扬子克拉通太古代崆岭群角闪岩相与麻粒岩相岩石的岩石磁学研究   总被引：1，自引：0，他引：1       下载免费PDF全文

刘庆生  高山  徐启东  凌文黎 《地球物理学报》1996,39(Z1):150-157

提供了扬子克拉通太古代基底崆岭群２０件代表性岩石样品的密度与磁性参数的测量结果．结果表明，变碎屑岩与ＴＴＧ（英云闪长－奥长花岗－花岗间长质）片麻岩（１３个样品）的磁化率与饱和剩磁普遍大于斜长角闪岩和辉长岩．前者的磁化率与饱和剩磁平均值分别为１２１３×１０^－６ＳＩ与１９．９４Ａ／ｍ，而后者的则为８０２×１０^－６ＳＩ与１０．７７Ａ／ｍ．变碎屑岩与ＴＴＧ片麻岩呈明显的亚铁磁性状态；斜长角闪岩和辉长岩则以顺磁性或顺磁性与亚铁磁性混合状态分布为主．热磁分析结果表明，变碎屑岩与ＴＴＧ片麻岩的剩磁载体以磁铁矿与磁赤铁矿为主；斜长角门岩和辉长岩则明显含有磁黄铁矿与次要的磁铁矿．变碎屑岩与ＴＴＧ片麻岩的磁性具有很强的非均一性．推断崆岭群中的变碎屑岩为麻粒岩相变质级，视深度相当于大陆下地壳；而斜长角闪岩的变质级明显低于变碎屑岩，可能为角门岩相，视深度相当于中地壳．变碎屑岩与ＴＴＧ片麻岩磁性的强非均一性可能与该区后期广泛发生的混合岩化作用密切相关。  相似文献   

江汉盆地马王庙油田自生磁铁矿与烃运移相互关系研究   总被引：2，自引：0，他引：2  

刘庆生  徐文凯 《地球学报》1996,17(Z1):84-90

研究表明，已知油井M36井Ⅱ油组的含油层（位于Ⅱ油组的中—下部）中有明显呈规律分布的强磁性层。以平均值为例，含油岩层屑的饱和磁化强度Js=352.58A/m，饱和剩磁Jc=60.43A/m；而干层的Js=147.34A/m，Jr=22.09A/m。磁滞回线特征表明，含油层岩屑中以偏软的磁性矿物为主（平均矫顽力Hc=33.5mT，饱和磁场Hs=0.25T），而干层岩屑中主要为磁性偏碱的磁性矿物（Hc=44.2mT，H8=0.4T）。重矿物分析结果显示，干井M46井Ⅱ油组岩屑中含沙射影有较多的碎屑磁铁矿。磁学与矿物学参量的对应分析表明，含油层强磁性岩层的载体为自生成因的磁铁矿，而菱铁矿与黄铁矿为非磁性矿物，对Ⅱ油组岩层的磁性没有影响。由此，我们提出M36井含油层中的自生磁铁矿可能是原油的生物降解作用、碎屑矿物中高价铁的被置换及后期菱铁矿的氧化作用等多种不同时空条件下形成的产物。  相似文献   

自生磁铁矿与烃的富集及运移之间相互关系的研究   总被引：6，自引：2，他引：6  

刘庆生  蔡振京 《地球科学》1991,16(5):565-571

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纤维塑料约束混凝土柱抗震性能研究综述   总被引：14，自引：1，他引：14  

于清  陶忠 《地震工程与工程振动》2002,22(2):66-72

作为一种新型建筑结构材料，纤维塑料（Fiber Reinforced plastic,简称FRP）在某些特定的条件下可替代传统的木、钢和钢筋材料，具有高强、轻质、抗腐蚀和耐疲劳，温度作用下稳定性好等特点，因而受到土木工程界的关注。本文简要从结构试验、计算理论和计算方法三个方面阐述了国内外研究者对FRP约束混凝土抗震性能的研究现状，并分析了研究中存在的不足。在比较了大量的研究成果之后，基于组成FRP约束混凝土的FRP及其核心混凝土之间组合作用的特点，探讨了FRP约束混凝土抗震性能研究中的若干关键问题。最后，展望了FRP约束混凝土结构抗震性能研究的发展前景。  相似文献   

X形和三角形钢板阻尼器的阻尼力模型（Ⅱ）——基于R-0本构关系   总被引：2，自引：0，他引：2  

李冀龙  欧进萍 《世界地震工程》2004,20(2):129-133

利用软钢的Ramberg-Osgood本构关系(R-O模型)，依据经典力学原理推导建立了X形和三角形钢板阻尼器的阻尼力滞回模型。首先，给出了循环加载下软钢材料的应力-应变R-O本构关系；其次，推导建立了基于R-O本构关系的钢板阻尼器的阻尼力模型；最后，将该阻尼力模型及其参数与试验结果和双线性强化模型进行了比较，验证了R-O理论模型的有效性，并分析了误差存在的原因。  相似文献   

Sea-level change and remagnetization of continental shelf sediments off New Jersey (ODP Leg 174A): magnetite and greigite diagenesis   总被引：1，自引：0，他引：1  

Hirokuni Oda  Masayuki Torii 《Geophysical Journal International》2004,156(3):443-458

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A Monte Carlo investigation of the representation of thermally activated single-domain particles within the Day plot     

