南昌市厚田乡风沙地貌形态特征与美学价值     

吴昊  李志文  郭福生  王志刚  梁丽婵 《华东地质》2019,(4):264-272

南昌市南部新建县广泛分布由古风沙和现代流沙组成的沙化土地。在野外地质调查的基础上,选择新建县南部厚田沙地作为研究对象,应用观察法、描述法和系统调查分析法等定性评价方法对上伏风沙地貌的类型和特征进行分析,并结合下覆古风沙的OSL年代、粒度组成及色度参数等定量分析方法,探讨亚热带湿润区风沙地貌遗产的美学特征。结果表明:厚田风沙地貌包括现代风沙沉积和晚第四纪古风沙沉积。现代风沙沉积大致始于14 ka B.P.,以纵向沙垄、穹形沙堆、辫状沙堆、平沙地等微地貌形态为主;晚第四纪古风沙沉积时间约为77.0~14.9 ka B.P.,以板状交错层理为主,地层序列丰富,是蕴含古环境演变信息的特殊地质遗迹,具有重要的科学研究价值。风沙地貌具有色彩美、旷远美、形式美和生命美等美学特征,具有良好的地学旅游开发价值。定性评价与定量分析相结合,可丰富风沙地貌美学研究的内容,也可为中国南方亚热带湿润区风沙地貌的地质遗迹保护和地学旅游开发提供参考。  相似文献   

Short-Term Morphological and Shoreline Changes at Trinkat Island,Andaman and Nicobar,India, After the 2004 Tsunami     

P. Yunus Ali 《Marine Geodesy》2013,36(1):26-39

The tsunami waves generated during the Sumatra-Andaman earthquake of 26 December 2004 devastated the coastal area along Trinkat Island, causing sudden changes to the morphology of the landforms. This study uses a series of satellite images to record the short-term morphological response and shoreline changes as well as the recovery of coastal land after its destruction. Results indicate that the island experienced substantial erosion and a significant reduction in land area. Shoreline erosion is more prevalent than accretion at an average linear regression rate of ～?9 m per year between 2004 and 2013. The major morphological changes at Trinkat Island were observed in coastal inlets, beaches, and bay head-lands. Straight beaches had almost recovered eight years after the tsunami; however, erosion is continually observed in other areas. Our study will help understanding the response and recovery of shorelines in Indian Ocean regions after the 2004 tsunami.  相似文献   

Seafloor Geomorphology and Processes on the Western Continental Margin of India based on Multibeam Acoustic Backscatter Data Analysis     

Sumanta Dandapath  Andrew Menezes  Bishwajit Chakraborty  John Kurian  Koppella N. Prudhvi Raju 《Marine Geodesy》2018,41(2):177-200

An assessment of the multibeam sonar data of the central Western Continental Margins of India has been carried out to evaluate the seafloor geomorphology and processes by examining the geomorphological attributes e.g., slope, sediments, structures, etc. associated with geomorphic features. The variation in relief and the features located in the region have been mapped and interpreted collectively by utilizing several geospatial mapping tools. The backscatter strength across the area, apparently congruent with the local relief, has helped to examine the sediment movement on the seafloor. The prominent features found in the region include faults, pockmarks, mounds, submarine terraces, and submerged fossil reefs. Several areas with varying topography engender comparable fractal dimension at short scale breaks, and the probability density functions (PDFs) utilizing backscatter data depicting overlapping classes. The present study highlights how fractals and scale break parameters can be utilized to determine the seafloor processes and associated sedimentological dynamics in a complex geographical environment with strong bottom currents, seasonal upwelling, and faulted structure. The role and impact of the various geomorphic processes on the reworking of sediment movement and the overall progression of the seafloor morphology has been revealed for the first time in this part of the ocean bottom.  相似文献   

