地震反射波法在浅层勘探中的应用     

蒋维平  孟宪民 《中国煤炭地质》2008,(9):59-60

常规多次覆盖反射波法地震勘探难以获得100ms（一般相当于80m）以上的有效地震反射信息,形成浅部地层勘探盲区。为有效解决浅层勘探难题,提出了单道自激自收或点组合小排列施工方法。该方法除对震源输出脉冲宽度、频率特性有要求外,还对震源适应性有较高的要求。实例表明：采用小药量震源激发,点组合小排列接收,可有效划分100ms以内的层位;而单道锤击自激自收反射波法,对地下敷设电缆、城市排水沟、地下管道及人防工程的探测效果明显高于常规地震勘探。  相似文献   

Mercury pollution from artisanal mercury mining in Tongren, Guizhou, China     

Ping Li  Xinbin Feng  Lihai Shang  Guangle Qiu  Bo Meng  Peng Liang  Hua Zhang   《Applied Geochemistry》2008,23(8):2055-2064

Concentrations of total Hg (T-Hg) were measured in mine waste, stream water, soil and moss samples collected from the Tongren area, Guizhou, China to identify potential Hg contamination to local environments, which has resulted from artisanal Hg mining. Mine waste contained high T-Hg concentrations, ranging from 1.8 to 900 mg/kg. High concentrations of Hg were also found in the leachates of mine waste, confirming that mine waste contains significant water-soluble Hg compounds. Total Hg distribution patterns in soil profiles showed that top soil is contaminated with Hg, which has been derived from atmospheric deposition. Data suggest that organic matter plays an important role in the binding and transport of Hg in soil. Elevated T-Hg concentrations (5.9–44 mg/kg) in moss samples suggest that atmospheric deposition is the dominant source of Hg to local terrestrial ecosystems. Concentrations of T-Hg were highly elevated in stream water samples, varying from 92 to 2300 ng/L. Particulate Hg in water constituted a large proportion of the T-Hg and played a major role in Hg transport. Methyl–Hg (Me–Hg) concentrations in the water samples was as high as 7.9 ng/L. Data indicate that Hg contamination is dominantly from artisanal Hg mining in the study area, but the extent of Hg contamination is dependent on the mining history and the scale of artisanal Hg mining.  相似文献   

Assessing vegetation dynamics impacted by climate change in the southwestern karst region of China with AVHRR NDVI and AVHRR NPP time-series   总被引：6，自引：0，他引：6  

J. Wang  J. J. Meng  Y. L. Cai 《Environmental Geology》2008,54(6):1185-1195

The relationship between climate change and vegetation dynamics in the southwestern karst region of China has been identified by recent studies. Based on previous researches and AVHRR (Advanced Very High Resolution Radiometer) GIMMS (Global Inventory Monitoring and Modeling Studies) NDVI (Normalized Difference Vegetation Index) (1982–2003) and AVHRR GloPEM (Global Production Efficiency Model) NPP (Net Primary Production) (1981–2000) datasets, vegetation dynamics impacted by climate change in the southwestern karst region of China were assessed. The results show that: (1) since the early 1980s, both vegetation cover density and net primary production have insignificant ascending tendencies. However, the inter-annual variation rates of vegetation indexes have apparent spatial differentiations; (2) the correlation coefficients between the inter-annual variations of vegetation indexes and the inter-annual variations of climate factors vary geographically; (3) as indicated by NDVI and NPP, various vegetation types have different responses to climate change, and the annual mean temperature variation has more significant impact on vegetation dynamics than the annual precipitation variation in the study area; (4) distribution laws of correlation coefficients between the inter-annual variations of vegetation indexes and the inter-annual variations of climate factors in different climate conditions are apparent. All these findings will enrich our knowledge of the natural forces which impact the stability of the karst ecosystems and provide scientific basis for the management of the karst ecosystems.  相似文献   

湘南中生代花岗质岩石成岩成矿的时限   总被引：30，自引：1，他引：29  

彭建堂  胡瑞忠  袁顺达  毕献武  沈能平 《地质论评》2008,54(5):617-625

位于南岭中段的湘南地区,中生代花岗质岩石广泛分布;该区W、Sn、Pb、Zn、Mo、Bi等金属矿床密集产出,很多钨、锡矿床达到大型、超大型规模,且找矿潜力巨大,构成一个世界级的有色金属矿集区。最近大量的同位素年代学研究表明,南岭中段钨、锡、铅锌等金属的成矿是一个爆发性、区域性的地质事件,成矿时间高度集中,成矿时限主要在150~160 Ma之间,与该区主要花岗岩的成岩时间相当吻合;对单个钨、锡矿床而言,其矿区的成岩、成矿存在着一种准同期性,即成矿与矿区花岗岩的成岩基本上是同时的、或稍晚于花岗岩的成岩作用。因此,该区中生代的花岗岩与钨锡成矿作用具有明显的时、空联系。南岭中段花岗岩大规模的侵入和钨、锡等金属的爆发性成矿均形成于一种岩石圈伸展减薄、地壳拉张的构造环境,可能与华南中生代第二幕岩石圈伸展事件密切相关。  相似文献   

