Present land use and cover patterns and their development potential in North Ningxia

With the objectives to acquire the fundamental data of the territorial resource, understand the impacts of human activities on the land use and cover patterns and evaluate the potential of the future exploitation, an intensive land cover classification with an accuracy of 93% has been completed for North Ningxia by remote sensing technique based on the adoption of a combination method composed of texture training, maximum likelihood classification and post-processing such as re-allocation and aggregation. This classification result was incorporated with the contemporaneous socio-economic and meteorological data for cross-sectional regression modelling to reveal the spatial determinants of the land cover patterns and understand the human-environmental relationships. A tentative evaluation on the potential of soil exploitation in the near future was carried out in combination with our land use and cover change detection results aiming at supplying some useful references for the central and local governments in their sustainable land use planning.     

基于像元二分模型的地表植被覆盖度估算模块化设计与实现

地表植被覆盖度是的一种应用广泛的定量遥感产品,在水文、生态、区域变化等方面都具有重要的意义。像元二分模型是应用最多的一种遥感估算地表覆盖度的方法。目前,用遥感的方法进行地表植被覆盖度估算没有完整、系统的工具,用户只能逐步进行操作,效率低下,鉴于上述情况,本文运用IDL交互式数据语言,基于ENVI二次开发了一个植被覆盖度估算程序,取得了一定的成效,对遥感定量产品的生产、应用具有一定意义。     

锡同位素研究进展及其在矿床学中的应用展望

锡同位素是一种新兴的非传统稳定同位素,其在考古学及天体化学中的运用显示出非常大的示踪潜力和价值,然而目前其在地质学(尤其是矿床学)中的研究和应用前景缺乏系统介绍.本文总结分析了世界上目前所发表的主要天然及人工样品的锡同位素数据,发现天然样品中锡同位素组成有较大差异,其中玻璃陨石最富重锡(其δ122/118 Sn值可达2.53‰),而黝锡矿(黄锡矿)最富轻锡(其δ120/116Sn值可达-1.71‰).其中,含锡矿物(如锡石和黝锡矿)中的锡同位素组成变化范围要远远大于全岩样品.地幔及地壳来源的不同岩性或地质体的全岩锡同位素组成有明显差别;锡同位素在一定条件下可以发生分馏,且分馏程度可能远远大于锡同位素的初始值差异.锡石锡同位素对成矿环境非常敏感,其形成时的流体成分、化学反应速率以及物化条件(如温度、盐度、氧逸度、pH值等)等因素均能影响其锡同位素的组成.深部流体(如岩浆来源)结晶的锡石富重锡,而浅部流体(如地层流体)的加入将使锡石富轻锡,因此锡石的锡同位素具有判别不同矿床成因类型的潜力.展望未来,锡同位素的研究有望在以下三方面取得突破:①各地球圈层锡同位素储库数据的精确测定;②矿物原位微区锡同位素的准确快速分析;③热液矿床锡同位素分馏机制的建立.聚焦岩浆-热液演化过程中含锡矿物的锡同位素组成变化,有望揭示含锡流体性质及物化环境,从成矿流体来源、演化、沉淀等角度探讨成矿过程中锡同位素分馏的控制因素及其示踪机制,建立复杂锡成矿系统中的锡同位素演化模型.系统的锡同位素研究可为深入认识多类型锡矿化的"源"、"运""储"过程提供新的思路,为判别有争议锡矿床的成因类型及成矿物质来源提供关键的锡同位素证据,进而为研究大规模锡多金属成矿作用提供全新的视角,具有重要的理论价值及现实意义.     