丹霞山国家珍稀濒危保护植物丹霞梧桐空间分布的微地貌环境特征研究   总被引：2，自引：2，他引：0  

欧阳杰  彭华  罗晓莹  陈再雄  张安新  马育宣 《地理科学》2017,37(10):1585-1592

以广东丹霞山狮子岩—阳元山景区为研究地,以国家珍稀濒危保护植物丹霞梧桐(Firmiana danxiaensis)的空间分布为研究内容,通过实地考察获取其空间分布的数据（经纬度、海拔、坡度和坡向等）,利用ArcGIS10.0在精度为1 m的DEM地形数据上进行空间分析,总结丹霞梧桐空间分布的微地貌环境特征。研究发现：① 研究区丹霞梧桐主要分布在海拔180 m等高线穿过坡度60o附近的土壤比较贫瘠的垂直节理或水平层理比较发育的崖壁上,并与圆叶小石积(Osteomeles subrotunda)、忽地笑(Lycoris aurea)、卷柏(Selaginella tamariscina)等植物伴生,属于比较耐旱的崖壁植物;② 丹霞梧桐的空间分布不受坡向因素的严格制约,坡度和海拔是影响丹霞梧桐分布的2个重要因素。根据以上分布规律,可以推测180 m等高线穿过坡度60o地带的丹霞山其他崖壁地带,亦可能会有丹霞梧桐的分布,并建议在目前已经发现丹霞梧桐分布比较集中的狮子岩东南坡,设立国家珍稀濒危保护植物丹霞梧桐重点保护带。  相似文献   

Automatic mapping of lunar landforms using DEM-derived geomorphometric parameters   总被引：1，自引：0，他引：1  

Jiao Wang  Weiming Cheng  Chenghu Zhou  Xinqi Zheng 《地理学报(英文版)》2017,27(11):1413-1427

Developing approaches to automate the analysis of the massive amounts of data sent back from the Moon will generate significant benefits for the field of lunar geomorphology. In this paper, we outline an automated method for mapping lunar landforms that is based on digital terrain analysis. An iterative self-organizing (ISO) cluster unsupervised classification enables the automatic mapping of landforms via a series of input raster bands that utilize six geomorphometric parameters. These parameters divide landforms into a number of spatially extended, topographically homogeneous segments that exhibit similar terrain attributes and neighborhood properties. To illustrate the applicability of our approach, we apply it to three representative test sites on the Moon, automatically presenting our results as a thematic landform map. We also quantitatively evaluated this approach using a series of confusion matrices, achieving overall accuracies as high as 83.34% and Kappa coefficients (K) as high as 0.77. An immediate version of our algorithm can also be applied for automatically mapping large-scale lunar landforms and for the quantitative comparison of lunar surface morphologies.  相似文献   

Schmidt‐hammer exposure‐age dating (SHD) of snow‐avalanche impact ramparts in southern Norway: approaches,results and implications for landform age,dynamics and development          下载免费PDF全文

John A. Matthews  Lindsey J. McEwen  Geraint Owen 《地球表面变化过程与地形》2015,40(13):1705-1718

Schmidt‐hammer exposure‐age dating (SHD) was applied to the problem of dating the diachronous surfaces of five distal river‐bank boulder ramparts deposited by snow avalanches plunging into the Jostedøla and Sprongdøla rivers in the Jostedalsbreen region of southern Norway. Approaches to local high‐precision linear age calibration, which controlled in different ways for boulder roundness, were developed. The mean age (SHD_mean) and the maximum age (SHD_max) of surface boulders were estimated for whole ramparts, crests and distal fringes. Interpretation was further assisted by reference to R‐value distributions. SHD_mean ages (with 95% confidence intervals) ranged from 520 ± 270 years to 5375 ± 965 years, whereas SHD_max ages (expected to be exceeded by <5% of surface boulders) ranged from 675 to 9065 years. SHD ages from the Jostedøla ramparts tended to be older than those associated with the Sprongdøla, rampart crests were younger than the respective distal fringes, and use of relatively rounded boulders yielded more consistent SHD ages than angular boulders. The SHD_mean ages indicate differences in recent levels of snow‐avalanche activity between ramparts and provide insights into rampart dynamics as boulders are deposited on rampart crests and, in smaller numbers, on the distal fringes. SHD_max ages provide minimum age estimates of rampart age (i.e. the time elapsed since the ramparts began to form) and suggest that at least some of the ramparts have been developing since the early Holocene. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

