘 ,因强烈的弧后裂谷作用产生了一系列边缘海盆地 ;在包括青藏高原南部在内的欧亚大陆南缘 ,既没有构造动力、也没有古地理和古地形证据支持在早白垩世末 ( 99Ma± )即出现强烈的抬升。 相似文献
13.
对青海东昆仑东山根矿区所采集的7个磷灰石样品进行分析,所获得的磷灰石裂变径迹年龄分布在136~67 Ma,具体分为136~112 Ma、101~95 Ma和74~67 Ma 3个年龄组,这较好地体现了该地区所经历的构造隆升事件。东山根矿区热历史可分为4个阶段：第1阶段(160~80 Ma),是羌塘地块与拉萨地块发生向欧亚板块挤压拼贴作用的响应阶段;第2阶段(120~80 Ma),经历了阿尔金断裂走滑,青藏高原北部隆升,以及燕山晚期冈底斯地体向北俯冲运动,直到早白垩世晚期发生快速冷却抬升;第3阶段(80~23 Ma),构造事件相对平稳,整体呈轻微抬升,样品随地质体隆升缓慢降温;第4阶段(23 Ma至今),快速冷却抬升,对应印度板块对欧亚板块的碰撞作用。 相似文献
14.
Lower Cretaceous strata in the Baingoin basin of the northern Lhasa terrane record initial collision between the Lhasa and Qiangtang blocks, followed by the early uplift of central Tibet. North-south traverses across the Baingoin basin highlight major differences between the Duba Formation in the north and the quasi-coeval Duoni Formation in the south. The Duba Formation documents upward transition from shallow shelf and deltaic environments to coarse-grained siliciclastic fluvial sedimentation. Abundance of detrital zircons yielding Jurassic-Cretaceous ages with εHf(t) values mainly between −2 and +10, occurrence of chert, Cr-spinel, and pyroxene grains, together with southward paleocurrent directions indicate that the Duba Formation was sourced from the southern Qiangtang terrane and Bangong-Nujiang suture zone to the north. The Duoni Formation in the south was deposited in shelfal to fan-delta and fluvial environments. Abundant volcanic clasts, detrital zircons yielding Cretaceous ages with mainly negative εHf(t) values, and northward paleocurrents indicate an active volcanic source located in the central Lhasa terrane to the south, with minor input from the northern Lhasa terrane. Only the northern part of the Baingoin basin was directly controlled by the Lhasa-Qiangtang collision and may thus be considered a peripheral foreland basin, whereas the southern part was mainly influenced by tectonic processes related to the northward subduction of Neotethyan lithosphere, and may thus be comparable to a retroarc foreland basin. But these sedimentary features and the 139–79 Ma Baingoin plutonic intrusion do not fit well with classical foreland-basin models. Zircon chronostratigraphy constrains the final consumption of Bangong-Nujiang oceanic lithosphere and initial collision between the Lhasa and Qiangtang microcontinents to have taken place by 122 Ma, which has major implications for paleotectonic reconstructions of the Tibetan Plateau. 相似文献
15.
东亚原特提斯洋(Ⅰ):南北边界和俯冲极性 总被引：1，自引：1，他引：0
原特提斯洋是从新元古代Rodinia裂解到早古生代发育于滇缅泰/保山微陆块以北、塔里木-华北陆块以南的一个复杂成因的洋盆。长期以来对原特提斯洋的南、北边界及其早古生代末俯冲极性还存在争论,而这是恢复重建Pangea超大陆聚合前构造背景的关键。本文综合利用野外地质、构造、岩浆、沉积学、地球化学、构造年代学和层析成像等最新成果,以期界定原特提斯域的南、北边界位置,确定原特提斯洋边界俯冲极性。集成分析结果表明,北界为古洛南-栾川缝合线(或宽坪缝合线)及其直至西昆仑的西延部分;南界为龙木措-双湖-昌宁-孟连缝合线。原特提斯洋北部在华北-阿拉善-塔里木陆块泥盆纪向南俯冲并与冈瓦纳大陆北缘拼合过程中,形成了一个巨型弯山构造,现保存在祁连-阿尔金-柴达木地区的中国中央造山带内。原特提斯洋南部分支也可能在泥盆纪闭合,使得包括羌北、若尔盖、扬子、华夏、布列亚-佳木斯等在内的大华南陆块、印支陆块等也向南俯冲与冈瓦纳北缘发生了聚合。 相似文献
16.
