青海喇家遗址地层划分及齐家文化废墟覆盖层成因分析     

王海燕  庞奖励  黄春长  周亚利  炊郁达  查小春  郭永强  张玉柱  尚瑞清  王兆夺 《地理科学》2020,40(5):853-862

对喇家遗址进行了全面的野外考察,在其北部发现完整连续的全新世黄土-古土壤地层剖面。通过系统采样、粒度和磁化率等多种指标测试,结合OSL技术测年断代,建立了完整的土壤地层序列。深入分析土壤沉积物性质与地表过程,揭示了覆盖齐家文化废墟的沉积物的成因。研究结果表明：喇家遗址土壤沉积物地层层序自地表向下依次为：现代土壤（MS,0~1.50 ka B.P.）→全新世晚期风成黄土（L₀,1.50~3.10 ka B.P.）→全新世中期古土壤（S₀,3.10~8.50 ka B.P.）→全新世早期过渡性风成黄土（L_t,8.50~11.50 ka B.P.）→晚更新世晚期马兰黄土（L₁,>11.50 ka B.P.）。其中全新世中期黑垆土古土壤（S₀）被3组红色粘土质泥流（RC₃、RC₂和RC₁）和山洪沙土（FFD）沉积层穿插分隔为4个亚层（S_0上、S_0中上、S_0中下和S_0下）。这证明黑垆土发育过程中,在OSL年龄3.96~3.65 ka,对应于¹⁴C年龄3.85~3.60 ka B.P.出现一个山洪泥流盛行期,来自于盆地北侧沟谷的大规模暴雨山洪泥流,在大红山前古洪积扇前沿溢出沟槽、扩散覆盖了黄河第二级阶地面的土地。其中与大地震相伴随的第一期暴雨山洪泥流过程,摧毁了喇家遗址齐家文化聚落,造成居室内人群的死亡。  相似文献   

一种快速非局部平均合成孔径雷达海洋图像斑点噪声抑制方法     

查国震  许德伟  杨燕明  宋新改  钟福煌 《海洋学报(英文版)》2019,38(11):140-148

合成孔径雷达在海洋环境监测和海洋研究中扮演着越来越重要的角色。受其成像机制的影响,合成孔径雷达图像总是受到斑点噪声的污染。斑点噪声的存在会增大目标识别、跟踪和分类的难度,也会降低雷达信号的信噪比。合成孔径雷达海洋图像具有一些特殊的性质：海洋现象在雷达图像中主要呈现为条带状或斑块状的结构。这些条带状或斑块状的结构呈现出高度的自相似性或信息冗余。非局部平均方法能够衡量图像中不同图像块之间纹理结构的相似性,并利用图像的自相似性对图像进行去噪。但非局部平均去燥方法存在计算量巨大、计算耗时长的缺点,这几乎限制了其实际应用。本文采用一种自适应方法将雷达图像中的像素点区分为纹理区像素点和平坦区像素点。对纹理区像素点,采用较大的相似窗和搜索窗,对平坦区像素点,采用较小的相似窗和搜索窗,从而提高计算速度。进一步,本文基于计算统一设备并行架构（CUDA）技术,利用计算机图形处理器（GPU）对前述算法进行并行加速。与经典非局部平均算法相比,加速后算法的计算效率提高了200倍。  相似文献   

Hydrochemical characteristics and controlling factors of natural water in the border areas of the Qinghai-Tibet Plateau     

Tian  Yuan  Yu  Chengqun  Zha  Xinjie  Gao  Xing  Dai  Erfu 《地理学报(英文版)》2019,29(11):1876-1894

Journal of Geographical Sciences - The special geography and human environment of the Qinghai-Tibet Plateau has created the unique hydrochemical characteristics of the region’s natural water,...  相似文献   

CHANGE OF REGIONAL ECONOMIC DEVELOPMENT POLICY IN CHINA     

查彦玉 《中国地理科学(英文版)》1992,2(1):1-9

After 40 years of painstaking work, much improvement has been made in regional difference. The road of that development, however, is by no means a smooth one, full of setbacks and failure. The past forty years may be roughly divided into four stages: 1.a stage of rehabilitation and large scale transition towards the interior( 1949-1959), 2. the dispersion stage with an emphasis on the construction of the interior (1960-1977), 3. a stage of moving back to the coastland and relative concentration of constructions of large scale industries (1978-1980), and 4. a stage of taking the coastland as the focal point for regional development (since 1981). Since the late 1970s, China began to carry out what is known as the Open-door policy. Great changes have taken place in regional development policy.  相似文献   

Holocene palaeoflood events recorded by slackwater deposits along the middle Beiluohe River valley,middle Yellow River basin,China          下载免费PDF全文

Yuzhu Zhang  Chun Chang Huang  Jiangli Pang  Xiaochun Zha  Yali Zhou  Xiaqing Wang 《Boreas: An International Journal of Quaternary Research》2015,44(1):127-138

