Landslide risk analysis between Giri and Tons Rivers in Himachal Himalaya (India)

The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies.     

Trace metal concentrations in lake and overbank sediments in southern Norway

 As, Be, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Se and Zn concentrations were determined and compared in lake and overbank sediments from 33 catchments without local pollution sources in southern Norway. There were no significant differences in concentrations of Be, Co, Cr, Cu, Ni, and V in overbank and pre-industrial lake sediments. In areas with shallow overburden, and significant influence from long-range atmospheric pollution, concentrations of As, Cd, Hg, Pb, Se, and Zn in overbank sediments were probably modified by vertical percolating water. In such areas, we suggest using lake sediments as a better sampling medium for mapping pre-industrial concentrations. Pre-industrial lake sediments yield natural concentrations of Hg and Se, which consist of both geogenic and natural atmospheric deposition. Important covariables like organic carbon content, Fe oxides, and fine mineral fraction were generally higher in pre-industrial lake sediments as compared to overbank sediments. By adjusting for such differences overbank sediments could be used as an alternative in mapping background concentrations of trace metals in regions with few lakes. Received: 19 February 1999 · Accepted: 17 April 1999     

全景立体视觉的快速近区重力地形改正方法

重力地形改正是区域重力测量工作中的一个关键步骤,目前重力地形改正的主要挑战是如何快速地重建测站附近高精度的三维地形。本文提出了一种基于全景立体视觉和摄影测量技术的快速近区重力地形改正方法,设计和开发了相应的快速测图系统。为了使该系统硬件尽量小型化并满足精度需求,我们进行了系统的理论精度分析和设计优化。所开发的研究系统可以从获取的全景立体图像自动生成DEM并计算重力地形改正值。该系统已经过野外多站多种地形的实验验证,结果表明其效率和精度明显优于传统的野外测量方法。     

发挥高精度磁测作用的几个实例

简要介绍了高精度磁测的应用现状.通过金厂沟金矿区辽河群大石桥岩组与盖县组接触界限的划分,以及阜新建设花岗岩与长英质糜棱岩边界的划分等实例,说明得用高精度磁测结果,在配合地质填图、划分地质界线、圈定矿体和寻找古墓及古坑道等地质问题方面的优越性.用于隐伏区地质填图时,不仅能确定强磁性岩石边界,而且还能确定弱磁性岩石边界.在提高信息密度的前提下,根据磁化率K值和剩余磁化强度J_r值的不同,在典型成矿区能直接圈定弱磁性矿体.     

PRB数字地质填图前期数据准备及PRB过程字典库建立

PRB数字地质填图前期数据准备包括软硬件准备、地形图数值化、前人资料的收集和室内录入、多元数据的叠加和整合、PRB过程字典库的编制等方面.PRB过程字典库由结构化字典、填缺式字典和描述性字典3部分组成.结构化字典和填缺式字典可直接查询, 为1~1.5级字典, 描述性字典为2级字典, 需要2级查询.不同的字典类型均以文本文档的形式存在, 文件名后缀为.DIC.      

三峡库区巫山县新城址中段滑坡的研究

移民是三峡工程成败的关键。巫山县新城址的地质问题是当前工程地质的热点问题 ,也是库区具有普遍性的问题。中段滑坡是新城址泥质灰岩整体滑坡的一部分 ,位于陡坡地带 ,形成最晚 ,结构最复杂 ,稳定性最差。滑坡的后期改造过程仍在继续 ,移民工程也严重影响着滑坡的稳定性。只有采取严格的防治措施才能进行移民工程建设。     

Magnetic susceptibility variations of carbonates controlled by sea-level changes

This paper presents magnetic susceptibility results of 578 samples from three Devono-Carboniferous carbonate successions in the Yangtze Block. They indicate that the magnetic susceptibility variations in carbonates are controlled by ancient sea-level changes. It is particularly so if the supply of detrital materials was low, when the magnetic susceptibility was mainly controlled by the content of authigenic minerals. If the supply of detrital materials was high, the average susceptibility value would be higher, but there is still a correlation between susceptibility and sea-level curves. A sea level rise would lead to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for the research of sequence stratigraphy.     

Magnetic susceptibility variations of carbonates controlled by sea-level changes--Examples in Devonian to Carboniferous strata in southern Guizhou Province, China

This paper presents magnetic susceptibility results of 578 samples from three Devono-Carboniferous carbonate successions in the Yangtze Block. They indicate that the magnetic susceptibility variations in carbonates are controlled by ancient sea-level changes. It is particularly so if the supply of detrital materials was low, when the magnetic susceptibility was mainly controlled by the content of authigenic minerals. If the supply of detrital materials was high, the average susceptibility value would be higher, but there is still a correlation between susceptibility and sea-level curves. A sea level rise would lead to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for the research of sequence stratigraphy.     

四川宝兴大板桥堵江滑坡作坝的可行性分析

针对四川宝兴县大板桥堵江滑坡堆积体,在现场调查分析的基础上,对其作坝存在的主要工程地质问题及作坝的可行性进行了分析研究,为开展堵江滑坡作坝提供参考。     

Doppler-Zeeman mapping of the rapidly rotating magnetic CP star HD 37776

We present the results of our analysis of magnetic-field configuration and abundance anomalies on the surface of the rapidly rotating, chemically peculiar helium-strong variable B2 V star HD 37776 with unresolved Zeeman components of spectral lines. Simultaneous inversion of the observed Stokes I and V profiles, which realizes the method of Doppler-Zeeman mapping [1], has been applied for the first time. Spectroscopic observations were carried out with the Main stellar spectrograph of the 6-m Special Astrophysical Observatory telescope equipped with a Zeeman analyzer and a CCD array, which allowed spectra in right-and left-hand circularly polarized light to be taken simultaneously at a signal-to-noise ratio S/N≥200 [2]. The profile width of winged spectral lines (reaching 5 Å) is determined by Zeeman line splitting; however, the observed Zeeman components are blurred and unresolved because of the rapid stellar rotation. When solving the inverse problem, we sought for the magnetic-field configuration in the form of a combination of arbitrarily oriented dipole, quadrupole, and octupole placed at the stellar center. The observed Stokes I and V profiles for eight spectral lines of He, O II, Al III, Si III, and Fe III averaged over the visible stellar surface were used as input data. We constructed a model of the magnetic field from the condition of coincidence of magnetic maps obtained from different lines of different chemical elements and from the condition of a minimum profile residual. This model is a combination of centered coaxial dipole and quadrupole with the dominant quadrupole component at 30°<i<50°, β=40°, and a maximum surface field strength H _s=60 kG. A comparison of our abundance maps with the field configuration shows that the He concentration is at a maximum in the regions of maximum radial field, while the maximum concentrations of O, Al, Si, and Fe coincide with the regions of maximum tangential field.