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1.
Owing to the remoteness of the Longriba area and the lack of dating records,it is extremely challenging to reconstruct the chronology and extent of the paleoglaciers in this area.In this paper,we combined limited observational data with automated modelling for paleoglacial reconstructions.We first identified a broadly distributed paleoglacier from satellite imagery and field investigation based on the sediment-landform assemblage principle and dated it to 23.1±1.4~19.5±1.2 ka by 10Be exposure dating,corresponding to the global Last Glacial Maximum(gLGM).Then,we reconstructed the extent and ice surface of 171 paleoglaciers formed during the similar period based on geomorphological evidence and‘ice surface profile’modelling.The results showed that the paleoglacial coverage was 426.5 km2,with an ice volume of 38.1 km3,in the Longriba area.The reconstructed equilibrium line altitudes(ELAs)based on modelled ice surfaces yielded an average of 4245±66 m above sea level(asl),~725±73 m lower than the present ELA(4970±29 m asl).The temperature was~5.51-6.68℃lower,and the precipitation was~30-34%less in Longriba,during the gLGM compared to the present day.This glacial advance was mainly driven by colder climate that was synchronous with Northern Hemisphere cooling events.  相似文献   

2.
美国矿山环境治理   总被引:3,自引:0,他引:3  
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3.
本文分析研究了美国测绘的机制和特点,提出了对我国测绘发展的启示作用。研究结果表明:建立起完整的由地理空间数据、影像和信息数据库组成的全数字化地理信息系统,是实现智慧城市、军事作战、物联网、互联网+乃至智慧中国的重要基础之一。  相似文献   

4.
Current and temperature data from a one-year-long instrument deployment in the region just northeast of Cape Hatteras have shown the oceanic variability to be, intense and quite complex. Changes in the position of the Gulf Stream’s path were observed to occur following cold core Gulf Stream passages through the area. The time between these changes was a few months. The Gulf Stream jet itself was seen to meander in a manner previously observed, as long as it was not undergoing a strong ring/stream interaction. Several isolated vortices progressed through the array, with the majority of them being in the submesoscale coherent vortex class. Two mid-depth, anticyclonic warm eddies progressed through the array. It is likely the two events were caused by two different transits of the same eddy. The deep waters below the main thermocline oscillated as topographic Rossby waves progressed through the array area.  相似文献   

5.
为恢复百色盆地渐新世古植被面貌并重建古气候, 对该盆地伏平组孢粉化石进行了采样、分析、鉴定, 共获得孢粉化石34属, 并划分为2个组合: (Ⅰ) Abietineaepollenites-Quercoidites-Polypodiaceaesporites组合; (Ⅱ) Abietineaepollenites-Pinuspollenites-Pediastrum组合。组合Ⅰ时代为渐新世Rupelian中期; 组合Ⅱ时代为渐新世Rupelian晚期至Chattian早期。植被面貌变化为: 针阔混交林, 底部生长着蕨类植被→针叶林。通过孢粉组合属性特征的研究得出孢粉组合Ⅰ代表了亚热带湿润性气候, 湿度相对较大; 孢粉组合Ⅱ代表了亚热带较湿润性气候。通过共存因子分析得出: 在渐新世Rupelian中期至Chattian早期时间段内百色盆地年均降雨量(MAP)在797.5~1 293.7 mm之间, 年均温度(MAT)在11.3~22.6℃之间, 为北亚热带气候特征。而现在的百色盆地位于南亚热带(年均温度: 22.0℃, 年均降雨量: 1 070.5 mm), 二者的差异可能与新生代印度板块与亚洲板块碰撞所造成的亚洲板块"右旋"有关。   相似文献   

6.
Aircraft industry is very important to the economy and security of a country, and aircraft industry clusters have already existed in the world. Based on Input-Output data and Czamanski’s method, the aircraft industry clusters in China and USA were identified quantitatively in this paper. Furthermore, this article carried out comparison analyses of the identification results. The research finds out: 1) a mature aircraft industry cluster would be generally composed of 7 industrial subgroups, including aircraft industry, metal making and products manufacturing industry, machinery and equipment industry, electronics industry, automobile industry, material industry and others, and electronics industrial subgroup will play a more and more important role in the cluster; 2) in the range of industry-covering, the level of industry-linkage, and the economic performance, there is a tremendously large gap between the aircraft industry cluster of China and that of USA; 3) the spatial evolution of these clusters or centers is highly consistent with the diffusion of a country’s industrialization. Finally, based on those findings, the paper gives some advice on how to improve Czamanski’s method and what China should do to develop its own competitive aircraft industry: 1) China should employ institutional innovation, and turn to be market-oriented; 2) China should abandon the traditional pattern of closed-development, and strengthen the interaction and collaboration between aircraft industry and related industries, especially the electronics industry; 3) China should rectify and perfect its spatial development planning of aircraft industry.  相似文献   

