南京汤山地区的地貌与岩溶发育演化

岩性和构造控制了南京汤山地区的地貌格局和碳酸盐岩山地岩溶地貌发育。研究表明,汤山地区岩溶演化具有长期性、多代性和继承性的特点,石炭纪中晚期及此前发育了第一期岩溶洞穴,三迭纪末至早侏罗纪是古岩溶最为发育的时期,晚第三纪以来进入了现代岩溶发育阶段。著名的南京直立人洞穴形成于晚第三纪之后。     

南京葫芦洞石笋生长速率及其气候意义讨论

一支连续发育4?000年纹层的末次盛冰期葫芦洞石笋的年际生长速率与高分辨率δ¹⁸O曲线对比分析表明,年际生长速率在不同时间尺度上对年均温和地表有效湿度的变化有着复杂的响应关系。对该洞内持续发育3~4万年的两支单体石笋实测了33个²³⁰Th年龄,其生长曲线显示MIS 2比MIS 3阶段平均生长速率增大了40%以上。以5000年为步长的同一洞穴17支石笋生长频率支持平均生长速率的研究结果,说明在轨道尺度上较大的石笋生长速率并不完全指示较暖湿的气候条件。作者认为,年际尺度的连续生长速率是决定石笋平均生长速率的关键因素。盛冰期条件下本区洞穴内外的温差效应导致了24~14ka B.P.年际尺度的石笋连续生长。     

南京幕燕山地森林植被恢复重建研究

在大量野外工作的基础上,借助AutoCAD技术,运用植被生态学、恢复生态学的原理与方法,对幕燕山地森林植被的恢复与重建进行了研究。建立了幕燕山地植被分类系统,包括3个植被型组、5个植被型、5个植被亚型、8个群系组、12个群系,绘制了幕燕山地1∶5000植被群系图,计算了幕燕山地各群系的面积。分析了南京地区山地森林植被10个主要群系(青冈+栓皮栎林,枫香林,白栎林,栓皮栎林,麻栎林,黄连木+黄檀林,朴树+构树林,刺槐林,马尾松林,黑松林)间的演替关系,构建了南京地区森林植被次生演替模式。根据上述研究结果,提出了幕燕山地森林植被恢复重建的关键措施,预测了上述措施实施后幕燕山地植被类型构成的变化,并绘制了幕燕山地森林植被恢复重建规划图(1∶5000)。     

Holocene evolution of meander bends in lowland river valley formed in complex geological conditions (the Obra River,Poland)

Ground‐penetrating radar surveys, coring and the analyses of satellite and aerial images have been carried out to study differences in the evolution of meander bends formed in various geological conditions. The research was conducted in the lower course of the Obra River (western Poland) characterized by a complex geology: particular sections of the valley were formed in glacial, stagnant water and fluvioglacial deposits. The research was conducted in four detailed study sites representing different formation conditions for the meander bends. Four types of meanders were distinguished: laterally migrating bends characterized by frequent changes of migration direction accompanied by river bed avulsions and cutoffs; bends with traces of continuous migration limited by stagnant water basin deposits; confined meanders in a narrow valley formed in glacial till characterized by the occurrence of mid‐channel islands; and meanders with traces of complex changes of the river bed migration influenced by anthropogenic intervention followed by intensive overbank deposition. Moreover, traces of an early development of the Obra valley and remains of multi‐channel pattern were discovered. The results also show that despite being formed in different geological conditions, a similar number of the meander migration phases were recorded in the floodplain architecture during the last 7000 years at each of the sites. It is also found that the development of the studied meanders was slow compared with cases of actively migrating meandering rivers.     

基于GWR的南京市住宅地价空间分异及演变

以南京市主城区为例,在空间自相关分析和蒙特卡罗检验的基础上,构建城市住宅地价地理加权回归模型,通过2003 年、2009 年住宅地价空间分异的对比,探讨不同影响因素对住宅地价影响的空间差异性及其随时间变化的特点,揭示住宅地价及其影响因素的空间变化关系,以促进地价的科学化管理。研究表明：① 随着影响因素数量不断增加以及合理均衡分布,区域差异性缩小,一般会减弱其对地价的影响。② 随着交通条件的不断完善,导致影响因素如CBD、主干道、公交等对地价的影响程度和范围发生变化。③ 随着时间推移,城市居民逐渐注重生活质量、居住品位的提高,公园绿地对地价的影响程度超过其他公用设施。     

