中国东北地区中生代火山岩的大地构造意义   总被引：101，自引：2，他引：99       下载免费PDF全文

林强  元钟宽 《地质科学》1998,33(2):129-139

中国东北地区中生代火山岩可划分为西部大兴安岭环状火山岩带、南部火山岩带和东部火山岩带,它们是古亚洲洋构造域向太平洋构造域转换时期不同构造环境的产物。西部大兴安岭环状火山岩带的形成与古亚洲洋闭合过程中壳幔相互作用引起的深部热地幔柱的上升有关,南部火山岩带与构造域转换时期走滑拉伸构造有关,而东部火山岩带则是太平洋板块斜向俯冲作用的产物。  相似文献   

Seismic response of base-isolated liquid storage tanks considering fluid–structure–soil interaction in time domain     

Kyung Hwan Cho  Moon Kyum Kim  Yun Mook Lim  Seong Yong Cho 《Soil Dynamics and Earthquake Engineering》2004,24(11):839-852

The seismic response analysis of a base-isolated liquid storage tank on a half-space was examined using a coupling method that combines the finite elements and boundary elements. The coupled dynamic system that considers the base isolation system and soil–structure interaction effect is formulated in time domain to evaluate accurately the seismic response of a liquid storage tank. Finite elements for a structure and boundary elements for liquid are coupled using equilibrium and compatibility conditions. The base isolation system is modeled using the biaxial hysteretic element. The homogeneous half-space is idealized using the simple spring-dashpot model with frequency-independent coefficients. Some numerical examples are presented to demonstrate accuracy and applicability of the developed method.Consequently, a general numerical algorithm that can analyze the dynamic response of base-isolated liquid storage tanks on homogeneous half-space is developed in three-dimensional coordinates and dynamic response analysis is performed in time domain.  相似文献   

有蒸发-风反馈和海-气相互作用的CISK开尔文波——热带季节内振荡机制的进一步研究   总被引：3，自引：0，他引：3  

Li Chongyin  Han-Ru Cho  Jough-Tai Wang 《大气科学进展》2002,19(3):379-390

将波动－CISK（积云对流加热反馈）、海－气相互作用和蒸发－风反馈都引入一个简单理论模式，研究了他们在驱动热带大气季节内振荡（ISO）中的作用。其结果表明：波动－CISK在减慢激发波的位相速度以接近观测到的热带ISO的移速过程中起主要作用；而蒸发－风反馈的主要作用是使激发波不稳定；海－气相互作用在减慢激发波的移速方面也有一定作用。因此，波动－CISK和蒸发－风反馈可认为是热带ISO的主要动力学机制。本研究还表明，由于蒸发－风反馈和海－气相互作用的影响，激发波是一种频散波，这种频散性可以更好地解释热带大气中ISO的活动特征。  相似文献   

Kinetics of the olivine→spinel transition: Implications to deep-focus earthquake genesis     

Chien-Min Sung  Roger G. Burns 《Earth and Planetary Science Letters》1976,32(2):165-170

The rate of the olivine→spinel transition at high overpressure increases with diminishing grain size, or increasing shear stress, temperature, and possibly pressure. The transition rate is higher in Fe-rich compositions than in Mg-rich compositions, and it can be greatly increased by adding water or other mineralizers. Of all variables controlling the kinetics of the olivine→spinel transition in the mantle, temperature is the most critical. The olivine→spinel transition can be suppressed below 500°C in Mg-rich compositions, even in geological period of time. Since the temperature within a downgoing slab varies greatly according to different models of calculation, it is not clear at this stage whether the temperature is low enough to suppress the olivine→spinel transition. If the olvine→spinel transition cannot be suppressed, it may not be responsible for the genesis of deep-focus earthquakes. However, the rise of the olivine-spinel boundary in the cold interior of downgoing slabs provides an additional driving force for the plunging of these slabs. The distortion of the olivine-spinel boundary may also control the stress distribution in downgoing slabs and may be responsible for the observed alignment of principal stress axes of deep-focus earthquakes.  相似文献   

Multi-stage volcanism in the Ulleung Back-arc Basin, East Sea (Sea of Japan)   总被引：4，自引：0，他引：4  

Sung Kwun  Chough Kyung Eun  Lee 《Island Arc》1992,1(1):32-39

Abstract Multichannel seismic reflection profiling in the Ulleung back-arc Basin reveals that the acoustic basement largely comprises volcanic materials. The volcanics are interlayered with sediment sequences, forming an anomalously thick layer. The volcanic activities resulted in a zonation of the acoustic basement, trending northeast-southwest. In the southeastern part, the acoustic basement is deep and obscure, whereas in the northwestern part it is shallow and forms mounds and seamounts. The volcanic activities were probably initiated in the Early Miocene ( ca 20Ma). The volcanism was time-transgressive northward, associated with the possible southward drift of the Japanese islands.  相似文献   

