金厂峪金矿床围岩蚀变特征与矿床成因     

秦大军  蔡新平  王杰  周以柏  祁学义  郝荣 《地质与资源》1999,8(1):7-14

为了更深入地理解金厂峪金矿床成矿作用,对该金矿床内蚀变围岩的矿物组合、成分及其变化进行了较详细的研究.蚀变带质量平衡分析表明Al₂O₃、MnO、P₂O₅等组分具不活动性.由蚀变围岩向钠长石英脉,在蚀变岩中元素无明显变化.钠长石英脉体的形成与围岩蚀变有关,但两者成因并不相同.金厂峪金矿床的形成可能与深源流体有关  相似文献   

Integrated urban and rural water affairs management reform in China: Affecting factors   总被引：1，自引：0，他引：1  

Dajun Shen  Bin Liu 《Physics and Chemistry of the Earth》2008,33(5):364-375

The institutional evolution is often induced by some factors. This paper intends to analyze the affecting factors in integrated urban and rural water affairs management reform in China. The integrated urban and rural water affairs management reform is to restructure the governmental organizational setting in water management by forms of water affair bureau or re-designing functions of current water resources bureau to incorporate part or all functions of resources management, service regulation and environment management in water sector. The analyses selected some natural and socio-economic factors. The results point out that the integrated urban and rural water affairs management reform is a factor-induced institutional evolution. The factors promoting this reform include occasional drought events, higher central water investment percentage; but the data from the urban sector do not provide the support to the reform.  相似文献   

Seafloor geodetic network establishment and key technologies     

Yang  Yuanxi  Liu  Yanxiong  Sun  Dajun  Xu  Tianhe  Xue  Shuqiang  Han  Yunfeng  Zeng  Anmin 《中国科学:地球科学(英文版)》2020,63(8):1188-1198

Seafloor geodetic network construction involves the development of geodetic station shelter, network configuration design, location selection and layout, surveying strategy, observation model establishment and optimization, data processing strategy and so on. This paper tries to present main technological problems involved in the seafloor geodetic network construction, and seek the technically feasible solutions. Basic conceptions of developing seafloor geodetic station shelters for shallow sea and deep-sea are described respectively. The overall criteria of seafloor geodetic network construction for submarine navigation and those of network design for crustal motion monitoring are both proposed. In order to enhance application performances of the seafloor geodetic network, the seafloor network configuration should prefer a symmetrical network structure. The sea surface tracking line measurements for determining the seafloor geodetic station position should also adopt an approximately symmetrical configuration, and we recommend circle tracking line observations combined with cross-shaped line(or double cross-shape line) observations for the seafloor positioning mode. As to the offset correction between the Global Navigation Satellite System antenna phase center and the acoustic transducer, it is recommended to combine the calibration through external measurements and model parameter estimation. Besides, it is suggested to correct the sound speed error with a combination of observation value correction and parameterized model correction, and to mainly use the model correction to reduce the influence of acoustic ray error on the seafloor positioning. Following the proposed basic designs, experiments are performed in shallow sea area and deep-sea area respectively. Based on the developed seafloor geodetic shelter and sufficient verification in the shallow sea experiment, a long-term seafloor geodetic station in the deep-sea area of 3000 m depth was established for the first time, and the preliminary positioning result shows that the internal precision of this station is better than 5 cm.  相似文献   

大、小兴安岭北部中生代火山岩区岩金矿床剥蚀程度的初步研究   总被引：1，自引：0，他引：1  

张宝林  蔡新平  王杰  徐兴旺  秦大军  高浩中 《地质论评》1999,45(7):414-421

大、小兴安岭北部中生代幔源火山岩发育,以中心式喷发为主,砂金分布面积广,是岩金成矿集中区,实现岩金找矿突破的关键是圈定有利的成矿构造部位和最佳保存条件。本文分析了火山岩区地质特征、火山活动的大地构造环境及其与金矿化的关系,从成矿元素组合、砂金成色分布规律、岩金矿床出露高度、残留火山机构等4个方面总结岩金矿床剥蚀程度的判别标志,并指出了岩金找矿方向。  相似文献   

太行山北段多金属矿床地球化学特征     

秦大军 《地质与资源》1997,6(3):161-170

太行山北段多金属矿床有3个金属元素富集带:1.中心(铜)钼矿带,形成斑岩型矿床;2.过渡带铁-铜、银-铜、铁和锌成矿带,形成矽卡岩型矿床;3.外带铅-锌-银带,形成脉状矿床.这种分带出现于多个矿区,但不同矿区显示出独特变化.一般以其中一个矿带最发育,其它两矿带次之,但有时也有两矿带相对发育.围绕花岗岩的金属元素区域分布,流体包裹体温度测定及H、O和S同位素分析结果,表明岩浆热液与冷的大气降水(含少量源于围岩的CO₂和H₂S)之间的混合作用可以解释金属元素沉淀及时空分带的形成.  相似文献   

Vertical structure of tidal currents in the Xuliujing Section of Changjiang River Estuary     

Zhigao Chen  Ya Ban  Xiaoye Chen  Dajun Li  Shengping Wang 《海洋学报(英文版)》2023,42(2):44-55

