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61.
CHENG Yuqi LIU Dunyi I.S. WILLIAMS JIAN Ping ZHUANG Yuxun GAO Tianshan Institute of Geology Chinese Academy of Geological Sciences Barwanzhuang Rd. Beijing China Research School of Earth Sciences Australian National University G.P.O Box Canberr A.C.T. Australia Anhui Geological Survey Changjiangdong Rd. Hefei Anhui China 《《地质学报》英文版》2000,74(4):748-765
The paper reports SHRIMP U-Pb zircon data of a dark eclogite and a post-eclogite garnet-bearing gneissic granitic rock from the Bixiling area, Yuexi County, Anhui Province, in the eastern Dabie Mountains. The eclogite, which is metamorphosed basic tuff, contains very scarce zircons in omphacite or garnet, but more zircons in quartz. They usually exhibit a double-layered texture, as shown clearly in cathodoluminescence images. Their inner main parts give a 206Pb/238U age of 757±7 Ma, representing the approximate age of the high-pressure (HP)- ultrahigh-pressure (UHP) metamorphic event during which the eclogite was formed. The outer peripheral parts of the zircons, which have been modified by late-stage fluids, give an age of 223±3 Ma. The granitic rock contains more zircons of anatectic origin found mostly in feldspar and quartz and usually also showing a similar composite texture. The inner main parts of the anatectic zircons with oscillatory zoning give a 206Pb/238U age of 727±15 Ma for the approxim 相似文献
62.
Weiwen Chen Sidao Ni Shengji Wei Zhenjie Wang Jun Xie Mengcheng National Geophysical Observatory University of Science Technology of China Hefei China CAS Key Laboratory of Geodynamical Geodesy 《地震学报(英文版)》2011,(2):221-227
Ground deformation as observed with GPS or InSAR has been broadly inverted in constraining source parameter of earthquakes. However, for earthquakes occurring beneath sedimentary basins, the very slow sub-surface shear velocity (v S , down to 200 m/s) may cause substantial bias to earthquake source inversion if simple crustal models are used. For Bohai basin, Sichuan basin and rock-sites, we test effects of sub-surface shear velocity structure on ground deformation, and find that up to a factor of 2 overest... 相似文献
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2001年3月2日11:00 至11:15 UT 期间,Cluster Ⅱ在南半球极尖区晨侧附近磁鞘内探测到3个通量传输事件(简称FTEs). 本文利用Cluster Ⅱ星簇4颗卫星观测到的磁场和等离子体资料研究了这些通量传输事件的磁场形态和粒子特征. 并利用它们探测到的空间磁场梯度资料由安培定律直接求出星簇所在区域的电流分布. 结果指出:(1)BY占优势的行星际磁场结构在磁层顶的重联可以在极尖区附近发生;(2)FTEs通量管形成初期内外总压差和磁箍缩应力不一定平衡,达到平衡有一发展过程;(3)FTEs通量管截面在L M平面内的线度约为1.89RE;(4)FTEs通量管中等离子体主要沿轴向场方向流动,整个通量管以慢于背景等离子体的速度沿磁层顶向南向尾运动;(5)FTEs通量管中不仅有轴向电流,也存在环向电流. 轴向电流基本沿轴向磁场方向流动. 轴向和环向电流在管内均呈体分布,因而轴向电流产生的环向磁场接近管心时不断减小到零,而环向电流生成的轴向场则不断增大到极值;(6)在通量管的磁鞘部分观测到磁层能量粒子流量的增强,这表明通量管通过磁层顶将磁鞘和磁层内部连通起来了. 相似文献
66.
中等地震对华南中强地震的指示意义 总被引:2,自引:1,他引:1
研究了华南地区14次中强地震前中等地震活动特征,据此提出了本区中强震短期预测判据:中期(或中短期)中等地震累积频度呈指数(加速)增长,短期至发震中等地震持续平静(通常小于3个月)。 相似文献
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与亚暴活动密切相关的磁尾等离子体团可以具有不同的拓扑位形,多数磁尾等离子体团具有 强核心场,是一种通量绳型磁结构. MHD模拟表明:地球磁尾不同拓扑位形磁结构的形成, 与越尾分量By的分布形态有关. 但是模拟研究所展示的通量绳结构,核心场强度远低 于尾瓣区磁场强度. 本文考虑磁尾通量绳结构中,螺旋形磁力线向侧翼伸展产生的压强损失 ,在MHD方程中引入修正项ρt|loss,Tt|loss 及Byt|inc. 对于 初始By分量为均匀分布,受晨昏电场产生的边界入流作用,磁尾通量绳结构重复形成 与逐一排放的两个算例,计入修正项后,多重磁结构峰值压强的平均值降低,核心场的平均 值明显增大. 两个算例中,背景By值较低的算例1(By0=1nT)中,核心 场的相对增幅较大. 相似文献
68.
Leaching Behavior of Fly Ashes from Power Plants 总被引:1,自引:0,他引:1
LIU Guijian GAO Lianfen ZHENG Liugen ZHANG Haoyuan PENG Zicheng School of Earth Space Science University of Science Technology of Chin Hefei Anhui Key Lab of Loess Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi''an Shaanxi 《《地质学报》英文版》2004,78(3):720-723
The Yanzhou mine district, located in southwestern Shandong Province, is about 1300 km2 with more than 8×109tons of proved coal reserves and there are 10 big power plants in this area. A large amount of coal ashes, which are regarded as waste materials, have been stockpiled in the area and have influenced the environment of the mine district. In this paper, analysis of fly ash samples from three power plants is carried out, the enrichment and concentration of trace elements, Pb, Zn, Cu and As, in coal ashes are analyzed, and petrological and mineralogical characteristics and chemical compositions of coal ashes are studied. The aim of this work is to provide basic scientific data for utilization of ashes and reduction of environmental pollutions. 相似文献
69.
In this paper, we firstly use finite element method (FEM) with Burgers model to simulate the postseismic viscoe-lastic relaxation taking 1960 Chile earthquake as an example. The postseismic deformation modeled with Burgers model includes co-seismic deformation, transient postseismic deformation and long-term postseismic deformation. So if we apply Burgers model to calculate postseismic deformation of 1960 Chile earthquake, there is no discrep-ancy phenomenon due to different durations of postseismic deforma... 相似文献
70.
INTRODUCTIONThemiddleandlowerreachesofChangjiangRiverareoneofthemainregionsinChinawhichischaracteristicofthewidespreaddistrib... 相似文献