基于GPR图像的河北昌黎海岸横向沙脊北段沉积构造及其成因

运用探地雷达对河北昌黎海岸带横向沙脊的沉积构造进行探测,通过对探地雷达探测影像进行处理与解译,获得海岸沙丘约20 m深度范围内的海岸横向沙脊沉积构造图像,包括沉积层理的倾向、倾角与平面展布信息等。研究发现,昌黎海岸横向沙脊北段的沉积构造主要由高角度交错层理和波状交错层理组成,两者之间界面应为古海滩沿岸沙坝的顶面。界面以上发育稳定的向SWW倾斜的高角度交错层理,倾角约为30°~32°,为向岸风作用形成的前积层理;横向沙脊的丘顶可见槽状交错层理,可能是沙丘脊顶部沉积作用对风向季节性变化的响应。界面以下波状交错层理发育,为波浪作用形成的海滩沉积构造。结合前人对探测区地层调查以及全新世晚期以来海岸线变迁研究成果综合分析,认为海岸横向沙脊是大约2000 aBP以来,以澙湖海滩沿岸沙坝为基础经长期风力吹扬作用持续增长而发育的风成沙丘。     

The Fractal Characteristics of Drainage Networks and Erosion Evolution Stages of Ten Kongduis in the Upper Reaches of the Yellow River,China

The fractal characteristics of drainage in the ten kongduis of the upper Yellow River were obtained using the box counting dimension, and the evolution stages of the watershed topography were defined by different ranges of the fractal dimensions of river networks (Dg). The results show that the fractal scaleless range of the Maobula River is 20–370 m based on a combination of artificial judgment, correlation coefficient test and fitting error. Other kongduis show good fractal characteristics in this fractal scaleless range as well. The box counting dimension can be used as a quantitative index of watershed topography fractal characteristics. The fractal dimension of stream networks is independent of the threshold contributing area used for extracting the drainage networks from the DEM. The values of Dg in the upper ten kongduis are in the range of 1.08?1.14. Both the runoff yield and the sediment yield are positively and linearly related with Dg. The positive relation between the sediment yield and Dg reflects the effect of landform features on sediment yield in the young and/or mature stages of landform evolution of the study area. By revising the critical value of Dg, the value of Dg of the basin in the young evolution stage is less than 1.06, while it is more than 1.06 for the basin in mature or old evolution stage. The upper ten kongduis are in the mature stage of landform evolution.     

中国西北部新疆地区沙漠的形成与演化——Ⅱ.古环境重建(英文)

Based on the palaeoclimatic and palaeoenvironmental evidences of geological history and human history periods, this paper reviews the researches and progresses on the development of the sandy deserts in Xinjiang. It pointed out that the features of tectonic structure in Xinjiang had made both the Tarim Basin and the Junggar Basin being influenced greatly by the foehn effects originated from the planetary wind system of westerly, the East Asian ocean-continental monsoon and the topographical mountain-valley winds. The regional patterns of climate and environment since the Quaternary were characterized by the overall persistent drought accompanied by fluctuations in the secondary scale. Formations of aeolian sediments in the basins and at the margins are a potential response to global climate change, particularly the aridification of the Asian hinterland deduced by the uprising of the Tibetan Plateau and its surrounding highlands. For the question about the formation time of the Taklamakan Desert, because the research methods, objects and information carriers used in previous studies are different, there are many disputes in the academic circles at present. Evidences from aeolian deposits/rocks at the edge and in the hinterland of these sandy deserts and their chronological data indicate that an arid climate and land surface aeolian processes have occurred at the edge of the Tarim Basin and its hinterland areas since the Tertiary period. However, the duration time of these processes at mass scale should have begun after the middle Pleistocene and lasted to the Holocene. Occurrence of dune fields in recent 2000 years in the oasis areas should be greatly influenced by human factors.     

Causes, effects and control of seasonal frost action in railways

Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain track geometry. Challenges culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased track maintenance and need for temporary speed restrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on non-frost-susceptible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and subsoil in frost action. In new construction the material specifications, design procedures and construction methods have been developed to ensure adequate performance of track substructures, but special challenges exist in managing existing tracks that were not designed for modern requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on integration of track geometry and ground penetrating radar (GPR) data has been developed and is summarized in this paper.