Structure and governance model of rural social space quality: A case study of Longxi County in the Loess Hilly Area of China

Journal of Geographical Sciences - The rural social space quality is an important indicator to measure the living standard and thinking ideas and so forth of rural residents in a certain region. In...     

Research Status and Advances in Chert and Permian Chert Event

Cherts are concret research objects for petro-tectonic framework and are widespreadly distributed in special sedimentary environments along orogenic belts and depositional basins. Cherts hold abundant origin related information, which plays important role in palogeographic and paleooceanograpic study. This paper reviewed the history and the advancement of research on chert, especially paying more attention to the research progress about both bedded chert and nodular chert in domestic and international research areas. Combined with Permian cherts distribution in China, we discuss research achivements of silica sources, sedimentary environments and original mechanism from cherts deposited in different sedimentary environments such as oceanic rift, oceanic basin and continent shelf. “Permian Chert Event” (PCE) has been used to discribe the widespread biogenic Permian cherts that occurred around the eastern margins of Panthalassa and Paleotethys Ocean. Research results on Permian cherts in eastern Paleotethys Ocean, particularly the Yangtze areas, are examined here, which suggest Permian cherts are not typically biogenic in origin but severely influenced by hydrothermal sedimentation. The seasonal melting of sea ice is assumed engine for PCE in northwest edge of Pangea Supercontinent, but that dose not work in China. Therefore, a hypothesis different form thermohaline circulation and upwelling is proposed here: there would be a periodical hydrothermal fluid system in the eastern Paleotethys Ocean, providing the source of silica for the development of Permian Chert Event on both south and north continent shelves. What is more, some intensively studied Permian outcrops in the Yangtze areas have the potential to be the typical outcrops for PCE research in China.     

中国西南纵向岭谷区孢粉空间组合对阻隔作用的指示意义

35 surface soil samples and 28 profile soil samples were collected in Longitudinal Range-Gorge Region, Southwest China. The distribution of pollen and spores and their relationship with the environment are analyzed. The results show that there are significant differences in pollen and spores taxa, amounts, dominant taxa and florae between the eastern and western flanks of the Ailao Mountain. There are more pollen and spores taxa, a greater amount and complexity on the western flank of the mountain than those on the eastern flank, while the dominant taxa are more centralized and prominent on the eastern flank of the Ailao Mountain. As for the plant florae distribution, there are significant differences in the number of taxa and composition between the eastern and the western flanks. The analysis of profile pollen and spores assemblage shows that its trends of variation are basically in accordance with the surface pollen and spores, which are also indicators of the environmental differences between the two flanks of the mountain. These significant spatial differences of pollen and spores are very close to the regional topography and climate difference. The mountain running perpendicular to the moisture-laden air flow serves as a barrier and the monsoon circulations the east and the west of the mountain result in different energy-moisture characteristics. We conclude that the main patterns of the pollen and spores can be attributed to the environmental differences.     

GIS Web Services技术在地下水取水许可管理系统中的应用

主要以地下水取水许可管理系统为例研究和探讨了基于GISWebServices的分布式电子政务系统的设计与实现。该电子政务系统具有和GIS系统无缝集成的优点,可以实现跨平台和异构系统无缝集成,实现了分布式计算。     

A Study of Monitoring,Simulation and Climate Impact of Greenland Ice Sheet

Greenland Ice Sheet is one of the two largest ice sheets on the planet. Under the background of climate warming, the melting of the Greenland ice sheet and its contribution to sea level rise has become an international hot issue. The whole melting of the Greenland ice sheet can cause the global sea level to rise by about 7.3 meters. However, the dynamic mechanism that affects the mass balance of ice sheet is still unclear and is the greatest uncertainty source for predicting the rise in sea level in the future. The National Key Research and Development Program of China “A Study of the Monitoring, Simulation and Climate Impact of Greenland Ice Sheet” conducts monitoring and simulation studies on the key processes of instability of the “ice sheet-outlet glacier-sea ice” system, and establishes a satellite-airborne-ground integrated observation system, supporting the numerical simulation and impact research of the ice sheet and its surrounding sea ice, laying the foundation for long-term monitoring and international cooperation in Greenland. This program will work to reduce the uncertainty of sea level change projections by improving the ice sheet dynamic model forced by the ice core records, reveal the driving mechanism of sea ice changes around the ice sheet, focusing on the Northwest Passage, evaluate and forecast the navigation window period. The results of the project will deepen the understanding of the changes and impacts of the Arctic cryosphere, serve the safe navigation and operation of the Northwest Passage, and provide scientific support for the comprehensive risk prevention of coastal zones in China.     

