内蒙古东南部晚古生代裂谷区花岗质岩石锆石SHRIMP U-Pb定年及其地质意义   总被引：12，自引：0，他引：12       下载免费PDF全文

鲍庆中张长捷  吴之理王 宏 李 伟桑家和  刘永生 《中国地质》2007,34(5):790-798

该区花岗质岩石主要岩性为石英闪长岩、英云闪长岩、花岗闪长岩、二长花岗岩和正长花岗岩。通过对石英闪长岩锆石SHRIMP U-Pb定年[1],所获得年龄为(313±5)Ma～(323±4)Ma,属于晚石炭世侵入体;前进场和达青二长花岗岩各单元岩体均侵入了该区早二叠世寿山沟组海陆交互相碎屑沉积岩,侵入接触关系明确,红柱石角岩发育。测得前进场岩体和达青岩体锆石SHRIMP U-Pb年龄分别为(280.8±3.6)Ma和(281.5±0.5)Ma,说明岩体形成于早二叠世晚期;乌兰陶勒盖正长花岗岩岩体获得了259Ma、羊角林高勒二长花岗岩为246～216Ma的U-Pb同位素年龄,说明在晚二叠世—三叠世又有一次侵入高峰。石炭—二叠纪裂谷发育时期,部分跨入三叠纪,先后有3次侵入高峰,即晚石炭世的石英闪长岩、早二叠世的英云闪长岩—二长花岗岩、晚二叠世—三叠纪的二长花岗岩-正长花岗岩。  相似文献   

内核地球自转动力学理论的研究进展(Ⅵ)—— 章动转换函数和内核的动力学效应          下载免费PDF全文

张捍卫  许厚泽  王爱生 《地球物理学进展》2007,22(2):422-426

本文是序列文章的第六篇，其主要内容包括：讨论了两种章动转换函数表达式以及它们系数之间的关系，指出了前人给出系数值的缺陷，以及某些公式表述的错误；基于内核地球模型的有关参数，利用Mathematica数学分析软件计算了PREM和1066A地球模型在FULL理论、MTIC和FIC近似下的章动本征模频率和章动转换函数的有关系数；计算了内核动力学对受迫章动的影响，结果表明其影响已在目前VLBI可检测的量级内.本文对地球章动转换函数进行了较完整的论述，期望对进一步研究地球自转动力学起重要作用.  相似文献   

Attenuation in the uppermost inner core from PKP recordings at African seismological stations     

M. Ivan  G. R. Moloto-A-Kenguemba 《Studia Geophysica et Geodaetica》2007,51(2):221-230

The attenuation factor Q_P at the top of the inner core is evaluated by using the amplitude spectral ratio of PKPdf and PKPbc phases observed at African stations (BGCA mostly), from strong deep earthquakes in the Pacific Ocean area. The maximum depth of penetration of the PKPdf phase into the inner core (IC) is roughly 377 km, and the sampled region of IC is centered beneath the Southern Indian Ocean. The derived mean value of Q_P is 249 ± 31 (95% confidence level) in the frequency range 0.2–2 Hz, where no frequency dependence of attenuation has been reliably observed. By using Student’s t-test, we show that the value is statistically significantly different (with a probability greater than 95%) from other mean values of Q derived by using the same method, for both the western (180 °W to 40 °E) and eastern (40 °E to 180 °E) hemispheres of the IC. The decrease of Q with the radius of the turning point (denoted by r^TP), according to Q_P = 840 − 0.62 r^TP, has a moderate statistical support (the R-squared value is 38%). A slightly increase of Q as a function of the angle of the PKPdf path within the inner core with respect to the Earth’s spin axis is observed, in agreement with various investigations performed in the time domain. However, the value of the anisotropy, if any, is suggested to be around 3%.  相似文献   

Detection of spheriodal free oscillation excited by Peru 8.2 <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript> earthquake with five international superconducting gravimeter data     

