Phase relations and P–T conditions of the Ryoke pelitic and psammitic metamorphic rocks in the Ina district, Central Japan     

Tomokazu  Tokada 《Island Arc》1998,7(4):609-620

The Ina district of the Ryoke Belt is divided into two mineral zones, based on the mineral parageneses of the pelitic and psammitic rocks at the peak metamorphism. A biotite–muscovite zone (quartz + plagioclase + biotite + muscovite with or without K-feldspar) constitutes the northwestern part, and a biotite–cordierite–K-feldspar zone (quartz + plagioclase + biotite + cordierite + K-feldspar) comprises the central to southern and eastern parts. The isograd reaction between two mineral zones is defined by a divariant reaction: Mg-rich biotite + muscovite + quartz = Fe-rich biotite + cordierite + K-feldspar + H₂O (1), which, in the K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O (KFMASH) system, occurs at ∼ 590 °C at 0.2 GPa and 660 °C at 0.4 GPa. Fibrolite accompanied by andalusite porphyroblasts in aluminous pelitic rocks of the biotite–muscovite zone and the low-grade part of the biotite–cordierite–K-feldspar zone, suggests that sillimanite was the stable aluminosilicate at the peak metamorphic condition throughout the area. In the high-grade part of the biotite–cordierite–K-feldspar zone, fibrolite mostly occurs as inclusions in cordierite or in plagioclase. The phase relations and the compositional zoning of plagioclase in relation to fibrolite inclusions suggest that fibrolite was formed under relatively high-pressure conditions, and that partial melting took place.  相似文献   

Verification and refinement of spectral magnitude calibrating functions for P-waves     

E. L. Lyskova  Yu. V. Roslov  T. B. Yanovskaya  S. J. Duda 《Journal of Seismology》1998,2(2):117-124

Calibrating functions for determination of P-wave spectral magnitudes calculated by Duda and Yanovskaya (1994) on the basis of the IASP91 velocity model and the PREM Q-model are verified empirically. For this purpose IRIS broadband records for 120 earthquakes are used, each earthquake having been recorded at about 100 stations. The discrepancies indicate that anelastic absorption assumed in PREM is too high. New calibrating functions are calculated on the basis of the AK135 velocity and anelasticity models (Kennet et al., 1995; Montagner and Kennet, 1996), in which Q in the mantle is higher than in PREM. The verification of the new calibrating functions based on the same observations yields magnitude figures less depending on the epicentral distance. In addition the parameter ₂in the Liu-Anderson Q(T) model is estimated, proceeding from the assumption that on the average the radiated spectra comply with the ²-model. The value of ₂ was assumed to be 0.1 s in the analysis and its use resulted in the verification of the ²-model for the source spectrum.  相似文献   

运用能谱测量相关系数的统计检验法确定岩体的侵入关系     

刘科友 《华东地质学院学报》1998,21(2):111-115

本文介绍应用铀,钍相关系数的统计检验法,来判断某两经岗岩侵入体的侵入关系。方法简便,准确度高。  相似文献   

旅游者行为规律与旅游地图编制关系的探讨   总被引：6，自引：1，他引：5  

黄志良  殷力 《地理科学》1998,18(6):549-554

旅游者行为规律是旅游地理研究的一个方面,行,吃,住,游,娱,购行为是旅游者空间行为的重要方面,它与旅游地图有着双向导的密切关系,是旅游地图的主要内涵。旅游实施行为指导旅游地图编制,旅游地图为旅游者引导旅游实施行为,为其提供服务。因此,研究旅游者行为规律对旅游地图编制和产品开发有着重要意义。  相似文献   

桩式复合地基承载特性的研究   总被引：8，自引：1，他引：7  

娄国充 《岩土力学》1998,19(1):70-74

以桩式复合地基为对象,将复合地基视为由垫层、桩和桩间土所组成的一个工作体系,考虑其各部分的工作特性及其相互影响,分析研究了复合地基的受荷机理,影响桩土应力比和复合地基承载力的诸多因素等。  相似文献   

八卦庙金矿床石英脉与金矿化关系再研究   总被引：3，自引：1，他引：2       下载免费PDF全文

韦龙明  吴烈善  朱桂田  曹远贵 《地质找矿论丛》1998,13(3):9-14

八卦庙特大型金矿床是近年发现的产于秦岭地区泥盆系浅变质细碎屑岩中规模最大的微细浸染型金矿,金矿化与石英脉关系非常密切,经过大量分析数据统计表明,金矿石品位与其石英脉带的发育规律,脉体内外硫化物的含量成正比,与脉体的规整程度成反比,与脉体的厚度具有一定的关系。一般说,产于节理中的石英细脉的含金量比顺层产出的石英大脉的含金量高;石英脉的含金量高于脉旁围岩的含金量数倍甚至几十倍,含金石英脉与脉旁蚀变岩石  相似文献   

