基于综合权重和改进物元可拓评价模型的地下水水质评价

鉴于物元可拓评价模型存在关联函数计算上的局限性,提出通过改进物元可拓评价模型的构造过程进行水质评价,并引入层次分析法和熵权法计算评价指标的综合权重以避免指标权重的绝对主观性和绝对客观性,建立了基于综合权重和改进物元可拓法的地下水水质评价模型,并从感官、一般化学、毒理学3个方面构建了地下水水质综合评价指标体系。将该模型应用于平度市古岘镇的地下水水质评价,并与综合评分法和属性识别法的水质评价结果进行比较分析。结果表明：该模型评价结果与其他两种方法评价结果的相同率均达70%,即使评价结果不同处的差异也基本在1个等级范围之内;而综合评分法和属性识别法评价结果的相同率仅为50%,且评价结果不同处的差异最大可达3个等级。     

扬子北缘晚古元古代A型花岗质岩:Columbia超大陆裂解的证据

为约束扬子陆块晚古元古代构造演化历史,以华山观岩体的钾长花岗岩和二长花岗岩为研究对象,开展地球化学、年代学、全岩Nd同位素及锆石Hf同位素分析。锆石U-Pb定年结果显示钾长花岗岩和二长花岗岩的结晶年龄分别为1860±12 Ma(MSWD=0.69)和1832±14 Ma(MSWD=0.48)。两类岩石都显示铝质A型花岗岩的地球化学特征,一致的ε_(Hf)(t)值(-10.9～-13.8)及其二阶段模式年龄(2962～3183 Ma),揭示其由同一套太古宙的地壳部分熔融形成。综合已有ε_(Hf)(t)值资料,表明扬子陆块广泛存在两套太古宙长英质地壳(3.0～3.5 Ga; 3.5～3.9 Ga),为华山观两类花岗岩的岩浆形成提供了物源。华山观岩体两类花岗岩的锆石饱和温度揭示源岩位于较深的地壳,且二长花岗岩的形成有更多热源的参与。结合扬子陆块同期(～1.85Ga)A型花岗岩的地球化学数据,认为华山观钾长花岗岩具有后碰撞A_2型花岗岩的特征,形成于后碰撞伸展环境,而华山观二长花岗岩具有A_1型花岗岩的地球化学特征,暗示造山后伸展到陆内裂谷过渡的构造背景,可能与Columbia超大陆裂解有关。     

华北陆块岩石圈减薄作用:热薄化与机械拉伸的数值模拟研究

针对华北陆块岩石圈减薄作用的动力学机制开展了一系列二维定量数值模拟研究。其模拟结果表明,在给定的岩石圈热传导和放射性生热条件下,岩石圈底部地幔热流(mantlethermalflux)的增加能导致岩石圈内热状态的明显改变,导致早古生代以来华北岩石圈厚度的巨大变化,当地幔热流达到35～40mWm-2,华北陆块的岩石圈厚度将减薄至100km以内。单纯的机械拉张同样能导致岩石圈厚度的薄化,但岩石圈厚度的减薄相对有限。即使拉张伸展率达25%,其岩石圈厚度最大减薄至150km。因此通过数值模拟的研究揭示了这样的事实,即华北陆块岩石圈厚度的减薄主要受制于岩石圈内热状态的变化,以热侵蚀的减薄方式为主,机械拉张作用可能对华北陆块岩石圈厚度的减薄作用有一定贡献。     

基于矢量数据库的地理本体映射与扩展方法

本文基于矢量数据库模型与地理本体模型之间的形式化对应关系,定义了从矢量数据库到地理本体的映射规则,实现了地理本体的自动构建;在此基础上,通过本体推理规则对地理本体进行推理,使本体中隐性知识显式化,从而实现地理本体的扩展.实验结果表明该方法减少了人工构造本体中出现的错误,提高了本体构建和利用的效率.     

Drainage integration and sediment dispersal in active continental rifts: A numerical modelling study of the central Italian Apennines

Progressive integration of drainage networks during active crustal extension is observed in continental areas around the globe. This phenomenon is often explained in terms of headward erosion, controlled by the distance to an external base‐level (e.g. the coast). However, conclusive field evidence for the mechanism(s) driving integration is commonly absent as drainage integration events are generally followed by strong erosion. Based on a numerical modelling study of the actively extending central Italian Apennines, we show that overspill mechanisms (basin overfilling and lake overspill) are more likely mechanisms for driving drainage integration in extensional settings and that the balance between sediment supply vs. accommodation creation in fault‐bounded basins is of key importance. In this area drainage integration is evidenced by lake disappearance since the early Pleistocene and the transition from internal (endorheic) to external drainage, i.e. connected to the coast. Using field observations from the central Apennines, we constrain normal faulting and regional surface uplift within the surface process model CASCADE (Braun & Sambridge, 1997, Basin Research, 9, 27) and demonstrate the phenomenon of drainage integration, showing how it leads to the gradual disappearance of lakes and the transition to an interconnected fluvial transport system over time. Our model results show that, in the central Apennines, the relief generated through both regional uplift and fault‐block uplift produces sufficient sediment to fill the extensional basins, enabling overspill and individual basins to eventually become fluvially connected. We discuss field observations that support our findings and throw new light upon previously published interpretations of landscape evolution in this area. We also evaluate the implications of drainage integration for topographic development, regional sediment dispersal and offshore sediment supply. Finally, we discuss the applicability of our results to other continental rifts (including those where regional uplift is absent) and the importance of drainage integration for transient landscape evolution.     