Xiang’e?LeiEmail author  Houze?Xu  Heping?Sun 《中国科学D辑(英文版)》2005,48(1):123-133

In this paper, authors obtain the spectral peaks of the earth free oscillation and check all normal modes from ₀S₀ to ₀S₄₈ accurately, with the Fourier analysis and the maximum entropy spectrum method dealing jointly with six groups of the observational residual data from five international superconducting gravimeter stations. By comparing the observational results in this paper with three former groups of observations or models, authors notice an extra discrepancy between two observational ₀S₂ modes excited separately by Peru earthquake and Alaska earthquake, which probably mirrors the anisotropy of the Earth’s inner core. The analysis on the splitting ₁S₂ mode shows that the asymmetric factor of rotationwise spectral splitting is possible to be different from that of anti-rotationwise spectral splitting.  相似文献   

New Developments in Seismic Risk Assessment in Italy   总被引：2，自引：1，他引：1  

Giacomo?Di?Pasquale  Giampiero?Orsini  Roberto?W.?RomeoEmail author 《Bulletin of Earthquake Engineering》2005,3(1):101-128

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Rotating Stratified Heterogeneous Oblate Spheroid in Newtonian Physics     

E.P. Esteban  S. Vazquez 《Celestial Mechanics and Dynamical Astronomy》2001,81(4):299-312

By solving the Euler hydrodynamical equations we have obtained closed form solutions for the angular velocities and pressures of a three stratified non-confocal heterogeneous oblate spheroid. Limiting and particular solutions cases, such as a spheroid with N layers, a stratified spheroid with the same eccentricities, as well as confocal layered spheroids are also explicitly written down. As an application, we have numerically estimated planet Earth's outer and inner cores' ellipticities to be _o=1/413.318 and _i=1/424.616, respectively. These Earth's ellipticities values are in good agreement with those found in the literature.  相似文献   

拉压性能不同材料圆环极限压力分析及应用   总被引：1，自引：0，他引：1  

李晓军  贝志辉  张登良 《岩土力学》2000,21(3):264-266

应用双剪应力强度理论对拉压异性材料制成的圆环进行了弹塑性应力分析, 得到了弹性极限内压力、弹塑性极限内压力与拉压比的关系式, 并举例说明了其在岩土材料抗拉强度测试中的应用。  相似文献   

城市内部居住环境评价的指标体系和方法   总被引：43，自引：7，他引：36  

张文忠 《地理科学》2007,27(1):17-23

“宜居城市”已经引起了政府、媒体和学者极大的关注,但主要集中在概念层面上,关于“宜居城市”的倡导或研究不应停留概念的炒作上,应该明确其内涵、量化其评价指标、确定其建设的方向和步骤等。立足于国内外相关研究基础,凸现“以人为本”的城市建设理念,就城市内部居住环境的评价内容、指标体系设计和评价方法等进行探讨。重点对构成居住环境评价的5大指标体系,安全性、环境的健康性、生活的便利性、出行的便捷度、居住的舒适度等具体评价内容、数据获取和方法选择等进行了研究。  相似文献   

Is there an observable lack of reciprocity in PKP(DF) traveltimes?     

Stefan Maus 《Geophysical Journal International》2000,143(1):274-277

On average, traveltimes of PKP_DF for equatorial ray paths through the quasieastern hemisphere of the inner core are around 0.5 s faster than equivalent ray paths through its quasiwestern hemisphere. In these observations, the eastern hemisphere is sampled primarily by westward and the western hemisphere by eastwardpropagating waves. Noting that westward propagation is faster than eastward propagation inside a rotating earth, I estimate the expected traveltime difference from Coriolis splitting of the displacement eigenfunctions of the PKP_DF equivalent modes. It turns out that Coriolis effects are too small to give rise to residuals of the required magnitude. Thus, the observations must be primarily due to velocity heterogeneities.  相似文献   

岩石破裂过程TMD耦合数值模型研究   总被引：1，自引：0，他引：1  

李连崇  杨天鸿  唐春安  黄小兰  李夕兵 《岩土力学》2006,27(10):1727-1732

从岩石的细观结构层次出发,应用损伤力学和热弹性理论,对热力耦合作用下岩石破裂过程中热-应力-损伤相互作用关系进行了分析。初步建立了细观热-应力-损伤（TMD model,thermal-mechanical-damage）耦合数值模型,并在岩石破裂过程分析系统RFPA2D中加实现。运用该数值模型计算模拟均匀与非均匀材料试样在热力耦合作用下的应力分布及破坏形 态,通过与理论及试验结果对比,证明了该数值模型的合理性和有效性。  相似文献