古海啸研究     

B．Rhodes M．Tuttle B．Horton L．Doner H．Kelsey A．Nelson M．Cisternas 《世界地震译丛》2007,(4):57-59

2004年12月26日印度洋海啸明确证实仅靠历史记录难以显示海啸的危险性。长期地质记录为评估海啸危险提供了更多信息。海啸遗留的沉积证据有助于评估过去洪水的水位深度和速度,估计源头位置,以及帮助了解海啸是如何影响滨海地区的生态和地貌。过去的沉积可以估计历史海啸的次数和重复周期。这些信息对于减轻未来海啸的影响和减少其带来的可能损失具有指导作用。古海啸研究引起了地震地质、古生物学、古生态学、地貌学、海洋物理学、地球物理学、海洋地质学、沉积学、地球化学、地震学、海岸工程学和社会学领域的科学家的兴趣,并可能导致不曾…  相似文献   

关于地震预报言过其实的宣称     

A．L．Kafka J．E．Ebel 《世界地震译丛》2007,(4):67-69

永久地成功预报地震的允诺,抓住了公众渴望了解不确定世界里确定事件的想象力。然而,即使缺乏可靠的地震预报方法(Geller,1997;Kagan and Jackson,1996;Evans,1997),在还远未弄清预报实际有多大成功把握时,地震学家们还得按惯例对推测可能成功预报地震的消息或故事进行解释。当记者和公共关系部门报道关于地震预报最新的“重大发现”时,地震学家们仅剩下一项极其乏味的任务,即向公众解释所宣称的“成功”与严肃的现实之间的巨大差距,即尚未有被科学证实了的地震预报方法。这种情形的一个惊人实例是,美国国家航天局(NASA)于2004年在其网…  相似文献   

潮湿地与深水生境:一种新的分类     

L.M.考沃丁  全亚黎 《地理科学进展》1983,2(4):40-44

潮湿地是什么?潮湿地指的是陆地生境至水生生境的连续部分。在个别人、有关学科和政府机构之间,对潮湿地这一概念的理解是不相同的。按照惯例,潮湿地是根据水文、土壤和植被的条件来确定的。  相似文献   

用岩石中的汞作为找矿标志     

黎青  L.M.阿扎利亚  J.A.卡里尔 《地质与勘探》1977,(5)

加斯佩斑岩铜矿位于加拿大魁北克省穆多奇维尔附近.本文研究了与加斯佩矿床伴生的岩石内汞的分布,以期阐明在寻找同类矿床时将汞作为一种探途元素的可能性.矿区地质加斯佩斑岩铜矿床位于昌波向斜西端的南翼(图1),昌波向斜是加斯佩半岛的主要构造.该矿床产在下泥盆纪沉积岩系内,这套岩石多为泥质、燧石质和灰质粉砂岩.热液蚀变作用使这些岩石褪色,形成一个面积为6.5平方公里的蚀变晕.蚀变作用的结果  相似文献   

SHORT COMMUNICATION AN EMPIRICAL MODEL FOR FITTING CHRONOPOTENTIOMETRIC DATA THROUGH THE USE OF DUMMY VARIABLES     

M.C.GARNICA  J.LóPEZPALACIOS  L.A.SARABIA 《地理学报(英文版)》1988,(Z1)

A procedure for determining the transition time in chronopotentiometry is proposed.The method isbased on the existence of three straight sections in a chronopotentiometric curve.The experimentalvalues are fitted by multilinear regression using dummy variables.Agreement between the proposedmethod and a classical graphical procedure is observed.  相似文献   

DEFORMATIONAL AND METAMORPHIC HISTORY OF THE CENTRAL LONGMEN MOUNTAINS, SICHUAN CHINA     

Chris J.L. Wilson  Brenton A. Worley  Shefa Chen  Mathew J. Harrowfield  Liu Shugen  Luo Zhili WT  ”BX 《地学前缘》2000,(Z1)

DEFORMATIONAL AND METAMORPHIC HISTORY OF THE CENTRAL LONGMEN MOUNTAINS, SICHUAN CHINA1　ArneDC ,WorleyBA ,WilsonCJL ,etal.Differentialexhumationinresponsetoepisodicthrustingalongtheeasternmar ginoftheTibetanPlateau[J] .Tectonophysics,1997,2 80 :2 39～ 2 56 . 2　ChenSF ,WilsonCJL ,WorleyBA .TectonictransitionfromtheSongpan GarzeFoldBelttotheSichuanBasin,south westernChina[J] .BasinResearch ,1995,7:2 35～ 2 53. 3　ChenSF ,WilsonCJL .Emplaceme…  相似文献   

The Complete Zeldovich Approximation     

Betancort-Rijo J  López-Corredoira M 《The Astrophysical journal》2000,534(2):L117-L121

We have developed a generalization of the Zeldovich approximation that is exact in a wide variety of situations, including planar, spherical, and cylindrical symmetries. We have shown that this generalization, which we call the complete Zeldovich approximation (CZA), is exact to second order at an arbitrary point within any field. For Gaussian fields, the third-order error has been obtained and shown to be very small. For statistical purposes, the CZA leads to results exact to the third order.  相似文献   

