Community‐Derived Standards for LA‐ICP‐MS U‐(Th‐)Pb Geochronology – Uncertainty Propagation,Age Interpretation and Data Reporting          下载免费PDF全文

Matthew S. A. Horstwood  George Gehrels  Simon E. Jackson  Noah M. McLean  Chad Paton  Norman J. Pearson  Keith Sircombe  Paul Sylvester  Pieter Vermeesch  James F. Bowring  Daniel J. Condon  Blair Schoene 《Geostandards and Geoanalytical Research》2016,40(3):311-332

The LA‐ICP‐MS U‐(Th‐)Pb geochronology international community has defined new standards for the determination of U‐(Th‐)Pb ages. A new workflow defines the appropriate propagation of uncertainties for these data, identifying random and systematic components. Only data with uncertainties relating to random error should be used in weighted mean calculations of population ages; uncertainty components for systematic errors are propagated after this stage, preventing their erroneous reduction. Following this improved uncertainty propagation protocol, data can be compared at different uncertainty levels to better resolve age differences. New reference values for commonly used zircon, monazite and titanite reference materials are defined (based on ID‐TIMS) after removing corrections for common lead and the effects of excess ²³⁰Th. These values more accurately reflect the material sampled during the determination of calibration factors by LA‐ICP‐MS analysis. Recommendations are made to graphically represent data only with uncertainty ellipses at 2s and to submit or cite validation data with sample data when submitting data for publication. New data‐reporting standards are defined to help improve the peer‐review process. With these improvements, LA‐ICP‐MS U‐(Th‐)Pb data can be considered more robust, accurate, better documented and quantified, directly contributing to their improved scientific interpretation.  相似文献   

A new assessment model for evacuation vulnerability in urban areas     

Xiaoyi Ma  Ci Song  Chenghu Zhou 《International journal of geographical information science》2016,30(12):2401-2420

In the high-speed urbanization process of China, the urban population has been increasing significantly, leading to a high-density aggregation of population. However, the sharp increase in population density has not produced commensurate improvements in the road networks. On the contrary, the population increase induced a serious evacuation vulnerability, which cities experience during various hazards and catastrophic events. Therefore, research on evacuation vulnerability is important to urban planning. To assess the evacuation vulnerability, the optimal and worst scenarios should be considered because all possible evacuation plans occur between these extremes. However, most previous evacuation vulnerability studies are based on the worst-case scenario, only providing an upper bound of a potential evacuation assessment. To provide a more comprehensive theoretical basis for decision-makers to understand the consequences caused by all possible evacuations, this paper proposes an optimal evacuation vulnerability assessment model that provides the lower bound on potential evacuation difficulties. The model is solved by a stepwise spreading algorithm based on Graph Theory. Subsequently, to evaluate the effectiveness of the model, the study adopts the model to assess the evacuation capability of different road network topologies. A comparison with previous research was performed. The model was demonstrated in an application to the South Luogu Alley of Beijing, China. The significance of this paper is that the combination of our model with previous research may provide a more complete theoretical basis for an evacuation vulnerability assessment.  相似文献   

Optimal routing for waste collection: a case study in Singapore     

Weijian Xue 《International journal of geographical information science》2016,30(3):554-572

ABSTRACT

To collect and dispose growing amounts of municipal solid waste (MSW) changed to be a hot topic along with the rapid urbanization in past decades. Cities are more and more dependent on the incineration instead of landfilling due to the cost-efficiency and environmental concerns. Considering the limited number of incineration plants and complicated situation of transportation in both spatial and temporal dimensions in different cities, the optimal routing for waste collection turns to be meaningful research topic. In this research, the ant colony optimization (ACO)-based multi-objective routing model coupled with min-max model and Dijkstra’s algorithm is proposed to address the question of which route to take from these waste-generating points to the target incineration plant(s) considering travel time, accident probability (black spots), and population exposure, so as to support the routing decision-making. The model is successfully implemented in Singapore and the effectiveness of the model has also been justified. Besides, few limitations of this research have also been discussed, some of which would also be the future directions of our research, especially the design and integration of a web-based routing decision-making support system.  相似文献   

Applying disk-based discontinuous deformation analysis (DDA) to simulate Donghekou landslide triggered by the Wenchuan earthquake   总被引：1，自引：0，他引：1  

S. Amir Reza Beyabanaki  Amvrossios C. Bagtzoglou  Lanbo Liu 《Geomechanics and Geoengineering》2016,11(3):177-188

In this paper, for the first time, disk-based discontinuous deformation analysis (DDA) is applied to simulate a real landslide triggered by an earthquake. For this purpose, the kinematic behaviour of the Donghekou landslide triggered by the Wenchuan earthquake is simulated and the results obtained using disk-based DDA are compared with actual data. The comparisons show that there is a good agreement between the results obtained using disk-based DDA and observed data. The simulation results provided an understanding of the failure behaviour and temporal evolution of the landslide. This study shows that disk-based DDA is a practical numerical tool that can be used to simulate the post-failure behaviour of landslides triggered by an earthquake.  相似文献   

Leachate studies on fly ash-stabilised expansive clay liners     

M. Uma Shankar 《Geomechanics and Geoengineering》2016,11(2):114-118

This paper presents leachate studies on fly ash-stabilised expansive clay liners. Fly ash in different contents (0%, 10%, 20% and 30%) by dry weight of the expansive clay was added to the clay, and the ash-clay blend was compacted as a liner overlying a compacted lateritic clay layer. Deionised water (DIW) and calcium chloride (CaCl₂) solutions of varying concentration (5 mM, 10 mM, 20 mM, 50 mM, 100 mM and 500 mM) were used as the permeating fluids in the leachate studies. Chemical analysis of the leachate was performed. For a given CaCl₂ concentration, the concentrations of both calcium ion and chloride ion in the leachate decreased up to a fly ash content of 20%, and thereafter they increased when the fly ash content was increased to 30%. Further, for a given fly ash content, concentrations of calcium ion and chloride ion increased with increasing CaCl₂ concentration.  相似文献   

