若尔盖盆地沙丘形成分布影响因素探讨   总被引：1，自引：0，他引：1  

魏振海  董治宝  胡光印  逯军峰 《中国沙漠》2009,29(6):1035-1042

应用遥感数据、DEM数据、野外采样数据和气象数据探讨若尔盖盆地沙丘形成分布的影响因素。气候变化与人类活动等多种因素导致的现代河相沉积物与活化出露的古河相湖相沉积物是重要沙源,风动力条件与沙源的时空结合在堆积床面形成沙丘,沙丘主要分布在河谷与丘陵山坡。沙丘分布随海拔高度增加面积减少,随坡度增大面积下降。河谷沙丘坡度小,主导坡向也不突出。丘陵沙丘坡度相对较大,以分布在斜坡和缓坡为主;主导坡向相对突出,主要分布在背风坡的东坡、东南坡。在沙源地下风方向随距离增大沙丘沉积物平均粒径变小,分选性变好。沙丘形成是沙源、风动力、堆积床面三者耦合作用的结果,这种耦合既表现在时间上,也表现在空间上。  相似文献   

若尔盖碳硅泥岩型铀矿成矿规律及控矿因素分析   总被引：1，自引：1，他引：0       下载免费PDF全文

王永飞 《中国地质调查》2015,2(8):17-24

西秦岭南亚带的若尔盖碳硅泥岩型铀矿床是中国重要的十大铀资源基地之一,但是在加大找矿深度、扩大资源量以及矿床成因等方面仍然存在一系列的问题。通过多年的详实野外勘查和研究,总结出了若尔盖地区硅泥岩型铀矿的矿体形态、产出特征及空间分布规律,即矿床主要产于下志留统一套浅变质硅质岩、灰岩、板岩层中,矿体形态呈似层状、透镜状、扁豆状,矿体严格受岩性、构造、硅灰岩组合体3要素控制; 提出了“断裂构造-硅灰岩组合体-岩性界面”3要素组合控矿的成矿规律,以及“组合成矿”和“深源流体”对若尔盖铀成矿起主导作用的新认识。  相似文献   

四川若尔盖阿细龙曲金矿成矿地质特征及找矿前景     

周兵  刘建华  黄昌华 《四川地质学报》2009,29(4):412-414

阿细龙曲金矿是川西北地区一种重要的金矿类型。通过对该矿区所处成矿地质背景、地质构造及矿床特征、成矿条件、矿化富集规律进行分析,认为区内成矿地质条件好,加强综合找矿,可望实现新的突破。  相似文献   

若尔盖盆地兴措湖沉积记录揭示的近代气候与环境   总被引：14，自引：2，他引：12  

吴敬禄  李世杰  王苏民  夏威岚  李万春  羊向东 《湖泊科学》2000,12(4):291-296

依据湖泊沉积记录进行古气候环境要素定量的是过去全球变化研究的重要内容,本文通过若尔盖盆地兴措湖近代湖泊沉积特征、沉积物总有机碳及其同位素指标分析,并与器测气象资料进行比较,对兴措湖泊近代湖泊沉积物中有机碳及其同位素指标所代表的气候环境信息进行了定量研究,在此基础上,建立了兴措湖沉积物总有机碳及其同位素记录与对应的降水和气温间的函数关系,为定量恢复该区长尺度历史时期古气候环境特征提供了基础。  相似文献   

Rangeland privatization and its impacts on the Zoige wetlands on the Eastern Tibetan Plateau   总被引：3，自引：0，他引：3  

YAN Zhaoli WU Ning 《山地科学学报》2005,2(2):105-115

The high Zoige Basin （Ruoergai Plateau） on the eastern Tibetan Plateau is a fault depression formed during intensive uplifting of the Tibetan Plateau. The wetland is globally important in biodiversity and is composed of marshes, bogs, fens, wet meadows and shallow water interspersed with low hills and sub-alpine meadows. Most of the Zoige wetlands have long been one of the most important grazing lands in China. Recent rangeland policy has allowed grazing, and usable wetland areas have been being legally allocated to individuals or groups of households on a long-term lease basis. Privatizafion of the wetland has impacted the Zoige wetlands in aspects of hydrologic condition, landscape and biodiversity. The uneven spatial distribution of water resources onprivatelands has led to the practice of extracting ground water, which has decreased the perched water table in Zoige. Fencing off the rangelands and grazing on expanding sand dunes have affected landscapes. Variation in the water table has led to the changes in vegetation diversity, resulting in the changes in wildlife and aquatic diversities and ecosystem processes. Making use all year round of the pasture that was previously grazed only in summer has shrunk the daily activity space of wildlife, and the newly erected fences blocked the movement of wild animals looking for food in the snow to lower and open areas. To maintain the favorable conditions of the Zoige wetland ecosystem, the author suggests that, in addition to biophysical research and implementation of conservation practices, there is an immediate need to initiate an integrated management program, increase public awareness of wetland functions and provide better training for the local conservation staff.  相似文献   

Analysis of dynamics and driving factors of wetland landscape in Zoige, Eastern Qinghai-Tibetan Plateau   总被引：3，自引：0，他引：3  

