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71.
72.
华北地区地壳水平运动演化特征研究 总被引:13,自引:6,他引:7
将华北地区划分为阴山-燕山、鄂尔多斯、山西、太行、冀鲁、胶辽6个块体,应用1995、1996、2001年GPS观测资料研究了这些块体的水平运动演化特征。结果显示出华北地区各块体的相对运动既有继承性也有差异性。华北各块体的总体水平运动趋势是向东漂移,但是个别块体,如鄂尔多斯块体,在1995~1996年期间出现了相对的西向运动。1995~1996年期间华北各块体的运动速率比1996~2001年期间的运动速率要大,特别是阴山-燕山块体。1995~1996年期间鄂尔多斯块体和相邻的山西块体表现为张性分离,阴山-燕山块体之间表现为左旋走滑,这一现象可能与1996~1999年期间发生在华北西北部的3个地震的孕震过程有关。进一步分析表明,加密的连续GPS观测可用于地震预报。 相似文献
73.
74.
A. Collier Cameron D. Pollacco R. A. Street T. A. Lister R. G. West D. M. Wilson F. Pont D. J. Christian W. I. Clarkson B. Enoch A. Evans A. Fitzsimmons C. A. Haswell C. Hellier S. T. Hodgkin K. Horne J. Irwin S. R. Kane F. P. Keenan A. J. Norton N. R. Parley J. Osborne R. Ryans I. Skillen P. J. Wheatley 《Monthly notices of the Royal Astronomical Society》2006,373(2):799-810
75.
Pierre North 《Astrophysics and Space Science》2006,304(1-4):219-221
35 Eclipsing binaries presenting unambiguous total eclipses were selected from a subsample of the list of Wyrzykowski et al. (2003). The photometric elements are given for the I curve in DiA photometry, as well as approximate teff and masses of the components. The interest of these systems is stressed in view of future spectroscopic observations. 相似文献
76.
根据点源孕震力学模型 ,应用福建 台湾地区GPS位移速度资料反演 1999年台湾南投Mw7.6大震前的孕震参数。反演所得的震中与实际发生的地震震中相差 6 7km ,主压应力场方向为 319.9°,倾角 - 2 8.6° ,即仰角2 8.6° ,与用震源机制解得到的P轴方向和倾角分别相差 17°和 8.6° ,与菲律宾板块向亚洲板块挤压的方向是一致的。用土耳其地区GPS位移速率资料反演 1999年土耳其Mw7.6地震前的孕震参数 ,反演得到的震中与实际震中相差 70km ,主应力方位角和倾角分别为 16 2 .5°、11.5°,与震源机制解结果分别差 2 4 .5°和 1.5°。 相似文献
77.
Hardage Kyle Street Joseph Herrera-Silveira Jorge A. Oberle Ferdinand K. J. Paytan Adina 《Journal of Paleolimnology》2022,67(2):131-162
Journal of Paleolimnology - Epikarst estuary response to hydroclimate change remains poorly understood, despite the well-studied link between climate and karst groundwater aquifers. The influence... 相似文献
78.
Compositions of Upper Mantle Fluids Beneath Eastern China: Implications for Mantle Evolution 总被引:2,自引:0,他引:2
ZHANG Mingjie WANG Xianbin LIU Gang ZHANG Tongwei BO WenruiInstitute of Geological Science Lanzhou University Lanzhou Gansu Key Lab of Gas-Geochemistry Lanzhou Institute of Geology CAS Lanzhou Gansu First Institute of Oceanography State Oceanic Administration Qingdao Shandong 《《地质学报》英文版》2004,78(1):125-130
The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in Iherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 a 相似文献
79.
ZHAO Shunbo Ass. Prof. North China Institute of Water Conservancy Hydroelectric Power Zhengzhou P. R. China. 《中国海洋工程》1998,(4)
An experimental program was carried out to study the shear behavior of the reinforced con-crete composite beam(RCCB)subjected to two-phase uniformly distributed load.A total of 12 reinforcedconcrete composite beams were tested:10 of them were the RCCB subjected to two-phase uniformly dis-tributed load,the other 2 were the comparative reinforced concrete beams cast at the same time as theRCCB subjected to one-phase uniformly distributed load.The interface of precast unit and recast concretewas natural and rough.The test range of the main composite factors:the ratio of precast section depth tocomposite section depth was from 0.35 to 0.65,the ratio of first-phase load moment to precast section ulti-mate bearing moment was from 0.25 to 0.65.Based on the test results,the stresses of the longitudinal rein-forcements and stirrups,the load-bearing properties of the interface,the crack state and the failure charac-teristics of the RCCB under uniformly distributed load are discussed.The effects of the stirrups,the 相似文献
80.
The release of dissolved actinium to the ocean: A global comparison of different end-members 总被引:1,自引:1,他引:0
Walter Geibert Matt Charette Guebuem Kim Willard S. Moore Joseph Street Megan Young Adina Paytan 《Marine Chemistry》2008,109(3-4):409
The measurement of short-lived 223Ra often involves a second measurement for supported activities, which represents 227Ac in the sample. Here we exploit this fact, presenting a set of 284 values on the oceanic distribution of 227Ac, which was collected when analyzing water samples for short-lived radium isotopes by the radium delayed coincidence counting system. The present work compiles 227Ac data from coastal regions all over the northern hemisphere, including values from ground water, from estuaries and lagoons, and from marine end-members. Deep-sea samples from a continental slope off Puerto Rico and from an active vent site near Hawaii complete the overview of 227Ac near its potential sources.The average 227Ac activities of nearshore marine end-members range from 0.4 dpm m− 3 at the Gulf of Mexico to 3.0 dpm m− 3 in the coastal waters of the Korean Strait. In analogy to 228Ra, we find the extension of adjacent shelf regions to play a substantial role for 227Ac activities, although less pronounced than for radium, due to its weaker shelf source. Based on previously published values, we calculate an open ocean 227Ac inventory of 1.35 * 1018 dpm 227Acex in the ocean, which corresponds to 37 moles, or 8.4 kg. This implies a flux of 127 dpm m−2 y− 1 from the deep-sea floor. For the shelf regions, we obtain a global inventory of 227Ac of 4.5 * 1015 dpm, which cannot be converted directly into a flux value, as the regional loss term of 227Ac to the open ocean would have to be included.Ac has so far been considered to behave similarly to Ra in the marine environment, with the exception of a strong Ac source in the deep-sea due to 231Paex. Here, we present evidence of geochemical differences between Ac, which is retained in a warm vent system, and Ra, which is readily released [Moore, W.S., Ussler, W. and Paull, C.K., 2008-this issue. Short-lived radium isotopes in the Hawaiian margin: Evidence for large fluid fluxes through the Puna Ridge. Marine Chemistry]. Another potential mechanism of producing deviations in 227Ac/228Ra and daughter isotope ratios from the expected production value of lithogenic material is observed at reducing environments, where enrichment in uranium may occur. The presented data here may serve as a reference for including 227Ac in circulation models, and the overview provides values for some end-members that contribute to the global Ac distribution. 相似文献