脐带缆在潜器下放过程中的运动建模与仿真   总被引：1，自引：0，他引：1  

李霄霄  马宁  刘晗  顾解忡 《海洋工程》2016,34(2):47-55

潜器在下放布置过程中需要考虑变长度的脐带缆对其运动的影响,在考虑流的情况下,对脐带缆的有限差分模型进行了改进,并采用最小二乘方法求解由时间和空间上的中心差分格式离散后的非线性方程组。为了验证模型改进的有效性,将潜器在均匀定常流中水平匀速直航时的数值解与该特殊情况下的解析解进行比较,两组解的吻合不仅证实了模型改进的有效性,而且表明上述数值计算方法是可靠且有效的。在潜器下放布置运动给定的情况下,脐带缆的运动仿真结果表明,潜器姿态角的调整会对拖曳点处的缆绳张力大小和变化趋势产生显著的影响,流在改变缆绳空间形状的同时引起了缆绳对潜器作用力和力矩的非线性和时变性,脐带缆总是阻止潜器自身动力对运动速度和姿态角的改变,且对纵荡运动的影响最大。  相似文献   

内蒙古北山额勒根乌兰乌拉一带土壤测量地球化学特征及找矿方向     

张善明  兰生科  贺中银  韩志敏  陈强  王永晖 《现代地质》2018,32(4):655

研究区位于内蒙古北山北带,成矿地质条件优越,1∶20万水系沉积物测量异常明显,且分布有额勒根乌兰乌拉斑岩型钼(铜)矿。以1∶5万土壤地球化学测量成果为依据,以地质认识为基础,研究了区内元素地球化学数据特征、地球化学场特征及综合异常特征。认为区内主成矿元素为Mo、Cu、Au,主要的控矿层位为咸水湖组火山岩段,成矿有利侵入体为石炭纪花岗闪长岩。划分出5种综合异常类型,其中与斑岩钼(铜)矿系统有关的综合异常和与奥陶系建造有关的综合异常是今后解剖找矿的重点。  相似文献   

Petrological and Os Isotopic Characteristics of Zedong Peridotites in the Eastern Yarlung–Zangbo Suture in Tibet     

LAI Shengmin  YANG Jingsui  Yildirim DILEK  XIONG Fahui  JIANG Rui  CHEN Yanhong 《《地质学报》英文版》2018,92(2):442-461

The Zedong ophiolites in the eastern Yarlung–Zangbo suture zone of Tibet represent a mantle slice of more than 45 km~2. This massif consists mainly of mantle peridotites, with lesser gabbros, diabases and volcanic rocks. The mantle peridotites are mostly harzburgite, lherzolite; a few dike-like bodies of dunite are also present. Mineral structures show that the peridotites experienced plastic deformation and partial melting. Olivine(Fo89.7–91.2), orthopyroxene(En_(88–92)), clinopyroxene(En_(45–49) Wo_(47–51) Fs_(2–4)) and spinel [Mg~#=100×Mg/(Mg+Fe)]=49.1–70.7; Cr~#=(100×Cr/(Cr+Al)=18.8–76.5] are the major minerals. The degree of partial melting of mantle peridotites is 10%–40%, indicating that the Zedong mantle peridotites may experience a multi–stage process. The peridotites are characterized by depleted major element compositions and low REE content(0.08–0.62 ppm). Their "spoon–shaped" primitive–mantle normalized REE patterns with(La/Sm)_N being 0.50–6.00 indicate that the Zedong ultramafic rocks belong to depleted residual mantle rocks. The PGE content of Zedong peridotites(18.19–50.74 ppb) is similar with primary mantle with Pd/Ir being 0.54–0.60 and Pt/Pd being 1.09–1.66. The Zedong peridotites have variable, unradiogenic Os isotopic compositions with ~(187)Os/~(188)Os=0.1228 to 0.1282. A corollary to this interpretation is that the convecting upper mantle is heterogeneous in Os isotopes. All data of the Zedong peridotites suggest that they formed originally at a mid-ocean ridge(MOR) and were later modified in supra–subduction zone(SSZ) environment.  相似文献   

高速公路通道下沉开裂治理实践     

张锦灵  豆敬峰  李金刚 《探矿工程》2018,45(6):75-80

河南省省道323线登封市大冶镇一段公路软弱地基以及路面出现不均匀沉降,通道箱涵开裂,边坡为欠稳定边坡。将事故路段分为4个区域进行加固治理。通过采用注浆加固路基基础、设置坡面排水系统、提高地基的承载能力等治理措施,保证了道路的通行能力。  相似文献   

郑州市地面沉降监测基岩标施工技术   总被引：3，自引：2，他引：1       下载免费PDF全文

王刚  李莹  黄烜  于丽 《探矿工程》2018,45(4):82-86

根据区域地质条件,郑州市地面沉降监测网基岩标建标场地选择在淮河西路与西三环交叉口东南600 m的河南省地质环境监测院内,建标深度为732 m。地质鉴别孔孔深780 m,孔径108 mm,全孔取心钻进,施工的重点是保证岩心采取率,采用泥浆护壁回转钻进,根据钻进层位的岩性不同配置不同特性的泥浆;基岩标标孔孔深780 m,孔径311 mm,施工的控制目标是孔身质量和垂直度。采用三牙轮钻头宝塔式钻具组合不取心钻进施工工艺。取得了较好的施工质量,创造了良好的效益。  相似文献