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1.
帕米尔造山带是印度-欧亚大陆会聚带的西构造结。木吉断层作为中-西帕米尔与东帕米尔的最北部边界转换断层,其运动性质和滑动速率的准确限定对于理解帕米尔现今应力状态和运动学特征等具有重要意义。本文以木吉断层东段布拉克村北位错特征显著的冰碛台地(39.2020°N,74.3910°E)为研究对象,基于高分辨率卫星影像解译、野外地质地貌调查、差分GPS测量和冰川漂砾宇宙成因核素10Be暴露测年,获得布拉克北冰碛台地形成(16.8±3.5 ka)以来木吉断层的累积右旋位错量、垂直位错量、南北向拉张量以及最小速率分别为约190 m、105±12 m、34±12 m和11.3±2.4 mm/a、6.3±1.5 mm/a、2.0±0.8 mm/a;三者的比值约为6:3:1,水平向的总滑动速率为11.5±2.3 mm/a。与位于断层中部近乎纯走滑的阿克萨依处相比,木吉断层在布拉克北以右旋走滑为主的同时,具有明显的正断分量。断层在布拉克北的水平向总滑动速率11.5±2.3 mm/a与阿克萨依处右旋走滑速率的最大值(9.4±0.9 mm/a)大致相当;因此尽管断层沿走向的运动性质发生了显著变化,其水平向滑动速率大致保持恒定。  相似文献   

2.
We derive a slip rate for a frontal thrust in the western Hexi Corridor along the northern Qilian Shan by combining topographic profiling and 10Be exposure dating. The active Yumen‐Beidahe thrust fault offsets late Pleistocene alluvial‐fan deposits, and a prominent north‐facing scarp is well preserved. To quantify the slip rate, we surveyed the uplifted terraces and sampled quartz‐rich pebbles on terrace surfaces and river channels to determine surface exposure ages and pre‐depositional inheritance. The minimum vertical slip rate of the fault is 0.73 ± 0.09 mm a?1. This represents a horizontal shortening rate of 1.26 ± 0.31 mm a?1 for a fault dip of 30 ± 5°. This estimated slip rate supports the inference made from previous geological and GPS constraints that NNE‐directed shortening across the western Qilian Shan and the Hexi Corridor is distributed on several active faults with a total shortening rate of 4–10 mm a?1.  相似文献   

3.
The exhumation history and tectonic evolution of the Qilian Shan at the north‐eastern margin of the Tibetan Plateau has been widely debated. Here, we present apatite fission‐track (AFT) data for 12 Ordovician granodiorite samples along a vertical transect in the eastern Qilian Shan. These thermochronometry data indicate that the eastern Qilian Shan experienced a three‐stage cooling history, including: (i) rapid initial cooling in the late Cretaceous; (ii) a stage of quasi isothermal quiescence from ~ 80 to 24 Ma; and (iii) rapid subsequent cooling beginning in the early Miocene. The inferred cooling rates for the three stages are 6.8 ± 4.9 °C Ma?1, 0.6 ± 0.2 °C Ma?1 and 2.7 ± 0.9 °C Ma?1 respectively (±1 σ). Assuming a geothermal gradient of 25 °C km?1, the exhumation rates for the three stages are 0.27 ± 0.20 mm a?1, 0.017 ± 0.007 mm a?1 and 0.11 ± 0.04 mm a?1 respectively (±1 σ). We suggest that the late Cretaceous cooling records collision of the Lhasa block with the Eurasian continent and that the Miocene cooling represents uplift/exhumation of the Qilian Shan.  相似文献   

