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1.
依据山前洪积扇顶部的扇形地形和向下游方向逐渐降低的地形特征,文中首先分析了断层面直立、向河流上游倾斜、向河流下游倾斜3种条件下左旋走滑断层错动在洪积扇顶部形成的断层陡坎的坡向和高度变化。其次,分析了左旋逆走滑断层、左旋正走滑断层在不同断层倾向条件下,断层错动在洪积扇顶部形成的断层陡坎的坡向和高度变化。利用无人机实测地形数据、谷歌卫星影像,结合野外地质地貌调查,发现新疆塔城盆地东缘NE-SW走向的冬别列克断裂近垂直穿过了自SE-NW发育的阿合别斗河。阿合别斗河处洪积扇的中轴线为NW向,坡向朝N,断层活动使其顶部发育了高约5.2m、坡向SE的反向断层陡坎。而在河床左、右两岸各1km之外的山前洪积扇上,断层陡坎为坡向NW的正向断层陡坎,坎高1～5m不等。阿合别斗河左岸T2、右岸T4与左、右两岸T5阶地的左旋水平位错量分别为(10.1±0.2) m、(10.6±0.7) m、(29.1±0.2) m、(20.0±0.7) m,垂直位错量分别为(1.5±0.1) m、(3.6±0.3) m、(4.7±0.2) m、(5.2±0.1) m。野外调查发现2处断层露头,断层面均倾向SE。根据阿合别斗河附近的断错地貌和走滑断层断错地貌模型,认为冬别列克断层在地貌面S1形成后为左旋逆走滑性质,T5阶地面形成后断层的性质转变为左旋正走滑并多次活动,形成了自SW-NE连续分布的正向断层陡坎—无陡坎—反向断层陡坎—无陡坎—正向断层陡坎的地貌现象。  相似文献   

2.
河流位错是沿走滑活动断层的重要构造地貌之一。然而,由于河流复杂的自然形态、沿走滑断层容易发生河流袭夺等因素,使得利用河流形态来判断走滑断层的滑动方向、位错量等存在一定的困难。文中系统介绍了利用基岩河道系统位错对沿走滑断层的河流位错地貌进行分析的方法。系统水系位错是构造过程和地表过程沿走滑活动断层相互作用的结果,是穿过走滑活动断层的河流累积位错量的同时在溯源侵蚀作用下向上游方向增长的现象。对青藏高原东部甘孜-玉树、鲜水河、昆仑东段3条走滑断裂带的河流位错地貌进行的解译、测量和统计表明,沿3条断裂带都发育系统水系位错,河流从源头到断层的上游长度(L)越长,其累积的位错量(D)越大,两者之间存在线性相关关系D=a·L。为研究青藏高原东部构造地貌演化过程中走滑断裂带的作用提供了重要依据。  相似文献   

3.
正活动造山带的地形地貌是构造运动与气候变化相互作用的产物。在地貌演化过程中,河流作为对构造-气候相互作用最为敏感的地貌单元,无论是流域平面展布还是河道剖面形态,都深受构造、气候、岩性等的影响;同时,这些因素及其变化特征也被流域水系所记录。研究造山带河流水系,从中提取构造活动和气候变化信息,有助于理解区域地貌演化过程,是构造地貌  相似文献   

4.
河流阶地演化与走滑断裂滑动速率   总被引：24，自引：9，他引：15  
断裂滑动速率是活动构造定量研究的最重要参数之一,不仅可以直接应用于活动构造的地震危险性预测和工程场地的地震安全性评价,还为地球动力学研究提供不可缺少的重要信息。原理上,断裂滑动速率可以用总位移量除以其累积时间而获得,但准确地确定断裂滑动速率并不是一件容易的事情,不同方法和研究者测定的同一条断裂的滑动速率可以相差3倍。文中通过对河流基座阶地演化及其对走滑断裂错动响应过程的分析发现,当一条山前河流切入河漫滩使其废弃形成阶地后,断裂的走滑位移使得河流两侧的阶地陡坎都遭到错动,其中一侧的下游阶地陡坎被错入河道而遭到河流的侵蚀,另一侧的下游阶地陡坎被错离河道,受到河流上游右侧地貌的保护而免遭侵蚀。因此,被错离河道一侧的阶地陡坎的位移在上阶地形成时就开始积累,阶地面的暴露年龄相当于位移累积的起始年代。另外,被错离河道一侧的阶地陡坎在下阶地停止侧蚀(可能同时开始接受沉积)时就开始累积位移,下阶地的初始沉积年代也代表阶地陡坎位移开始累积的时间。当然,如果能够获得被位移阶地陡坎的上下阶地年龄,就更能够把滑动速率限定在可靠的范围之内。在上述分析的基础上,提出3种利用河流阶地确定走滑断裂滑动速率的方法:第一是利用上下阶地年龄限定  相似文献   

