A Reconstruction for the Late Paleozoic Tectonic Evolution of the Tekes Daban Area, Western Tianshan Mountains: Evidence from Unconformities

The identification of unconformities is the key to reconstructing tectonic evolution, revealing crust movement and establishing tectonic cycle. For a long time, there were some controversial issues on the episodes of Variscan cycle (especially on the period of Carboniferous-Permian stages) of the Tianshan area. The essential questions fall on the numbers and property of unconformities in this area, for example, in the western Tianshan area. Previous research only recognized three or four fold movements. Detailed regional geological mapping of 1:50000 in the Tekes Daban area, western Tianshan have allowed us to characterize the seven unconformities within the Carboniferous-Permian strata and understand its implications for tectonic reconstruction of the Tianshan orogen. Seven angular unconformities, which indicate that seven tectonic episodes occurred in the Late Paleozoic Period, were identified in this area. Therein, the newly discovered unconformities based on the angle-unconformity between the Dongtujinhe and Keguqinshan Formations, and angle-unconformity between the Wulansayi and Wulang Formations, respectively indicates the Tekes episode and Gongliu episode. The unconformity between the Dongtujinhe and Yishijilike Formations is angle-unconformity instead of parallel unconformity indentified by previous research, so the former Bogda ascending can be revised as Bogda movement. Therefore, these newly identified seven episodes, including the Tekes episode, suggest that there are seven tectonic movements in the Tianshan area at least. This has significant implications for reconstruction of the Late Paleozoic tectonics in the Tianshan Area, NW China     

Notes Light and electron microscopic study on Lymphocystis of cage cultured kelp bass, Epinethelus moara (Temminck et Schlegel)

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First measurements from a deep-tow transient electromagnetic sounding system

An electromagnetic sounding system has been developed to map the shallow electrical conductivity structure of the deep sea floor. The instrument consists of a magnetic source and several colinear magnetic receivers forming an array which is towed along the seafloor. The source generates a time varying magnetic field; the shape of the resulting magnetic field waveform at the receivers depends on the electrical conductivity below the seafloor between the receivers and the source. The instrument can be towed systematically over a study area under acoustic transponder or GPS navigation to construct a map of the electrical conductivity. Towing speeds of greater than 1 m s^–1 (2 knots) can be achieved without adversely effecting data quality. The instrument is sufficiently robust to survive continual contact with thinly sedimented, abrasive basalt. We present the first results from a deployment in August, 1990 near the Cleft Segment of the Juan de Fuca Ridge along an 8 km track to the west of the spreading center. Unforeseen problems with the instrument restricted the utility of the measurements for constructing detailed vertical conductivity profiles, but the measurements were adequate to determine an average conductivity in the upper 25 m, at more than 70 stations. The conductivity was found to vary from 0.1 to 0.4 S/m along the track.     

系统动力学方法在喀斯特地区人口环境容量研究中的应用—— 以贵州省紫云县为例

以贵州省紫云县为例,首次运用系统动力学方法建立了喀斯特地区人口环境容量的系统动力学模型。模型包括粮食生产、烤烟生产、经济作物生产、牧业、林业和人口6个子系统。分析了所建模型的结构,对模型进行了仿真模拟,并针对模拟结果提出了政策建议。本研究模型可以为当地制定人口政策和移民方案提供科学依据。      

Response of the low-frequency fluctuations of sea level to atmospheric forcing along the coasts of the Huanghai Sea and the East China Sea

In this paper, the low-frequency fluctuations of sea level and their relationship to atmospheric forcing along the coasts of the Huanghai Sea and the East China Sea are studied. Spectrum analyses are made for the time series of daily mean sea level, atmospheric pressure and wind stress at seven coastal stations. It is found that at all the stations, the main part of the energy of the sea level fluctuations, within the (2-60)-day period, is concentrated on the (12-60)-day period band and that an obvious spectral peak appears at the 3-day period. Along the coast of the Huanghai Sea, variations in the sea level are greater in winter than in summer. In winter, along the coasts of the Huanghai Sea and the East China Sea there is a kind of sea level fluctuations propagating southwards. Among the many factors causing sea level variation, the most obvious one is atmospheric pressure, followed next by the alongshore wind stress.     

利用卫星测高与卫星重力数据进行中国近海上层地转流速度分析

利用卫星测高技术获取的海面高、卫星重力数据以及最新的Argo漂流速度数据确定我国海域稳态海面地形,研究分析中国近海上层地转流的变化特征。结果表明,中国近海地转流沿x方向分量流速范围为0.1～1.6m/s,其误差在±0.97m/s以内;沿y方向分量流速范围是0.1～1.70 m/s,最大误差为±0.66 m/s。     

Slide roof system for dynamic response reduction

A slide roof system (SRS) is proposed to reduce the dynamic response of buildings to earthquake excitations. A SRS consists of a roof structure, springs and friction materials, providing mass, stiffness and damping, respectively. The method of optimization of stiffness and friction coefficient for the SRS is introduced. A numerical analysis of an eight‐story frame structure subjected to ground motions and shaking table tests of a five‐story frame was carried out to study the effectiveness of the SRS. The results show that the SRS can reduce the maximum dynamic response as much as 60–70% in the first resonate band and 35–50% in the second resonate band. Copyright © 2007 John Wiley & Sons, Ltd.     

2008年度地理学基金项目评审及成果分析

着重分析了2008年面上项目、青年基金项目及地区基金项目的申请情况及资助概况,2007年在研项目的进展情况,以及2007年底结题项目完成情况。同时介绍了2007年度主要学科方向取得的突出研究进展。     

辽东湾现代沉积物中畸形底栖有孔虫及环境指示意义

对渤海辽东湾海域10根柱状样的305个沉积物样品进行了有孔虫定量分析,共识别出畸形有孔虫8属10种。10种畸形有孔虫根据壳体形态可分为5大类,分别为房室异常、口孔异常、脐异常、绕旋异常、壳圈异常。通过对有孔虫畸形属种的畸变类型进行统计描述,一定程度上弥补了畸形有孔虫研究的不足。对比发现辽东湾海域环境污染程度由近岸向远岸逐渐递减,该特征符合人类活动对海洋环境的影响。     

中、新生代超级汇聚背景下的陆内差异变形:华北伸展裂解和华南挤压逆冲

中、新生代期间,太平洋板块向西俯冲、印度板块向北俯冲于欧亚板块下以及中生代鄂霍次克海的消亡导致中亚造山带的向南俯冲,三者围限的中心三角形地带正是中国东部两个核心地块--华北和华南地块,而且,该区中、新生代始终处于全球三大构造域超级汇聚的中心.但是,在这种超级汇聚背景下,分别于华北和华南陆块的核部形成了两种截然相反的构造...