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1.
龙门山中段推覆构造的变形特征 总被引：7，自引：0，他引：7
论述了龙门山三大推覆体和推覆面的构造变形特征，认为耿达一汶川推覆体为褶皱冲断推覆体，映秀一白水河推覆体为冲断推覆体，彭灌推覆体为冲断褶皱推覆体，并将其划分为两个次级推覆体，而相应的推覆面分别为韧性变形为主叠加后期脆性变形；脆一韧性变形以脆性为主及脆性变形的特征，其形成次序由北西向南东，即前展式扩张方式，主要活动时期为印支期和喜马拉雅期。 相似文献
2.
《现代地质》2016,(1)
通过对江西南城地区侏罗系林山群与下伏前泥盆纪变质地层、白垩纪地层与前白垩纪地层接触关系调查和谢家构造窗、竺由新村构造窗、上乌石构造窗、望天石飞来峰的发现及钻孔验证,初步厘定了区内燕山期滑覆构造和喜马拉雅期推覆构造。燕山期滑覆构造发生在中侏罗世末,主滑面沿华力西—印支构造层(D—T2)、燕山构造层(T3—K1)与下伏地层间角度不整合面扩展而成,泥盆纪—早白垩世地层为滑覆体,滑覆在前泥盆纪变质地层之上,动力学来源为太平洋板块由南东向北西对欧亚板块俯冲。喜马拉雅期推覆构造规模大、动力学机制复杂(顺层和切层推覆),彻底打破了华南地区原有的地层沉积层序,形成了现存的横向分带、纵向分层的多层叠瓦、堆垛推覆构造格局。前白垩纪地质体为外来推覆体,由南东向北西推覆堆垛在白垩纪地层之上,白垩纪地层呈"构造窗"分布于前白垩纪地质体之下,动力学来源可能为印度板块与欧亚板块碰撞形成。 相似文献
3.
大兴安岭北部漠河逆冲推覆构造的特征及演化 总被引：2，自引：0，他引：2
漠河逆冲推覆构造发育在上黑龙江盆地的西北侧,是漠河地区的主要构造样式。逆冲推覆构造在空间上由一系列规模大小不等、近平行排列的逆冲断层构成,剖面上表现为犁式逆冲断裂所构成的单冲式叠瓦状构造。按其岩石组合、变形变质特征和推覆体不同可划分为4条构造分带。推覆方向总体由NW向SE,具有前展式的扩展方式,运移距离大于4 km,形成于晚侏罗世中期—早白垩世中期。并在较为系统研究漠河逆冲推覆构造特征的基础上,探讨了其生成演化的过程。 相似文献
4.
根据变形特征和构造组合形式,兰盆构造地西南缘推覆构造可划分为中央推覆带、前陆冲断带和前陆滑脱带。中央推覆带的雏型形成于印支期,叠加了后期的构造变形,以大面积岩浆活动和大幅度隆升为主要特征;前陆冲断带形成始于燕山期,叠加了喜马拉雅期的构造变形,其变形特征主要表现为逆冲构造和反冲构造,形成了冲断构造样式;前陆滑脱带形成于喜马拉雅期,以滑脱变形为主要特征,形成了隔档式褶皱。整个推覆构造经过了印支期、燕山期的强烈变形,于喜马拉雅期形成了现今的构造格局;其扩展方式为前展式,从临沧岩浆弧向盆地内部,构造活动的时间依次逐渐变新,变形强度依次逐渐减弱,由断裂(冲断)变形演变为褶皱(滑脱)变形。 相似文献
5.
滇西弥沙河断裂带构造特征及演化 总被引：1，自引：0，他引：1
弥沙河断裂带为金沙江断裂带的南段,其构造变形复杂。该断裂带由构造混杂带和推覆构造带两个构造单元组成。构造混杂带宽约２ｋｍ,由劈理化基质和构造岩片组成。推覆构造带由五套推覆体构成。这些推覆体在空间上层层叠置,并形成构造倒序结构。弥沙河断裂带的早期活动是在晚海西期,大规模的逆冲－推覆作用是在喜马拉雅期。 相似文献
6.