朝鲜中生代构造   总被引：1，自引：0，他引：1  

金贞焕 《地球学报》1994,15(Z1):32-44

朝鲜中生代构造作用以多旋回的克拉通内变形为特，其中包括：a)韧性或脆必剪切走滑作用；b)挤压期的褶皱、冲断和走滑压扭作用；c）引张期的正断层或多米诺断裂系统和张扭走滑作用形成的盆地。它们发生于3个构造事件期间：Sougnim、Daebo和Bulgugsa造山期。晚二叠世一早三叠世的 Songuim 造山可分为两个阶段。当Songnim造山作用减弱时，后构造花岗岩石发生侵位，在张性构造环境下形成 Daedong盆地。晚三叠世-早侏罗世 Daedong 群沉积之后，Daebo造山随之发生，形成NE走向的褶皱和  相似文献   

Design sensitivity analysis for vertical free vibration of hull girder     

Dae-Seung Cho   《Ocean Engineering》2007,34(5-6):902-907

This paper presents a calculation method of derivatives of natural frequencies and mode shapes to parameters affecting vertical hull girder vibration based on design sensitivity analysis. The method premises free vibration analysis of hull girder using the transfer matrix method. Governing sensitivity equation is derived from the direct differentiation of state vector and transfer matrix to design variables. Derivatives of natural frequencies and mode shapes are determined after two trial calculations of the equation. By using the obtained derivatives, the changes of natural frequencies can be rationally and efficiently predicted in case of ship design modification and loading variation.  相似文献   

The effects of drag reduction by ribbons attached to cylindrical pipes   总被引：1，自引：0，他引：1  

S. H. Kwon  J. W. Cho  J. S. Park  H. S. Choi 《Ocean Engineering》2002,29(15):1945-1958

This study proposes a drag reduction device that uses three ribbons attached 120 degree apart to vertical pipes. Experiments were conducted in a circulating water channel to investigate the effects of the ribbon length and the direction of the flow on various current velocities. Drag on a vertical cylinder was measured by a resistance dynamometer. Flow visualizations were conducted using laser sheet beams. Laser Doppler Velocimetry (LDV) was used to measure the velocity field in the wake. This experiment demonstrates that attached ribbons can be used to reduce the drag force on vertical pipes for various directions of incoming flows. The ribbon-type device is very simple and easy to fabricate for field applications. The results are promising for the application to offshore structures.  相似文献   

Bragg reflection of sinusoidal waves due to trapezoidal submerged breakwaters     

Chan-Hoo Jeon  Yong-Sik Cho   《Ocean Engineering》2006,33(14-15):2067-2082

Numerical and laboratory experiments are performed to investigate characteristics of the Bragg reflection due to multi-arrayed trapezoidal submerged breakwaters. The numerical model is based on the Reynolds averaged Navier–Stokes equations with the VOF method and the k–ε turbulence closure model. As expected, the reflection coefficients increase as the array of submerged breakwaters increases in both laboratory measurements and numerical results. The resonant periods provide similar relative wave numbers regardless of the permeability and the number of arrays. The reflection coefficients due to porous breakwaters are smaller than those due to non-porous breakwaters. The velocity contours for two and three arrays are also described.  相似文献   

The ultraluminous and hyperluminous infrared galaxies in the Sloan Digital Sky Survey, 2dF Galaxy Redshift Survey and 6dF Galaxy Survey     

Ho Seong Hwang  Stephen Serjeant  Myung Gyoon Lee  Kang Hwan Lee  Glenn J. White 《Monthly notices of the Royal Astronomical Society》2007,375(1):115-127

We present a result of cross-correlating the Infrared Astronomical Satellite Faint Source Catalogue with the spectroscopic catalogues of galaxies in the Fourth Data Release of the Sloan Digital Sky Survey, the Final Data Release of the 2dF Galaxy Redshift Survey (2dFGRS) and the Second Data Release of the 6dF Galaxy Survey. We have identified 324 ultraluminous infrared galaxies (ULIRGs) including 190 newly discovered ULIRGs, and two hyperluminous infrared galaxies. Adding these new ULIRGs, we increase the number of known ULIRGs by about 30 per cent. The reliability of the cross-correlation is estimated using the likelihood ratio method. The incompleteness of our sample introduced by the identification procedure in this study is estimated to be about 5 per cent. Our sample covers the redshift range of   z = 0.037–0.517  with a median redshift of     , which is larger than that     of the sample of previously known ULIRGs.  相似文献