哈长城市群城镇用地扩展进程及其驱动因素研究

以Landsat TM/ETM+/OLI遥感影像为主要数据源,提取哈长城市群1990、2000、2010、2015 年4 个年份的建设用地信息,采用年均扩展指数、景观扩展指数、多距离空间聚类函数、空间分维度等对城镇用地扩展进程进行分析。结果表明,1990~2015年间,哈长城市群城镇用地增加57 321.47 hm²,增长率为21.05%,整体扩展强度呈上升趋势;空间扩展表现出以中心城市为核心的扩展模式,边缘式增长在各个时期均为主导增长方式;空间扩展聚集性总体表现出“先增强、后减弱”趋势,整体空间结构相对稳定。国家宏观政策、非农业GDP增量和第三产业GDP增量是影响哈长城市群城镇用地扩展的重要因素。GDP增量、非农业人口增量、第二产业GDP增量对城镇用地的扩展起阶段性作用;人均GDP增量与城市用地扩展相关性不显著。     

Extension 3.0: Managing Agricultural Knowledge Systems in the Network Age

This article develops the idea of “Extension 3.0” as an approach to agricultural extension that capitalizes on the network structure of local agricultural knowledge systems. Over the last century, agricultural knowledge systems have evolved into networks of widely distributed actors with a diversity of specializations and expertise. Agricultural extension programs need to manage these networks in ways that maximize the synergy between experiential, technical, and social learning. Using empirical research from California farmers, we highlight the structure of these networks within and across contexts, and the importance of boundary-spanning relationships. We provide some initial recommendations about actions needed to realize the goal of Extension 3.0, which is to deliver relevant agricultural knowledge to the right people, at the right time and place.     

Agricultural Extension in Balochistan,Pakistan： Date Palm Farmers＇ Access and Satisfaction

This study analyzed information gathered from 200 date palm households in the mountainous Panjgur District of Balochistan in Pakistan with the aim of determining date farmers＇ access to and satisfaction with agricultural extension services. Information was collected through a structured questionnaire survey, group discussions and semi- structured personal interviews. The findings of the analysis revealed very poor access to extension services. The results of logistic regression analysis identified five variables out of six which significantly influence date farmers＇ access to extension services： household bead＇s age, household bead＇s literacy, number of date palm trees owned, mostly inherited date palm trees, and percentage of dead date palm trees. The overwhelming majority of farmers were dissatisfied with all three main types of extension services being provided by public extension officials. Explanations for this as well as for associations between access to extension services and the six independent variables are provided. Important policy conclusions are drawn based on the findings.     

内蒙古海莫赛格酸性火山岩锆石U-Pb年龄、地球化学特征及其意义

内蒙古海莫赛格地区发育有中-晚侏罗世酸性火山岩,锆石U-Pb定年结果显示,火山岩形成于164.0±1.0~155.5±0.9 Ma,属中-晚侏罗世。主量元素分析表明,火山岩具高硅(SiO2=62.09%~77.57%)、富碱(K2O+Na2O=7.27%~10.13%)、富钾(K2O/Na2O=1.10~2.82)、贫钙镁(CaO=0.16%~2.46%,平均为0.73%;MgO=0.10%~1.08%,平均为0.29%,Mg#多小于45)和高FeOT/MgO(2.37~7.22,平均为4.49)值的特征,属准铝质-过铝质(A/CNK=0.98~2.29)高钾钙碱性-钾玄岩系列岩石。微量元素数据显示,稀土元素总量∑REE为137.6×10-6~315.3×10-6,轻、重稀土元素分馏比较明显[(La/Yb)N=2.84~17.81],轻稀土元素(LREE)较为富集,重稀土元素分布相对平坦,球粒陨石标准化配分模式为右倾型,中等-弱负铕异常(δEu=0.14~0.79,1个样品为1.54),微量元素富集大离子亲石元素(LILE)Rb、Ba、Th、K,贫Sr并亏损高场强元素(HFSE)Nb、Ta、P、Ti;岩石具低Sr(46.2×10-6~799.3×10-6,平均208.0×10-6)、高Yb(2.02×10-6~4.23×10-6)含量。综合最新区域资料及本文研究成果,笔者认为研究区中-晚侏罗世火山岩岩浆来源于壳源物质不同程度的部分熔融,为造山后伸展阶段的产物,可能与古太平洋板块大角度北向斜向俯冲作用导致的走滑-拉伸作用有关。关键词:中-晚侏罗世;满克头鄂博组;锆石U-Pb年龄;造山后伸展;内蒙古