Taxonomy,location of origin and health status of proboscideans from Western Canada investigated using stable isotope analysis          下载免费PDF全文

Jessica Z. Metcalfe  Fred J. Longstaffe  Christopher N. Jass  Grant D. Zazula  Grant Keddie 《第四纪科学杂志》2016,31(2):126-142

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Correlations between re and PGE concentrations in rocks,ores, and minerals of mafic-ultramafic associations     

F. P. Lesnov  G. N. Anoshin 《Doklady Earth Sciences》2011,437(1):387-392

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Comparison of Joint Shearing Resistance Obtained with the Barton and Choubey Criterion and with Direct Shear Tests     

D. Sow  P. Rivard  L. Peyras  P. Breul  Z. A. Moradian  C. Bacconnet  G. Ballivy 《Rock Mechanics and Rock Engineering》2016,49(8):3357-3361

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Elastic Anisotropy of a Metamorphic Rock Sample of the Canadian Shield in Northeastern Alberta     

Judith Chan  Douglas R. Schmitt 《Rock Mechanics and Rock Engineering》2015,48(4):1369-1385

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The variable star SBS 0150+339     

L. K. Erastova 《Astrophysics》2011,54(1):143-145

Plates from the Second Byurakan Survey reveal two large increases in the brightness of this star in 1972 and 1975. Spectra of this variable have been obtained for the first time. It is not visible in plate H2133 from the Hamburg survey, which has a limiting brightness of ~18m. Our data confirm that the star is an eruptive variable, most likely of the U Gem type.  相似文献   

Editorial to the 40th anniversary of the international research society INTERPRAEVENT: hazard analysis and mitigation of mass movements in an alpine environment     

Johannes Hübl  Florian Rudolf-Miklau  Gernot Fiebiger 《Natural Hazards》2011,56(2):421-423

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Erratum to: Polymorphic phase transition in Superhydrous Phase B     

M. Koch-Müller  P. Dera  Y. Fei  H. Hellwig  Z. Liu  J. Van Orman  R. Wirth 《Physics and Chemistry of Minerals》2014,41(9):725-725

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Zircon U–Pb ages and Hf isotope compositions of migmatites from the North Qinling terrane and their geological implications     

Q. Liu  Y.‐B. Wu  H. Wang  S. Gao  Z.‐W. Qin  X.‐C. Liu  S.‐H. Yang  H.‐J. Gong 《Journal of Metamorphic Geology》2014,32(2):177-193

Migmatites are predominant in the North Qinling (NQ) orogen, but their formation ages are poorly constrained. This paper presents a combined study of cathodoluminescence imaging, U–Pb age, trace element and Hf isotopes of zircon in migmatites from the NQ unit. In the migmatites, most zircon grains occur as new, homogeneous crystals, while some are present as overgrowth rims around inherited cores. Morphological and trace element features suggest that the zircon crystals are metamorphic and formed during partial melting. The inherited cores have oscillatory zoning and yield U–Pb ages of c. 900 Ma, representing their protolith ages. The early Neoproterozoic protoliths probably formed in an active continental margin, being a response to the assembly of the supercontinent Rodinia. The migmatite zircon yields Hf model ages of 1911 ± 20 to 990 ± 22 Ma, indicating that the protoliths were derived from reworking of Palaeoproterozoic to Neoproterozoic crustal materials. The anatexis zircon yields formation ages ranging from 455 ± 5 to 420 ± 4 Ma, with a peak at c. 435 Ma. Combined with previous results, we suggest that the migmatization of the NQ terrane occurred at c. 455–400 Ma. The migmatization was c. 50 Ma later than the c. 490 Ma ultra‐high‐P (UHP) metamorphism, indicating that they occurred in two independent tectonic events. By contrast, the migmatization was coeval with the granulite facies metamorphism and the granitic magmatism in the NQ unit, which collectively argue for their formation due to the northward subduction of the Shangdan Ocean. UHP rocks were distributed mainly along the northern margin and occasionally in the inner part of the NQ unit, indicating that they were exhumed along the northern edge and detached from the basement by the subsequent migmatization process.  相似文献   

Elastic lateral dynamic impedance functions for a rigid cylindrical shell type foundation          下载免费PDF全文

R. He  R.Y.S. Pak  L.Z. Wang 《国际地质力学数值与分析法杂志》2017,41(4):508-526

Elastic lateral dynamic impedance functions are defined as the ratio of the lateral dynamic force/moment to the corresponding lateral displacement/rotation at the top ending of a foundation at very small strains. Elastic lateral dynamic impedance functions have a defining influence on the natural frequencies of offshore wind turbines supported on cylindrical shell type foundations, such as suction caissons, bucket foundations, and monopiles. This paper considers the coupled horizontal and rocking vibration of a cylindrical shell type foundation embedded in a fully saturated poroelastic seabed in contact with a seawater half‐space. The formulation of the coupled seawater–shell–seabed vibration problem is simplified by treating the shell as a rigid one. The rigid shell vibration problem is approached by the integral equation method using ring‐load Green's functions for a layered seawater‐seabed half‐space. By considering the boundary conditions at the shell–soil interface, the shell vibration problem is reduced to Fredholm integral equations. Through an analysis of the corresponding Cauchy singular equations, the intrinsic singular characteristics of the problem are rendered explicit. With the singularities incorporated into the solution representation, an effective numerical method involving Gauss–Chebyshev method is developed for the governing Fredholm equations. Selected numerical results for the dynamic contact load distributions, displacements of the shell, and lateral dynamic impedance functions are examined for different shell length–radius ratio, poroelastic materials, and frequencies of excitation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Numerical simulation on mining-induced water inrushes related to geologic structures using a damage-based hydromechanical model   总被引：2，自引：1，他引：1  

W. C. Zhu  C. H. Wei 《Environmental Earth Sciences》2011,62(1):43-54

A large number of statistics indicate that water inrush has a direct relationship with geological structures such as fault and karst collapse columns. Understanding the mechanism of water inrushes controlled by geologic structures is of vital importance for adopting effective measures to prevent their occurrence. The work begins with formulization of a damage-based hydromechanical model based on elastic damage theory. Next, the model is numerically implemented with finite element method by employing a finite element package called COMSOL Multiphysics, and is also validated against some existing experimental observations. Finally, the model is used to simulate the mining-induced groundwater inrushes when the effect of faults and karst collapse columns is considered in the numerical simulation, and some suggestive conclusions for preventing water inrushes and optimizing underground mining operations are drawn.  相似文献