三维任意形体高密度电阻率法数值模拟方法     

杨文强 《物探化探计算技术》1997,19(3):270-273,278

为研究高密度电阻率法对各种三维地电体的反映规律，本文介绍了正演程序编制的方法并给出了计算实例。  相似文献   

东川铜矿床同位素地球化学研究:I.地层年代与铅同位素化探应用   总被引：7，自引：0，他引：7  

常向阳  朱炳泉  孙大中  邱华宁  邹日 《地球化学》1997,(2)

采用Ｐｂ－Ｐｂ等时线法测定了昆阳群中亚群落雪组白云岩、黑山组碳质板岩和上亚群大营盘组碳质板岩样品，获得了（１７１６±５６）Ｍａ、（１６０７±１２８）Ｍａ和（１２５８±７０）Ｍａ的年龄，确定了昆阳群中亚群时代约为１６００—１８００Ｍａ，属晚古元古代，上亚群大营盘组约为１２００—１３００Ｍａ，属中元古代。还应用铅同位素化探技术系统研究了汤丹铜矿１号硐中段西１４穿脉岩石－矿石的铅同位素组成，结果表明铅同位素Ｖ１值与铜含量呈反相关系。这是运用系统剖面方法开展铅同位素化探的首次尝试。  相似文献   

Recent Advances in Prediction and Processing of Strong Ground Motions     

Alexei G. Tumarkin  Ralph J. Archuleta 《Natural Hazards》1997,15(2-3):199-215

We present an overview of our recent results on utilizing small earthquakes in the earthquake engineering practice. Site-specific ground motion time-histories of large earthquakes can be successfully simulated using recordings of small earthquakes which are often referred to as 'empirical Green's functions' in seismology. Another important practical problem is whether and how these observations can be used in seismic risk studies which are based on empirical attenuation relations for ground motion parameters. We study a possibility of extrapolating attenuation relations for small earthquakes, to larger magnitudes using the data from the Garner Valley downhole array in Southern California. Finally we introduce efficient ground motion processing techniques in frequency- and time-domains and apply them to site response estimation.  相似文献   

Seismic Ground Motion Expected for the Eastern District of Naples     

C. Nunziata  F. Vaccari  G.F. Panza  G. Luongo  D. FÄH 《Natural Hazards》1997,15(2-3):183-197

The seismic ground motion of a test area in the eastern district of Naples is computed with a hybrid technique based on the mode summation and the finite difference methods. This technique allows us the realistic modelling of source and propagation effects, including local soil conditions. In the modelling, we consider the 1980 Irpinia earthquake, a good example of strong shaking for the area of Naples, which is located about 90 km from the epicenter.The detailed geological setting is reconstructed from a large number of drillings. The sub-soil is mainly formed by alluvial (ash, stratified sand and peat) and pyroclastic materials overlying a pyroclastic rock (yellow neapolitan tuff), representing the neapolitan bedrock. The detailed information available on mechanical properties of the sub-soil and its geometry warrants the application of the sophisticated hybrid technique.As expected, the sedimentary cover causes an increase of the signal's amplitudes and duration. If thin peat layers are present, the amplification effects are reduced, and the peak ground accelerations are similar to those observed for the bedrock model. This can be explained by the backscattering of wave energy at such layers, that tend to seismically decouple the upper from the lower part of the structure.For SH-waves, the influence of the variations of the S-wave velocities on the spectral amplification is studied, by considering locally measured velocities and values determined from near-by down-hole measurements. The comparison between the computed spectral amplifications confirms the key role of an accurate determination of the seismic velocities of the different layers.The comparison performed between a realistic 2-D seismic response and a standard 1-D response, based on the vertical propagation of waves in a plane layered structure, shows considerable difference, from which it is evident that serious caution must be taken in the modelling of expected ground motion at a specific site.  相似文献   

电法勘探的发展和展望   总被引：9，自引：1，他引：9       下载免费PDF全文

何继善 《地球物理学报》1997,40(Z1):308-316

电法勘探在经历了近一个世纪的发展后，其方法理论、仪器设备、野外数据采集、处理和解释等方面都经历了一系列重大变化．本文以方法理论的进展为主线，回顾、展望了目前电法勘探中几个重要而令人关注的研究焦点．这些问题的研究进展将会对21世纪的电法勘探产生深远的影响．  相似文献   

