First Record of Fossil Mesocupes from China （Coleoptera： Archostemata： Cupedidae）          下载免费PDF全文

TAN Jingjing HUANG Diying REN Dong 《《地质学报》英文版》2007,81(5):688-696

Three new fossil species of the genus Mesocupes of fossil cupedids,M.angustilabialis sp. nov.,M.latilabialis sp.nov.and M.collaris sp.nov.,are described from the Jiulongshan Formation of Inner Mongolia,China.These new species are the first three records of fossil Mesocupes in China as well as the oldest ones in the world now.This finding also extends the geographical distribution of this genus from Central to East Asia.In addition,based on the ratio of the length of the last to the penultimate abdominal ventrites of new beetles distinctly lower than that of the species from the Karabastau Formation,the age of Daohugou fossil-bearing beds might be older than that of Karatau assemblage and consequently of Middle Jurassic.  相似文献   

新疆库车凹陷侏罗系多粒级黏土矿物分析方法及其对沉积-成岩环境的指示     

吴朝东  王琪琪冯雪 顾萧 《岩石学报》2007,23(7):1655-1663

本文选取库车坳陷侏罗系阿合组—齐古组的碎屑岩样品,利用 Stokes 原理,通过同步跟进与离心分析相结合的多粒级提取的方式提取不同粒径的黏土矿物,包括>20μm;20μm～5μm;5μm～2μm;2μm～0.2μm和<0.2μm。不同粒径组分的黏土矿物呈现出不同的型貌特征,在20～2μm范围内的样品中,自生黏土矿物少见,大量可见碎屑来源的黏土矿物,由于经过了长期的机械搬运,难见完整的晶型。在<2μm的样品中大量存在自生黏土矿物,大量成集合体,同时也存在碎屑蚀变成因的黏土矿物。通过 XRD 方法定量分析了所分离出的不同粒径黏土矿物的相对含量,黏土粒径范围内的黏土矿物相对含量呈现些规律变化。碎屑伊利石含量有随着粒级的减小而减少的趋势,而自生伊利石和伊蒙混层只在2～0.2μm及0.2μm以下粒级才出现,并且集中在0.2μm以下粒级范围内;在古气候,沉积环境和母岩特性及分布基本一致的情况下,高岭石的分布有随着岩性的变粗呈现升高的趋势,而伊利石呈负相关关系。碎屑岩中黏土矿物的形貌特征表明,黏土矿物有陆源碎屑来源与自生两种成因,应用 Decoform 软件对0.2μm以下黏土矿物中不同成因的伊利石进行了计算,并就存在的比例与粒径的关系进行了讨论。黏土矿物组合揭示侏罗纪沉积环境由酸性环境向微碱性环境过渡,早侏罗世和中侏罗世早期为气候潮湿时期,高岭石的含量明显高于侏罗世晚期地层,恰克马克期到齐古期高岭石含量开始出现减小的趋势。从恰克马克期开始,气候缓慢向干旱变化,高龄石含量降低,而伊利石的平均含量明显增加,反映黏土矿物组合主要受沉积环境和成岩作用共同影响。  相似文献   

Deformation Mechanism and Stability of a Rocky Slope   总被引：1，自引：1，他引：1  

黄润秋肖华波  巨能攀赵建军 《中国地质大学学报(英文版)》2007,18(1):77-84

A high slope is located on the side of the spillway at a hydropower station in Southwest China, which has some weak inter-layers inclining outwards. Parts of the slope show heavy weathering and unloading. There appeared deformation and tensile crack either on the surface or on the afteredge of the slope during excavation, and under a platform （elev. 488 m）, two levels of slopes collapsed on the downriver side. Based on the investigation in situ and the analysis of the geological structure, the conceptual model of deformation and failure mechanism was erected for this slope. Furthermore, the deformation characteristics were studied with FLAC^3D numerical simulation. Comprehensive analysis shows that the whole deformation of the slope is unloading rebound in certain depth scope and the whole body does not slide along any weak interlayer. In addition, two parts with prominent local deformation in the shallow layer of the slope show the models of ＂creep sfiding-tensile cracking＂ and ＂slidlng-tensile cracking＂, respectively. Based on the above analysis, the corresponding project of support and reinforcement is proposed to make the slope more stable.  相似文献   

