陕西凤县八卦庙金矿床成矿地质特征及外围找矿前景分析   总被引：3，自引：0，他引：3  

张万业  刘方杰  黄长青 《矿产与地质》2003,17(2):136-139

阐述了八卦庙金矿床经历了长期、复杂的非线性成矿过程，着重分析了：含矿建造为与同生伸展断裂伴生的海底喷流热水沉积岩、热水浊积碎屑岩；脆-韧性剪切构造控制着主成矿过程；后期幔源岩浆气液叠加富集使其成为超大型金矿床。指出矿床成因为热水同生沉积细碎屑岩-剪切蚀变岩-幔源岩浆气液叠加富集型。八卦庙金矿床外围仍有巨大的找矿前景。  相似文献   

灵山岩体演化特征及其与稀有金属的成矿关系   总被引：5，自引：0，他引：5  

黄定堂 《地质与勘探》2003,39(4):35-40

从岩体时空分布、岩石化学成分、造岩矿物、副矿物、微量元素、稳定同位素、成岩温度、压力等特征，论述了灵山岩体演化与钽铌等稀有金属成矿的关系，简述了区内典型稀有金属矿床主要成矿地质特征及其与岩体的成因联系，进而肯定了区内钽铌等稀有金属找矿的良好前景，并提出了今后找矿的方向和建议。  相似文献   

静力触探中土层界面效应试验研究   总被引：2，自引：2，他引：2  

陈维家  汪火旺 《水文地质工程地质》2003,30(2):25-27

根据成层土模型试验结果,对静力触探中土层面效应进行试验研究和机理分析,取得了成层土界面效应的规律性,为利用静力触探划分土层提供了理论和实践依据。  相似文献   

Evaluation of liquefaction potential using neural-networks and CPT results   总被引：1，自引：0，他引：1  

M. H. Baziar  N. Nilipour   《Soil Dynamics and Earthquake Engineering》2003,23(7):631-636

In this research, a reliable Cone Penetration Test data set was gathered with a wide range of parameters. This data was incorporated in a Neural-Networks computer software called STATISTICA Neural-Networks. The back propagation algorithm with a multilayer perceptron network is utilized to analyze the liquefaction occurrence in different sites. In this study, different sets of effective parameters for the neural-network analyses are selected such that to reduce the noise and to obtain more accurate results.Considering the relative importance of effective parameters in liquefaction assessment, it is indicated that σ₀, σ′₀ together play a more important role than what previously was assumed and hence the relative importance of the q_c and seismic parameters are decreased compared with the previous works. The results presented here have more accuracy than previous works while at the same time, the range of the parameters used in this study is much wider than what was previously used. This range of parameters makes the proposed method applicable for practical purposes.  相似文献   

U–Pb zircon chronostratigraphy of early-Pliocene ignimbrites from La Pacana, north Chile: implications for the formation of stratified magma chambers     

Axel K Schmitt  Jan M Lindsay  Shan de Silva  Robert B Trumbull 《Journal of Volcanology and Geothermal Research》2003,120(1-2):43-53

High spatial resolution U–Pb dates of zircons from two consanguineous ignimbrites of contrasting composition, the high-silica rhyolitic Toconao and the overlying dacitic Atana ignimbrites, erupted from La Pacana caldera, north Chile, are presented in this study. Zircons from Atana and Toconao pumice clasts yield apparent ²³⁸U/²⁰⁶Pb ages of 4.11±0.20 Ma and 4.65±0.13 Ma (2σ), respectively. These data combined with previously published geochemical and stratigraphic data, reveal that the two ignimbrites were erupted from a stratified magma chamber. The Atana zircon U–Pb ages closely agree with the eruption age of Atana previously determined by K–Ar dating (4.0±0.1 Ma) and do not support long (>1 Ma) residence times. Xenocrystic zircons were found only in the Toconao bulk ignimbrite, which were probably entrained during eruption and transport. Apparent ²³⁸U/²⁰⁶Pb zircon ages of 13 Ma in these xenocrysts provide the first evidence that the onset of felsic magmatism within the Altiplano–Puna ignimbrite province occurred approximately 3 Myr earlier than previously documented.  相似文献   

Petrology and Geochemistry of the Volcanic Rocks Dredged from the Geophysicist Seamount in the Kurile Basin: Evidence for the Existence of Thinned Continental Crust     

