南海东北部峡谷体系的地貌特征与发育控制因素     

王玉宾  吴自银  尚继宏  殷绍如  赵荻能  周洁琼 《海洋学报》2020,42(11):62-74

海底峡谷在全球陆缘广泛分布,是浅海沉积物向深海运移的主要通道,对于理解深海浊流触发机制、深海沉积物的搬运模式、深海扇的发育历史和深海油气资源勘探等均具有重要意义。本文基于高分辨率高精度的多波束测深数据,首次对南海东北部海底峡谷体系进行了研究,精细刻画了高屏海底峡谷、澎湖海底峡谷、台湾浅滩南海底峡谷和东沙海底峡谷等4条大型海底峡谷的地貌特征并分析其发育控制因素。海底坡度、构造运动、海山与海丘是影响南海东北部峡谷群走向与特征的重要因素,其中,海底坡度对于峡谷上游多分支与“V”字特征有显著的控制作用;构造运动是控制高屏海底峡谷走向的因素,澎湖海底峡谷的走向则与菲律宾海板块与欧亚板块碰撞有关,东沙海底峡谷的走向则与东沙运动相关,台湾浅滩南海底峡谷上段受NW向断裂构造的控制;海山的阻挡作用造成峡谷局部走向和特征改变。海底峡谷群输送大量陆源沉积物到深海盆并形成大面积的沉积物波,海山和沉积物波的发育导致东沙海底峡谷下段“回春”和转向。  相似文献   

川西高山峡谷区的耕地资源态势及其对粮食生产影响研究——以四川省甘孜藏族自治州九龙县为例     

肖蓉  王雷  任平 《国土资源情报》2009,(8):37-41

研究目的：根据1996～2007年土地利用变更调查和社会经济统计数据,分析四川省甘孜藏族自治州九龙县的耕地资源动态变化特征及粮食生产能力。研究方法：定量分析法、文献资料法、归纳分析法、比较分析法。研究结果：九龙县耕地资源稀缺、质量不高、后备资源不足;粮食作物播种面积呈总体下降趋势,严重制约了九龙县的粮食增产;粮食总产量波动下降,自给率持续下降,同时粮食消费量和缺口不断扩大,不能自主满足生存性粮食需求。建议合理展开土地整理复垦,提高复种指数,加大农业科技投入,改善水利等农业基础设施条件是促进九龙县粮食增产的有效途径。  相似文献   

Application of sediment traps in global change research in mountain lakes     

G. R. KATTEL 《山地科学学报》2009,6(3):228-239

Representativity of biota in the biosphere also have similar significance in the lithosphere after their death. Recently, taphonomic representation of biota in the lithosphere has been widely used for minimizing the biases in palaeo-environmental reconstructions including global climate change. In September 2001, a sediment trap was installed at the central area of the Loch Coire Fionnaraich （LCFR）, a small, oligotrophic mountain loch in northwest Scotland for a taphonomic study of cladoceran zooplankton. The trap was emptied on a seasonal basis, where an average 0.14 g dry material was recovered in each season, January, May and August 2002 respectively. A sediment core was also taken from near the sediment trap location. The top 0.5 cm section, the ＇core＇ was used for a comparative study with the trap sediment samples. The planktonic Cladocera consisted of Bosmina coregoni and appeared to have excellent preservation in the trap assemblages. Moreover, some common littoral Cladocera such as Alonella excisa and Aloha guttata appear to be less well preserved in the fossil assemblages. Large littoral taxa such as Eurycercus lamellatus and Aloha quadrangularis were rare in the trap but relatively common and well preserved in the sediment-water interface. It is suggested that taphonomic processes play a dominant role on deposition of fossil remains of Cladocera and caution should be taken while inferring the past environmental changes whilst using fossil assemblages recovered from the lake centre as a representation of the entire cladoceran community in the lake.  相似文献   

Distribution of borehole temperature at four high-altitude alpine glaciers in Central Asia     