Three long-term fixed acoustic Doppler current profilers were first used for investigating the vertical structure of tidal currents in Xuliujing Section of Changjiang River Estuary. Moreover, three different periods(spring, summer and fall) were also considered for investigating seasonal variations. The semi-diurnal tides were the most energetic, with along-channel speed of up to 80 cm/s for M₂ constituent, which dominates at all stations with percent energy up to 65%–75% during seaso...  相似文献   

一种用于图像特征提取的改进ORB-SLAM算法     

张良桥  陈国良  许晓东  连达军  王睿 《测绘通报》2019,(3):16-20

针对复杂室内环境下视觉SLAM定位存在实时性差、轨迹漂移等问题，本文提出了一种基于图像特征提取方法的ORB-SLAM算法。该算法在前端中提高图像特征检测与匹配的效率和精度，引入闭环检测策略优化相机位姿轨迹，提高定位精度。以不同来源图像对比分析不同特征提取算法SIFT、SURF、ORB的有效性，运用该算法估计机器人运动轨迹，与真实轨迹相对位姿误差为0.144 8 m，试验表明所提出的方法切实可行，具有较高的稳健性。  相似文献   

Using hydrochemical,stable isotope,and river water recharge data to identify groundwater flow paths in a deeply buried karst system          下载免费PDF全文

Dajun Qin  Zhanfeng Zhao  Yi Guo  Wencai Liu  Muhammed Haji  Xiaohong Wang  Baodong Xin  Yu Li  Yong Yang 《水文研究》2017,31(24):4297-4314

The deeply buried river‐connected Xishan karst aquifer (XKA) in western Beijing, China, has been suffering from diminishing recharge for several decades, which in turn leads to the disappearing of spring water outflows and continuously lowering of groundwater level in the area. Thus, it is important to correctly recognize the groundwater recharge and flow paths for the sustainable development of the XKA. To investigate these issues, the hydrochemical and isotopic compositions are analysed for both surface water and groundwater samples collected over an area of about 280 km². Results show that (a) the river water is characterized by high Na contents; (b) the δ²H and δ¹⁸O values in the river water are distinctively higher than those of groundwater samples, after experiencing the long‐time evaporative enrichment in the upstream reservoir; (c) the Sr concentrations and ⁸⁷Sr/⁸⁶Sr ratios of groundwater clearly indicated the interaction between water and carbonate minerals but excluded the water–silicate interaction; and (d) the groundwater samples in the direct recharge area of the XKA have the lowest Na concentrations and the δ²H and δ¹⁸O values. Based on the large differences in the Na contents and ¹⁸O values of groundwater and surface water, a simple two‐component mixing model is developed for the study area and the fractions of the river water are estimated for groundwater samples. We find that the distribution pattern of the river water fractions in the XKA clearly shows a change of directions in the preferential flow path of the groundwater from its source zone to the discharge area. Overall, our results suggest that the recharged surface water can be a useful evidence for delineating the groundwater flow path in river‐connected karst aquifer. This study improves our understanding of the heterogeneity in karst groundwater systems.  相似文献   

RS image fusion technique for information preservation     

Wu Lianxi  Su Xiaoxia  Li Dajun 《地球空间信息科学学报》2013,16(4):274-278

A simple spectral preserving image fusion technique, Edge Enhancement Color Normalized (EECN), was proposed to merge two kinds of image data. In addition, a mathematical model was also proposed to evaluate spectral property of the fused production of EECN. The results were clearly demonstrated by an image fusion experiment using Landsat-5 TM and IRS-1C Panchromatic images of Beijing, China. The visual evaluation and mathematical analysis compared with Brovey transform confirmed that the fused image of EECN is quite similar in color to the lower resolution multi-spectral images, and its space resolution is the same as the higher solution panchromatic image.  相似文献   

Effect of the Vertical Diffusion of Moisture in the Planetary Boundary Layer on an Idealized Tropical Cyclone     

Hongxiong XU  Dajun ZHAO 《大气科学进展》2021,38(11):1889-1904

Previous numerical studies have focused on the combined effect of momentum and scalar eddy diffusivity on the intensity and structure of tropical cyclones. The separate impact of eddy diffusivity estimated by planetary boundary layer(PBL) parameterization on the tropical cyclones has not yet been systematically examined. We have examined the impacts of eddy diffusion of moisture on idealized tropical cyclones using the Advanced Research Weather Research and Forecasting model with the Yonsei University PBL scheme. Our results show nonlinear effects of moisture eddy diffusivity on the simulation of idealized tropical cyclones. Increasing the eddy diffusion of moisture increases the moisture content of the PBL, with three different effects on tropical cyclones:(1) an decrease in the depth of the PBL;(2) an increase in convection in the inner rain band and eyewall; and(3) drying of the lowest region of the PBL and then increasing the surface latent heat flux. These three processes have different effects on the intensity and structure of the tropical cyclone through various physical mechanisms. The increased surface latent heat flux is mainly responsible for the decrease in pressure. Results show that moisture eddy diffusivity has clear effects on the pressure in tropical cyclones, but contributes little to the intensity of wind. This largely influences the wind–pressure relationship, which is crucial in tropical cyclones simulation. These results improve our understanding of moisture eddy diffusivity in the PBL and its influence on tropical cyclones, and provides guidance for interpreting the variation of moisture in the PBL for tropical cyclone simulations.  相似文献