仲巴微地体夹持在拉萨地块和特提斯喜马拉雅之间,两侧均被蛇绿混杂岩带所围限,是雅鲁藏布江西段重要的地质单元。揭示其构造亲缘性对于探讨新特提斯洋构造演化和青藏高原多地体拼合过程具有重要意义。仲巴微地体中段马攸木地区较好地出露一套志留系—石炭系沉积地层,其中志留系为片理化钙质片岩、大理岩夹砂岩,泥盆系为一套片理化的结晶灰岩夹钙质片岩,石炭系为一套砂岩、粉砂岩夹钙质片岩的碎屑岩组合。碎屑锆石年代学数据表明,志留系、泥盆系和石炭系均表现出约530 Ma和950 Ma的特征年龄峰值,年龄分布样式与西羌塘地体和喜马拉雅地体具有高度的相似性,缺乏拉萨地体以约1 170 Ma的特征的年龄峰值。结合区域地层对比,认为在志留纪—石炭纪,仲巴微地体具有明显的喜马拉雅亲缘性,其构造位置临近印度大陆北缘,是西羌塘—大印度—特提斯喜马拉雅构造体系的一部分。 相似文献
17.
《Gondwana Research》2014,25(1):170-189
The Lhasa terrane in southern Tibet is composed of Precambrian crystalline basement, Paleozoic to Mesozoic sedimentary strata and Paleozoic to Cenozoic magmatic rocks. This terrane has long been accepted as the last crustal block to be accreted with Eurasia prior to its collision with the northward drifting Indian continent in the Cenozoic. Thus, the Lhasa terrane is the key for revealing the origin and evolutionary history of the Himalayan–Tibetan orogen. Although previous models on the tectonic development of the orogen have much evidence from the Lhasa terrane, the metamorphic history of this terrane was rarely considered. This paper provides an overview of the temporal and spatial characteristics of metamorphism in the Lhasa terrane based mostly on the recent results from our group, and evaluates the geodynamic settings and tectonic significance. The Lhasa terrane experienced multistage metamorphism, including the Neoproterozoic and Late Paleozoic HP metamorphism in the oceanic subduction realm, the Early Paleozoic and Early Mesozoic MP metamorphism in the continent–continent collisional zone, the Late Cretaceous HT/MP metamorphism in the mid-oceanic ridge subduction zone, and two stages of Cenozoic MP metamorphism in the thickened crust above the continental subduction zone. These metamorphic and associated magmatic events reveal that the Lhasa terrane experienced a complex tectonic evolution from the Neoproterozoic to Cenozoic. The main conclusions arising from our synthesis are as follows: (1) The Lhasa block consists of the North and South Lhasa terranes, separated by the Paleo-Tethys Ocean and the subsequent Late Paleozoic suture zone. (2) The crystalline basement of the North Lhasa terrane includes Neoproterozoic oceanic crustal rocks, representing probably the remnants of the Mozambique Ocean derived from the break-up of the Rodinia supercontinent. (3) The oceanic crustal basement of North Lhasa witnessed a Late Cryogenian (~ 650 Ma) HP metamorphism and an Early Paleozoic (~ 485 Ma) MP metamorphism in the subduction realm associated with the closure of the Mozambique Ocean and the final amalgamation of Eastern and Western Gondwana, suggesting that the North Lhasa terrane might have been partly derived from the northern segment of the East African Orogen. (4) The northern margin of Indian continent, including the North and South Lhasa, and Qiangtang terranes, experienced Early Paleozoic magmatism, indicating an Andean-type orogeny that resulted from the subduction of the Proto-Tethys Ocean after the final amalgamation of Gondwana. (5) The Lhasa and Qiangtang terranes witnessed Middle Paleozoic (~ 360 Ma) magmatism, suggesting an Andean-type orogeny derived from the subduction of the Paleo-Tethys Ocean. (6) The closure of Paleo-Tethys Ocean between the North and South Lhasa terranes and subsequent terrane collision resulted in the formation of Late Permian (~ 260 Ma) HP metamorphic belt and Triassic (220 Ma) MP metamorphic belt. (7) The South Lhasa terrane experienced Late Cretaceous (~ 90 Ma) Andean-type orogeny, characterized by the regional HT/MP metamorphism and coeval intrusion of the voluminous Gangdese batholith during the northward subduction of the Neo-Tethyan Ocean. (8) During the Early Cenozoic (55–45 Ma), the continent–continent collisional orogeny has led to the thickened crust of the South Lhasa terrane experiencing MP amphibolite-facies metamorphism and syn-collisional magmatism. (9) Following the continuous continent convergence, the South Lhasa terrane also experienced MP metamorphism during Late Eocene (40–30 Ma). (10) During Mesozoic and Cenozoic, two different stages of paired metamorphic belts were formed in the oceanic or continental subduction zones and the middle and lower crust of the hanging wall of the subduction zone. The tectonic imprints from the Lhasa terrane provide excellent examples for understanding metamorphic processes and geodynamics at convergent plate boundaries. 相似文献
18.
