安徽月山闪长岩的成因探讨——锆石U-Pb定年及Hf同位素证据   总被引：6，自引：0，他引：6  

刘园园  马昌前  张超  佘振兵  张金阳 《地质科技情报》2009,28(5)

对安徽月山岩体开展了锆石原位U-Pb测年及Lu-Hf同位素研究.锆石的LA-ICP-MS年代学研究表明,月山闪长岩的U-Pb年龄为(139.3 ±1.5)Ma,与长江中下游成矿带早白垩世成铜岩体的年龄一致.月山闪长岩中的锆石具有均一的Hf同位素初始比值,介于0.282 430～0.282 491间.这些锆石的ε(Hf)(t)介于-9.05～-6.90间,亏损地幔模式年龄介于1.06～1.17 Ga间.结合长江中下游地区岩浆岩其他地球化学特征,认为月山岩体可能是在俯冲体系下由幔源岩浆经结晶分异作用且局部伴有一定程度的同化混染作用所形成.  相似文献   

We Are All Makers: The Method of Keyword Selection in Teaching and Learning Human Geography   总被引：1，自引：0，他引：1  

Chao Ye  Renjie Ji 《The Professional geographer》2013,65(3):462-471

Abstract

Geographers continue to engage in public debate “inside the Beltway” by participation within and through federal agencies and through the National Research Council. Several examples illustrate the level and kind of this engagement, which has been concentrated on environmental and spatial data and analysis themes. Most professional geographers have the opportunity to engage in this form of public debate through participation in the activities of the National Research Council. The level of this participation has been surprisingly strong, given the small size of the community of professional geographers, and has helped to shape both U.S. and international research agendas relevant to geographic research. Participation, however, is concentrated in a few programs and individuals, raising questions about the sustainability of geography's voice in this public activity.

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不同地形特征下云南沿边村寨农户生计资产研究     

王丹丹  甘淑  张超  孙冠华 《云南地理环境研究》2013,(6):41-47

依据英国国际发展署(DFID)提出的可持续生计分析框架为指导,选取与农户生计资产密切相关的评价因子,建立农户生计资本评价指标体系,对云南省25个沿边县域中具有不同地形特征的64个村寨生计资本进行了测算、对比和分析。研究发现,研究区生计资本总体水平偏低,不同地形特征下村寨间生计资本差异性较大,生计资本不平衡,针对不同的生计脆弱性,提出如下讨论:(1)人力资本上,着重加强和巩固教育和培训力度;(2)金融资本、社会资本上,加大农业现代化水平的投资力度,加大加强农业合作组织的建设;(3)物质资本上,建议增加对农业基础设施和信息媒体的建设;(4)在自然资本的脆弱性上,要在可持续性利用的基础上,大力发展循环经济。  相似文献   

中国东南屯溪-温州宽角地震资料去广角效应成像     

张智  董超  李飞  王海燕 《地球物理学进展》2013,28(3)

由于长排列广角地震采集中必定存在超临界角的广角反射信息,广角反射信息相对临界角内反射信息存在随偏移距变化的时移现象.本文研究了去广角效应下的走时反演成像,并将其应用到东南屯溪—温州的宽角地震资料.通过拾取中国东南屯溪—温州剖面宽角实际地震资料中P波垂直分量拾取到的反射P波走时,继而使用遗传反演方法进行处理,得到了该区丰乐、新安江、松阳、青田以及洞头五炮去广角效应与未考虑广角效应情况下的一维速度深度曲线,并对比了去广角效应前后的地壳结构界面形态.结果表明,广角效应去除前后影响主要体现在壳内层速度差异,地壳浅层界面深度的广角效应明显强于深层界面.  相似文献   

Comprehensive flood risk assessment based on set pair analysis-variable fuzzy sets model and fuzzy AHP   总被引：10，自引：1，他引：9  

Qiang Zou  Jianzhong Zhou  Chao Zhou  Lixiang Song  Jun Guo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(2):525-546

