东秦岭金堆城大型斑岩钼矿床同位素及元素地球化学研究

文章系统研究了金堆城钼矿床的含矿钾长斑岩、围岩、矿石、矿石中的黄铁矿及矿化围岩的地球化学特征,深入探讨了矿区成矿物质的来源.金堆城含矿斑岩的稀土元素分布和特征地球化学参数显示,金堆城含矿斑岩富集LREE(LaN/YbN=540～1684),轻、重稀土元素分馏较明显,Eu异常不明显或无Eu异常(δEu=070～096).矿石中黄铁矿富集LREE(LaN/YbN=315～2628),具有弱的Eu负异常,无Ce异常(δEu=064～081, δCe=088～103),并与金堆城含矿钾长斑岩和矿石具有一致的球粒陨石标准化配分曲线和特征的地球化学参数,显示金堆城钼矿床的成矿物质来源与钾长斑岩同源.矿床铅、硫、碳和氢-氧同位素地球化学综合研究表明,成矿物质来源于深部,与钾长斑岩同源.围岩在矿化和蚀变过程中元素的迁移计算结果表明,在热液成矿过程中Mo随成矿流体加入到围岩并使围岩发生蚀变和矿化.钼矿床的成矿物质主要来自钾长斑岩,围岩不提供成矿物质.金堆城含矿斑岩和钼矿化的发生处于秦岭造山带在中新生代的挤压-伸展转变期,受板片断离作用和壳幔边界附近发生的基性岩浆底侵作用影响,加厚的华北地块南缘下地壳物质发生熔融形成花岗质岩浆,并沿构造薄弱带上升到浅部侵位,形成金堆城等同熔型斑岩和斑岩型矿床.     

The usability of climate information in sub-national planning in India,Kenya and Uganda: the role of social learning and intermediary organisations

Correctly estimating the effect of elevated CO₂ (eCO₂) on biomass production is paramount for accurately projecting agricultural productivity, global carbon balances and climate changes. Plant physiology suggests that eCO₂ should result in a strongly positive CO₂ fertilisation effect (CFE) via positive effects on photosynthesis and water use efficiency. However, the CFE in CO₂ experiments is often constrained because of other factors of which rainfall pattern is particularly important. Here, we apply a generally applicable, empirically derived relationship between the CFE and an index of seasonal rainfall balance (SRB), to identify how historical and projected future rainfall patterns modify the CFE using 25 native grassland sites in south-eastern (SE) Australia as a test case. We found that historical and projected rainfall produced SRBs that varied widely from year-to-year resulting in a CFE that was only positive in about 40% of years, with no or even negative biomass responses in the remainder of years; a finding that is in marked contrast to other studies that have not taken account of relationships between rainfall seasonality and plant responses to CO₂. The dependence of the CFE on SRB also means that using the CFE from a specific eCO₂ experiment can be misleading as the result will be heavily influenced by the SRB during the period of experimentation but this problem can be avoided by using a robust general relationship of the kind used in this study. Generalisations of grassland biomass responses to the rising CO₂ concentration are contextual in terms of the variability in precipitation seasonality; as such, this provides a new lens by which to view aboveground responses to the rising CO₂ concentration and fosters a novel approach for cross-site comparisons among experiments.     

The impacts avoided with a 1.5 °C climate target: a global and regional assessment

The 2015 Paris Agreement commits countries to pursue efforts to limit the increase in global mean temperature to 1.5 °C above pre-industrial levels. We assess the consequences of achieving this target in 2100 for the impacts that are avoided, using several indicators of impact (exposure to drought, river flooding, heat waves and demands for heating and cooling energy). The proportion of impacts that are avoided is not simply equal to the proportional reduction in temperature. At the global scale, the median proportion of projected impacts avoided by the 1.5 °C target relative to a rise of 4 °C ranges between 62 and 95% across sectors: the greatest reduction is for heat wave impacts. The 1.5 °C target results in impacts that would be between 27 and 62% lower than with the 2 °C target. For each indicator, there are differences in the proportions of impacts avoided between regions depending on exposure and the regional changes in climate (particularly precipitation). Uncertainty in the proportion of impacts that are avoided for a specific sector depends on the range in the shape of the relationship between global temperature change and impact, and this varies between sectors.     

Empirical calibration of climate policy using corporate solvency: a case study of the UK’s carbon price support

Emission reductions improve the chances that dangerous anthropogenic climate change will be averted, but could also cause some firms financial distress. Corporate failures, especially if they are unnecessary, add to the social cost of abatement. Social value can be permanently destroyed by the dissolution of organizational capital, deadweight losses paid to liquidators, and unemployment. This article proposes using measures of corporate solvency as an objective tool for policy makers to calibrate the optimal stringency of climate change policies, so that they can deliver the least loss of corporate solvency for a given level of emission reductions. They could also be used to determine the generosity of any compensation to address losses to corporate solvency. We demonstrate this approach using a case study of the UK’s Carbon Price Support (a carbon tax).

