望儿山金矿生产勘探超前期限与范围合理性的选择和应用     

汤磊  罗先熔 《矿产与地质》2005,19(4):426-428

望儿山金矿浅部生产已接近尾声,其生产正向深部转移,但望儿山金矿深部地质条件十分复杂,为使其生产能更好的延续下去,通过对生产勘探的超前期限与范围合理性的研究和探讨,在总结前人经验的基础上,根据望儿山金矿实际,采用价值法的分析,得出其现有生产勘探合理的超前期限与范围.  相似文献   

Long‐term landscape evolution: linking tectonics and surface processes     

Paul Bishop 《地球表面变化过程与地形》2007,32(3):329-365

Research in landscape evolution over millions to tens of millions of years slowed considerably in the mid‐20th century, when Davisian and other approaches to geomorphology were replaced by functional, morphometric and ultimately process‐based approaches. Hack's scheme of dynamic equilibrium in landscape evolution was perhaps the major theoretical contribution to long‐term landscape evolution between the 1950s and about 1990, but it essentially ‘looked back’ to Davis for its springboard to a viewpoint contrary to that of Davis, as did less widely known schemes, such as Crickmay's hypothesis of unequal activity. Since about 1990, the field of long‐term landscape evolution has blossomed again, stimulated by the plate tectonics revolution and its re‐forging of the link between tectonics and topography, and by the development of numerical models that explore the links between tectonic processes and surface processes. This numerical modelling of landscape evolution has been built around formulation of bedrock river processes and slope processes, and has mostly focused on high‐elevation passive continental margins and convergent zones; these models now routinely include flexural and denudational isostasy. Major breakthroughs in analytical and geochronological techniques have been of profound relevance to all of the above. Low‐temperature thermochronology, and in particular apatite fission track analysis and (U–Th)/He analysis in apatite, have enabled rates of rock uplift and denudational exhumation from relatively shallow crustal depths (up to about 4 km) to be determined directly from, in effect, rock hand specimens. In a few situations, (U–Th)/He analysis has been used to determine the antiquity of major, long‐wavelength topography. Cosmogenic isotope analysis has enabled the determination of the ‘ages’ of bedrock and sedimentary surfaces, and/or the rates of denudation of these surfaces. These latter advances represent in some ways a ‘holy grail’ in geomorphology in that they enable determination of ‘dates and rates’ of geomorphological processes directly from rock surfaces. The increasing availability of analytical techniques such as cosmogenic isotope analysis should mean that much larger data sets become possible and lead to more sophisticated analyses, such as probability density functions (PDFs) of cosmogenic ages and even of cosmogenic isotope concentrations (CICs). PDFs of isotope concentrations must be a function of catchment area geomorphology (including tectonics) and it is at least theoretically possible to infer aspects of source area geomorphology and geomorphological processes from PDFs of CICs in sediments (‘detrital CICs’). Thus it may be possible to use PDFs of detrital CICs in basin sediments as a tool to infer aspects of the sediments' source area geomorphology and tectonics, complementing the standard sedimentological textural and compositional approaches to such issues. One of the most stimulating of recent conceptual advances has followed the considerations of the relationships between tectonics, climate and surface processes and especially the recognition of the importance of denudational isostasy in driving rock uplift (i.e. in driving tectonics and crustal processes). Attention has been focused very directly on surface processes and on the ways in which they may ‘drive’ rock uplift and thus even influence sub‐surface crustal conditions, such as pressure and temperature. Consequently, the broader geoscience communities are looking to geomorphologists to provide more detailed information on rates and processes of bedrock channel incision, as well as on catchment responses to such bedrock channel processes. More sophisticated numerical models of processes in bedrock channels and on their flanking hillslopes are required. In current numerical models of long‐term evolution of hillslopes and interfluves, for example, the simple dependency on slope of both the fluvial and hillslope components of these models means that a Davisian‐type of landscape evolution characterized by slope lowering is inevitably ‘confirmed’ by the models. In numerical modelling, the next advances will require better parameterized algorithms for hillslope processes, and more sophisticated formulations of bedrock channel incision processes, incorporating, for example, the effects of sediment shielding of the bed. Such increasing sophistication must be matched by careful assessment and testing of model outputs using pre‐established criteria and tests. Confirmation by these more sophisticated Davisian‐type numerical models of slope lowering under conditions of tectonic stability (no active rock uplift), and of constant slope angle and steady‐state landscape under conditions of ongoing rock uplift, will indicate that the Davis and Hack models are not mutually exclusive. A Hack‐type model (or a variant of it, incorporating slope adjustment to rock strength rather than to regolith strength) will apply to active settings where there is sufficient stream power and/or sediment flux for channels to incise at the rate of rock uplift. Post‐orogenic settings of decreased (or zero) active rock uplift would be characterized by a Davisian scheme of declining slope angles and non‐steady‐state (or transient) landscapes. Such post‐orogenic landscapes deserve much more attention than they have received of late, not least because the intriguing questions they pose about the preservation of ancient landscapes were hinted at in passing in the 1960s and have recently re‐surfaced. As we begin to ask again some of the grand questions that lay at the heart of geomorphology in its earliest days, large‐scale geomorphology is on the threshold of another ‘golden’ era to match that of the first half of the 20th century, when cyclical approaches underpinned virtually all geomorphological work. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

A non‐baseline algorithm for damage locating in flexural structures using dynamic distributed macro‐strain responses     

