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21.
1994年1月17日美国加州北岭地震现场考察报告   总被引:1,自引:0,他引:1  
本文是国家地震局地震专家代表团于北岭地震后赴美进行实地考察的简要工作报告。内容包括地震序列特征、地震地质背景、震害和预防以及应急等情况。  相似文献   
22.
山东莒南后左山恐龙公园早白垩世恐龙足迹化石初步研究   总被引:8,自引:5,他引:8  
山东省莒南县后左山恐龙公园内保存了数量众多、形态各异的恐龙足迹化石。该足迹化石群产于早白垩世大盛群田家楼组,主要是兽脚类、鸟脚类恐龙的足迹,尤以前者占优质。最大的一个为椭圆形,大小100cm×70cm,可能系鸟脚类恐龙的足迹。鸟脚类足迹大多为椭圆形,长轴一般30~40cm,常呈幻迹保存。最大的兽脚类足迹为三趾型,长49cm,宽35cm,是大型肉食龙类的足迹;最小的一个长8.5cm,宽4.5cm,可能是虚骨龙类的足迹。另外还发现了少量可能是驰龙的足迹,具有2个很长的趾(Ⅲ和Ⅳ趾),趾间角极小,二者几乎平行。鸟脚类恐龙足迹层位分布局限,但密度较大,产出的层面常发育泥裂、波痕,甚至冰晶痕,与泥岩、粉砂质泥岩等层位相关性较强。  相似文献   
23.
北祁连东部两类Ⅰ型花岗岩定年及其地质意义   总被引:21,自引:7,他引:21  
北祁连东部早古生代地层中产出两种特征不同的I型花岗岩类,其一以井子川岩体为代表,暗色矿物以角闪石为主,稀土总量为90×10~(-6)~106×10~(-6),轻重稀土比值小于8,锆石的SHRIMP年龄为464±15Ma,岩体形成的构造环境类似于岛弧;其二是以黄羊河岩体为代表,暗色矿物以黑云母为主,稀土总量为214×10~(-6)~250×10~(-6),轻重稀土比值大于8,锆石的LA-ICP-MS年龄为383±6 Ma,岩体形成于碰撞后环境。  相似文献   
24.
1 INTRODUCTION Sediment resuspension, particularly in response to episodic storm events, is a common characteristic of coastal and nearshore environments. The resulting 揵enthic storms?may play a significant role in the dynamics of benthic systems, including structuring the physical characteristics of the bottom, providing a mechanism for the recycling of biogeochemically important materials to the water column, and driving horizontal and cross margin transport of suspended particulates …  相似文献   
25.
Based on improvement of a distributed hydrology-soil-vegetation model (DHSVM for short)and its application to North China,a nested regional climatic-hydrologic model system is developedby connecting DHSVM with RegCM2/China.The simulated climate scenarios,including controland 2×CO_2 outputs,are downscaled to 8 stations in Luanhe River and Sanggan River Basins todrive the hydrology model.According to simulation results,under double CO_2 scenarios,annualmean temperature and evapotranspiration will increase 2.8C and 29 mm,respectively;precipitation also increase but with different value for each basin,6 mm for Luanhe River Basinwhile 46 mm for Sanggan River Basin;runoff change for the two basins is different too,27 mmdecrease for Luanhe River Basin while 26 mm increase for Sanggan River Basin.As a result,therunoff in future for Luanhe River Basin and Sanggan River Basin will be 74 mm and 71 mm,respectively,which is approximately a quarter of annual mean runoff(284 mm)of the wholecountry.Total streamflow for the two basins will decrease about 2.5×10~8m~3.All these indicatethat the warm and dry trend will continue in the two river basins under double CO_2 scenarios.Thenested model system,with both climatic and hydrologic prediction ability,could also be applied toother basins in China by parameter adjustment.  相似文献   
26.
Interest in the Moon started to increase at the beginning of the 21st century,and henceforth,more and more attention has been paid to the content and distribution of water ice in the lunar polar regions.The existence of water or ice in the regolith can apparently change its dielectric features.Therefore,in this article,the Dobson model is adopted and improved according to the Moon's environmental features,to construct the relationship between the volumetric water ice content and the dielectric constant.Ther...  相似文献   
27.
In recent years,with the development of terrestrial sequence stratigraphy,more attention has been focused on the study of the terrestrial lacustrine sequence stratigraphic model globally. Different viewpoints are preferred by researchers.Under the guidance of the theory of sequence stratigraphy,the findings of this paper indicate that climate is a major factor controlling the formation of the fourth-order sequence,based upon the study of the sequence stratigraphy in the Green River Formation of the Uinta...  相似文献   
28.
The South China Sea (SCS) is significantly influenced by El Nio and the Southern Oscillation (ENSO) through ENSO-driven atmospheric and oceanic changes.We analyzed measurements made from 1960 to 2004 to investigate the interannual variability of the latent and sensible heat fluxes over the SCS.Both the interannual variations of latent and sensible heat fluxes are closely related to ENSO events.The low-pass mean heat flux anomalies vary in a coherent manner with the low-pass mean Southern Oscillation Index ...  相似文献   
29.
Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005(the spring-summer period),and from 2 October 2007 to 20 January 2008(the autumn-winter period),surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l.by using an automatic weather station(AWS).The...  相似文献   
30.
Long steel piles with large diameters have been more widely used in the field of ocean engineering.Owing to the pile with a large diameter,soil plug development during pile driving has great influences on pile driveability and beating capacity.The response of soil plug developed inside the open-ended pipe pile during the dynamic condition of pile-driving is different from the response under the static condition of loading during service.This paper addresses the former aspect.A numerical procedure for soil plng effect prediction and pile driveability analysis is proposed and described.By taking into consideration of the pile dimension effect on side and tip resistance,this approach introduces a dimensional coefficient to the conventional static equilibrium equations for the plug differential unit and proposes an improved static equity method for the plug effect prediction.At the same time,this approach introduces a simplified model by use of one-dimensional stress wave equation to simulate the interaction between soft ping and pile inner wall.The proposed approach has been applied in practical engineering analyses.Results show that the calculated plug effect and pile driveability based on the proposed approach agree well with the observed data.  相似文献   
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