New chitinozoans from the historical type area of the Hirnantian Stage and additional key sections in the Wye Valley,Wales, UK

The type locality for several core elements of the Hirnantia brachiopod fauna is a small disused quarry on the western slopes of Cwm Hirnant. There, the Hirnant Limestone Member of the Foel‐y‐Ddinas Mudstone Formation yields a new, well‐preserved chitinozoan assemblage, attributed to the Spinachitina taugourdeaui Biozone. This allows tight correlation with the Hirnantian of Baltica and Laurentia and neatly ties the chitinozoan zonation with the classical brachiopod fauna. Nearby, the chitinozoan assemblage from the Caradoc Cymerig Limestone Member at Gelli‐grîn belongs to the Spinachitina cervicornis Biozone?, and is identical to that recovered from the Burrellian in the Onny Valley, Welsh Borderland. A Silurian assemblage higher up section, discovered in the Cwm‐yr‐Aethnen Formation, is attributed to the globally recognized Eisenackitina dolioliformis Biozone. Attempts to integrate the chitinozoan and graptolite biozonation, in the central Welsh Rhayader area, were less successful. Copyright © 2008 John Wiley & Sons, Ltd.     

Undrained lower bound solutions for end bearing capacity of shallow circular piles in non-homogeneous and anisotropic clays

The undrained bearing capacity of shallow circular piles in non-homogeneous and anisotropic clay is investigated by the lower bound (LB) finite element limit analysis (FELA) under two-dimensional (2D) axisymmetric condition using second-order cone programming, and the new solution of the problem is presented. Modified from the isotropic von Mises yield criterion, a cross-anisotropic undrained strength criterion of clays under the axisymmetric state of stress requiring three input shear strengths in triaxial compression, direct simple shear, and triaxial extension is employed in the 2D axisymmetric LB FELA. Parametric studies on the effects of pile embedment ratio, dimensionless strength gradient, anisotropic strength ratio, and pile roughness are investigated extensively, while the predicted failure mechanisms associated with these parameters are discussed and compared. Numerical results of undrained end bearing capacity of shallow circular piles are summarized in the form of design tables that are useful for design practice and represent a new contribution to the field of pile capacity considering the combined effects of undrained strength non-homogeneity and anisotropy.     

Global method for stability analysis of anchored slopes

Based on the global method, an approach is proposed to consider the effect of anchor reinforcement on slope stability, where equilibrium conditions are formulated in terms of the whole slip body. Anchor pre-tension is assumed to be undertaken by the whole slip body instead of individual slices, causing internal force within slope more realistic. Meanwhile, the optimization model for locating the critical slip surface is of weak nonlinearity and easy to solve using the conventional optimization procedures. The effects of anchoring orientation and position are thoroughly investigated, and interesting results are obtained.     

极限平衡方法在夏日哈木镍钴矿山拟建露天采场边坡角优化中的应用

夏日哈木镍钴矿为大型镍钴硫化物矿床,现拟建大型露天采场,边坡采用分台阶式高边坡,最高边坡高度超过600m。该工程具有开挖成本高,边坡一但失稳后果严重的特点。为此需要选择一个即节约经济成本又保障整体边坡稳定的最佳边坡角。本文采取Geostudio软件中的Slope模块极限平衡方法对拟建露天采场假设开挖边坡角的整体边坡稳定性进行分析,提出最佳设计边坡角。　本次边坡角优化的思路：首先根据场地工程地质条件和拟建边坡的高度等因素将拟建边坡划分为5个区,选择典型边坡工程地质剖面并进行工程地质岩体分段,然后通过岩石强度指标折减计算（本文采用费辛柯法、M.Georgi法和经验法）给各分段的岩体赋予凝聚力、内摩擦角等计算参数,采用极限平衡方法（Geostudio软件中的Slope模块法）对不同角度下对各分区边坡的破坏形式及安全系数进行计算,最后提出了各分区边坡的最佳设计边坡角。     

夏季南亚高压与邻近上对流层下平流层区水汽变化的联系

利用1979-2015年ERA-interim月平均再分析资料,分析了夏季南亚高压（SAH）与邻近上对流层下平流层（UTLS）区水汽空间分布特征,讨论了二者的相关关系和因果联系。结果表明:（1）在对流层上层,水汽大值区位于南亚高压的东南侧,并随高度升高向西北倾斜到100 hPa,水汽大值中心基本位于南亚高压中心附近。（2）南亚高压偏强（弱）时,南亚高压东部UTLS区水汽显著偏多（少）,而南亚高压西北部水汽异常不显著。（3）南亚高压偏强（弱）时南亚高压中部UTLS区水汽偏多（少）可能与南亚高压对水汽的抽吸和对水汽输送屏障有关。（4）而南亚高压东南侧UTLS区水汽偏多（少）时南亚高压偏强（弱）可能与深对流输送的水汽潜热释放有关。      

Reducing global GHG emissions by replicating successful sector examples: the ‘good practice policies’ scenario

This article shows the potential impact on global GHG emissions in 2030, if all countries were to implement sectoral climate policies similar to successful examples already implemented elsewhere. This assessment was represented in the IMAGE and GLOBIOM/G4M models by replicating the impact of successful national policies at the sector level in all world regions. The first step was to select successful policies in nine policy areas. In the second step, the impact on the energy and land-use systems or GHG emissions was identified and translated into model parameters, assuming that it would be possible to translate the impacts of the policies to other countries. As a result, projected annual GHG emission levels would be about 50 GtCO₂e by 2030 (2% above 2010 levels), compared to the 60 GtCO₂e in the ‘current policies’ scenario. Most reductions are achieved in the electricity sector through expanding renewable energy, followed by the reduction of fluorinated gases, reducing venting and flaring in oil and gas production, and improving industry efficiency. Materializing the calculated mitigation potential might not be as straightforward given different country priorities, policy preferences and circumstances.