7.
This paper proposes a scheme for detecting the swell decay of a moving typhoon. We considered a typhoon that was neither far from a point source nor had a belt-like homogenous source,as previously studied. We tracked the swell close to the source during a typhoon in the western North Pacific Ocean. We used wind speed and significant wave height data derived from the Geophysical Data Record of the Jason-1 altimeter and the best-track information of the typhoon from the China Meteorological Administration tropical cyclone database. We selected three specific cases to reveal the decay characteristics of the swell generated by a moving typhoon. Based on an altimeter-based typhoon swell identification scheme and the dispersion relationship for deep water,we relocated the swell source for each altimeter measurement. The subsequent statistical decay coefficient was comparable to previous studies,and effectively depicted the swell propagation conditions induced by the typhoon. We hope that our results provide a new understanding of the characteristics and wave energy budget of the North Pacific Ocean,and significantly contribute to wave modeling in this region.  相似文献   

8.
摘 要:中国南方地区下志留统龙马溪组富有机质页岩与美国阿巴拉契亚盆地中泥盆统Marcellus页岩,在形成构造背景、沉积环境方面具有一定的相似性,均形成于前陆盆地构造背景下的陆棚-斜坡浅海,沉积环境具有半封闭性。同时,二者也存在一定差异性,Marcellus页岩形成于前陆盆地早期快速沉降阶段斜坡带,其后期经历的构造变形相对较弱;中国南方龙马溪组页岩形成于前陆盆地持续沉降背景下,但其后期经历的构造改造作用多期复杂,其中四川盆地处于距离造山带较远的隆后凹陷构造位置,其除经历了频繁的升降运动外,挤压、拉张改造相对其周缘地区较弱。二者在具体地质特征方面也具有一定差异,主要表现在龙马溪组页岩埋藏较深、有效厚度大、热演化程度相对较高以及有机质含量相对较低。二者形成沉积构造背景以及地质特征的对比研究,对中国南方志留系龙马溪组页岩气进一步的勘探评价以及研究工作具有重要的指导意义。   相似文献   

9.
RECONSTRUCTIONOFPALEOVEGETATIONANDPALEOCLIMATEOFHOLOCENEHYPSITHERMALINTHEHEMUDUREGIONZhouZikang(周子康);XiaYuejiong(夏越炯);LiuWeil...  相似文献   

10.
美国作为地震多发国之一,在应对地震灾害时有其独到的“撒手锏”。  相似文献   

11.
Introduced species may outcompete or hybridize with native species, resulting in the loss of native biodiversity or even alteration of ecosystem processes. In this study, we reported an alien distromatic Ulva species, which was found in an embayment (Holly Pond) connected with Long Island Sound, USA. The morphological and anatomical observations in combination with molecular data were used for its identification to species. Anatomy of collected specimens showed that the cell shape in rhizoidal and basal regions was round and the marginal teeth along the basal and median region were not found. These characteristics were primarily identical to the diagnostic characteristics of Ulva laetevirens Areschoug (Chlorophyta). The plastid-encoding tufA and nucleusencoding ITS1 were used for its molecular identification. Phylogenetic analysis for the tufA gene placed the specimens from Holly Pond in a well-supported clade along with published sequences of U. laetevirens identified early without any sequence divergence. In ITS tree, the sample also formed well-supported clades with the sequences of U. laetevirens with an estimated sequence divergence among the taxa in these clades as low as 1%. These findings confirmed the morpho-anatomical conclusion. Native to Australia, this species was reported in several countries along the Mediterranean coast after the late of 1990s. This is the first time that U. laetevirens is found in the northeast coast of United States and the second record for Atlantic North America.  相似文献   

12.
运用GAMIT10.34解算成都地区的GPS可降水量   总被引:3,自引:0,他引:3  
基于麻省理工学院(MIT)2008年发布的GAMIT最新版(v10.34),就其在Linux操作系统上的安装方法以及解算天顶总延迟(ZI'D)和反演PwV的流程进行探讨,并以成都地区地基GPS观测网的运用为例,总结GAMIT软件的使用经验及注意事项。  相似文献   

13.
Magnetic susceptibility (MS) data were obtained from 11 sections of the Doushantuo (Ediacaran) cap carbonate that directly overlies the Nantuo glacial diamictite in the southeastern margin of the Yangtze platform. The MS data revealed two regionally correlatable peaks at the bottom and top of the cap carbonate, separated by an interval of low values. The lower MS peak coincides with high percentage of insoluble siliciclastic residues that are compositionally identical to the matrix of the underlying diamictite, suggesting its origin controlled mainly by detrital components during the first phase of cap carbonate deposition at the end of the glaciation. The upper MS peak is associated with high clay content and iron sulfides, and can be interpreted as either derived from enhanced greenhouse weathering that could have brought more terrigenous components into the ocean, or the result of ocean anoxia at the late stage of cap carbonate deposition that could led to formation of abundant iron sulfides. The regionally consistent MS curves from the cap carbonates provided the first geophysical record for the rapid climate change from icehouse to greenhouse conditions in the aftermath of the Neoproterozoic “snowball Earth” event.  相似文献   