非洲乍得盆地玄武岩K-Ar和39Ar-40Ar年代学及其动力学背景

乍得的Doba、Bongor和Lake Chad盆地是早白垩世中非右行走滑应力场控制下形成的一系列中新生代陆内拉分盆地,形成与中、赤道及南大西洋打开有关。钻井揭示了盆地内分布有大量的中新生代玄武岩。系统的K-Ar、Ar-Ar法年代学研究发现,至少可识别出2个周期的火山活动旋回,即（1）95-75Ma,只分布于Doba盆地;（2）66-52Ma,分布于Bongor和Lake Chad盆地。研究表明,乍得盆地内中新生代火山活动是板内伸展应力机制下的产物,与白垩纪整个西中非地区的区域构造背景相一致,岩浆作用与裂谷作用密切相关。     

激发极化法在甘肃瓜州县辉铜山铜矿外围隐伏铜矿勘查中的应用

通过分析辉铜山铜矿体特征及矿山开采时深部找矿成果,发现矿体具SE向倾伏趋势,地表被大面积第四系覆盖。对测区岩(矿)石进行物性测量,发现区内矿石具高极化中低阻电性特征,与围岩电性差异明显,可用激发极化法进行深部地球信息探测。在1∶1万矿区地质填图基础上,采用激电中梯和激电测深2种方法进行矿产勘查,圈定2处明显的激电异常。结合区内地质特征和钻孔资料,发现高极化中低阻激电异常与推测的隐伏铜矿体具良好的空间对应关系,显示该矿区具良好的深部找矿潜力,为进一步详查工作提供了依据。     

山东半岛近海不同粉砂粒级含量分布的空间差异性及其沉积学意义

粉砂是现代陆架和河口沉积物最主要的粒级组分,但由于其复杂的沉积动力学行为,我们对于不同粉砂粒级的沉积学特征和行为并没有完全掌握。本文分析了山东半岛近海表层沉积物中不同粉砂粒级组分含量的空间分布特征,探讨了其控制因素。结果表明,山东半岛周边近海沉积物类型以泥质沉积为主,但不同粉砂粒级组分具有明显的空间分布差异性。极细粉砂、细粉砂与黏土组分的含量变化一致,表明了其相似的沉积动力学行为。粗粉砂组分的含量空间变化最大,在山东半岛的北部泥质条带、东部“泥楔”和南部近岸具有明显的高含量,其含量与其他各粉砂组分具有明显的负相关性。从表层沉积物的粒度组分与分布规律,可以证明研究区表层沉积物主要以黄河携带物质为主,但流入本区的一些中小型河流也明显提供了部分物源,只是其提供物质的扩散范围有限。结合水动力分析和物理海洋学等方面的认识,我们认为造成不同粉砂组分空间分布差异性的原因主要受物源、区域水动力学条件、局部地形（底形）等因素控制。另外,还发现了山东半岛“泥楔”沉积物的粗粉砂组分含量偏高、现代沉积速率也偏大,这些现象在空间上与“海洋锋面”位置一致,对于海洋锋面的沉积学意义还需要进一步的调查研究和数值模拟工作。     

Influence of Spur Dike on Hydrodynamic Exchange Between Channel and Shoal of Generalization Estuary in Physical Model Test

Widely applied in maintaining estuarial waterway depth, the spur dike has played an important role in currents and sediment exchange between channel and shoal and sediment back-silting in the channel. Through establishing a generalized physical model at a bifurcated estuary and conducting current tests under the joint action of runoff and tide, the influence of the spur dike length on current exchange between channel and shoal is analyzed. Results show that when the spur dike length reaches a certain value, the direction of the flow velocity shear front between the channel and shoal will change. The longer the spur dike, the larger the transverse fluctuating velocity at the peak of flood in the channel shoal exchange area, while the transport of the transverse hydrodynamics is obvious in the process of flood. There is an optimum length of spur dike when the shear stress in the channel and the longitudinal velocity in flood and ebb reach the maximum, and the flow velocity will decrease when the spur dike length is smaller or larger than the optimum. For a certain length of spur dike, the larger the channel shoal elevation difference, the larger the peak longitudinal flow velocity in the middle of the navigation channel in flood and ebb. However, the transverse flow velocity will first decrease and then increase. The transverse transportation is obvious when the channel shoal elevation difference increases.