西藏谢通门县德新铅锌矿地质特征及找矿标志

德新铅锌矿位于西藏自治区谢通门县,地处西藏冈底斯Cu、Mo、Pb、Zn、Au、Fe成矿带中段。矿体主要赋存于岩浆岩与第三系火山岩的接触带,地层、岩浆岩控制了矿体的总体展布方向和空间位置。早期东西向构造对成矿起了导矿作用,晚期近南北向、北西、北东向构造是主要的容矿、储矿构造。属标准的地层、构造、岩浆岩＂三位一体＂的成矿模式。矿床成因可能属火山隐爆角砾岩型。本文提出了区内8条找矿标志。     

Determination of 3-D Velocity Anomalies of the Nanbei Tectonic Zone of China Based on Local Earthquakes

In this paper, 3-D velocity images of the crust and upper mantle beneath the Nanbei tectonic zone of China are constructed using P-wave travel time residuals of earthquakes, with the data supplied by China's seismic networks and the International Seismic Centre.During the model parameterization in the tomographic inversion the interpolation function of grid node velocities is used as the space function of velocity, and the velocity function is allowed to be discontinuous. The difficulties caused by large memory demand and high computing cost in solving the system of equations are avoided by utilizing the least squares QR decomposition algorithm. Thus, the stability of the algorithm is ensured. Though resolution images are not derived in the inversion process based on the resolution theory of Backus and Gilbert, a covariance resolution method is put forward by the authors. The resolution analyses have proved the reliability of the image results. 3-D ray tracing is conducted to obtain the ray paths in a s     

Temporal variation in soil detachment under different land uses in the Loess Plateau of China

Measurements of temporal variations in soil detachability under different land uses are badly needed to develop new algorithms or evaluate the existing ones for temporal adjustment of soil detachability in continuous soil erosion models. Few studies have been conducted in the Loess Plateau to quantify temporal variations in detachment rate of runoff under different land uses. The objectives of this study were to investigate the temporal variations of soil detachment rate under different land uses and to further identify the potential factors causing the change in detachment rate in the Loess Plateau. Undisturbed soil samples were collected in the fields of arable land (millet, soybean, corn, and potato), grassland, shrub land, wasteland, and woodland and tested in a laboratory flume under a constant hydraulic condition. The measurements started in mid‐April and ended in early October, 2006. The results showed that soil detachment rate of each land use fluctuated considerably over time. Distinctive temporal variation in detachment rate was found throughout the summer growing season of measurement in each land use. The maximum detachment rates of different land uses varied from 0·019 to 0·490 kg m^–2 s^–1 and the minimum detachment rates ranged from 0·004 to 0·092 kg m^–2 s^–1. Statistical analysis using a paired‐samples t‐test indicated that variations in soil detachment rate differed significantly at the 0·05 level between land uses in most cases. The major factors responsible for the temporal variation of soil detachment were tillage operations (such as planting, ploughing, weeding, harvesting), soil consolidation, and root growth. The influence of tillage operations on soil detachment depended on the degree of soil disturbance caused by the operations. The consolidation of the topsoil over time after tillage was reflected by increases in soil bulk density and soil cohesion. As soil bulk density and cohesion increased, detachment rate decreased. The impact of root density was inconclusive in this study. Further studies are needed to quantify the effects of root density on temporal variations of soil detachment. This work provides useful information for developing temporal adjustments to soil detachment rate in continuous soil erosion models in the Loess Plateau. Copyright © 2009 John Wiley & Sons, Ltd.     

地震剖面中走滑断层旋向判断模型——以塔东阿拉干北断层为例

地震剖面解释中尚无走滑断层旋向的直接判别标志,本文提出了一个在地震剖面解释中直接判断走滑断层旋向的模型。该模型假定断层作用前既存的某个地层厚度有变化,则垂直或斜交地层厚度变化方向的走滑断层必定在穿过断层的地震剖面中两盘地层厚度不等。确定了地层厚度变化方向,又测定了剖面中两盘地层厚度,则走滑断层的旋向就可以唯一地确定下来。穿过塔里木盆地东部阿拉干北右行走滑断层的地震剖面资料证实了这一模型的适用性。     

不同排列方式和间隙比下双圆柱流致振动特性研究

采用基于ALE的流固耦合分析方法,将圆柱体振动模型简化为平面双自由度质量-弹簧-阻尼系统,进行了计算参数无关性分析。对不同θ角和间隙比T下的双圆柱流致振动进行数值模拟,并与单圆柱振动计算结果进行比较,得到了不同θ角和间隙比T下中心圆柱的升阻力系数、流场分布和运动轨迹变化情况。通过分析发现小间隙比下由于两圆柱间的相互干扰,改变了中心圆柱的尾涡结构,导致了升力和阻力系数随不同θ角而发生变化;小间隙比下由于两圆柱间的相互干扰影响,均使中心圆柱的轨迹在不同θ角下发生了较大的变化,顺流向的振动频率与单圆柱振动时相比出现了多倍频,导致其运动轨迹发生了变化。     