Yaping Liu  Shugui Hou  Yetang Wang  Linlin Song 《山地科学学报》2009,6(3):221-227

The distribution of borehole temperature at four high-altitude alpine glaciers was investigated. The result shows that the temperature ranges from -13.4℃ to -1.84℃, indicating the glaciers are cold throughout the boreholes. The negative gradient （i.e., the temperature decreasing with the increasing of depth） due to the advection of ice and climate warming, and the negative gradient moving downwards relates to climate warming, are probably responsible for the observed minimum temperature moving to lower depth in boreholes of the Gyabrag glacier and Miaoergou glacier compared to the previously investigated continental ice core borehole temperature in West China. The borehole temperature at 10m depth ranges from -8.0℃ in the Gyabrag glacier in the central Himalayas to -12.9℃ in the Tsabagarav glacier in the Altai range. The borehole temperature at 10 m depth is 3-4 degrees higher than the calculated mean annual air temperature on the surface of the glaciers and the higher 10 m depth temperature is mainly caused by the production of latent heat due to melt-water percolation and refreezing. The basal temperature is far below the melting point, indicating that the glaciers are frozen to bedrock. The very low temperature gradients near the bedrock suggest that the influence of geothermal flux and ice flow on basal temperature is very weak. The low temperature and small velocity of ice flow of glaciers are beneficial for preservation of the chemical and isotopic information in ice cores.  相似文献   

琼东南盆地中央峡谷的形态及成因   总被引：11，自引：0，他引：11  

苏明  李俊良  姜涛  田姗姗  张成  解习农 《海洋地质与第四纪地质》2009,(4)

琼东南盆地中央峡谷平面上呈"S"型、NE向展布,西起莺歌海盆地中央凹陷带,经乐东凹陷、陵水凹陷、松南凹陷、宝岛凹陷、长昌凹陷,向东延伸进入西沙海槽。剖面形态上存在"V"型、"W"型、"U"型和复合型等4种类型。通过不同区域峡谷下切底界面的形态变化及充填特征,将中央峡谷划分为东段、西段和转换段3个区段,转换段与琼东南盆地的构造转换段相一致,即以西地区控凹断裂为NE向,而以东地区控凹断裂渐变为NEE或EW向。琼东南盆地中央峡谷的成因与构造作用和深水沉积作用关系密切,峡谷东段主要受构造作用控制,特别是深部隆起的存在为黄流期中央峡谷的形成提供了"限制性"作用,并且为后期中央峡谷的发育提供了"限制性通道";西段则受深水沉积作用的控制,重力流沉积为中央峡谷的下切和充填提供了来源。每期中央峡谷的形成均稍早于或与该时期陆坡的发育同期,最早形成于盆地东部,并随陆坡的持续向西迁移表现为不断向西上溯,下切能力逐渐减弱。  相似文献   

Living in a High Mountain Border Region： the Case of the ＇Bhotiyas＇ of the Indo-Chinese Border Region   总被引：6，自引：2，他引：4  

Marcus Nüsse 《山地科学学报》2008,5(3):209-217

This article introduces one of South Asia＇s most important border regions into academic discourse, namely, the Central Himalayan mountain rim separating India and the Tibetan Autonomous Region （People＇s Republic of China）. What makes this border region so interesting is a tangled interplay of changing environmental, cultural, and political forms to which the local populations constantly have to adapt in order to make a living there. We focused on the so-called ＇Bhotiyas＇ of Uttarakhand, former trans- Himalayan traders whose ethnicity and livelihood was traditionally associated with the Indo-Chinese border that was sealed as a result of the India-China war in 1962. Drawing on the work of borderland scholarship, we identified the key processes and developments that changed the perspective of this area. Competing political aspirations as well as the ＇Bhotiyas＇ countervailing strategies were considered equally important for understanding local livelihoods and identities within the dynamics of a ＇high mountain border region＇. Through an exemplary analysis of historical differences of power in one ＇Bhotiya＇ valley, we further explored the ways in which shifting socio-spatial constellations are creatively re-interpreted by the borderlanders.  相似文献   

Glacier Extent and Volume Change （1966-9000） on the Su-lo Mountain in Northeastern Tibetan Plateau,China   总被引：2，自引：2，他引：0  