Residual strength of slip zones of large landslides in the Three Gorges area, China   总被引：2，自引：0，他引：2  

B.P. Wen  A. Aydin  N.S. Duzgoren-Aydin  Y.R. Li  H.Y. Chen  S.D. Xiao 《Engineering Geology》2007,93(3-4):82-98

Slip zones of the large landslides in the Three Gorges area are commonly composed of fine-grained soils with substantial amount of coarse-grained particles, particularly gravel-sized particles. In this study, residual strength of the soils from slip zones of these landslides were examined in relation to their index properties based on a survey of 170 landslides. It was found that laboratory-determined residual friction angle using gravel-free fraction of the disturbed soils from the slip zones was closely related to clay content, liquid limit and plasticity index. On the other hand, in-situ residual friction angle of these soils (i.e. including gravel fraction) showed very weak correlations with clay content and Atterberg limits, but was largely dependent on gravel and fines (clays + silts) contents, increasing with gravels and decreasing with fines, and displayed strong linear correlation with the ratio of gravel to fines contents. These observations indicate that among the index properties, clay content and Atterberg limits can be used to estimate residual strength of the soils finer than 2 mm, but they are not appropriate evaluate the residual strength of the soils containing considerable amount of gravel-sized particles. For the latter, particle size distribution (particularly the ratio of gravel to fines contents) appears to be a useful index. Additionally, it was found that there was no identifiable correlation between relative abundance of individual major clay minerals and residual friction angles of both gravel-free fraction of disturbed and in-situ soils, suggesting that influence of clay minerals on residual strength of these soils can not be simply evaluated based on their abundance.  相似文献   

Hydrogeochemical processes of thallium in a rural area of Southwest Guizhou, China     

何立斌  肖唐付  李航  孙伟 《中国地球化学学报》2007,26(1):52-57

The water system in a rural area of Lanmuchang in Southwest Guizhou is facing a risk of thallium (Tl) contamination due to Tl mineralization around the area. The major trace elements and Tl in the water system are studied to understand the hydrogeochemical processes of Tl constrained by Tl mineralization. The results showed that the dispersion pattern of Tl follows a descending order in concentration from mine groundwater (deep groundwater) →stream water→shallow groundwater→background water, reflecting the impact of Tl mineralization on the hydrogeochemical composition. Tl concentrations in stream water in both regimes are remarkably higher (2-30 fold) downstream than up- and mid-streams, probably caused by the unidentified discharge of deep groundwater. Low Tl levels are detected in the current drinking water, however, the highly elevated Tl in stream water and ground water may pose a potential environmental risk through daily washing and agricultural irrigation. This study suggests that human activities, such as agricultural irrigation, could intensify the environmental risk of Tl.  相似文献   

Temporal and spatial dynamical simulation of groundwater characteristics in Minqin Oasis   总被引：1，自引：0，他引：1  

XIAO DuNing    LI XiaoYu  ?  SONG DongMei & YANG GuoJing Cold  Arid Regions Environmental  Engineering Research Institute  Chinese Academy of Sciences  Lanzhou  China  Institute of Applied Ecology  Chinese Academy of Sciences  Shenyang  China  Institute of Geographic Sciences  Natural Resources Research  Chinese Academy of Sciences  Beijing  China 《中国科学D辑(英文版)》2007,50(2):261-273

Application scope of geostatistics has been gradually extended from original geologic field to soil science and ecological field, etc. and its successful application results have been widely demonstrated. But little information is reported as to the direct use of geostatistical method to work out the distribu- tion map of groundwater characteristics. In this paper the semivariogram of geostatistics, in combina- tion with GIS, was used to quantitatively study the spatial variation characteristics of groundwater table depth and mineralization degree and their relation to the landuse changes. F test of the used spherical model reached a very significant level, and the theoretical model can well reflect the spatial structural characteristics of groundwater table depth and mineralization degree and achieve an ideal result. This shows that the application of the method in the dynamical simulation of groundwater is feasible. And this paper also provides useful reference for the application of geostatistics in the study of the dy- namical variations of groundwater resources in the oasis.  相似文献   

Geological analysis and FT dating of the large-scale right-lateral strike-slip movement of the Red River fault zone   总被引：1，自引：1，他引：1  