Early Cenozoic Mega Thrusting in the Qiangtang Block of the Northern Tibetan Plateau 总被引：2，自引：0，他引：2
WU Zhenhan YE Peisheng Patrick J. BAROSH HU Daogong LU Lu ZHANG Yaoling 《《地质学报》英文版》2012,86(4):799-809
Recent mapping and seismic survey reveal that intensive compression during the Early Cenozoic in the Qiangtang block of the central Tibetan Plateau formed an extensive complex of thrust sheets that moved relatively southward along several generally north-dipping great thrust systems. Those at the borders of the ~450 km wide block show it overrides the Lhasa block to the south and is overridden by the Hohxil-Bayanhar block to the north. The systems are mostly thin-skinned imbricate thrusts with associated folding. The thrust sheets are chiefly floored by Jurassic limestone that apparently slid over Triassic sandstone and shale, which is locally included, and ramped upward and over Paleocene-Eocene red-beds. Some central thrusts scooped deeper and carried up Paleozoic metamorphic rock, Permian carbonate and granite to form a central uplift that divides the Qiangtang block into two parts. These systems and their associated structures are unconformably overlain by little deformed Late Eocene-Oligocene volcanic rock or capped by Miocene lake beds. A thrust system in the northern part of the block, as well as one in the northern part of the adjacent Lhasa block, dip to the south and appear to be due to secondary adjustments within the thrust sheets. The relative southward displacement across this Early Cenozoic mega thrust system is in excess of 150 km in the Qiangtang block, and the average southward slip-rate of the southern Qiangtang thrusts ranged from 5.6 mm to 7.4 mm/a during the Late Eocene-Oligocene. This Early Cenozoic thrusting ended before the Early Miocene and was followed by Late Cenozoic crustal extension and strike-slip faulting within the Qiangtang block. The revelation and understanding of these thrust systems are very important for the evaluation of the petroleum resources of the region. 相似文献
19.
从特提斯到青藏高原形成:构造-岩浆事件的约束 总被引：58，自引：2，他引：58
青藏高原被誉为“世界第三极”。然而,从特提斯的形成演化到青藏高原的形成,经历了一个漫长的复杂过程。这一过程分为三个明显的演化阶段:古特提斯阶段、新特提斯阶段、印度-欧亚大陆碰撞与青藏高原形成阶段。古特提斯洋自早石炭世开始打开,形成三个主支(修沟—玛沁洋、金沙江—哀牢山洋、澜沧江—昌宁孟连洋),至早二叠世扩张到最大规模后开始俯冲消减,逐渐缩小,至晚三叠世末—早侏罗世初洋盆闭合,冈瓦纳古陆的前缘与劳亚古陆的前缘碰撞拼合。这大约经历了150Ma的时间。大致与此同时或略早,古特提斯以南的新特提斯洋两支同时打开,并大致于早—中侏罗世之交扩张到最大规模,然后开始消减、缩小。北支班公湖—怒江洋在晚侏罗世初到早白垩世末(大致在160~100Ma的时间间隔内)闭合,完成拉萨地块与羌塘地块的碰撞拼合过程。南支雅鲁藏布洋闭合较晚,在白垩纪/古近纪之交(65/70Ma左右)印度大陆开始与拉萨地块(即欧亚大陆南缘)碰撞。新特提斯洋从打开到闭合,经历了约140Ma。印度-欧亚大陆碰撞是青藏高原形成的直接原因,从开始到完成,整个碰撞过程用了约20Ma(大致在65~40/45Ma时间间隔内);然后转入后碰撞阶段至今。很显然,几亿年时间尺度和几万公里空间尺度的特提斯的开合、演化、特别是印度-欧亚大陆碰撞和青藏高原隆升,必定对应着地球各圈层间巨大的物质与能量的调整和交换。而正是这种巨大的物质、能量交换,才是形成青藏高原及其资源环境效应的基本动力。 相似文献
20.
班公湖-怒江洋形成演化新视角:兼论西藏中部古-新特提斯转换 总被引：8，自引：7，他引：1
班公湖-怒江洋的形成演化是认识班公湖-怒江成矿带成矿地质背景的关键,近几年中国地质调查局在青藏高原部署了大量1∶50000区域地质调查工作,取得了很多重要发现。对班公湖-怒江结合带两侧关键性海陆沉积地层对比研究,认为南羌塘地块与拉萨地块晚古生代-晚三叠世地层沉积特征及岩石组合基本一致,二者在班公湖-怒江中生代洋盆形成以前是一个整体,为冈瓦纳大陆北缘被动陆缘环境。班公湖-怒江洋在早中侏罗世裂解形成,至中侏罗世趋于稳定且范围最大;向北俯冲消减作用始于中晚侏罗世,晚侏罗世-早白垩世演化为残留海,早白垩世中晚期出现短暂的裂解,致使海水重新灌入;晚白垩世班公湖-怒江洋盆进入闭合后的隆升造山阶段,发生了残留盆地迁移,形成了磨拉石建造。班公湖-怒江洋类似古加勒比海(现今墨西哥湾地区)的形成机制,并与大西洋、太平洋的形成过程关系密切。对于班公湖-怒江洋的闭合和冈底斯弧的形成,本文提出了另一种可能解释,即,新特提斯洋向北俯冲下,岩浆弧逐步南迁,在弧后形成了一系列伸展性质的弧后盆地,两者组成微陆块由北向南逐渐增生形成了现今的拉萨地体,持续向北俯冲也导致了班公湖-怒江洋最终闭合。 相似文献