5.
为定量认识畹町断裂带地貌特征及其对构造的指示意义,基于30 m的DEM数据,采用空间分析方法,提取该断裂带地形剖面、地形起伏度、坡度、水系偏转角、河流纵剖面上凹指数等参数数值,得到了畹町断裂带构造地貌的一些定量化特征,并通过这些数值特征讨论了其指示的构造意义。结果表明,研究区总体地势以畹町断裂为界东北高西南低,海拔沿断层垂直方向随距离的增加而增加到1 500~2 000 m后趋于平稳。垂直断层方向的地形剖面反映的阶地特征与普通意义的侵蚀阶地的特征差异明显,表明畹町断裂在很大程度上控制了区域河流阶地的发育及其形态特征。断裂两侧水系分布明显不对称,沿走滑断裂水系发生系统性拐弯,且水系级别越高,其拐弯距离越长。沿畹町断裂(怒江干流)走向分布的11条水系偏转角的角度大致在45°~175°之间,多数分布在100°范围内,高于100°的有3个。畹町断裂带水系偏转角的数值特征说明水系在断层左旋走滑作用的长期影响下,汇入角发生了偏转。区域内92.31%的河流纵剖面上凹指数b1,纵剖面为凹形,反映了畹町断裂对其发育的影响。  相似文献   

6.
西秦岭北缘断裂带是青藏高原东缘一条大型左旋走滑活动断裂带和历史强震带。前人对该断裂漳县以西段曾开展过大量研究工作,获得其最新构造活动的地质地貌证据,而中段(武山—天水段)和东段(天水—宝鸡段)最新活动时代一直存在分歧。基于高分辨率卫星影像解译、地质地貌调查与综合分析、探槽开挖和~(14)C测年等方法,对西秦岭北缘断裂带武山—天水段进行详细研究,结果表明:该段断裂晚第四纪以来活动显著,地貌上主要表现为断层垭口、断层沟槽、山脊与水系及阶地同步左旋位错、断层陡坎等;多个探槽剖面及测年结果显示其最新构造活动断错了全新世地层,为该段断裂全新世活动和大震危险性分析提供了新的证据。  相似文献   

7.
阿拉善地块南缘地处青藏高原东北缘地壳扩展前锋带的北侧，对该地区活动断裂晚第四纪的运动性质、滑动速率等开展研究，有助于理解阿拉善地块的晚第四纪构造变形特征及其对青藏高原向N扩展的响应。文中结合遥感影像解译与野外地质地貌考察，对阿拉善地块南缘的北大山断裂进行了分段和活动性研究。结果表明，北大山断裂左旋走滑断错晚第四纪洪积扇和阶地等地貌，形成显著的位错阶地坎、冲沟以及断层陡坎。通过对断错地貌线等标志的测量、复原、统计分析等，发现断裂的地貌位移值分布于3～20m,发育新鲜断层自由面的断层陡坎和左旋错动的纹沟指示了断层的最新一次活动。基于同期洪积扇年龄估算得到北大山断裂晚更新世以来的左旋滑动速率为0.3～0.6mm/a。北大山断裂的运动学特征与区域NE向应力场一致，可能受到了青藏高原NE向扩展的影响。  相似文献   