Palaeohydrological investigations were carried out in the middle Beiluohe River valley in the middle Yellow River basin. Palaeoflood slackwater deposits (SWDs) are natural records of overbank flooding and are often identified in the Holocene aeolian loess–soil profiles along the river valley. Three bedsets of palaeoflood SWDs were found within the mid‐Holocene Climatic Optimum palaeosol (S₀) on the right riverbank. Both the sedimentary and the analytical results, including magnetic susceptibility, grain‐size distribution and concentrations of chemical elements, indicate that these palaeoflood SWDs were deposited from the suspended sediment load of overbank flooding. We identified three episodes of extraordinary overbank flooding events. These hydro‐climatic events were dated to 7600–7400, 5800–5000 and 4200–4000 a BP, from optically stimulated luminescence (OSL) dating and pedostratigraphical correlation. The minimum flood peak discharges were estimated to have been between 12 600 and 14 100 m³ s^?1 using the slope–area method. These hydro‐climatic events are considered to be a regional expression of known climatic events and demonstrate that the mid‐Holocene climate was far from stable. These results show that the magnitudes of floods are highly sensitive to climate change in semi‐arid and sub‐humid regions with a monsoonal climate.  相似文献   

基于互联网的国土资源信息“申请—应答”服务系统构架   总被引：1，自引：0，他引：1  

查宗祥  贾文珏 《国土资源信息化》2009,(2)

本文在分析当前国土资源信息服务模式的基础上,针对现有模式难以满足的国土资源信息服务需求,提出了国土资源信息"申请—应答"式服务模式,设计了一个基于互联网的国土资源信息"申请—应答"式服务系统,并成功应用于土地登记信息查询服务。  相似文献   

考虑历史洪水资料的期望概率权重矩法参数估计统计试验研究          下载免费PDF全文

王俊珍  宋松柏 《水文》2014,34(1):7-13

为有效利用历史洪水资料,提高洪水资料系列参数的估计精度,研究期望概率权重矩法在广义极值分布参数估计中的应用。采用蒙特卡洛试验研究期望概率权重矩法的统计特性,并与部分概率权重矩法做比较。结果表明:期望概率权重矩法具有良好的稳定统计特性,并且是具有历史洪水资料系列进行参数估计的一种简单、稳定和有效的参数估计方法,具有推广意义。  相似文献   

ECO-ENVIRONMENT CHANGE AND SOIL EROSION PROCESS IN THE RECLAIMED FORESTLAND OF THE LOESS PLATEAU     

ZHA Xiao-chun  TANG Ke-li 《中国地理科学(英文版)》2003,13(3):232-237

1INTRODUCTIONSerioussoilerosionhasmadetheeco-environmentfragileintheLoessPlateau.InthemodernsoilerosionoftheLoessPlateau,theman-madeerosionwasthedominanterosionpattern (TANGetal.,1993a,1993b).Manyhumanactivitiesacceleratesoilerosion,butthemostinfluentialactivitiesaretodestroyforestandgrass,eventodestroyallvegetation.Reclamationbydestroyingforestlandandgrasslandartificiallycouldrapidlyincreasesoilerosionintensityinshorttimeandenlargeerosionspacegradually,evenchangeerosiondirectionandwor…  相似文献   

柴北缘西端冷湖盐场北山辉长岩地球化学及年代学研究   总被引：2，自引：0，他引：2       下载免费PDF全文

董增产  辜平阳  焦和  查显锋  陈锐明  张海迪 《地质科学》2014,49(4):1132-1149

柴北缘冷湖盐场北山镍铜矿区发育辉长岩和角闪辉长岩;属亚碱性岩石系列。球粒陨石、 原始地幔标准化曲线呈两组特征;但配分型式基本一致;反映其来自同一源区。稀土标准化曲线表现为弱右倾型;Eu基本无异常;说明斜长石分离结晶作用不明显。Rb、 Nb、 Zr、Cr等微量元素丰度及比值具有近似平行部分熔融的演化趋势。结合岩体Mg^#值和岩体固结指数（SI）高等特点;揭示原始岩浆具有幔源原生玄武岩浆特征;认为其成因与俯冲板片流体交代地幔楔源区的部分熔融有关;而且;Nb、 Zr、 Y元素丰度表明辉长岩源区为过渡型地幔。另外;两类岩体强烈亏损Nb、 Ta、 Zr、 Hf、 Ti等高场强元素（HFSE）;富集Ba、 Th、 U、 Pb等大离子亲石元素;反映明显的消减带和岛弧环境岩浆岩典型特征。LA-ICPMS锆石U-Pb测年结果表明辉长岩形成于254±3 Ma;结合该时期区域地质构造背景;认为柴北缘晚二叠世处于俯冲作用之下的岛弧构造环境;具有活动大陆边缘性质。  相似文献   

Source model of the 11th July 2004 Zhongba earthquake revealed from the joint inversion of InSAR and seismological data     

Don Helmberger 《地震学报(英文版)》2011,(2):207-220

We use interferometric synthetic aperture radar (InSAR) and broadband seismic waveform data to estimate a source model of the 11th July, 2004 M W 6.2 Zhongba earthquake, Tibet of China. This event occurred within the seismically active zone of southwestern Tibetan Plateau where the east-west extension of the upper crust is observed. Because of limitations in one pair of InSAR data available, there are trade-offs among centroid depth, rupture area and amount of slip. Available seismic data tightly constrain ...  相似文献