重庆钢铁公司岸坡古滑坡系统形成机制研究     

胡新丽 《地质科技情报》1998,(Z2)

系统分析了重庆钢铁公司岸坡古滑坡系统的地质条件,提出了从新构造运动、河谷演变着手,依据系统发展的观点,研究滑坡系统形成机制的方法。分析结果表明该古滑坡系统由多级滑坡体组成,各滑体在时空上具有成生联系,目前滑坡系统除三角地带古滑体需整治外,其余地段均处于稳定状态。  相似文献   

INTERACTION BETWEEN ATMOSPHERE AND OCEAN AND TELECONNECTION IN THE ATLANTIC DURING THE COLD SEASON          下载免费PDF全文

Jiang Quanrong  J. M. Wallace 《Acta Meteorologica Sinica》1992,6(1):38-46

In this paper,the WA teleconnection pattern of SST in the Atlantic during the cold season is confirmed.The resultsshow the WA pattern of atmosphere is linked to the SST pattern and relative higher frequencies account for most of theWA signal.The linked pair of atmosphere and ocean patterns might be mutually supportive and exhibit“quasi-annualcycle”.The possible explanation for the polarity reversal of WA pattern is also discussed.  相似文献   

Scattering attenuation and the fractal geometry of fracture systems     

Ian G. Main  Sheila Peacock  Philip G. Meredith 《Pure and Applied Geophysics》1990,133(2):283-304

Scattering of seismic waves can be shown to have a frequency dependenceQ ^{–1 3–v} if scattering is produced by arrays of inhomogeneities with a 3D power spectrumW _3D(k) k ^–v. In the earth's crust and upper mantle the total attenuation is often dominated by scattering rather than intrinsic absorption, and is found to be frequency dependent according toQ ^–1 , where –1<–0.5. IfD ₁ is the fractal dimension of the surface of the 3D inhomogeneities measured on a 2D section, then this corresponds respectively to 1.5<D ₁1.75, since it can be shown that =2(D ₁–2). Laboratory results show that such a distribution of inhomogeneities, if due to microcracking, can be produced only at low stress intensities and slow crack velocities controlled by stress corrosion reactions. Thus it is likely that the earth's brittle crust is pervaded by tensile microcracks, at least partially filled by a chemically active fluid, and preferentially aligned parallel to the maximum principal compressive stress. The possibility of stress corrosion implies that microcracks may grow under conditions which are very sensitive to pre-existing heterogeneities in material constants, and hence it may be difficult in practice to separate the relative contribution of crack-induced heterogeneity from more permanent geological heterogeneities.By constrast, shear faults formed by dynamic rupture at critical stress intensities produceD ₁=1, consistent with a dynamic rupture criterion for a power law distribution of fault lengths with negative exponentD. The results presented here suggest empirically thatD ₁-1/2(D+1), thereby providing the basis for a possible framework to unify the interpretation of temporal variations in seismicb-value (b-D/2) and the frequency dependence of scattering attenuation ().This is PRIS contribution 046.  相似文献   

贵州威宁X波段双偏振雷达反射率因子的衰减订正分析     

曾勇  李怀志  邹书平  李皓  李丽丽 《中低纬山地气象》2022,46(5):88-94

针对贵州威宁X波段双偏振雷达的衰减订正问题,在利用综合小波去噪方法对差分传播相移ФDP进行质量控制基础上,基于自适应衰减订正算法对雷达反射率因子ZH进行衰减订正分析,订正结果与昭通C波段新一代天气雷达进行对比,结果表明：（1）综合小波去噪能够有效去除ФDP存在的脉动和毛刺,保证ФDP的连续性和平滑度;（2）订正前后雷达反射率因子在距离雷达较近处（20-35 km）强度廓线基本重合,订正前后差别不大,随着对流区（雨区）距离的增加,电磁信号出现衰减,订正后反射率值加强,总体上订正后的反射率值比订正前高1-12 dB,其中在35～75 km距离范围内,订正后的反射率值达到50 dBz以上,雷达反射率因子更加接近真实情况;（3）使用综合小波去噪配合自适应衰减订正算法可以提高雷达反射率因子衰减订正的准确率,方法具有普适性,在今后科研业务中可以采用该订正方法以进一步提高对粒子相态识别、降水估测精度。  相似文献