4.
帕米尔东北缘-西昆仑的构造地貌及其构造意义   总被引：5，自引：2，他引：3  
帕米尔东北缘-西昆仑位于青藏高原西北部,受三条大型断裂:康西瓦断裂、主帕米尔-铁克里克断裂和公格尔断裂的制约.通过野外考察、卫星遥感图像解译、ASTER GDEM高程数据的分析,对上述三条断裂及整个区域进行构造地貌研究,并探讨其构造意义.结果表明:康西瓦断裂为左行走滑断裂;主帕米尔-铁克里克断裂为逆冲断裂;公格尔断裂和塔什库尔干断裂分别为右行、左行走滑正断层,连接两者的是塔合曼正断裂.通过ASTER GDEM高程数据的高程分布、局部高程差和坡度分析,表明帕米尔东北缘-西昆仑至塔里木盆地存在三级特征地貌(塔里木盆地、塔里木盆地南缘山前褶皱逆冲带和帕米尔东北缘-西昆仑);西昆仑地区受印度/亚洲板块碰撞而产生垂向物质运动,由于三条大型断裂控制在西侧断裂附近存在水平方向的物质运动,垂直和水平两种运动的存在促使靠近康西瓦和公格尔断裂形成高山地貌.  相似文献   

5.
We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high‐resolution multibeam echo‐sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate‐boundary structures are a series of strike‐slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre‐existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike‐slip regime. Along the most recent trace of the SOFZ, we measured a strike‐slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS‐derived motion of 9.8 ± 2 mm a?1 has remained stable during the entire Quaternary.  相似文献   

6.
Although it has long been proposed that active crustal shortening within the Qilian Shan accommodates slip along the Altyn Tagh fault, questions regarding the temporal and spatial amount of slip transfer remain debated. Traditional shortening calculations cannot yet be made accurately, because the geology is not known well enough. Following the view that long, linear drainage basins in the north‐western Qilian Shan developed in response to internal shortening associated with slip transfer along the Altyn Tagh fault, we targeted this special irregular drainage basin geometry to develop an alternative way to estimate shortening. We infer a total of ~66 km of shortening in the western Qilian Shan with a north‐eastward decrease in the magnitude of shortening. This ~39% shortening strain is comparable to previous estimates. Estimates of dates of initiation support the view that significant shortening and topographical growth within the north‐western Qilian Shan occurred in post‐Middle Miocene time.  相似文献   

7.
The North Anatolian Fault Zone (NAFZ) is one of the most hazardous active faults on Earth, yet its Pliocene space‐time propagation across the north Aegean domain remains poorly constrained. We use low‐temperature multi‐thermochronology and inverse thermal modelling to quantify the cooling history of the upper crust across the Olympus range. This range is located in the footwall of a system of normal faults traditionally interpreted as resulting from superposed Middle–Late Miocene N–S stretching, related to the back‐arc extension of the Hellenic subduction zone, and a Pliocene‐Quaternary transtensional field, attributed to the south‐westward propagation of the NAFZ. We find that accelerated exhumational cooling occurred between 12 and 6 Ma at rates of 15–35 °C Ma?1 and decreased to <3 °C Ma?1 by 8–6 Ma. The absence of significant Plio‐Pleistocene cooling across Olympus suggests that crustal exhumation there is driven by late Miocene back‐arc extension, while the impact of the NAFZ remains limited.  相似文献   

8.
This study identified soft–sediment deformation structures(SSDS) of seismic origin from lacustrine sediments in the late Quaternary paleo–dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS 14 C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yr BP and 22710±80 yr BP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China.  相似文献   

9.
The northern margin of the Tibetan Plateau (NMTP) is a major intracontinental Cenozoic transpressional zone that comprises a series of active strike-slip faults and thrust faults. It is important to document cumulative horizontal displacements along the NMTP in order to understand quantitatively strain partitioning in East Asia since the India–Eurasia collision. Based on an analysis of horizontal slip along major active faults, the total amount of horizontal displacements is estimated up to 700 km between the Tibetan Plateau and the Tarim Basin since the convergence of India and Eurasia. Along the western and middle segment of the Altyn Tagh fault to the northern margin of the Qaidam Basin, there are abundant evidence that show that the net displacement is 400 km since 40–35 Ma, and along the Shulenan Shan and southeast of middle Qilian Shan since 25–17 Ma, the amount of offset is 150 km. The largest horizontal slip in Qilian Shan–Hexi Corridor to the northeast of the Altyn Tagh fault is also 150 km since late Oligocene to early Miocene. It decreases to only 60 km along the Haiyuan fault (since late Miocene) and to 25 km along the Zhongwei–Tongxin fault since the Pliocene (about 5.3–3.4 Ma), at the northeast margin of the Tibetan Plateau. This clearly implies northeastward diminishing of the total horizontal displacement and temporal getting younger of the fault slip along the NMTP. However, this tendency is very complicated at different times and different segments as a result of the uplift, growth and rotation of different segments of the NMTP at different stages during the convergence of India and Eurasia.  相似文献   