Hard X-Ray Emission from the Galaxy Cluster A2256     

Fusco-Femiano R  Dal Fiume D  De Grandi S  Feretti L  Giovannini G  Grandi P  Malizia A  Matt G  Molendi S 《The Astrophysical journal》2000,534(1):L7-L10

After the positive detection by BeppoSAX of hard X-ray radiation up to approximately 80 keV in the Coma Cluster spectrum, we present evidence for nonthermal emission from A2256 in excess of thermal emission at a 4.6 sigma confidence level. In addition to this power-law component, a second nonthermal component already detected by ASCA could be present in the X-ray spectrum of the cluster, which is not surprising given the complex radio morphology of the cluster central region. The spectral index of the hard tail detected by the Phoswich Detection System on board BeppoSAX is marginally consistent with that expected for the inverse Compton model. A value of approximately 0.05 μG is derived for the intracluster magnetic field of the extended radio emission in the northern regions of the cluster, while a higher value of approximately 0.5 μG could be present in the central radio halo, which is likely related to the hard tail detected by ASCA.  相似文献   

Petrogenesis of Late Cretaceous Jiangla’angzong I-Type Granite in Central Lhasa Terrane, Tibet, China: Constraints from Whole-Rock Geochemistry, Zircon U-Pb Geochronology, and Sr-Nd-Pb-Hf Isotopes     

LIU Hong  LI Guangming  HUANG Hanxiao  CAO Huawen  YUAN Qian  LI Yingxu  OUYANG Yuan  LAN Shuangshuang  Lü Menghong  YAN Guoqiang 《《地质学报》英文版》2018,92(4):1396-1414

The Jiangla'angzong granite in the northern part of the Central Lhasa Terrane is composed of syenogranite and adamellite. LA-ICP-MS zircon U-Pb analyses suggest that syenogranite has a weighted mean ~(206) Pb/~(238) U age of 86±1 Ma(mean square weighted deviation=0.37), which is in accordance with the muscovite Ar-Ar age(85±1 Ma) of Cu-Au ore-bearing skarns and the zircon U-Pb age(84±1 Ma) of adamellite. This suggests that the Jiangla'angzong magmatism and Cu–Au mineralization events took place during the Late Cretaceous. The granite contains hornblende, biotite, and pyroxene, and does not contain Al-bearing minerals, such as muscovite, cordierite, and garnet. It has high contents of SiO_2(65.10–70.91 wt%), K_2O(3.44–5.17 wt%), and total K_2O+Na_2O(7.13–8.15 wt%), and moderate contents of A_(12)O_3(14.14–16.45 wt%) and CaO(2.33–4.11 wt%), with a Reitman index(σ43) of 2.18 to 2.33, and A/CNK values of 0.88 to 1.02. The P_2O_5 contents show a negative correlation with SiO_2, whereas Pb contents show a positive correlation with SiO_2. Th and Y contents are relatively low and show a negative correlation with the Rb contents. These characteristics suggest that the Jiangla'angzong granite is a high K calc–alkaline metaluminous I–type granite. It is enriched in light rare earth elements(LREE) and large ion lithofile elements(LILE), and depleted in heavy rare earth elements(HREE) and high field strength elements(HFSE), with LREE/HREE ratios of 11.7 to 18.1. The granite has negative Eu anomalies of 0.58 to 0.94 without obvious Ce anomalies(δCe=1.00–1.04). The relatively low initial 87 Sr/86 Sr ratios of 0.7106 to 0.7179, positive εHf(t) values of 1.0 to 4.1, and two-stage Hf model ages(TDM2) ranging from 889 Ma to 1082 Ma, These geochemical features indicate that the granite derived from a juvenile crust. The(~(143) Nd/~(144) Nd)_t values from the Jiangla'angzong granite range from 0.5121 to 0.5123, its εNd(t) values range from-10.17 to-6.10, its(~(206) Pb/~(204) Pb)_t values range from 18.683 to 18.746, its(~(207) Pb/~(204) Pb)_t values range from 15.695 to 15.700, and its(~(208) Pb/~(204) Pb)_t values range from 39.012 to 39.071. These data indicate that the granite was formed by melting of the upper crust with the addition of some mantle materials. We propose that the Jiangla'angzong granite was formed during the postcollision extension of the Qiangtang and Lhasa terranes.  相似文献   

A Quantitative Method for Evaluating the Transporting Capacity of Oil‐Source Faults in Shallow Formation of Oil‐Rich Sags     

JIANG Youlu  ZHAO Kai  LIU Jingdong  Lü Xueying 《《地质学报》英文版》2018,92(4):1678-1679

正Objective Oil-source faults have an important effect on reservoir formation and distribution in shallow formations with nonhydrocarbon generation in oil-rich fault-related basins(Jiang Youlu et al.,2015).However,the fault transporting capacity cannot be evaluated quantitatively at present.Taking the Zhanhua Sag in the Bohai Bay Basin as an  相似文献