8.
前人对位于青藏块体北部与阿拉善块体接触带的金塔南山断裂是否存在左旋走滑新活动一直存在争议。文中基于航空照片和高分辨率遥感影像解译、地质地貌调查与填图、差分GPS测图、开挖剖面等方法,详细研究了金塔南山断裂的地质、地貌表现,分析是否存在左旋走滑的新活动特征。结果表明:金塔南山断裂晚第四纪以来有左旋走滑活动,地貌上表现为正、反向交替的断层陡坎、冲沟和微地貌的左旋位错、拉分盆地和挤压隆起等现象;地质剖面上表现为高倾角的断层面、倾向和性质不固定的断层面、花状构造。通过对比分析,得到金塔南山断裂晚更新世以来的左旋走滑速率约为(0.19±0.05)mm/a,与倾滑速率以及地表抬升速率相当,但远小于阿尔金断裂的走滑速率。综合分析认为,祁连山逆冲断裂系向NE的挤压扩展与应变分配可能是金塔南山断裂左旋走滑运动的动力学来源。  相似文献   

9.
阿尔金断裂东段第四纪活动的时空特征   总被引：10，自引：1，他引：10  
本文从断裂带的几何形态、活动断层的地貌特点、断层的剖面性状、力学性质的转换、水系的错动量以及古地震现象等几方面探讨了阿尔金断裂东段的第四纪活动性状,指出了该断裂的活动强度、力学性质和破裂发展的时空特征,讨论了占地震的震级、重复率以及断裂的全新世活动状态。  相似文献   

10.
利用数字高程模型(DEM)，对亚东-谷露构造带进行了三维地貌合成，通过对地貌面、盆地形态和地形剖面的研究，并在结合地表构造分析的基础上，以雅鲁藏布江为界将亚东-谷露构造带分为南、北二段。南段自亚东至雅鲁藏布江，地形坡度东陡西缓，总体表现为东侧断陷活动较强的特征；北段自雅鲁藏布江至谷露北，地形坡度西陡东缓，地堑主要受其西边界断裂的控制，东边界断陷活动相对较弱。构造带南段伸展规模和最大垂直位错都不亚于北段，南段和北段构造活动性相当。构造带发生多次强烈断陷作用，在盆地两侧形成不对称发育的多级层状地貌面，构造带同时具有左旋张剪性质。  相似文献   

11.
《国际泥沙研究》2019,34(6):537-549
Dam removal can generate geomorphic disturbances, including channel bed and bank erosion and associated abrupt/pulsed release and downstream transfer of reservoir sediment, but the type and rate of geomorphic response often are hard to predict. The situation gets even more complex in systems which have been impacted by multiple dams and a long and complex engineering history. In previous studies one-dimensional (1-D) models were used to predict aspects of post-removal channel change. However, these models do not consider two-dimensional (2-D) effects of dam removal such as bank erosion processes and lateral migration. In the current study the impacts of multiple dams and their removal on channel evolution and sediment delivery were modeled by using a 2-D landscape evolution model (CAESAR-Lisflood) focusing on the following aspects: patterns, rates, and processes of geomorphic change and associated sediment delivery on annual to decadal timescales. The current modeling study revealed that geomorphic response to dam removal (i.e., channel evolution and associated rates of sediment delivery) in multiple dam settings is variable and complex in space and time. Complexity in geomorphic system response is related to differences in dam size, the proximity of upstream dams, related buffering effects and associated rates of upstream sediment supply, and emerging feedback processes as well as to the presence of channel stabilization measures. Modeled types and rates of geomorphic adjustment, using the 2-D landscape evolution model CAESAR-Lisflood, are similar to those reported in previous studies. Moreover, the use of a 2-D method showed some advantages compared to 1-D models, generating spatially varying patterns of erosion and deposition before and after dam removal that provide morphologies that are more readily comparable to field data as well as features like the lateral re-working of past reservoir deposits which further enables the maintenance of sediment delivery downstream.  相似文献   