Key policy insights

• Considerable emissions reductions globally would be possible, if a selection of successful policies were replicated and implemented in all countries worldwide.

• This would significantly reduce, but not close, the emissions gap with a 2°C pathway.

• From the selection of successful policies evaluated in this study, those implemented in the sector ‘electricity supply’ have the highest impact on global emissions compared to the ‘current policies’ scenario.

• Replicating the impact of these policies worldwide could lead to emission and energy trends in the renewable electricity, passenger transport, industry (including fluorinated gases) and buildings sector, that are close to those in a 2°C scenario.

• Using successful policies and translating these to policy impact per sector is a more reality-based alternative to most mitigation pathways, which need to make theoretical assumptions on policy cost-effectiveness.

     

The Middle and Upper Devonian in southeastern flank of the Siberian platform (Southern Verkhoyansk Region,Sette-Daban Mountain Range)

Data on Middle and Upper Devonian deposits studied in southeastern flank of the Siberian platform are considered. A scheme of stratigraphic zoning in the study region is presented. Nineteen sedimentological and biotic events, which are recorded in the studied sections, are of the regional, interregional and global ranks. Their connection with eustatic sea-level fluctuations is established. Sections of the formation and regional horizon stratotypes and parastratotypes are described. The revision of species Mucrospirifer novosibiricus (Toll) is carried out.     

同生断层及其伴生褶曲的组合式样

石油钻探遇断层而失败的情形时有发生,其中多数是由于对同生断层及其伴生褶曲认识的错误所引起。为减少勘探失误,本文讨论了同生断层及其伴生褶曲空间组合的一些规律。（1）同生断层可分为盆地边界同生断层和内部同生断层两大类。边界同生断层的断面产状基本形态有勺形、椅形、阶形和坎形四种。（2）边界同生断层是追踪盆前的一组或两组基底断裂发育而成的。单向追踪的边界同生断层平面伸展较平直;双向追踪的边界同生断层平面伸展呈锯齿形。（3）内部同生断层及其伴生褶曲在剖面上的组合式样有正牵引和同向y字形派生断层、逆牵引和反向y字形派生断层。这两类四种形变可单一出现,也可在同一剖面中共存。（4）内部同生断层系的平面组合基本式样有帚状和雁列两种。构成地堑式的两条同生断层断距都较大时就会有挤压背斜出现（构成w形构造）。（5）中国东部裂谷系盆地中的所谓“滚动背斜”都不具备标准的“滚动”特征;它只产生在特定的层位上;对它与其称“滚动背斜”,不如称“逆牵引背斜”为宜。     

Seismic structure of the upper mantle beneath the western Philippine Sea

We investigate the seismic structure of the western Philippine Sea using two sets of seismological observations: ScS reverberations, which provide the layering framework for a regional upper mantle model, and observations of frequency-dependent phase delays for direct S waves, surface-reflected phases (sS, SS, sSS), and surface waves (R₁, G₁), which constrain the velocity and anisotropy structure within the layers. The combined data set, comprising 17 discontinuity amplitudes and layer travel times from the ScS-reverberation stack and more than 1000 frequency-dependent phase delays, was inverted for a path-averaged, radially anisotropic model. Mineralogical estimates of the bulk sound velocity and density are incorporated as complementary constraints. The final model, PHB3, is characterized by a 11.5-km thick crust, an anisotropic lid bounded by a sharp negative G discontinuity at 89 km, an anisotropic low-velocity layer extending to 166 km, a subjacent high-gradient region, and transition-zone discontinuities at depths of 408 km, 520 km and 664 km. The lid is slower than in a comparable model for the Tonga–Hawaii corridor (PA5), but also significantly thicker, requiring a compositional variation between the two regions. We explore the hypothesis that the thickness of the oceanic lid is controlled by the melting depth at the spreading centers during crust formation, and that the thicker crust and lid in the Philippine Sea results from deeper melting owing to a higher potential temperature and perhaps a higher water content in the upper mantle.     

Modeling pollutant migration in the Upper Palar River Basin, Tamil Nadu, India

 Palar River Basin, a crystalline rock region in North Arcot District (Tamil Nadu), India, possesses vast groundwater potential along and near the river course and its lands are fertile. Serious contamination of both surface water and groundwater has been reported in this basin as a result of uncontrolled discharge of untreated effluents by the tanning industries for the last three decades. The health of the rural farming community and people working in the tanning industries has been seriously affected and they are suffering from occupational diseases such as asthma, chromium ulcers and skin diseases. About an 11000 hectares area of fertile land has lost its fertility. Total dissolved solids (TDS) concentration in groundwater at some pockets varies from 3000 to 10000 mg/l. As the discharge of effluents is continuing, a prognosis of further pollutant migration is carried out using a mathematical model. A numerical model of the Upper Palar River Basin was developed using the finite difference technique coupled with method of characteristics and used to predict TDS migration for the next 20 years. Sensitivity analysis was carried out to identify the parameters which are influencing the contaminant migration. Sensitivity analysis shows that advection and not dispersion is the predominant mode of solute migration in Palar Basin. Prognosis using the model confirms that the polluted area zone as well as the concentration of pollutants in the groundwater will continue to increase in future. The study also indicated that even if the pollutant sources are reduced to 25% of the present level, the TDS concentration level in the groundwater, even after 20 years, will not be reduced below 50% of its 1992 level. Received: 20 June 1998 · Accepted: 26 October 1998