福建省推覆构造研究及其意义 总被引：14，自引：3，他引：14
本文主要是根据“闽西南地区推覆构造与隐伏煤田预测研究”的主要成果来写的。在概述两次研究课题取得主要成果的同时，对福建省重大基础地质有关的问题提出了新的认识。文中重点是总结了福建省推覆构造发育的特征，将推覆构造划分为两大类（逆冲推覆构造，拆离构造）和五种类型（中深层次逆冲推覆构造、浅层次逆冲推覆构造、褶皱逆冲推覆构造和拆离（滑脱）构造、褶皱拆离构造），对各类型的主要特征、分布规律、组合特征和推覆构造的发生和发展进行系统的总结，明确指出了燕山早期中深层次边冲推覆构造是福建省规模最大、对今后寻找隐伏矿产关系最密切和最重要的推覆构造，对研究我省的推覆构造具有重要意义。并结合福建省的实际，从基础地质和找矿两方面进行论述。 相似文献
7.
论宁镇山脉推覆构造的特征与形成 总被引：1，自引：0，他引：1
葛肖虹 《吉林大学学报(地球科学版)》1987,(2)
本文通过对宁镇山脉构造特征的分析,认为宁镇山脉是由三个自南而北推掩的构造片体组成的推覆构造。每个构造片体的表层褶皱与逆冲、逆掩断裂组合都是深层滑移的地面表象,反映了统一的构造应力场。推覆构造的主体北东东向延伸,略呈向北突出的弧形,主要形成于三叠纪晚期的印支运动即南象运动。属于扬子、华北两个古板块碰撞带的后缘构造。燕山中—晚期北北东向挤压构造对其产生横跨和叠加。 相似文献
8.
云南澜沧地区的逆冲推覆构造很发育．可划分为老厂、孟连一澜沧、孟梭及竹塘一澜沧等四个带。推覆构造由推覆体、飞来峰、构造窗、逆冲断层及原地系统等组成，推覆体变形弱、褶皱不发育，符合冲断式推覆模式，具有双重逆冲构造结构．宏观与微观构造都表明形成于较浅的构造层次。推覆构造的形成演化与澜沧裂谷的发展有关，可划分为三期。逆冲推覆的区域应力来自地体向东的碰撞拼接，是印度板块与扬子板块汇聚的重要构造事件。 相似文献
9.
武当山推覆构造由主滑脱面、前缘叠瓦褶断带、中央推覆体带和后缘挤压－伸展带４种构造成分组成，中央推覆体带划分为７个推覆体，各推覆体在平面上呈鳞片状越覆，在剖面上呈道冲叠覆，构成鳞片叠覆的几何模式。 相似文献
10.
兴隆矿区外围推覆构造及煤田预测 总被引：3，自引：0，他引：3
论述了兴隆矿区外围推覆构造上覆席体、下伏岩系、推覆剪切滑移带变形特征、构造岩特征和推覆构造形成过程。应用Ramsay等人有限应变测量新方法,估算了推覆位移距离。在推覆体下预测出52km2的隐伏煤系分布区。 相似文献
11.
How Alpine or Himalayan are the Central Andes? 总被引：2，自引：0，他引：2
Although non-collisional mountain belts, such as the Andes, and collisional mountain belts, such as the Alps and the Himalayas–Tibet,
have been regarded as fundamentally different, the Central Andes share several features with the Himalayas–Tibet. The most
important of these are extremely thickened (≥70 km) continental crustal roots supporting high plateaus and mountain fronts
characterized by large basement thrusts. The main prerequisite for very thick crustal roots and extreme mountainous topography
appears to be large-scale underthrusting of continental crust of normal thickness, irrespective of whether the crustal thrusts
are antithetic with respect to subduction as in the Andes, or synthetic with respect to preceding subduction of oceanic lithosphere
as in the Himalayas. In both cases sole thrusts near the base of the continental crust nucleated in thermally anomalous zones
of the hinterland and then propagated across ramps into shallower detachments located within thick sedimentary or metasedimentary
cover rocks. In contrast to the Central Andes and the Himalayas, the Alps are characterized by intracrustal detachment which
allowed both the subduction of lower crust and a stacking of relatively thin upper crustal slivers, which make up a narrow
mountain chain with a more subdued topography.
Received: 10 August 1998 / Accepted: 1 March 1999 相似文献
12.