14.
1 INTRODUCTION One of the most intriguing phenomena in the late Neoproterozoic (~750 to 543 Ma) is the globa occurrence of thin carbonates that directly overlie glacial deposits in almost every continent (Kennedy 1996; Hoffman et al., 1998; Hoffman and Schrag 2002; Brasier and Shields, 2000; James et al., 2001 Jiang et al., 2003; Nogueira et al., 2003). These “cap carbonates”, commonly several to tens of meters thick, have attracted enormous interests because o their unusually negati…  相似文献   

15.
Fine-grained disseminated carbonate was found in Holocene sediments in a core taken from the northern basin of Lake Baikal. The core had two distinct facies. a terrigenous blue-clay overlain by a diatomaceous silt. Oxygen and carbon stable isotope analyses, combined with SEM , X-ray diffraction and .palynology, show that the carbonate in the blue-clay layer is pedogenic in origin, rather than biogenic or authigenic . The S C values in the blue clay suggest that the carbonate is derived from a single source , while the carbonate in the diatom-rich layer might be transported by winds from different sources. On the assumption that the carbonate was formed during the post-glacial age and was transported primarily by river runoff, the 18O isotopic values suggest that the annual temperature in the northern Baikal drainage area was about 3℃ warmer during the middle Holocene (8500-7000 a, B. P.) than during the early Holocene (11 000-8 500a, B.P.) when the blue clay was being deposited . This interpretation is  相似文献   

16.
The 2nd Member of Kongdian Formation has been made up of a large number of oil shale and mudstone in the Kongnan aera of Huanghua depression around the Bohai Bay.In the Kongnan area,the lake basins were very large and deep during the deposition of the 2nd Member of Kongdian Formation.During that period,the lakes were sealed,uncommunicated with the sea water and the paleoclimate was very warm and wet in Kongnan area.Analyzing the content of the trace element and the rare earth element,carbon and oxygen isotope in the disquisition,The authors prove the two views correct.  相似文献   

17.
区域气候模式RegCM3对中国夏季降水的模拟   总被引:5,自引:0,他引:5  
利用意大利国际理论物理中心(ICTP)最新发布的区域气候模式RegCM3检验我国包括青藏高原地区夏季降水的模拟能力。初始值及边界值取自美国国家环境预测中心(NCEP)和国家大气中心(NCAR)的全球再分析资料。模式积分时间为2005年5月1日到2005年8月31日,考虑到模式的“spin-up”时间,只对6月1日-8月31日的模式结果进行分析。模式水平分辨率取为60km,范围包括整个青藏高原在内的我国及周边地区(14°-55°N,70°-140°E)。结果表明:RegCM3具有模拟我国夏季降水主要分布特征的能力,尤其在观测站点稀少的青藏高原地区可提供局地降水分布的较可靠信息。模式较好地模拟了包括整个青藏高原在内的我国区域降水的月际尺度变化和空间分布等基本特征,但对我国东南地区的夏季降水模拟能力有待进一步提高。  相似文献   

18.
19.
The relation between runoff and sediment and land cover is investigated in the Cedar Creek Watershed (CCW), located in Northeastern Indiana, United States. The major land cover types in this watershed are cultivated land, woodland and pasture /Conservation Reserve Program (CRP), which account for approximate 90 % of the total area in the region. Moreover, land use was changed tremendously from aooo to 9004, even without regarding the effect of the crop rotation system (corn & soybean). At least 49 % of land cover types were changed into other types in this period. The land cover types, ranking by changing area from high to low series, are rye, soybean, corn, woodland and pasture/CRP. The CCW is divided into 21 subwatersheds, and soil and water loss in each sub-watershed is computed by using Soil and Water Assessment Tool (SWAT). The results indicate that the variations in runoff and sediment have positive relation to the area of crops (especially corn and soybean); sediment is more sensitive to land cover changes than runoff; more heavy rainfall does not always mean more runoff because the combination of different land cover types always modify runoff coefficient; and rye, soybean and corn are the key land cover types, which affected the variation in runoff and sediment in the CCW.  相似文献   

20.
Glaciers in the western Nyainqentanglha Range are an important source of water for social and economic development. Changes in their area were derived from two Chinese glacier inventories; one from the 1970 1:50,000 scale Chinese Topographic Maps series and the other from Landsat TM/ETM+ images acquired in 2009. Analyses also included boundaries from 2000 and 2014 Landsat TM/ETM+ images. A continuing and accelerating shrinkage of glaciers occurred here from 1970 to 2014, with glacier area decreasing by 244.38 ± 29.48 km~2(27.4% ± 3.3%)or 0.62% ± 0.08% a~(–1). While this is consistent with a changing climate, local topographic parameters, such as altitude, slope, aspect and debris cover, are also important influences. Recession is manifested by a rise in the elevation of the glacier terminus. The shrinkage of glaciers with NE, N and NW orientations exceeded that of other aspects, and glaciers with SE and S orientations experienced less shrinkage. Changes in the average positive difference of glaciation(PDG) show that the western Nyainqentanglha Range has unfavorable conditions for glacier maintenance which is being exacerbated by a warming climate since 1970.  相似文献   

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