XIANG HongFa  WAN JingLin  HAN ZhuJun  GUO ShunMin  ZHANG WanXia  CHEN LiChun & DONG XingQuan Institute of Geology  China Earthquake Administration  Beijing  China  Earthquake Administration of Yunnan Province  Kunming  China 《中国科学D辑(英文版)》2007,50(3):331-342

Tectonically, the large-scale right-lateral strike-slip movement along the Red River fault zone is char-acterized at its late phase with the southeastward extension and deformation of the Northwestern Yunnan normal fault depression on its northern segment, and the dextral shear displacement on its central-southern segment. Research of the relations between stratum deformation and fault movement on the typical fault segments, such as Jianchuan, southeast Midu, Yuanjiang River, Yuanyang, etc. since the Miocene Epoch shows that there are two times dextral faulting dominated by normal shearing occurring along the Red River fault zone since the Miocene Epoch. The fission track dating (abbrevi-ated to FT dating, the same below) is conducted on apatite samples collected from the above fault segments and relating to these movements. Based on the measured single grain’s age and the con-fined track length, we choose the Laslet annealing model to retrieve the thermal history of the samples, and the results show that the fault zone experienced two times obvious shear displacement, one in 5.5 ± 1.5 MaBP and the other in 2.1± 0.8 MaBP. The central-southern segment sees two intensive uplifts of mountain mass in the Yuanjiang River-Yuanyang region at 3.6―3.8 MaBP and 1.6―2.3 MaBP, which correspond to the above-mentioned two dextral normal displacement events since the late Miocene Epoch.  相似文献   

不同标度震级关系和台基影响问题探讨   总被引：2，自引：1，他引：2  

张宏志  刁桂苓  赵明淳  王勤彩  张骁  黄媛 《中国地震》2007,23(2):141-146

利用近年中国数字地震台网观测报告中的中国及邻区地震目录资料,取能够同时计算面波震级MS和近震震级ML的地震,拟合出2种震级之间的关系,发现与过去使用30余年的换算公式存在系统差别。考虑现代化地震数字观测系统有动态范围大、频带宽、台站多、覆盖区域广、测定精度高的特点,由此拟合的关系应当更可靠。考虑不同误差因素统计面波震级MS和近震震级ML的关系表明,2种震级之间换算和不换算的差别并不大,因此建议MS和ML震级之间不换算为宜。分析地震台站的场地响应发现:一些基岩台的放大因子在1附近,场地响应不随频率变化;处于沉积土层的台站,放大因子在低频段大于1,高频段小于1;还有一些台站在某个频段范围大于1,或者小于1。另外,沉积土层台站的单台震级和台网平均震级差也随周期增大,呈现由负到正的增长趋势。看来并不存在固定的台站校正系数,因此不能把台站校正作为提高震级测定精度的方法。  相似文献   

1954年山丹7.3级地震灾害     

董治平  陈玉华  王平  陈瑶  代炜 《中国地震》2007,23(2):157-165

1954年2月11日,中国西部河西走廊发生山丹7.3级强烈地震,这是建国以来发生在西北地区的第一个大地震。地震造成47人死亡,332人受伤,数万人无家可归;房屋损坏7277间,估计财产损失远高于2003年山丹6.1级地震灾害的直接经济损失。极震区烈度达Ⅺ度,红寺湖盆地、山丹县城破坏最重,山丹地区受灾面积4800km2。本文简要介绍了山丹地震参数、地震烈度及震区环境;重点描述了房屋建筑物破坏,分析了地震灾害特点及其经济损失估计。最后探讨了这次地震震害的成因、防震减灾的经验及其借鉴意义。  相似文献   

高压断路器隔震体系抗震可靠度分析   总被引：1，自引：0，他引：1  

冯东  陈玲俐  叶志明 《世界地震工程》2007,23(3):98-103

给出了基于随机地震动模型的高压断路器抗震可靠性分析方法。通过建立高压断路器及其隔震体系的有限元计算模型，分析了在断路器底部瓷套管根部加设叠层橡胶垫后的动力性能，分析中利用随机地震动模型，充分考虑地震动的随机作用，给出了四类场地土条件下结构的地震响应均值和标准差；利用一次二阶矩理论计算得到高压断路器的可靠度，给出了各场地土条件下的震害率曲线。结果表明不同场地土条件下隔震垫的减震效果有所差异。  相似文献