萨拉乌苏组沉积时代的重新厘定   总被引：9，自引：0，他引：9  

苏志珠  董光荣 《沉积学报》1997,15(4):159-164

重新认识我国北方地区晚更新世河湖相标准地层--萨拉乌苏组的形成时代，对于萨拉乌苏组与马兰黄土的关系，与冰期气候对比等具有重要意义。笔者近年来根据野外层位对比和地层沉积相的划分，采用绝对年代控制，并结合黄土－古土壤序列研究的最新成果，初步建立了可以与黄土、深海沉积记录和冰期气候波动对比的萨拉乌苏组地层序列。认为河湖相沉积的萨拉乌苏组形成于约１４００００～７００００ａ.Ｂ.Ｐ.的末次间冰期，大致与深海氧同位素第５阶段对应，与黄土高原古土壤Ｓ１发育同期。城川组风成细砂形成于约７００００～１００００ａ.Ｂ.Ｐ的末次冰期，与黄土高原的马兰黄土是同期异相地质体.  相似文献   

Thermodynamic Modelling of Ore-Forming Mechanism of the Changkeng Gold-Silver Deposits in Guangdong Province     

Zhang Sheng  Li Tongjin  Wang LiankuiGuangzhou Institute of Geochemistry  Chinese Academy of SciencesWushan  Guangzhou 《《地质学报》英文版》1997,71(4):433-445

The Changkeng gold-silver deposits consist of a sediment-hosted, disseminated gold deposit and a replacement-type silver deposit. The mineralizations of gold and silver are zoned and closely related to the silicification of carbonate and clastic rocks, so that siliceous ores dominate in the deposit. The mineralizing temperature ranges mainly from 300 to 170℃, and K+, Na+, Ca2+, Mg2+, and Cl- are the major ions in the ore-forming fluid. Calculations of distribution of metal complexes show that gold is mainly transported by hydrosulphide complexes, but chloride complexes of silver, iron, lead, and zinc, which are transformed into hydroxyl and hydrosulphide complexes under neutral to weak-alkaline circumstances in the late stage, predominate in the ore-forming solutions. Water-rock interaction is confirmed to be the effective mechanism for the formation of silver ores by computer modelling of reaction of hydrothermal solution with carbonate rocks. The solubility analyses demonstrate that the precipitation  相似文献   

地壳介质弹性和电性各向异性研究的新进展   总被引：3，自引：2，他引：3       下载免费PDF全文

李清河  阮爱国  范小平  金淑梅 《地震工程学报》2004,26(1):10-17

分析了地壳介质各向异性研究的现状，指出了弹性和电性各向异性研究中存在的问题，提出了联合利用弹性和电性各向异性研究地球介质特征及提取物性参数的正反演方法．理论研究和地震过程的实际资料表明，将弹性和电性结合起来研究地壳介质各向异性具有清晰明确的物理意义，是各向异性研究的一个非常有发展前景的新领域。  相似文献   

Observational and Numerical Study on the Influence of Large-Scale Flow Direction and Coastline Shape on Sea-Breeze Evolution     

Robert C. Gilliam  Sethu Raman  Dev Dutta S. Niyogi 《Boundary-Layer Meteorology》2004,111(2):275-300

In this study radar, surface observations and numericalsimulations are used to examine the inland penetrationand intensity of the sea breeze during various large-scaleflow regimes along the curved coastline of the Carolinas,U.S.A. The results clearly indicate that the flow directionrelative to the curved coastline has a significant effecton the sea-breeze evolution.Overall, during northerly flow regimes alongthe curved North Carolina coast, observationsand numerical simulations show that the sea-breezefront has a tendency to remain close to the south-facingcoast. During these same flow regimes the frontmoves further inland relative to the east-facingcoast. The sea-breeze front during westerly flowcases progressed further inland relative to the southcoast and less so from the east-facing coastline.South-westerly flow allows the sea breeze to moveinland from both coastlines but the coastal shapeinfluence makes the inland penetration less fromthe easterly facing beaches. During periods of lightonshore flow (south-east), the sea breeze movesconsiderable distances inland but is not discernableuntil later in the afternoon. The simulations indicatedthat the sea-breeze intensity is greatest (least) when thelarge-scale flow direction has an offshore (onshore)component. Model results indicate the existence of astrong front well inland in the late afternoon duringlight onshore flow. Also noted was that the simulatedsea-breeze front develops earlier in the afternoon duringoffshore regimes and later in the day as the large-scaleflow becomes more onshore. It is concluded that thecoastline shape and coast-relative flow direction areimportant factors in determining how the sea-breezecirculation evolves spatially.  相似文献   

吐哈盆地西南缘水西沟群古气候演变特征及其层序地层学意义     

吴伯林  徐高中 《华东地质学院学报》2004,27(2):135-140

通过对水西沟群(J1-2sh)古植物、古孢粉化石组合特征等系统的研究，对八道湾组(J1b)、三工河组(J1s)、西山窑组(J1x)古气候类型进行了区分；并据此认为西山窑组(J1x)为一套气候地层层序，相应划分为四个体系域：即低水位、湖泊扩张，高水位及湖泊收缩体系域。再结合一些岩性岩相等特殊标志，对十红滩东部外围地层层序进行了划分，结果与十红滩矿区地层层序本质是一致的。  相似文献