Lasafam Iturrizaga 《GeoJournal》1999,47(1-2):277-339
An abridged version of a geomorphological inventory and typology of Postglacial debris accumulations in High Asia is presented,
with selected examples from the Hindu Kush, the Karakoram and the Himalayas. The debris accumulations were surveyed in the
course of four research expeditions lasting a total of ten months in selected valley systems of High Asia (the eastern Hindu
Kush, the northwestern Karakoram, the Nanga Parbat massif (Pakistan), the Ladakh and Zanskar ranges, the Nun Kun massif, the
Kumaon and Garhwal Himalayas with the Kamet, Trisul and Nanda Devi massifs (India) and in the central Himalayas with the Kanjiroba,
Annapurna, Manaslu and Makalu massifs (Nepal)). The study areas being widely scattered, a supraregional comparison of the
debris accumulations proved possible. The debris accumulations are considered in centre-to-periphery sequences from the mountain
interior to the mountain fringes, and in vertical sequences, i.e. altitudinal zones, taking into account their topographical
relationship to adjoining elements of the landscape. Supraregional and climate-specific types of debris accumulation are distinguished
and it is recognized that the debris accumulations of the Karakoram and the Himalayas resemble each other more closely with
increasing elevation.
The core of the study is the dominant role played by past glaciation in the formation of Postglacial debris accumulations
in the high mountains of Asia. This glacial-history-oriented concept of debris accumulation stands in sharp contrast to previous
opinions about the genesis of the debris accumulation landscape in the extreme high mountains of Asia. The study shows that
at many places morainic deposits mask extensive portions of the valley sides up to several hundred metres above the valley
floor. These moraines are the main debris sources and exert a strong influence on, or even suppress, the purely slope-related
formation of debris accumulations. Resedimentation of morainic material in combination with additional talus delivery leads
to numerous characteristic composite types of debris accumulations, which are here termed transitional glacial debris accumulations.
Various stages in the transition from moraine to slope-related debris accumulations were observed, making it necessary to
consider the evolutional element in the development of debris accumulations by taking into account both genetic series of
debris accumulations and formations of debris accumulations. A significant proportion of debris accumulations are also due
to collapse processes which result from pressure release at the valley sides after deglaciation and occur in the course of
glacial trough valleys being transformed into more stable fluvial V-shaped valleys.
The residual morainic landscape has left debris accumulations that are basically similar in study areas of different climate
– i.e. in the Hindu Kush and the Karakoram on the one hand, and the Himalayas on the other. The age classification of the
debris accumulations was based on the location of the slope-derived debris accumulations in relation to the corresponding
stages of glaciation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
青藏高原南缘处于重力不均衡状态,由北向南可依次分为高原近重力均衡区、喜马拉雅山正均衡异常区和山前盆地负均衡异常区,正、负异常呈现壮观的镜像分布。本文选取喜马拉雅中东部的均衡重力异常数据,结合地貌高程、地壳厚度、降雨量、冰川及山前沉积等的分布状况,探讨地貌分异与均衡重力异常分布的相互关系。由上述资料获得3条跨越喜马拉雅山的综合剖面,结果显示喜马拉雅中东部正均衡重力异常的分布与冰川、河流等代表的地表剥蚀作用存在明显的空间耦合关系,而与降雨量无直接联系,山前盆地负均衡重力异常与沉积厚度的分布也存在很好的耦合。利用数值模型计算得到了喜马拉雅地区的均衡调整时间域在1 Ma左右的时间尺度内。通过与地貌响应时间域相对比,以及对地表剥蚀厚度的估计,认为山脉地区的正均衡异常主要由地壳厚度补偿不足引起(侧重Airy假说),而山前盆地的负均衡异常主要由低密度沉积层的分布引起(侧重Pratt假说),由于地貌响应时间快于均衡调整时间,在大约5～2 Ma以来,地壳的均衡调整始终延迟于山脉的持续剥蚀和山前的持续沉积,使得岩石圈朝着"反均衡"方向演变,最终形成了喜马拉雅现今壮观的镜像均衡重力异常分布。 相似文献
14.