Pengfei Qiu  Ning Wu  Peng Luo  Zuyuan Wang  Maihe Li 《山地科学学报》2009,6(1):42-55

Zoige Wetland is one of the largest plateau wetlands in the world. This paper provides a dynamic analysis of spatial and temporal patterns of the wetland in Zoige, Eastern Qinghai-Tibetan Plateau, supported by ERDAS8.7 and ArcGIS9.0. It is the first comparative analysis of a system of rapidly changing wetland with landscape patterns in Zoige, using 3 classified landsat Thematic Mapper images of 1977, 1994 and 2001. The classified images were used to generate wetland distributing maps, and shape index （S）, diversity index （H）, dominance index （D）, evenness index （E）, fragmentation index （F） and fractal dimension （Fd） were calculated and analyzed spatiotemporally across pure grazing area in Zoige for each landscape type and in different periods （before 1977, during 1977-1994 and 1994-2001）, as well as the driving forces of natural and anthropogenic. The study shows that for a comprehensive understanding of the shapes and trajectories of the shrinking and desertificated land expansion of the wetland, a spatiotemporal landscape metrics analysis in different periods is an improvement than only with landscape changing rates. This type of analysis can also be used to infer underlying social, economic, and political processes that drive the observed wetland forms. The results indicate that wetland patterns can be changed over relatively short periods of time. The total area of lake reduced by 164.86 km^2, grassland extended by 141.74 km^2, semi-marsh extended by 105.94 km^2, marsh reduced by 86.00 km^2 the number of landscape patches reduced by 56, and their average area decreased by 2.68 km^2, the successions within lake, marsh, semi-marsh and grassland were found obviously. S decreased stepwise： D and F increased but H decreased： The changing rate after 1994 was 2.3 to 2.9 times greater than that before. The change of the wetland landscape patterns resulted in the interaction between socio-ceenomic and natural forces of positive and negative aspects; and natural factors affected as assistant aspect. Some important human activities in this period led to the change of the landscape patterns in this region directly. Some measurements made by government and NGO delayed the converting process partly.  相似文献   

510-1铀矿床垂直分带规律的发现及其成因意义   总被引：2，自引：0，他引：2  

张成江 《地质与勘探》2010,46(3):434-441

510-1铀矿床中与成矿有关的石英、方解石脉在空间分布上显示出与华南地区花岗岩型铀矿床相似的"上酸下碱"的垂直分带规律。矿床上部(1中段)为"酸帽",主要发育石英脉;中部(2～4中段)为"酸碱共生带",石英脉与方解石脉均较发育;而下部(5～6中段及以下)则为"碱性基底",大量发育方解石脉,未见石英脉,表明矿床第5中段附近(距现今地表深约200m)为"酸碱分离"的地球化学界面。由矿床浅部向深部,总体上方解石中Sr、Zr、Ba、Zn、U、Ni、Cr等微量元素的含量明显增加,其中第5中段附近为多种微量元素的聚集地带。方解石、石英的δCe、δEu值垂向变化也反映出5中段附近为成矿流体演化的氧化还原过度带,与矿床"酸碱分离"的界面一致,暗示这一部位为一重要的流体成矿地球化学界面,亦是铀发生突发成矿作用产生高度富集的部位。垂直分带规律显示出该矿床属于典型的热液矿床,深部找矿潜力还很大。  相似文献   

若尔盖高原湿地景观与环境要素的DCCA多元相关分析     

叶宇  刘高焕  黄翀  宁吉才  李亚飞 《地球信息科学学报》2011,13(3):313-322

以9个指标反映若尔盖高原湿地生境的环境特征,在ArcGIS 9.2平台下进行随机样方布设,采用DCCA排序方法定量分析湿地景观与环境要素之间的关系。结果表明：(1)排序前2轴累计解释了湿地景观与环境要素关系的79.4％,表明其具有有效的目标研究显示度;(2)沿地形指数所近似表达的水分状况梯度,研究区各景观类型具有明显的...  相似文献   

地下水位和土壤含水量对若尔盖木里苔草沼泽甲烷排放通量的影响   总被引：1，自引：0，他引：1  

李丽  雷光春  高俊琴  吕偲  周延  贾亦飞  杨萌  索郎夺尔基 《湿地科学》2011,9(2):173-178

在若尔盖湿地国家级自然保护区典型的木里苔草（Carex muliensis）沼泽地中,选择地下水位不同的4个采样点,其植物生长季的平均地下水位分别为距离地表53.94 cm、31.35 cm、11.50 cm和4.74 cm。利用密闭式静态箱定期采集气体样品,并在实验室用Shimadzu GC212A气相色谱仪测定CH₄气体浓度,分析了CH₄排放通量与地下水位和土壤含水量之间的关系。研究结果表明,地下水位和土壤含水量对CH₄排放通量产生明显影响,6～9月观测日中,CH₄排放通量随着地下水位的升高而呈指数增加;10～40 cm土层的土壤含水量与CH₄排放通量呈现显著正相关（n=36,p<0.05）,而0～10 cm土壤含水量与生长季CH₄排放通量不相关（n=12,p>0.05）,逐步线性回归分析表明,20～30 cm土层的土壤含水量是影响CH₄排放通量的主要因素（n=12,p<0.01）。  相似文献   

鼠害在若尔盖草原沙漠化进程中的作用与机理     

姚正毅  李晓英  董治宝 《中国沙漠》2017,37(6):1093-1101

若尔盖草原是中国高寒湿润地区发生大面积沙漠化的典型案例,其沙漠化的成因及发展趋势一直受到极大关注。通过野外考察、遥感卫星影像解译等,着重探讨了鼠害在若尔盖草原沙漠化的形成和发展过程中的作用。结果表明：旱獭洞的分布与丘陵沙丘在坡度和坡向上有高度的相似性。地表致密草皮层发生机械性破坏,致使下伏松散沙暴露是若尔盖草原沙漠化的关键一步。旱獭洞的坍塌在草皮层的破坏过程中起到了至关重要的作用。草皮层破坏后,下伏松散沙被侵蚀,引起草皮层坍塌,导致古沙丘活化,形成流动沙丘。在此过程中,自然因素如风、降水、冻融、重力,人为因素如过牧、牲畜活动,都起到了不同的作用。小型鼠类如高原鼢鼠、高原鼠兔的严重鼠害区可以形成轻度沙漠化。  相似文献