Key policy insights

• Solvency metrics could be used to empirically calibrate the optimal stringency of climate policies.

• An idealized solvency trajectory for firms affected by climate change policy would cause corporate solvency to initially decline – approaching but not exceeding ‘distressed’ levels – and then gradually improve to a new ‘steady state’ once the low-carbon transition had been achieved.

• In terms of the UK’s Carbon Price Support, corporate solvency of energy-intensive industries was found to be stable subsequent to its introduction. Therefore, the available evidence does not support its later weakening.

     

SlugIn 1.0: A Free Tool for Automated Slug Test Analysis

The correct characterization of aquifer parameters is essential for water‐supply and water‐quality investigations. Slug tests are widely used for these purposes. While free software is available to interpret slug tests, some codes are not user‐friendly, or do not include a wide range of methods to interpret the results, or do not include automatic, inverse solutions to the test data. The private sector has also generated several good programs to interpret slug test data, but they are not free of charge. The computer program SlugIn 1.0 is available online for free download, and is demonstrated to aid in the analysis of slug tests to estimate hydraulic parameters. The program provides an easy‐to‐use Graphical User Interface. SlugIn 1.0 incorporates automated parameter estimation and facilitates the visualization of several interpretations of the same test. It incorporates solutions for confined and unconfined aquifers, partially penetrating wells, skin effects, shape factor, anisotropy, high hydraulic conductivity formations and the Mace test for large‐diameter wells. It is available in English and Spanish and can be downloaded from the web site of the Geological Survey of Spain. Two field examples are presented to illustrate how the software operates.     

Accuracy assessment of the Mexican National Forest Inventory map: A study in four ecogeographical areas

The accuracy of the Mexican National Forest Inventory (NFI) map is derived in four distinct ecogeographical areas, using an assessment design tailored for the project. A main achievement of the design was to integrate the high diversity of classes encompassed at the most detailed subcommunity level of the classification scheme within a cost‐controlled statistically sound assessment. A hybrid double sampling strategy was applied to the 2.5 million‐ha study area. A total of 5955 reference sites were verified against their NFI map label. The availability of detailed quasi‐synchronous reference data for the 2000 Landsat‐derived NFI and the high diversity of mapped classes allowed a careful thematic analysis on the selected regions, relevant for national extrapolation. Global accuracy estimates of 64–78 per cent were registered among the four ecogeographical areas (two with mainly temperate climate and the other two with mainly tropical climate), with the lower accuracy levels found in areas more densely covered with forests. According to the estimates, the NFI map tends to underestimate the presence of temperate forest (especially oak) and overestimate the presence of tropical forest in the areas investigated. The analysis of confusions reveals difficulties in unambiguously interpreting or labelling forests with secondary vegetation, herbaceous and/or shrub‐like vegetation as well as distinguishing between aquatic vegetation types. The design proved useful from the perspective of accuracy assessments of regional maps in biodiverse regions.     

Mise en évidence d'un nouveau front de chevauchement dans l'Atlas tunisien oriental de Tunisie par sismique réflexion. Contexte structural régional et rôle du Trias salifère

Structural interpretations of newly acquired seismic lines in northeastern Tunisia allow us to highlight a new thrust front for the Atlasic range of Tunisia, in contrast to the previously Zaghouan fault thrust Dorsale zone. This new thrust front takes place on weakness tectonic zones, materialized by inherited faults anchored on the pre-Triassic basement. This front seems to be a paleogeographic trend controlling structural style and basin fill with a synsedimentary activity. The front is expressed by reverse faults, thrust faults, back thrusting, and decollement structures. To cite this article: S. Khomsi et al., C. R. Geoscience 336 (2004).     

中国城市群多中心网络的拓扑结构

在既有理论基础上扩展了城市群多中心网络的度量工具,考察中国12个城市群总部—分支机构的企业关联网络,比较梳理了地级城市空间联系的拓扑结构。实证研究发现：①包括长三角、珠三角和京津冀三大典型城市群在内,中国城市群内部网络系统的拓扑结构依然发育不完善,在联系数据方面均呈现出一定的稀疏矩阵特征,空间组合关系均为树状结构。②总部区位(出度)的层级性差异均高于分支机构区位(入度)的层级性差异,显示出城市群内部空间“流”的不对称性。③针对12个城市群内部网络的拓扑结构聚类分析表明：长三角、珠三角、京津冀、山东半岛、海峡西岸地区的城市群内部网络联系较为紧密,呈现出一定程度的一体化网络特征;其中三大典型城市群存在明显的企业总部集聚核心,其余城市群内部的网络联系松散,跨城企业联系比重较低,在拓扑结构上大多呈现出以省会或副省级城市为指向的向心式联系。