12.
While it is well recognized that vegetation can affect erosion, sediment yield and, over longer timescales, landform evolution, the nature of this interaction and how it should be modeled is not obvious and may depend on the study site. In order to develop quantitative insight into the magnitude and nature of the influence of vegetation on catchment erosion, we build a landscape evolution model to simulate erosion in badlands, then calibrate and evaluate it against sediment yield data for two catchments with contrasting vegetation cover. The model couples hillslope gravitational transport and stream alluvium transport. Results indicate that hillslope transport processes depend strongly on the vegetation cover, whereas stream transport processes do not seem to be affected by the presence of vegetation. The model performance in prediction is found to be higher for the denuded catchment than for the reforested one. Moreover, we find that vegetation acts on erosion mostly by reducing soil erodibility rather than by reducing surface runoff. Finally, the methodology we propose can be a useful tool to evaluate the efficiency of previous revegetation operations and to provide guidance for future restoration work. © 2019 John Wiley & Sons, Ltd.  相似文献   

13.
YAN Bing  JIA Dong 《地震地质》2017,39(6):1127-1142
Offset river is one of the characteristic landforms along active strike-slip fault. Whereas because of various factors such as natural meander, river capture, etc, difficulties exist while interpreting slip motion and offset amount using landforms of offset rivers. In this study, we introduced the systematic offset of bedrock channels as a method to analyze offset rivers along strike-slip fault. Systematic offset of bedrock channels is the result of coupling between tectonic process and surface process. It also describes the phenomenon of synchronous accumulation both of the offset amount and the upstream length because of head-ward erosion. Based on the interpretation, measuring and statistics of the offset river landforms, it is found that systematic offset of bedrock channels have developed along the Ganzi-Yushu, Xianshuihe and eastern Kunlun fault zones on the eastern Tibetan plateau. There is a linear relationship between the upstream length (L), measured from the headwater to the fault, and the offset amount (D):D=a·L. This study provides useful implications to the role of strike-slip faults during the geomorphic evolution of the eastern Tibetan plateau.  相似文献   

14.
Delta channels are important landforms at the interface of sediment transfer from terrestrial to oceanic realms and affect large, and often vulnerable, human populations. Understanding these dynamics is pressing because delta processes are sensitive to climate change and human activity via adjustments in, for example, mean sea level and water/sediment regimes. Data collected over a 40-year period along a 110-km distributary channel of the Yellow River Delta offer an ideal opportunity to investigate morphological responses to changing water and sediment regimes and intensive human activity. Complementary data from the delta front provide an opportunity to explore the interaction between delta channel geomorphology and delta-front erosion–accretion patterns. Cross-section dimensions and shape, longitudinal gradation and a sediment budget are used to quantify spatial and temporal morphological change along the Qingshuigou channel. Distinctive periods of channel change are identified, and analysis provides a detailed understanding of the temporal and spatial adjustments of the channel to specific human interventions, including two artificial channel diversions and changes in water and sediment supply driven by river management, and downstream delta-front development. Adjustments to the diversions included a short-lived period of erosion upstream and significant erosion in the newly activated channel, which progressed downstream. Channel geomorphology widened and deepened during periods when management increased water yield and decreased sediment supply, and narrowed and shallowed during periods when management reduced water yield and the sediment load. Changes along the channel are driven by both upstream and downstream forcing. Finally, there is some evidence that changing delta-front erosion–accretion patterns played an important role in the geomorphic evolution of the deltaic channel; an area that requires further investigation. © 2020 John Wiley & Sons, Ltd.  相似文献   

15.
活动断层填图中的航片解译问题   总被引：7，自引：3，他引：4       下载免费PDF全文
何宏林 《地震地质》2011,(4):938-950
遥感技术和高精度遥感信息的进步,极大地推动了活动构造和地震地质研究的发展,各种遥感技术在最近几年活动断层填图工作中得到了广泛的应用.如何充分利用各种遥感技术,充分挖掘各种遥感信息以提高填图工作的效率和精度,引起了广大相关科技人员的重视.航空照片以其高精度和高直观性在所有遥感信息源中占据着重要的地位.20世纪中晚期,中国...  相似文献   