非线性弹性地基上矩形薄板的主参数共振

分析非线性弹性地基上受参数激励小挠度矩形薄板的主参数共振问题,由冯卡门方程和伽辽金方法得到系统的非线性振动方程,它是杜分-马休型方程,应用非线性振动的多尺度法得到平均方程。数值计算结果表明：阻尼系数、地基系数、几何参数对主参数共振曲线影响明显。     

丝绸之路沿线的兰州城市空间演变及其影响因素

丝绸之路沿线的城市是丝绸之路文明演变的聚焦和投影, 研究历史时期丝绸之路沿线城市空间演变及影响因素是理解丝绸之路沿线城市发展的有效视角, 对解释丝绸之路沿线人地关系规律具有科学意义。本研究以兰州市作为丝绸之路沿线典型城市, 以历史文献资料为基础, 结合空间分析技术对历史时期兰州城市空间演变及其影响因素进行分析, 得出以下结论: 丝绸之路的兴衰与兰州城市空间演变的扩张呈现正相关性, 兰州的行政建制始于秦始皇三十三年(214 BC), 隋文帝开皇元年(581 A.D.)"兰州"首次见于诸史册, 兰州城市空间由隋唐时期(907 A.D.)的0.40 km2增加到2015年的132.67 km2。历史时期兰州城市空间演变包括4个主要阶段: 城市萌芽期的"缓慢发展", 军事职能主导下的"约束性"扩张, 王朝兴盛所带动的"年轮式"增长, 国家政策推动的"跨越式"扩展。影响兰州城市空间演化的因素涵盖丝绸之路兴衰、军事政治、交通贸易及自然环境等, 各种影响因素共同驱动着兰州城市由早期的黄河渡口、军事据点向西北地区政治、经济、文化、交通中心演变。     

基于WRF驱动的CLM模型对青藏高原地区陆面过程模拟研究

NCAR-CLM是目前国际上发展较为完善的陆面过程模型.鉴于大多数研究利用气象站点的数据驱动CLM模型, 尝试将WRF气候模型的模拟结果作为驱动CLM的面上强迫场数据来对青藏高原陆面能量特征进行模拟研究.对WRF气候模型模拟的输出结果与青藏高原气象站观测数据进行比较分析表明, WRF模拟输出的气温和向下短波辐射数值与观测值的相关系数大于0.92(p >0.05), 气压和比湿的R²在0.80以上(p >0.05), 降雨和风速的模拟性能不稳定, 但WRF模拟输出的强迫场也可以作为CLM模型的驱动数据. CLM模拟的地表温度、 感热和潜热通量与青藏高原气象站观测的地表温度以及涡度通量数据验证分析表明, 虽然CLM对地表温度的模拟在合理范围内, 但模拟与观测值还是有较大偏差, 潜热和感热之间的相关系数分别为0.87和0.68(p >0.05), 表明CLM的模拟结果在单点上是可靠的.据此, 在此模拟结果基础上分析了青藏高原地区的陆面能量时空分布特征.     

阿拉善高原古湖岸堤释光测年与晚第四纪湖面变化

阿拉善高原位于现代西风环流与东亚季风环流过渡带,该地区分布的湖泊对全球性气候变化响应极为敏感,阿拉善高原广泛分布的古湖岸堤为较准确地重建晚第四纪湖泊水位变化提供了良好载体。近年对黑河、石羊河尾闾湖泊以及吉兰泰盐池、雅布赖盆地等地的古湖岸堤的沉积地层以及石英和钾长石释光测年研究,重建了不同区域较高分辨率的末次间冰期以来湖泊时空演化过程。发现早在300 ka以前阿拉善高原就已经形成了高水位湖泊,黑河尾闾额济纳盆地在MIS 11或更早、MIS 9、MIS 7、MIS 5和MIS 1形成了高湖面湖泊,高湖面湖泊形成存在100 ka的周期。阿拉善高原在末次间冰期及全新世形成了稳定高湖面湖泊,但间冰期内部湖面波动具有空间差异性,东部区域湖泊高湖面出现在MIS 5e~5c和中全新世,西部湖泊高湖面出现在MIS 5a~5c和晚全新世。湖面变化的空间差异性很可能与冰期-间冰期旋回尺度及间冰期内部东亚夏季风与西风气候系统在阿拉善高原的相互作用密切相关。

     

热带环流异常对1998年长江流域特大洪涝的影响

分析了造成1998年长江流域特大洪涝灾害的大尺度热带环流成因。指出1998年处在热带环流强度偏弱的气候阶段，西太平洋暖池地区对流活动偏弱，南海热带季风持续异常偏弱，副热带夏季风偏强度是造成长江持续强降水的主要原因；西太平洋热带对流层高低层环流系统的异常分布，为1998年长江特大洪涝提供了有利的环流背景，还探讨了热带环流异常影响换国夏季降水的可能途径，它们的关系在1998年夏季降水预测中得到应用。