10.
The westernmost Betic Cordillera front is located along the arcuate alpine belt formed by the interaction of the Eurasian‐African plate boundary and the Alboran continental domain in between. Although classical geological data suggest that the western Cordillera front is inactive, recent GPS data show a westward–north‐westward motion of up to 3.4 mm a?1 with respect to the foreland. In addition, the increasing thickness of Guadalquivir sedimentary infill towards the Cordillera, and the rectilinear character of the front formed by soft sediments, suggest that the Cordillera is still active. Large ENE–WSW‐oriented open folds detected in the field, seismic reflection profiles and new audiomagnetotellurics data are consistent with active deformation. Fracture analysis in Quaternary deposits evidences recent NW–SE horizontal compression. The GPS motion and maximum stress orientation may be due to north‐westward tectonic collision of the westernmost Betic Cordillera, accommodated at depth by active continental subduction of the Iberian lithosphere.  相似文献   

11.
蔡志慧  何碧竹  刘若涵 《岩石学报》2020,36(10):3137-3151
帕米尔高原是受到印度-亚洲大陆碰撞、持续汇聚影响最显著的地区之一,以强烈地壳增厚和缩短、大量断裂和片麻岩穹窿的形成以及广泛的陆内岩浆活动为特征。以往有关帕米尔陆内岩浆岩的讨论多集中于对其地球化学成分及其所指示的构造背景的研究方面,而对岩浆形成与大型新生代构造之间的联系研究较少。本文通过对东北帕米尔塔什库尔干温泉地区新生代花岗岩及其围岩中锆石U-Pb和Ar-Ar年代学研究,结合该地区新生代构造变形分析,揭示岩浆侵入与区域构造变形之间的关系。U-Pb及Ar-Ar测年结果显示温泉地区花岗岩脉形成时代为中新世（11.8±0.2Ma）,其及其围岩在10.8±0.1Ma冷却到300℃左右;中新世花岗岩脉中继承锆石及围岩片岩中碎屑锆石U-Pb的年龄分布特征迥异,它们分别具有类似松潘-甘孜地体以及中帕米尔地体的物质来源。花岗岩内部几乎无变形,围岩片岩变形主要体现为近E-W向的伸展构造,反映其形成于拉张为主的构造应力环境。结合区域构造背景,推测温泉中新世花岗岩脉为公格尔山、慕士塔格峰构造单元岩石部分熔融产物,是在东北帕米尔地壳从挤压增厚向局部伸展转换的过程中形成的,此时,公格尔伸展断裂系可能已经开始发育;此后,直到6~4Ma,公格尔伸展断裂系开始快速运动,与之相伴公格尔-慕士塔格片麻岩穹窿快速折返。  相似文献   