16.
Strike-slip faults and normal faults are dominant active tectonics in the interior of Tibetan plateau and control a series of basins and lakes showing extension since the Late Cenozoic, by contrast with the thrust faulting along the orogenic belts bordering the plateau. The late Neotectonic movement of those faults is key information to understand the deformation mechanism for Tibetan plateau. The Gyaring Co Fault is a major active right-lateral strike-slip fault striking~300° for a distance of~240km in central Tibet, in south of Bangong-Nujiang suture zone. The Gyaring Co Fault merges with the north-trending Xainza-Dinggye rift near the southern shore of Gyaring Co. From NW to SE, Dongguo Co, Gemang Co-Zhangnai Co, Zigui Co-Gyaring Co form the Gyaring Co fault zonal drainage basin. Some scholars have noticed that the formation of lakes and basins may be related to strike-slip faults and rift, but there is no analysis on the Gyaring Co fault zonal drainage basin and its response to regional tectonics. In recent years, a variety of quantitative geomorphic parameters have been widely used in the neotectonic systems to analyze the characteristics of the basin and its response mechanism to the tectonic movement. In this paper, we applied ASTER GDEM data on the ArcGIS platform, extracted the Gyaring Co fault zonal drainage basin based on Google Earth images (Landsat and GeoEye) and field work. We acquired basic geomorphic parameters of 153 sub-basin (such as grade, relief, average slope, area) and Hypsometric Index (HI) value and curve. Statistical results have indicated significant differences in scale(area and river network grade)in north and south sides of the fault. Southern drainage basins' relief, slope, HI value are higher than the northern basins, and the overall shape of hypsometric curve of northern basins are convex compared with southern concavity. Along the strike of the Gyaring Co Fault, average slope, and HI value are showing generally increasing trending and hypsometric curve become convex from west to east. By comparing and analyzing the lithology and rainfall conditions, we found that they have little influence on the basic parameters and HI value of drainage basins. Therefore, the changes of basin topographic differences between northern and southern side of fault and profile reveal the Gyaring Co Fault has experienced differential uplift since the late Cenozoic, southern side has greater uplift compared to the north side, and the uplift increased from NW to SE, thus indicate that normal faulting of the Gyaring Co Fault may enhanced by the Xainza-Dinggye rift. The early uplift of the Gangdise-Nyainqentanglha Mountain in late Cenozoic might provide northward inclined pre-existing geomorphic surfaces and the later further rapid uplift on the Gangdise-Nyaingentanglha Mountain and Xainza-Dinggye rift might contribute to the asymmetrical development of the Gyaring Co fault zonal drainage basin.  相似文献   

17.
Much research has been devoted to the development of numerical models of river incision. In settings where bedrock channel erosion prevails, numerous studies have used field data to calibrate the widely acknowledged stream power model of incision and to discuss the impact of variables that do not appear explicitly in the model's simplest form. However, most studies have been conducted in areas of active tectonics, displaying a clear geomorphic response to the tectonic signal. Here, we analyze the traces left in the drainage network 0.7 My after the Ardennes region (western Europe) underwent a moderate 100–150 m uplift. We identify a set of knickpoints that have traveled far upstream in the Ourthe catchment, following this tectonic perturbation. Using a misfit function based on time residuals, our best fit of the stream power model parameters yields m = 0.75 and K = 4.63 × 10‐8 m‐0.5y‐1. Linear regression of the model time residuals against quantitative expressions of bedrock resistance to erosion shows that this variable does not correlate significantly with the residuals. By contrast, proxies for position in the drainage system prove to be able to explain 76% of the residual variance. High time residuals correlate with knickpoint position in small tributaries located in the downstream part of the Ourthe catchment, where some threshold was reached very early in the catchment's incision history. Removing the knickpoints stopped at such thresholds from the data set, we calculate an improved m = 0.68 and derive a scaling exponent of channel width against drainage area of 0.32, consistent with the average value compiled by Lague for steady state incising bedrock rivers. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