S. Z. Li  Z. S. Wu 《地震工程与结构动力学》2007,36(9):1109-1125

The concept of distributed strain‐sensing techniques has been proposed in our recent research, which was dedicated to utilizing the strain distributions throughout the full or partial areas of structures to detect arbitrary and unforeseen damage. An algorithm not requiring a detailed analytical model is presented for damage locating in flexural structures through the direct use of dynamic responses recorded by distributed long‐gauge strain sensors. The modal macro‐strain vector (MMSV), which has been proven to have a mapping relation with displacement mode shape, can be extracted directly from macro‐strain time‐series data, from which a damage evaluating index can be derived and used as an indicator for locating damage. Numerical examples are simulated to verify the sensitivity and effectiveness of the index in different cases. Furthermore, experimental investigations on a cantilevered beam with various long‐gauge fibre optic sensors placements are carried out to examine the feasibility and applicability of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

辽宁岫岩5.4级地震临震预测     

谷光裕  于龙伟  王安东  卢良玉  王玉莹 《地震》2001,21(1):78-84

简要介绍了1999年11月29日辽宁岫岩Ms5.4地震成功预报的震前主要预测依据及基本思路。通过对震前辽宁地区地震中短期危险性的分析，确定辽南地区是未来主震的危险地区。根据地震活动的区域特性及岫岩偏岭震群活动的规律，判定岫岩震群的前震性质。利用地震活动性参数计算结果和震前在震中及邻近地区出现前兆短临异常的统计分析，进一步论述了震前预测地震三要素的基本依据。  相似文献   

利用地磁场总强度预测地震三要素初探          下载免费PDF全文

王庆玺  欧阳小龙 《地震工程学报》2001,23(2):131-136

计算了河南省6个台站的相邻时段的地磁场总强度观测资料的自相关系数分析了各台自相关系数的变化与地震的关系，各台的自相关系数曲线对应地震的效果较好，发震时间一般在异常低值后1-8个月，统计得出了各台所对应的地震震级与自相关系数异常面积和震中距的经验公式，利用3个以上台站的经验公式和交汇法，即可以求出震中位置和地震震级，经震例检验，该方法基本可行。  相似文献   

随州-信阳M_L4.2地震前定点形变异常特征          下载免费PDF全文

胡卫建  张俊山  周小川  谢智  王志敏  李安印  李平林  谢健健  刘丽君 《地震工程学报》2001,23(3):274-278

分析了2000年1月28日随州和信阳交界处发生的ML4．2地震前，信阳地震台（△＝35km)定点形变中短期及临震异常特征。分析研究表明：该次地震前信阳台目视水管倾斜仪EW向测值从1999年6开始出现反向变化，NS向测值从1999年3月开始出现加速变化；水平摆倾余仪EW向和NS向测值分别从1999年2月和1999年6月开始出现反向变化。这些异常于2000年下半年结束。震前3天水管倾斜仪EW向测值出现加速变化；震前5－8天NS向测值除了出现加速变化外，还出现突跳。城前约20天，水平摆倾斜仪2个方向测值构出现了准周期性波动变化。另外，形变固体潮潮汐因子也有明显异常。  相似文献   

地震非均匀度在华北地震中短期预报中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

王炜  宋先月  王峥峥 《地震工程学报》2001,23(4):339-345

利用空间扫描方法研究了华北地区中强以上地震前地震非均匀度GL值的中短期异常变化特征，结果表明在中强地震前1年左右，未来震中周围的GL值中期异常区通常出现明显的收缩或消失，一些地震临震前数月还再次出现GL值异常区，讨论了使用GL值进行地震中短期预报的有关问题。  相似文献   

LONG TERM EFFECTS OF REHABILITATION MEASURES ON BED LOAD TRANSPORT AT THE SALZACH RIVER     

Sven HARTMANN Institute for Hydrosciences  German Armed Forces University Munich  Neubiberg  Germany. 《国际泥沙研究》2001,16(2)

1 BASIC PROBLEMFlood protecton, sPreaing of settlements and occuPatin Of river valleys were maor reasons to damand lindt rivers throughout Europe in the ndd 19th century. Engineers of those days often knew very wellabout the effects of their plannings: shortening the river length would accelerat the now and thusencourage the erosion into the river's sedAnents. Two vital advanages could be obtalned from that kindof constrUction, landuse of the fOrmer flood plains on the one and increasin…  相似文献   

RESUSPENSION OF FINE SEDIMENT IN RESERVOIRS - A CASE STUDY OF THE LOWER INN RIVER     

Thomas ELSNERand Sven HARTMANN Institute for Hydrosciences  German Armed Forces University Munich  Neubiberg  Germany. Institute for Hydrosciences  German Armed Forces University Munich  Neubiberg  Germany. 《国际泥沙研究》2001,16(2)

1 THE LOWhR unR INNThe Inn river has its source in the alPine region of the GraubUnden canton of Switzerand. ThecatChment area of about 260(X} kIn2 includes mountains of the central Alpes up to 40(X) m. The river runs5l7 km thrOugh the countries of SwitZerand, Austria and Germany on itS way into the Danube mver. Thedischarge of the river at its mouth in the city of Passau is mainly infiuenced by the snow melt in themountainous catchment area and vches between apProx. 200 m3ls durin…  相似文献   

日本历次地震预报计划概述     

谢雪芳  罗岚 《国际地震动态》2001,(9):11-13

1995年兵库县南部地震后，日本地震学家的思路有所改变，制订出更切合实际的新地震预报计划。  相似文献