Mosaic desert pavement influences water infiltration and vegetation distribution on fluvial fan surfaces

Desert pavements (DPs) are critical for maintaining ecological stability and promoting near-surface hydrological cycling in arid regions. However, few studies have focused on eco-hydrological processes of DPs in the ecological systems of fluvial fans. Although DP surfaces appear to be barren and flat, we found that the surfaces are characterized by surface mosaic patterns of desert pavement (mosaic DP) and bare ground (mosaic BG). We investigated the effects of mosaic DP on water infiltration and vegetation distribution at six sites in fluvial fans (one on a hillside and five within the sectors of fans) along a southwest belt transect in northern Linze County, in the central Hexi Corridor (China). We found significant differences in mosaic DP between the hillside and sector sites in terms of pavement thickness and vesicular horizon thickness (Av thickness), particle composition, and bulk density, although significant differences were absent for mass soil water content, gravel coverage, and surface gravel size. The mosaic DP inhibited water infiltration by the pavement layer, where the sorptivity (S), initial infiltration rate (i_int), steady-state infiltration rate (i_sat) and infiltration time (T) averaged 1.19 cm/min^-0.5, 0.64 cm/min, 0.13 cm/min and 12.76 min, respectively. Where the pavement layer was scalped, the S, i_int, and i_sat increased by 0.27 cm/min^-0.5, 0.52 cm/min, and 0.40 cm/min, respectively, and the T reduced by 7.42 min. Water infiltration was mainly controlled by the pavement layer thickness (+), Av thickness (−), surface gravel coverage (−), fine earth (+) and fine gravel (−) in the pavement layer. The DP surfaces only had a sparse covering of shrubs, but an abundance of herbs. Few shrubs were present on the mosaic DP, but a greater number of shrubs and herbs grew on the mosaic BG. It can be concluded that DPs can maintain vegetation stability for different surface mosaic patterns. This study deepens our understanding of the eco-hydrological cycle of DP landscapes in arid regions.     

三叠纪牙形石的古环境与古地理意义

牙形石广泛分布于寒武纪至三叠纪的海洋里。三叠纪牙形石的种类、形态、大小和产出频率受海水盐度、深度、温度和水动力条件等因素控制，不同的牙形石生态特征即牙形石相反映不同的沉积环境，所以，根据三叠纪牙形石相和牙形石特征属种的丰度，不但可区分三叠纪不同的沉积相区（台地相区、台地边缘相区、盆地相区），恢复三叠纪古地理面貌，而且可划分出牙形石生物地理区。中国早三叠世牙形石归属特提斯生物大区亚洲生物省，并可进一步划分出两个生物亚省和若干生态区。     

辽东湾辽东带中南部古近纪古地貌恢复和演化及其对沉积体系的控制

采用井-震联合地层恢复法，对辽东湾辽东带中南部的古近纪进行了古地貌恢复。在此基础上拓宽了坡折带研究，将古地貌（包括古坡折带、古沟谷、古凸起等）纳入古物源供给系统的框架内探讨其对沉积体系的控制作用。分析表明：在构建完整物源供给系统的前提下，古地貌诸单元及其组合样式对沉积体系有着明显的控制作用。主要表现为：不同级次的物源体系导致沉积体类型和规模存在差异；物源区沟谷的分布及其赋存时期制约着砂体的主要分布位置、时期及规模；坡折带样式决定砂体的类型、规模及分布；古地貌组合样式控制储集体的成因、富集位置和规模大小。因此，古地貌分析对储层的预测和识别具有明显的指导作用。勘探实践证明，将其与常规储层预测方法联用，能够很大程度地提高储层预测的精度。     

SWAN雷达产品在甘肃河东地区冰雹短临预报中的应用

选取2011年7月发生在甘肃省河东地区的7次冰雹个例,综合分析SWAN系统输出的雷达产品资料的主要特征,提取冰雹天气的雷达产品资料的指标,根据这些指标利用SWAN系统外推算法资料生成冰雹临近预报产品。通过2012年甘肃河东地区的2次冰雹天气过程对与其同时的临近预报产品检验结果表明,预报效果良好,具有较高的业务应用价值。     

兰州新一代天气雷达数据误差来源分析

新一代天气雷达目前已经成为对兰州市及周边地区短时强烈天气进行监测的主要手段之一。为了方便资料的处理和分析,提高观测资料准确度,为预报员和科研人员分析资料提供方便,通过对雷达数据前端生成和后端处理传输2个过程的分析,找出兰州新一代多普勒天气雷达数据误差的来源,并进行分析,发现地物回波、雷达天线增益、测量距离等因素和数据插值、坐标转换、远距离多终端传输等因素分别是前端数据产生过程中和后端数据处理传输过程中数据误差的主要来源。