On the basis of the disaster system theory and comprehensive analysis of flood risk factors, including the hazard of the disaster-inducing factors and disaster-breeding environment, as well as the vulnerability of the hazards-bearing bodies, the primary risk assessment index system of flood diversion district as well as its assessment standards were established. Then, a new model for comprehensive flood risk assessment was put forward in this paper based on set pair analysis (SPA) and variable fuzzy sets (VFS) theory, named set pair analysis-variable fuzzy sets model (SPA-VFS), which determines the relative membership degree function of VFS by using SPA method and has the advantages of intuitionist course, simple calculation and good generality application. Moreover, the analytic hierarchy process (AHP) was combined with trapezoidal fuzzy numbers to calculate the weights of assessment indices, thus the weights for flood hazard and flood vulnerability were determined by the fuzzy AHP procedure, respectively. Then SPA-VFS were applied to calculate the flood hazard grades and flood vulnerability grades with rank feature value equation and the confidence criterion, respectively. Under the natural disasters risk expression recommended by the Humanitarian Affairs Department of United Nations, flood risk grades were achieved from the flood hazard grades and flood vulnerability grades with risk grade classification matrix, where flood hazard, flood vulnerability and flood risk were all classified into five grades as very low, low, medium, high and very high. Consequently, integrated flood risk maps could be carried out for flood risk management and decision-making. Finally, SPA-VFS and fuzzy AHP were employed for comprehensive flood risk assessment of Jingjiang flood diversion district in China, and the computational results demonstrate that SPA-VFS is reasonable, reliable and applicable, thus has bright prospects of application for comprehensive flood risk assessment, and moreover has potential to be applicable to comprehensive risk assessment of other natural disasters with no much modification.  相似文献   

库车坳陷复杂高陡构造地震成像研究   总被引：2，自引：1，他引：1       下载免费PDF全文

符力耘  肖又军  孙伟家  吴超  管西竹  张敬洲 《地球物理学报》2013,56(6):1985-2001

复杂构造地震成像主要取决于叠前地震数据品质、偏移速度可靠性和偏移算子成像精度. 库车坳陷异常复杂的近地表条件导致极低信噪比的地震采集数据. 该区逆冲推覆高陡构造刺穿盐体大面积分布, 盐层厚度变化大、顶底面形态复杂, 盐下断裂带破碎、小断块发育, 形成异常复杂的地震成像问题. 本文重点研究三个关键环节:(1)精细的叠前地震预处理研究: 根据该区地震地质复杂性和地震资料特征, 采用一些新的方法技术和技术组合从振幅与时移的大、中、小尺度变化三个层次来解决资料信噪比问题, 重建深部反射信号; (2)三级偏移速度分析研究:利用库车坳陷盐刺穿逆冲推覆构造建模理论及变速成图配套技术解决叠前时间偏移速度场时深转换问题,利用井约束低频速度地震迭代反演技术解决连井层速度场与偏移速度场的融合问题,实现从DMO速度分析、叠前时间偏移速度分析到叠前深度偏移速度分析的有机衔接,建立拓扑结构相对保持的叠前深度偏移速度模型;(3)基于退化Fourier偏移算子的半解析波动方程叠前时间和深度偏移研究, 极大地改善了地震偏移过程中高波数波的成像问题. 通过对库车坳陷大北、博孜、却勒、西秋4和西秋10等复杂高陡构造的叠前时间和深度偏移地震成像处理,取得了较好的应用效果.  相似文献   

Application of singular spectrum analysis to identify the degrading structure using deteriorating distributed element model     

Chin‐Hsiung Loh  Jung‐Huan Li  Shu‐Hsien Chao 《地震工程与结构动力学》2013,42(5):743-761

Reinforced concrete structure may exhibit significant inelastic hysteretic behavior when subject to strong earthquake excitation. To investigate such an inelastic behavior, in this study, a new system identification technique is applied by using the deteriorating distributed element (DDE) model to simulate the hysteretic behavior of a degrading structure. Through the advanced signal processing technique, the multiple singular spectrum analysis (SSA) and the nonlinear SSA, the recorded inelastic restoring force of a deteriorating structure can be decomposed into several independent additive components in its sequentially degrading order and with decreasing weight. With each decomposed hysteresis loop, the model parameters of the DDE model are identified. The evolutionary properties of the progressive stiffness degradation behavior of reinforced concrete structure can be observed from the identified model parameters. Finally, comparison on the physical properties of the identified DDE model with respect to the seismic response data of the deteriorating structure is also discussed. The result shows that the proposed identification technique can have a good estimation on the seismic behavior of the degrading structure. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Earthquake response analyses of a full‐scale five‐story steel frame equipped with two types of dampers     