笔者首次将海拔高度的概念及现代冰川理论 ,并结合古地磁资料 ,提出罗圈冰期时古天山 -秦岭山脉是一条大约位于赤道 -北回归线之间、由众多高山组成的 ,且许多山峰至少在 4 0 0 0m以上 ,已形成冰川、或许局部地区存在冰原的山脉 ,总的地理特征类似于今天的喜马拉雅山脉。而华北地块和库鲁克塔格地块是高原或平原 ,此二地块的南边是海域。古秦岭的南坡是现代秦岭的北坡。冰川融化时冰水携带的冰碛物向南流入海 ,所以华北地块上无冰碛物存在大地构造上 ,晋宁期以前 ,上述各地块相互独立。震旦纪时它们开始发生作用 ,秦岭地块和阿克苏—乌什地块分别向华北地块与库鲁克塔格地块汇聚 ,引起后者上升 ,逐渐发展成为山脉。至震旦纪末期 ,山脉上升到 4 0 0 0m以上 ,形成冰川。此后 ,山脉被剥蚀夷平 ,至寒武纪初 ,华北、库鲁克塔格两地块又降到海平面之下接受沉积 ,该山脉消亡。由此我们恢复了新元古代超大陆一条造山带 ,并推测新元古宙末期华北、华南、塔里木三大地块曾经汇聚在一起 相似文献
15.
Impact of seismic factors on landslide susceptibility zonation: a case study in part of Indian Himalayas 总被引：6，自引：0，他引：6
Landslides are one of the most widespread natural hazards in high mountain terrains such as the Himalayas, which are one of
the youngest tectonically and seismically active mountain ranges in the world. The crustal movements along the longitudinal
thrusts and transverse faults give rise to earthquakes and in turn initiate landslides in the region. In fact, in addition
to various static factors causing landslides, earthquakes are one of the major causes of landslides. It is thus imperative
to incorporate seismic factor also while carrying out landslide susceptibility zonation map preparation in a seismically active
areas like Garhwal Himalayas. In this paper, a study on the effect of earthquakes on landslide susceptibility zonation has
been demonstrated by taking Chamoli earthquake as an example. 相似文献
16.
Analysis of landslide causes and associated damages in the Kashmir Himalayas of Pakistan 总被引：1，自引：1，他引：0
This article deals with the analysis of landslide causes and associated damages in the Kashmir Himalayas of Pakistan. The present study is based on Muzaffarabad, which lies in the lesser Himalayas. Geologically, the Kashmir Himalaya is the young and most dynamic system in the world. In Muzaffarabad, mostly, people live on the fragile mountain slopes, and therefore, they are highly vulnerable to the risk of landslides. To achieve the objectives of the study, data were collected both from primary and secondary sources. Primary data were obtained through intensive field work and human perception survey, while secondary data were obtained from the related line agencies. The analysis reveals that in the study area, immature geology, active seismic zone, wide range of temperature and seasonal rain are the major physical factors, whereas human interventions on the fragile slopes are intensifying factors which in effect contribute to the landslide incidence. As a result, the adverse impacts on housing, sources of livelihood earnings and human casualties are escalating day-by-day. There are several implementing agencies which are responsible for reducing the risk of landsliding. So far, these agencies have not reduced the landslide damages rather their intensity and frequency have been increased especially after 2005 Kashmir earthquake. 相似文献
17.
Interaction between surface processes and deep tectonic processes plays a key role in the structural evolution, kinematics
and exhumation of rocks in orogenic wedges. The deformation patterns observed in analogue models applied to natural cases
of present active or ancient mountain belts reflect several first order processes that result of these interactions. Internal
strain partitioning due to mechanical behaviour of a thrust wedge has a strong impact on the vertical component of displacement
of tectonic units that in return favour erosion in domains of important uplift. Such strain partitioning is first controlled
by tectonic processes, but surface processes exert a strong feed back on wedge dynamics. Indeed, material transfer in thrust
wedges not only depends on its internal dynamics, it is also influenced by climate controlled surface processes involving
erosion and sedimentation. Effects of erosion are multiple: they allow long term localization of deformed domains, they favour
important exhumation above areas of deep underplating and combined with sedimentation in the foreland they contribute to maintain
the wedge in a critical state for long time periods. The simple models illustrate well how mountain belts structure, kinematics
of tectonic units and exhumation are determined by these complex interactions. 相似文献
18.