西秦岭迭山西北部冰川地貌分布及其特征     

赵井东  王杰  沈永平  殷秀峰  伍云飞 《冰川冻土》2013,35(4):841-847

迭山西北部位于青藏高原的东缘, 属西秦岭山脉的西段. 在海拔3 700 m以上保存有类型较为齐全的冰蚀地形(冰斗、刃脊、U形谷、悬谷、粒雪盆、鲸背岩与基岩磨光面等)与冰碛地形(侧碛垄与终碛垄). 采用野外考察、遥感影像解译与填图等方法对该区的冰川地貌分布及其特征进行了探讨. 基于研究区冰川地形分布与特征, 结合青藏高原现代的抬升速率、邻近山地冰川地形的年代学资料以及其他古环境研究成果进行综合分析得出: 该区的古冰川发育于末次冰期, 末次冰期最盛期是其最主要的形成期. 冰川最盛时面积约38 km², 为具有暖底性质的冰帽冰川.  相似文献   

龙门山古冰川作用   总被引：1，自引：1，他引：0  

周尚哲  汪耀华  许刘冰  郑本兴 《冰川冻土》2017,39(2):292-298

汶川地震中央区域龙门山主山九顶山海拔4 984 m,山脊北坡有三处成排分布不少规模较小的冰斗-冰川谷地形,恢复当时雪线高度在4 100 m高度。根据其形态保存程度、古今雪线高度差等情况判断,应当是2阶段冰川作用遗存。据气温和降水资料,现在九顶山雪线高度在5 000 m,刚好超出九顶山顶部。故而九顶山3 800 m以上目前处于冰缘环境,石冰川、石环、融冻泥流等冰缘现象比较突出。九顶山不存在更老的冰川作用及其地貌遗存,是青藏高原以东5 000 m上下的高山只是在末次冰期时抬升跨越冰期雪线而发育冰川这一新观点的又一证据,也是青藏高原第四纪晚期剧烈抬升的又一证据。  相似文献   

The impact of agriculture on solute and suspended sediment load on a Mediterranean watershed after intense rainstorms     

Luís Outeiro  Xavier Úbeda  Joaquim Farguell 《地球表面变化过程与地形》2010,35(5):549-560

The solute and suspended‐sediment load following five rainstorms (2005–2007) with varied intensities were studied at the Vernegà experimental watershed, north‐western Spain. Two land‐use areas are located within this watershed, the upstream one (forest) with 160 ha a 100% forested area, and the downstream one (agricultural) with 97 ha being 9 ha conventional agricultural field and 88 ha forest. This study investigates the capacity of each land‐use to yield water, suspended sediment concentration (SSC) and dissolved solid concentration (DSC). The hypothesis is that DSC and SSC from the agricultural area are greater than DSC and SSC of the forest area. Results showed that the agriculture area produced significantly greater mean DSC than in the forest area, the main contribution was the Ca²⁺ (24·68 ± 46·52 mg l^?1) ion at the agricultural area. A long‐term sediment production rate at the agricultural outlet was calculated (69·1 tonnes per 100 years) based on the total sediment discharge (TSD) and the recurrence interval of the largest event of the five rainstorms (October 2005). Geographic information system (GIS) spatial data layers of the watershed were produced to determine the relation of tracks, landforms, slopes and forest management to SSC yield in the forest outlet (133·89 ± 308·14 mg l^?1) during the five rainstorms. Agriculture practices are the main cause of soil erosion at the study area. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

龙陵-瑞丽断裂(南支)北段晚第四纪活动性特征   总被引：5，自引：0，他引：5       下载免费PDF全文

黄学猛  杜义  舒赛兵  谢富仁 《地震地质》2010,32(2):222

遥感影像解译和野外地质地貌调查表明,龙陵-瑞丽断裂(南支)北段是以左旋走滑为主兼张性正断的区域性活动断裂。根据一些断错地貌点的大比例尺填图、实地测量及其年代学分析,确定了该断裂为全新世活动断裂,断裂晚更新世以来的平均水平滑动速率为2.2mm/a,平均垂直滑动速率为0.6mm/a;全新世以来的平均水平滑动速率为1.8～3.0mm/a,平均垂直滑动速率为0.5mm/a。断裂晚更新世以来的滑动速率在不同的时间尺度上变化不大,反映了该断裂晚更新世以来的活动强度比较平稳  相似文献