WANG Yetang  ;HOU Shugui  ;HONG Sungmin  ;HUR Soon Do  ;LIU Yaping 《山地科学学报》2008,5(4):299-309

The topographic maps of 1：50, 000 scales, aerial photographs taken in 1966, one Landsat image taken in 1999, and SRTM data from 2000 were used to quantify the losses in area and volume of the glaciers on the Su-lo Mountain, in the northeastern Tibetan Plateau, China in the past 30 years. The total glacier area decreased from 492.9 km^2 in 1966 to 458.2 km^2 in 1999. The volume loss of the studied glaciers reached 1.4 km^3 from 1966 to 2000. This agrees with documented changes in other mountain glaciers of the whole Tibetan Plateau.  相似文献   

Effect of snow-cover duration on plant species diversity of alpine meadows on the eastern Qinghai-Tibetan Plateau   总被引：2，自引：1，他引：1  

Wennian Chen  Yan Wu  Ning Wu  Peng Luo 《山地科学学报》2008,5(4):327-339

Although snow cover plays an important role in structuring plant diversity in the alpine zone, there are few studies on the relationship between snow cover and species diversity of alpine meadows on the eastern Qinghai-Tibetan Plateau. To assess the effect of snow cover on plant species diversity of alpine meadows, we used ten parallel transects of 60 m × 1 m for this study and described the changes in species diversity and composition associated with snow depth. With the division of snow depth into six classes, the highest species richness （S） and species diversity （H′） occurred with an intermediate snow depth, i.e., class Ⅲ and class Ⅳ, showing a unimodal curve with the increase in snow depth. The relationship between snow depth and plant diversity （both richness and Shannon index） could be depicted by quadratic equations. There was no evident relationship between diversity （both S and H′） and soil water content, which implied that other more important factors influenced species diversity. The patterns of diversity found in our study were largely attributed to freeze-thaw alteration, length of growing season and disturbances of livestock grazing. Furthermore, snow depth affected species composition, as evaluated by the Sorensen＇s index of similarity. In addition, almost all species limited to one snow depth class were found only in class Ⅲand class Ⅳ, indicating that intermediate snow depth was suitable for the survival and growth of many alpine species.  相似文献   

深切峡谷地区地壳浅表层地应力状态变化分析   总被引：1，自引：0，他引：1       下载免费PDF全文

谭成轩  孙炜锋  张春山  吴树仁  彭华  孙叶 《地球物理学进展》2007,22(4):1353-1359

本文以三峡水库引水工程秦岭特长隧洞水压致裂地应力测量为例,在野外地质调查、室内超前预测分析、现场和室内测试等的基础上,对深切峡谷地区地壳浅表层地应力状态进行了系统分析,结果表明深切峡谷地区地壳浅表层分为应力降低区、应力增高区和原始应力区,原始应力区（即构造应力面）的深度大致等于地应力测点周围山体和沟谷之间的相对高差.  相似文献   

峡谷地形对两次极端降水的作用          下载免费PDF全文

李银娥  吴翠红  陈赛男  柳草  张文言 《气象科学》2021,41(4):484-494

利用地面加密自动站、常规观测资料、NCEP再分析资料和两种模式产品,对发生在宜昌峡谷地区2016年7月7日局地极端短时强降水过程和2018年4月22日稳定性极端降水过程形成原因及模式预报性能进行检验分析。结果表明:(1)强的块状回波稳定少动,造成7月7日高效率的对流降水。4月22日降水既有沿山中尺度对流回波造成的对流降水,也有螺旋状涡旋回波形成的锋面层状云降水。(2)山谷风形成中尺度切变线,触发对流,中尺度切变线发展为中尺度涡旋使对流加强是极端短时降水形成的主要原因。(3)地形强迫抬升使对流降水强度明显增大,锋面层状云回波受地形阻挡影响长时间维持是稳定性极端降水形成主要原因。(4)地形相差大的地区模式预报性能差异较大,模式对复杂地形下的对流降水预报偏弱,导致系统强度出现差异,进而影响降水强度预报。  相似文献