综合青藏高原第四纪冰川早期记录的研究进展和典型盆地地层、沉积、古生物、古环境研究的系统成果,扎达盆地香孜组上部冻融层的出现代表了区域的古海拔达到了高原冰缘的高度,即3 500 m以上.这一段地层的时代可能从2.3 Ma前后开始.并与贡巴砾石层下部冰水沉积层的时代基本一致.卓奥友冰期和希夏邦马冰期的时代与扎达盆地沉积结束后,直接覆盖其上的终碛垄和冰碛垄的时代大致相当,展现了这一时期喜马拉雅山脉的山岳冰川进一步发育,也说明喜马拉雅山脉作为青藏高原海拔最高的地区开始冰冻圈的环境很可能在早更新世早中期.川西地区的早更新世的冰川沉积说明东喜马拉雅构造结附近地区这一时期已经抬升至冰冻圈高度,但是,海拨高度与气候环境与喜马拉雅山脉应有不同.具体的时代仍需要深入工作.青藏高原普遍开始冰冻罔记录是在中更新世早期.伴随着全球冰期的到来,这一时期的冰川作用在青藏高原最为发育和广泛.这些暗示着青藏高原在中更新世早期整体性地较快速抬升进入冰冻圈,即海拔3 500 m以上.详细的过程仍有待深入研究. 相似文献
19.
Active faults that rupture the earth's surface leave an imprint on the topography that is recognized using a combination of geomorphic and geologic metrics including triangular facets, the shape of mountain fronts, the drainage network, and incised river valleys with inset terraces. We document the presence of a network of active, high-angle extensional faults, collectively embedded in the actively shortening mountain front of the Northern Apennines, that possess unique geomorphic expressions. We measure the strain rate for these structures and find that they have a constant throw-to-length ratio. We demonstrate the necessary and sufficient conditions for triangular facet development in the footwalls of these faults and argue that rock-type exerts the strongest control. The slip rates of these faults range from 0.1 to 0.3 mm/yr, which is similar to the average rate of river incision and mountain front unroofing determined by corollary studies. The faults are a near-surface manifestation of deeper crustal processes that are actively uplifting rocks and growing topography at a rate commensurate with surface processes that are eroding the mountain front to base level. 相似文献
20.
A. V. Zubovich V. I. Makarov S. I. Kuzikov O. I. Mosienko G. G. Shchelochkov 《Geotectonics》2007,41(1):13-25
The results of longstanding GPS measurements in the northwestern part of Central Asia are discussed. These results impose certain constraints for modeling of intraplate tectonic processes. In the territory covered by observations, the velocity vectors of recent motions of the Earth’s surface relative to the stable portion of Eurasia decrease northward. The plane field of velocities, which rules out the development of extension zones, indicates the impossibility of the mountain building driven by ascending mantle flows beneath the lithosphere of these regions. The nonuniform spatial distribution of the motions is suggestive of the discrete character of the Earth’s crust and its deformation. The crust is brittle, at least in its upper part, and capable of breaking into blocks. The blocks, which move at different velocities, interact with one another and change their original orientation and position, while experiencing independent deformations. This phenomenon has been exemplified in the Tarim Block and the Tien Shan. Within the limits of the constraints imposed by the GPS measurements, the mechanism of intracontinental mountain building related to the lateral flow of asthenospheric material and to the drag of the overlying lithospheric layers is discussed. This mechanism springs from Argand’s ideas [2, 29] and the plate tectonic concept [10, 23]. The upper-mantle convective flow in the direction of the Indian Plate’s motion was the main cause of the crustal deformation. The detachment of the lithospheric mantle from the Indian Plate approximately 25 Ma ago and its subduction beneath the Himalayas and Tibet, along with simultaneous ascent of the remaining crust and uplift of the Tibetan Plateau, allowed the mantle flow to spread far northward beneath the Asian continent. This process is accompanied by consecutive separation and sinking of the cooling asthenospheric material over the entire area from the Himalayas to Siberia as the subcrustal material cools. As a result, the flow velocity decreases, the roof of the active flow plunges, and the lithosphere becomes thicker. The motion and deformation of the lithospheric layers dragged by deep flow cannot follow the asthenospheric flow strictly, owing to the rigidity of the layers. Therefore, a difference of tangential velocities originates between the flow and the lithosphere, thus giving rise to horizontal shear stresses. These stresses affect the overlying lithospheric layers, including the crustal ones, and bring about their drag and tectonic delamination. Simultaneously, the decreasing velocity in the direction of the mantle flow results in bending of the lithospheric layers that is accompanied by local warping of the crust and its stacking and fragmentation into blocks. The different velocities of block motions lead to their mechanical interactions. This scenario of intracontinental mountain building allows an explanation of the many specific features of tectonic processes and orogeny in within-plate mountainous regions. 相似文献