12.
In the Thrace Peninsula, Neogene units were deposited in two areas, the Enez Basin in the south and the Thrace Basin in the north. In the southwesternmost part of the peninsula, upper lower–lower upper Miocene continental to shallow marine clastics of the Enez Formation formed under the influence of the Aegean extensional regime. During the last stage of the transpressional activity of the NW-trending right-lateral strike–slip Balkan–Thrace Fault, which had controlled the initial early middle Eocene deposition in the Thrace Basin, a mountainous region extending from Bulgaria eastwards to the northern Thrace Peninsula of Turkey developed. A river system carried erosional clasts of the metamorphic basement southwards into the limnic depositional areas of the Thrace Basin during middle Miocene time. Deposition of fluvial, lacustrine, and terrestrial strata of the Ergene Formation, which conformably and transitionally overlie the Enez Formation, began in the late middle Miocene in the southwest part and in the late Miocene in the north‐northeast part of the basin. Activity along the NE-trending right-lateral strike–slip faults (the Xanthi–Thrace Fault Zone) extending from northeast Greece northeastwards through the Thrace Peninsula of Turkey to the southern shelf of the western Black Sea Basin began during the middle Miocene in the northern Aegean, at the beginning of the late Miocene in the southwest part, and at the end of the late Miocene in the northeast part of the Thrace region. Although the Neogene deposits in the Thrace Basin were evaluated as the products of a northerly fault, our data indicate that the NW-trending northerly fault zone became effective only during the initial stage of the basin development. The later stage deposition in the basin was controlled by the NE-trending Xanthi–Thrace Fault Zone, and the deposits of this basin progressively evolved north/northeastwards during the late Miocene. During the late early Miocene–late Miocene interval, extension within the Thrace region was part of the more regional Aegean extensional realm, but from latest Miocene time, it has been largely decoupled from the Aegean extensional realm to the south.  相似文献   

13.
The Aleutian island arc collides with the Kuril–Kamchatka arc in the area of the Cape Kamchatka peninsula. Field studies of neotectonic structures and apatite fission track analysis provide evidence for crustal plate shortening onshore the Cape Kamchatka peninsula. Tectonic blocks show differential mean exhumation rates varying from 0.18 ± 0.04 mm yr−1 in the north up to 1.2 ± 0.18 mm yr−1 in the south of the peninsula. A few of the fission track length data point to an unsteady exhumation rate. The blocks are separated by major dextral fault zones splaying off from Aleutian island arc fault zones. Across the western segment of the North American–Pacific Plate boundary the strain is partitioned along the fault zones and increases from north to south. Results from this study suggest that indentation and accretion of island arc fragments has recently occurred in the southeastern part of the Cape Kamchatka peninsula.  相似文献   

14.
PETROLOGIC AND GEOCHRONOLOGIC STUDIES  相似文献   

15.
喀什凹陷西部位于塔里木盆地、帕米尔构造带和南西天山构造带的交接处,在新生代以来接受了大量来自于南天山和帕米尔的沉积物,并记录了新生代以来南西天山构造抬升的信息。本文选择了位于南西天山山前的铁热克萨孜晚新生代剖面开展磁组构研究。铁热克萨孜剖面晚新生代沉积序列自下而上为一套整体上粒度逐渐变粗的陆相沉积,由河流湖泊相逐渐变为扇三角洲相,并最终变为冲积扇相和洪积扇相。岩石磁学结果的分析表明剖面晚新生代沉积序列中的主要磁性矿物为赤铁矿,仅在帕卡布拉克组下部为以磁铁矿为主。磁组构结果表明该剖面的磁组构为早期的同沉积弱变形磁组构,指示了当时构造应力的方向和变化。在22.1Ma以来南西天山山前晚新生代磁组构所反映的构造应力整体上为N-S向挤压,这与帕米尔和南天山的南北向持续汇聚作用相一致。在安居安组和西域组时期,应力方向由N-S向挤压变为NNE-SSW向挤压,这一变化可能是由塔拉斯-费尔干纳断裂的活动所导致的。塔拉斯-费尔干纳断裂(Talas-Fergana Fault, TFF)的右行走滑活动可能吸收了南西天山晚新生代的部分应变量,使得南西天山山前的构造应变量相对TFF以东的南天山山前地区要更小,使得TFF以东的晚新生代山前冲断带活动相对TFF以西地区更为发育和活跃。  相似文献   