18.
Floods are an important geomorphic agent that accelerate sediment supply from bank failures. The quantitative proportions supplied by lateral inputs and the transport conditions of the channel can create local or extended accumulation zones within the channel reaches. These accumulation zones play an important role in the geomorphic regime of the stream. Knowledge of long‐term history of sediment supply is necessary to determine how these input and deposition forms developed. This study introduces a new approach for the quantification of past sediment supply via lateral erosion (incised banks and individual bank failures), using a case study of the confluence of three partial tributaries in the accumulation zone in the Outer Western Carpathians. For each tributary, as well as the channel reach downstream of the confluence zone, we calculated the mean of the largest bed particles and the unit stream power as indicators of transport capacity. We found that two of the tributaries supply significant amounts of sediment to the accumulation zone because of their higher unit stream power related to their higher transport potential, and observed coarser bed sediment. Seventy‐three bank failures with a total volume 395.5 m3 were mapped, and the sediment supply volume was dated using dendrogeomorphic analysis of 114 scarred tree roots (246 samples). The total volume of the dated sediment supply in the individual tributaries was 193.9 m3, whereas the volume of erosion in the accumulation zone was only 4.9 m3 for a period of approximately 30 years. The period represented by the dated tree roots included 12 years in which erosion events occurred and impacted the total sediment budget in the study area. Although sediment supply was greater than erosion in the accumulation zone, there are no present‐day signs of accretion. The rupture of a dam in an old pond (which is situated approximately 50 m below the accumulation zone) probably increased the transport conditions in the accumulation zone so that it balanced the high sediment supply from individual tributaries. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

19.
Many numerical landform evolution models assume that soil erosion by flowing water is either purely detachment‐limited (i.e. erosion rate is related to the shear stress, power, or velocity of the flow) or purely transport‐limited (i.e. erosion/deposition rate is related to the divergence of shear stress, power, or velocity). This paper reviews available data on the relative importance of detachment‐limited versus transport‐limited erosion by flowing water on soil‐mantled hillslopes and low‐order valleys. Field measurements indicate that fluvial and slope‐wash modification of soil‐mantled landscapes is best represented by a combination of transport‐limited and detachment‐limited conditions with the relative importance of each approximately equal to the ratio of sand and rock fragments to silt and clay in the eroding soil. Available data also indicate that detachment/entrainment thresholds are highly variable in space and time in many landscapes, with local threshold values dependent on vegetation cover, rock‐fragment armoring, surface roughness, soil texture and cohesion. This heterogeneity is significant for determining the form of the fluvial/slope‐wash erosion or transport law because spatial and/or temporal variations in detachment/entrainment thresholds can effectively increase the nonlinearity of the relationship between sediment transport and stream power. Results from landform evolution modeling also suggest that, aside from the presence of distributary channel networks and autogenic cut‐and‐fill cycles in non‐steady‐state transport‐limited landscapes, it is difficult to infer the relative importance of transport‐limited versus detachment‐limited conditions using topography alone. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
Beaver dam analogs (BDAs) are a stream restoration technique that is rapidly gaining popularity in the western United States. These low-cost, stream-spanning structures, designed after natural beaver dams, are being installed to confer the ecologic, hydrologic, and geomorphic benefits of beaver dams in streams that are often too degraded to provide suitable beaver habitat. BDAs are intended to slow streamflow, reduce the erosive power of the stream, and promote aggradation, making them attractive restoration tools in incised channels. Despite increasing adoption of BDAs, few studies to date have monitored the impacts of BDAs on channel form. Here, we examine the geomorphic changes that occurred within the first year of restoration efforts in Wyoming using high-resolution visible light orthomosaics and elevation data collected with unoccupied aerial vehicles (UAVs). By leveraging the advantages of rapidly acquired images from UAV surveys with recent advancements in structure-from-motion photogrammetry, we constructed centimeter-scale digital elevation models (DEMs) of the restoration reach and an upstream control reach. Through DEM differencing, we identified areas of enhanced erosion and deposition near the BDAs, suggesting BDA installation initiated a unique geomorphic response in the channel. Both reaches were characterized by net erosion during the first year of restoration efforts. While erosion around the BDAs may seem counter to the long-term goal of BDA-induced aggradation, short-term net erosion is consistent with high precipitation during the study and with theoretical channel evolution models of beaver-related stream restoration that predict initial channel widening and erosion before net deposition. To better understand the impacts of BDAs on channel morphology and restoration efforts in the western United States, it is imperative that we consistently assess the effects of beaver-inspired restoration projects across a range of hydrologic and geomorphic settings and that we continue this monitoring in the future.  相似文献   

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