D. Heslop 《Studia Geophysica et Geodaetica》2005,49(2):163-176

Hysteresis based measurements are a standard part of many rock magnetic investigations. Whilst they provide information on the various magnetic minerals present in a natural sample they can also offer an insight into the domain state of the grains. The most commonly employed method to derive such structural information from hysteresis measurements is the Day plot, which employs ratios of different parameters to demarcate the possible domain states. Numerous experimental and modelling investigations have demonstrated that interpretation of the Day plot is not a simple task because the position at which an assemblage of magnetic grains plots within the space of the diagram is not solely a function of domain state. Here two mechanisms that appear to influence the Day plot are investigated. It is well known that thermal activation of an assemblage has the effect of randomising the magnetisation of grains until at sufficiently high temperatures they become superparamagnetic. A collection of Monte Carlo simulations for uniaxial, single-domain, Stoner-Wohlfarth (SW) grains with atomic moments that rotate coherently (Stoner and Wohlfarth, 1948), are utilised to demonstrate that the expression of this process could be easily misinterpreted as the signature of a different domain state. Secondly, the different published methods for determining the coercivity of remanent magnetisation are assessed and it is shown that the same sample can plot in a variety of different locations within the space of the Day plot depending on which method is employed.  相似文献   

Modelling the hysteresis in the velocity pattern of slow‐moving earth flows: the role of excess pore pressure     

T. W. J. van Asch 《地球表面变化过程与地形》2005,30(4):403-411

This paper describes the velocity pattern of a slow‐moving earth flow containing a viscous shear band and a more or less rigid landslide body on top. In the case of small groundwater fluctuations, Bingham's law may describe the velocity of these slow‐moving landslides, with velocity as a linear function of excess shear stress. Many authors have stated that in most cases a non‐linear version of Bingham's law best describes the moving pattern of these earth flows. However, such an exponential relationship fails to describe the hysteresis loop of the velocity, which was found by some authors. These authors showed that the velocity of the investigated earth flows proved to be higher during the rising limb of the groundwater than during the falling limb. To explain the hysteris loop in the velocity pattern, this paper considers the role of excess pore pressure in the rheological behaviour of earth flows by means of a mechanistic model. It describes changes in lateral internal stresses due to a change in the velocity of the earth flow, which generates excess pore pressure followed by pore pressure dissipation. Model results are compared with a hysteresis in the velocity pattern, which was measured on the Valette landslide complex (French Alps). Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Seismological evidence for nonlinear elastic ground behavior during large earthquakes     

Igor A. Beresnev  Kuo-Liang Wen  Yeong Tein Yeh 《Soil Dynamics and Earthquake Engineering》1995,14(2)

Amplification of earthquake-induced seismic waves by soft superficial deposits often causes significant damages in the urban areas. In predicting this effect for large future earthquakes, the linear elastic response of soils is customarily assumed. To check this assumption, we have analyzed surface and downhole acceleration data from the SMART1 and SMART2 strong motion arrays in Taiwan, covering peak accelerations of up to 0·3 g. First, frequency-dependent amplification induced by the alluvial deposits at the SMART1 array was estimated using spectral ratio technique, where the records at rock site were taken as a reference motion. Statistically validated reduction in soil amplification in the strong motion relative to the weak motion in the frequency range between approximately 1 and 9 Hz was detected. Secondly, relative site responses between the Pleistocene and recent sedimentary deposits at the SMART2 array were studied. Relative amplification was shown to be clearly dependent on the excitation level. Thirdly, we compared experimentally recorded uphole/downhole spectral ratios on weak and strong ground motion with the theoretical response yielded by the geotechnical code DESRA2 which assumes hysteretic constitutive relationship of soil. Major symptoms of nonlinear ground behavior predicted by the model were found in the observed data. Back-calculation of the shear wave velocities to the depth of 47 m shows nearly 50% decrease in the strongest quakes, also accounted for by the nonlinear soil behavior.  相似文献   

The role of dust source area and pedogenesis in three loess-palaeosol sections from North Bulgaria: A mineral magnetic study     

V. I. Avramov  D. Jordanova  V. Hoffmann  W. Roesler 《Studia Geophysica et Geodaetica》2006,50(2):259-282

Rock magnetic studies of three loess-palaeosol sections from Bulgaria (Harletz and Orsoja in the NW and Durankulak in the NE at the Black Sea coast) have been carried out. Thermomagnetic analyses of magnetic susceptibility point to magnetite as the major ferrimagnetic carrier in the loess and palaeosol units. Maghemite gives a significant contribution to the total magnetic signal in the recent soils (S₀), while in one of the sections-Orsoja-hematite may also be present. The effective magnetic grain sizes deduced from the hysteresis measurements and the ratios M_rs/M_s and B_cr/B_c fall in the pseudo single domain (PSD) range, but the data distributions in a Day diagram for the three different sections are shifted. This is suggested to be caused by different detrital input (e.g. different dust source areas) and varying degrees of pedogenic modification. The calculated background susceptibilities χ_bg differ significantly as well. The lowest value is obtained for the Durankulak section-χ_bg = 9.95 × 10⁻⁸ m³/kg, which is in accordance with the data from other studies of loess-palaeosol profiles from the Black Sea area. The corresponding background susceptibilities for the other two sections studied-Harletz and Orsoja-are significantly higher (33.1 and 17.75 × 10⁻⁸ m³/kg, respectively). Both parent material and pedogenesis are found to be responsible for the observed differences in the magnetic characteristics.  相似文献