Igor A. Tararin  Eugeniy P. Lelikov  Reinhard Werner 《Gondwana Research》2003,6(4):757-765

Dredged samples from the Geophysicist seamount volcano in the northeastern part of the Kurile Basin include volcanic and volcanoclastic rocks ranging from basalt to andesite. The rocks have geochemical features typical of high-K island-arc calc-alkaline volcanism. They are enriched in LILE and depleted in Zr, Ti, Nb, Ta and Y. The chondrite-normalized REE patterns are characterized by enrichment of LREE similar to those of island-arc lava from the submarine volcanoes of rear-arc zone of the Kurile Island Arc. The volcanic rocks have a wide range of ⁸⁷Sr/⁸⁶Sr ratios (0.70287-0.70652), varying ¹⁴³Nd/¹⁴⁴Nd and Pb isotopic ratios. Their trace-element compositions and Sr-Nd-Pb isotope signatures may be explained by a small addition of crustal continental component to mantle-derived magmas that suggest the existence of thinned continental basement under the eastern part of the Kurile Basin.  相似文献   

Empirical correlations of soil parameters based on Cone Penetration Tests (CPT) for Greek soils     

A. Anagnostopoulos  G. Koukis  N. Sabatakakis  G. Tsiambaos 《Geotechnical and Geological Engineering》2003,21(4):377-387

This study presents the results of Cone Penetration Tests (CPT) and estimated correlations with the results of other in-situ tests (standard penetration test, cross-hole, seismocone) and laboratory tests (classification and undrained shear strength tests). These tests cover nearly all types of penetrable soils in Greece and, together with the formulation of empirical correlations, complement and improve on previous studies due to the significant number of CPT measurements.  相似文献   

Creating a GIS application for retail centers in Jeddah city   总被引：2，自引：0，他引：2  

AbdulKader A. Murad   《International Journal of Applied Earth Observation and Geoinformation》2003,4(4):329-338

The aim of this paper is to identify the role of geographical information systems (GIS) in supporting retail planners in monitoring and analyzing retail development and growth. At first, a review about retail planning and its relevant issues is made. Second, GIS is defined together with its applications in retail planning. The third part discusses the created GIS application that is designed for two retail centers in Jeddah city, Saudi Arabia. This application is created to help planners in defining the distribution of retail demand, describing customers profile, analyzing trade areas and modeling retail flows. Two useful models have been produced by this study. One is called market penetration and the other is based on spatial interaction technique. The former is created to examine retail center catchment area, while the latter is used to model the interaction between demand areas and retail centers.  相似文献   

长白山天池火山区长白-敦化剖面结晶基底的探测和研究     

潘素珍  张先康  杨卓欣  张成科  赵金仁  潘纪顺  任青芳  张建狮 《地震研究》2003,26(3):271-274

时间项分析法中，应用广义最小二乘法进行反演，对长白山天池火山区岩浆系统的长白—敦化(L1)剖面的Pg波到时进行了计算处理，得到了Pg波时间项及基底速度值；取上部地壳的介质平均速度为4．5km/s，经反演求得了各点的深度值，给出了长白山天池火山区结晶基底的厚度分布。结晶基底厚度一般在2．0km左右，而在长白山天池下方结晶基底最厚处接近4．0km；在万宝和敦化附近各有一不太明显的凹陷，其原因可能与在这两个位置处有几条断裂穿过有关。  相似文献   

岩浆驱动破裂的形态研究     

栾锡武  秦蕴珊  宋海斌  石耀霖 《地球物理学进展》2003,18(1):138-141

轴地壳岩浆房是活动扩张中心海洋地壳结构的一个重要组成部分，轴地壳岩浆房通过深部岩浆源的补充，内部岩浆的同化熔融、结晶分异等岩浆房过程，其中的岩浆会破裂上覆的岩石层形成岩浆破裂，并沿岩浆破裂继续向上迁移。本文建立了岩浆迁移的层流模型，从理论上对岩浆迁移问题进行了探讨，并将遗传算法引入到该问题中来，用遗传算法求解了描述岩浆驱动破裂传播的积分方程。如果假设岩浆破裂在远离破裂末梢处的权限宽度为1M，则靠近末梢，破裂的宽度逐渐加大，在末梢处宽度为2m左右。并根据文献对岩浆流体的一些观测参数计算得出，岩浆破裂权限宽度不会很大，一般在1m左右的量级。  相似文献