16.
刘健  史杰  姚鑫  李钦  常志勇 《中国地质》2018,45(4):681-692
帕米尔东北缘位于青藏高原西北部,是新构造运动最强烈的地区之一。受控于公格尔拉张断裂作用的塔什库尔干盆地,活动构造强烈,高的大地热流值和丰富的地下水,使其具备地热资源形成的地质构造和水文条件。基于塔什库尔干盆地北部的曲曼地区地质构造、湖相地层年代学调查研究,该地区发育晚更新世的NNE向f_1和f_2正断层以及第四纪沉积物之下存在隐伏的近EW向的断层f_3。这3条断层是塔什库尔干断裂在不同构造演化时期形成的次级断层。结合EH-4电磁成像和钻孔及抽水试验等资料表明NNE向f_1和f_2正断层是地热系统的导水通道,而近EW向f_3断层为导热通道。该地区地热模式是大地热流为热源-地下水深循环逐渐加热-构造控水和控热。  相似文献   

17.
THE NORTHWARD PROPAGATION OF THE ARC TECTONICS OF THE NORTHEAST PAMIR AND NORTHWEST TARIM BASINThisworkispartoftheresearchproject“themechanismofJiashistrongearthquakeswarmandprediction ofearthquakeriskinthenortheastPamir  相似文献   

18.
A displacement history and slip rates were determined for the Reelfoot fault in the New Madrid seismic zone from a seismic reflection profile and trench data. Based on calculations from the seismic reflection line the average slip rate over the last 80 million years is 0.0009 mm year−1. Slip rate during the Late Cretaceous was 0.0007 mm year−1, 0.002 mm year−1 during the Paleocene Midway Group, 0.001 mm year−1 during Paleocene–Eocene Wilcox Formation time, 0.0003 mm year−1 during the post-Wilcox/pre-Holocene period, and a Holocene slip rate of 1.8 mm year−1. Based on trench data, slip rate on the Reelfoot fault has been 4.4 mm year−1 over the last 2400 years and a maximum of 6.2 mm year−1 during the two most recent earthquake cycles between AD 900 and AD 1812. The Holocene slip rate is at least four orders of magnitude higher than the average Late Cretaceous and Cenozoic slip rates for the Reelfoot fault. It would appear that there has been a Quaternary change in the stress field in the central United States or the Reelfoot fault is experiencing a short-lived burst of seismic activity.  相似文献   

19.
We explore the controls of the litho‐tectonic architecture on the erosional flux in the 370‐km2 Glogn basin (European Alps). In this basin, the bedding and schistosity of the bedrock dip parallel to the topographic slope on the NW valley flank, leading to a non‐dip slope situation on the opposite SE valley side. While the dip slope condition has promoted the occurrence of landslides (e.g. the c. 30‐km2 deep‐seated Lumnezia landslide), the opposite non‐dip slope side of the valley hosts >100‐m‐deeply incised tributary streams. 10Be concentrations of stream sediments yield catchment‐averaged denudation rates that vary between 0.27 ± 0.03 and 2.19 ± 0.37 mm a?1, while the spatially averaged denudation rate of the entire basin is 1.99 ± 0.34 mm a?1. Our 10Be‐based approach reveals that the Lumnezia landslide front contributes c. 30–65% of the entire sediment budget, although it covers <5% of the Glogn basin. This suggests a primary control of the bedrock bedding on erosion rates and processes.  相似文献   

20.
Multi‐method thermochronology along the Vakhsh‐Surkhob fault zone reveals the thermotectonic history of the South Tian Shan–Pamirs boundary. Apatite U/Pb analyses yield a consistent age of 251 ± 2 Ma, corresponding to cooling below ~550–350°C, related to the final closure of the Palaeo‐Asian Ocean and contemporaneous magmatism in the South Tian Shan. Zircon (U–Th–Sm)/He ages constrain cooling below ~180°C to the end of the Triassic (~200 Ma), likely related either to deformation induced by the Qiangtang collision or to the closure of the Rushan Ocean. Apatite fission track thermochronology reveals two low‐temperature (<120°C) thermal events at ~25 Ma and ~10 Ma, which may be correlated with tectonic activity at the distant southern Eurasian margin. The late Miocene cooling is confirmed by apatite (U–Th–Sm)/He data and marks the onset of mountain building within the South Tian Shan that is ongoing today.  相似文献   

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