Yi‐Jer Yu  Keh‐Chyuan Tsai  Chao‐Hsien Li  Yuan‐Tao Weng  Ching‐Yi Tsai 《地震工程与结构动力学》2013,42(9):1301-1320

The seismic performance tests of a full‐scale five‐story passively controlled steel building were conducted on the E‐Defense shaking table in Japan in March 2009. Before the tests, a blind prediction contest was held to allow researchers and practitioners from all over the world to construct analytical models and predict the dynamic responses of the steel frame specimen equipped with buckling‐restrained braces (BRBs) or viscous dampers (VDs). This paper presents the details of two refined prediction models made and results obtained before the tests. When the proposed analytical modeling techniques are adopted as in the two refined prediction models, the overall prediction accuracy is about 90%. Sensitivity studies conducted after the tests are also presented in this paper. The effects of varying each modeling feature on the response simulation accuracy have been investigated. The analytical results suggest that considering concrete full‐composite actions for beam members could improve prediction accuracy by about 20% against using the simplified bare steel beam model. Adopting refined BRB stiffness computed from incorporating finite‐element gusset stiffness only improves the overall prediction accuracy by 0.9%. Considering the BRB dynamic loading test results for analytical BRB strength reduces the error by 1.9%. For the VD frame, incorporating the brace and VD stiffness could improve the overall prediction accuracy by about 15%. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Controlling of cements and physical property of sandstone by fault as observed in well Xia503 of Huimin sag, Linnan sub-depression     

GAO LiHua  HAN ZuoZhen  HAN Yu  HAN Chao  WEI FeiFei  QIN Zhen 《中国科学:地球科学(英文版)》2013,56(11):1942-1952

Cement content of carbonate in tight sandstone near section is much higher than that of the normal sandstones far away from the fault of well Xia503,in the Huimin sag in Linnan sub-depression.In order to understand the origin and its impact on fault sealing,analyses of the whole-rock minerals,casting thin sections,cathodoluminescence,isotope and physical properties are conducted on cores from well Xia503.It is found that 13C varies from 0.1‰to 0.6‰with the average value of 0.42‰,18O varies from 13.5‰to 12.3‰with the average of 13.1‰,and C–O isotope plotting points are distributed in the low to moderate temperature area of the hydrothermal dolomite.According to the occupied relationship,cathodoluminescence,and C–O isotope feature,the carbonate cementation could be divided into four stages:calcites,dolomite,ankerite,and ferrocalcite.It is discovered that the carbonate cementation is negatively related to reservoir physical property,with the porosity of 4.8%,permeability of 0.37 mD,and displacement pressure of 1.97 MPa in the tight sandstone,which have increased by almost one order of magnitude compared to the porosity of 14.3%,permeability of 3.73 mD,and displacement pressure of 0.27 MPa in the normal sandstone,which is far away from the fault.Regardless of the lithology of the counterpart wall of the fault,only the displacement pressure difference caused by carbonate cementation between the tight sandstone and the normal sandstone could seal 41 m high oil column.  相似文献   

Frost heave control of fine round gravel fillings in deep seasonal frozen regions     

ZuRun Yue  TianLiang Wang  Chao M  TieCheng Sun 《寒旱区科学》2013,5(4):0425-0432

Fine round gravel soil is widely employed in the subgrade of high speed railways in cold regions to prevent frost heaving and thawing. The lower the fines content in fine round gravel soil, the smaller the quantities of frost heaving and thawing, but compaction difficulty increases. This study is to obtain the optimum fines content and limited frost heaving and thawing. The fine round gravel soil filling (FRGSF) used in the Harbin-Qiqihaer Passenger Dedicated Line is taken as the study object. Influence of fines content on optimum water content, maximum dry density and frost heaving properties of FRGSF were studied by means of compaction and frost heaving tests. Results show that the maximum dry density of the FRGSF increases first and then decreases with an increase of fines content, namely there is an optimum fines content for easy compaction. The method of surface-vibratory instrument is fit for coarse-grained soils, and wet state of coarse-grained soil is in favor of compaction. Considering the relationship of fines content with maximum dry density and the frost heaving ratio of FRGSF, the fines content should be limited to within the range of 9%-10%, so that the frost heaving ratio is less than 1%, and the FRGSF is easily compacted. Water supply is proved to be an important factor influencing the amount of frost heaving of FRGSF. We also conclude that in the field, it is imperative to control waterproofing and drainage measures.  相似文献