BDS网络RTK参考站三频整周模糊度解算方法   总被引：1，自引：1，他引：0  

高猛  徐爱功  祝会忠  葛茂荣  杨秋实 《测绘学报》2017,46(4):442-452

北斗卫星导航系统是目前唯一一个全星座提供三频观测数据的卫星导航定位系统,三频观测值有助于载波相位整周模糊度的快速、准确固定。本文提出了一种BDS网络RTK参考站三频整周模糊度解算方法。首先利用B2、B3频率的观测值及严格的模糊度固定标准确定超宽巷整周模糊度,将固定的超宽巷整周模糊度与其他宽巷整周模糊度的线性关系作为约束条件,然后估计宽巷整周模糊度、相对天顶对流层延迟误差和电离层延迟误差,并搜索确定宽巷整周模糊度。利用固定的宽巷整周模糊度与三频载波相位整周模糊度的整数线性关系,将线性关系加入载波相位整周模糊度参数估计观测模型中,然后确定载波相位整周模糊度。使用实测的CORS网BDS三频观测数据进行算法验证,结果表明,该方法可正确有效地实现参考站间三频载波相位整周模糊度的快速解算。  相似文献   

一种GPS多路径反射信号的雪深反演     

税广通  郑南山  周方平  严薛峰  史永鹏  班盟  祁作栋 《测绘科学》2017,42(10)

针对传统雪深测量缺乏必要时空敏感性的不足,该文在分析GPS信号多路径反射模型的基础上,利用GPS信噪比观测数据,通过分离提取多路径反射分量研究其时频特性,探讨GPS多路径信号与雪深及其变化关系并进行反演建模。依据菲涅尔反射区理论,确定了反射区域范围,进一步探讨卫星、波段选择及初始反射高度确定等。对比实验研究表明,反演结果与实测值吻合较好,相关系数为0.93,均方根误差为8.6cm;信噪比多路径反射分量的频率能有效跟踪积雪深度的变化。  相似文献   

Simulating the role of gravel in freeze–thaw process on the Qinghai–Tibet Plateau     

Pan  Yongjie  Lyu  Shihua  Li  Suosuo  Gao  Yanhong  Meng  Xianhong  Ao  Yinhuan  Wang  Shujin 《Theoretical and Applied Climatology》2017,127(3-4):1011-1022

Soils containing gravel (particle size ≥2 mm) are widely distributed over the Qinghai–Tibet Plateau (QTP). Soil mixed with gravel has different thermal and hydrological properties compared with fine soil (particle size <2 mm) and thus has marked impacts on soil water and heat transfer. However, the most commonly used land models do not consider the effects of gravel. This paper reports the development of a new scheme that simulates the thermal and hydrological processes in soil containing gravel and its application in the QTP. The new scheme was implemented in version 4 of the Community Land Model, and experiments were conducted for two typical sites in the QTP. The results showed that (1) soil with gravel tends to reduce the water holding capacity and enhance the hydraulic conductivity and drainage; (2) the thermal conductivity increases with soil gravel content, and the response of the temperature of soil mixed with gravel to air temperature change is rapid; (3) the new scheme performs well in simulating the soil temperature and moisture—the mean biases of soil moisture between the simulation and observation reduced by 25–48 %, and the mean biases of soil temperature reduced by 9–25 %. Therefore, this scheme can successfully simulate the thermal and hydrological processes in soil with different levels of gravel content and is potentially applicable in land surface models.

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基于非期望产出的城市发展效率时空差异探讨——以中国东部沿海地区城市为例   总被引：1，自引：1，他引：0  

狄乾斌  孟雪 《地理科学》2017,37(6):807-816

基于非期望产出视角,采用SBM模型测度2005~2014年中国东部沿海地区53个城市（不包括港、澳、台、三沙市）的城市发展效率,并分析其时空差异特征及其影响因素。结果表明：① 考虑非期望产出的城市发展效率值低于不考虑非期望产出的城市发展效率值,并且更符合城市实际发展; ② 中国东部沿海地区城市发展效率整体水平不高,波动幅度大,阶段特征明显,整体呈先上升后下降的趋势;③ 在时空分析特征中,城市发展效率的区域差异明显,近2 a有缩小的趋势;整体城市发展效率空间呈现“北部围绕青岛市,中部围绕上海市,南部围绕深圳市”的发展格局;④ 在影响因素分析中,经济规模对城市发展效率产生正向影响,第二产业结构水平和污染处理能力对城市发展效率产生负向影响,传统的加工制造业、高耗能重污染工业和污染处理不到位是导致城市发展效率降低的主要原因。  相似文献   

RAIM算法研究   总被引：5，自引：0，他引：5  

秘金钟  李毓麟  LI Yu-lin 《测绘通报》2001,(3):7-9

用户自主完备性监测RAIM算法是广域差分GPS的关键和核心技术之一。在已有RAIM算法的基础上，讨论了粗差探测和定位的方法，并给出了Parity方法中剔除多个粗差的算法，最后用‘99南海实测数据进行了验证。  相似文献   

东秦岭虎豹河砾岩砾石的地球化学特征及其构造意义   总被引：2，自引：1，他引：2  

张成立  孟庆任 《沉积学报》1997,15(3):115-119

东秦岭虎豹河砾岩为复成分砾岩层。砾岩中火成央砾石显示了ＬＩＬＥ中等富集，丰富变化不大，Ｂｂ（Ｔａ）有一定亏损，Ｔｈ－Ｔａ比值高，并具有来自岛弧演化不同阶段的两个岩浆源区的地球化学特征，反映它们主要受消减物质影响，且地壳物贡献不大的岛弧钙碱性岩浆的成因特征。  相似文献