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121.
地震孕育机制与破裂机制的研究 总被引:6,自引:0,他引:6
在理论上得出地震孕育发生的普遍物理机制是:地震前孕震区在垂直向会逐步形成、发展弹性的“拉疏隆起—压缩凹陷”的不稳结构,在水平向也多会形成对称相间分布的两个弹性压缩区及两个弹性拉疏区。应变的“压缩区与拉疏区同时产生、对应存在、共为一体”的这种双向应变结构是地壳构造运动中形成孕震体与非孕震体的根本区别,也是能用以首先找到孕震地区的主要依据;地震的破裂机制是:孕震体形成的双向应变结构,构成了应力集中后的失稳与剪切破裂的必要条件,当初始破裂后,就会引起压缩区与拉疏区发生逆转性的弹性膨胀与收缩的相互配合而不断提供位错空间,从而能使应力与破裂快速地传递与扩张。这一地震孕育与破裂机制的认识,几乎能解释绝大多数的地震前兆现象及震时震后的冒砂、冒水与断层的破裂、错动现象。 相似文献
122.
《Climate Policy》2013,13(3):242-254
The Clean Development Mechanism (CDM) under the Kyoto Protocol allows industrialized countries to use credits from greenhouse gas (GHG) abatement projects in developing countries. A key requirement of the CDM is that the emission reductions be real, measurable and additional. This article evaluates how the additionality of CDM projects has been assessed in practice. The analysis is mainly based on a systematic evaluation of 93 registered CDM projects and comes to the conclusion that the current tools for demonstrating additionality are in need of substantial improvement. In particular, the application of the barrier analysis is highly subjective and difficult to validate in an objective and transparent manner. Key assumptions regarding additionality are often not substantiated with credible, documented evidence. In a considerable number of cases it is questionable whether the emission reductions are actually additional. Based on these findings, practical recommendations for improving the assessment of additionality are provided. 相似文献
123.
Yang Liu 《Climate Policy》2013,13(6):767-783
This study assesses the effectiveness of a mix of policy instruments including the Clean Development Mechanism (CDM) and the Feed-in Tariff (FIT) to induce wind technology diffusion in China. Relying on a panel dataset consisting of information from 1207 CDM wind projects in thirty provinces over the period 2004–2011, the empirical analysis indicates that: first, wind energy deployment responds primarily to those counterfactual emissions which would have occurred in the absence of the wind projects; second, the dynamic efficiency of the FIT subsidy shows a potential incompatibility with the CDM incentive; third, the leverage of the CDM on wind investment is supported by the industry and technology policy package, which explains in large part the decrease in the FIT subsidy. Given these findings, suggestions are made regarding the design of a future carbon offset scheme and its link with mitigation action in developing countries. 相似文献
124.
125.
Klaus Eisenack 《Climate Policy》2013,13(4):491-504
The climate negotiations recognize that adequate and additional funds are needed to assist adaptation in developing countries. This article analyses whether a future 2% or any higher adaptation levy (AL) can achieve this, whether it causes – as it is a tax on the Clean Development Mechanism (CDM) – a significant excess burden, and how it alters the relation between adaptation financing and mitigation. While former studies have focused on single AL levels, this article determines the transfers from the CDM and the AL for a range of emission reduction targets and AL levels with a partial equilibrium model based on marginal abatement cost estimates for 2020. Revenues from a 2% AL are negligible and remain inadequate for ambitious emission reductions and an AL that maximizes transfers (e.g. US$15 billion for 30% reduction target). Revenues are mostly subtracted from CDM transfers, so little additional funds are raised (e.g. less than $2.4 billion for 30% reduction target). Adaptation financing increases disproportionally with more stringent reduction targets for a rising levy, and the share of Annex I country expenditures devoted to transfers increases slightly. Both effects are only small. The excess burden is larger than 85% of the additional funds. Policy relevance Financing adaptation in developing countries has become a cornerstone of a global climate agreement. The mechanism for raising additional funds has not yet been determined. This article assesses the potential of upscaling one option that is already in place under the Kyoto Protocol: the 2% AL on the CDM. It is estimated that even a much higher AL does not generate substantial additional funds, mainly redistributes transfers within non-Annex I countries, does so at social costs in the same order of magnitude as additional funds, and increases the share of Annex I country expenditures devoted to transfers. It is unwise to link mitigation and adaptation as CDM and AL jointly do, since this taxes a beneficial activity. Financial instruments with transfers that decrease with or are independent from climate protection would be preferable. 相似文献
126.
127.
华北南缘古元古代末岩墙群侵位的磁组构证据 总被引:4,自引:3,他引:4
华北克拉通南缘的中条山及邻区广泛发育元古宙放射状基性岩墙群,与五台山-恒山和大同地区的北北西向基性岩墙群以及熊耳中条拗拉谷的火山岩在时空分布和地球化学方面均具有密切的相关性。中条山及邻区放射状基性岩墙群的宏观和微观流动构造(包括捕虏体、冲痕构造、矿物线理和定向斑晶)指示岩墙群以一定的仰角向北西侵位。通过该区岩墙群磁化率各向异性(AMS)测量得到磁组构的最大磁化率长轴优势方位分布图和磁组构各向异性特征分析进一步指示华北南缘古元古代末岩墙群从熊耳中条拗拉谷的底部向北西侵位。岩墙群的流动构造和磁组构的统计成果夯实了华北克拉通古元古代末基性岩墙群与熊耳中条拗拉谷的成生联系。 相似文献
128.
Gold geochemical provinces in China were delineated through stream sediment or catchment sediment sampling in this study. Each gold geochemical province delineated by a threshold value of 2.5 ng/g covers an area of thousands of kilometers. It is a dilemma that geochemists traditionally thought that gold could not migrate for a long distance in rivers or streams to form a large-scale geochemical anomaly due to its chemical inertness and high specific density. The quantitative spectroscopic analysis and observations under a scanning electron microscope(SEM) indicate the presence of submicroscopic gold particles(5 μm in diameter) in large quantities, and observations under a Transmission Electron Microscopy(TEM) further suggest the presence of nanoscale gold particles(several tens of nanometre in diameter) in ores, rocks, soils and stream sediments. Particularly, submicroscopic and nanoscale gold particles less than 5 μm were only found in samples having a low gold content(10ng/g). This result shows that geochemical provinces, delineated by a threshold value of 2.5 ng/g, are formed by long-distance transport of ultrafine gold in streams. The findings may provide direct microscopic evidence for gold migration to form geochemical provinces. 相似文献
129.
The research achievements of geogas prospecting through the mechanisms of geogas prospecting and its applied research in the area of concealed uranium deposits prospecting were analyzed. Geogas prospecting is a new means of deeply concealed deposits exploration that started to develop gradually from the 1980s and is at an initial stage of research in concealed uranium deposits exploration. Furthermore, comments and suggestions were provided for following research work by summarizing the shortcomings and problems of current studies in this paper. A general upward micro-flow of geogas could carry the metal nanoparticles associated with ore body underground to the surface of earth to come into being anomaly halos of elements contents above the ore body, and with these anomaly halos, the relevant information of deeply concealed uranium deposits (or other classes of metal ore bodies) would be reflected. The depth that geogas measurement could achieve for prospecting concealed deposits under the covering layers is up to a thousand meter. Geogas prospecting can be used for investigating in small scales, surveying generally and in detail in big scales and locating the ore bodies. At the present stage, there are three primary under-mentioned problems in the studies of geogas prospecting: ①On the one hand, the researches of how mediums (covering layer) would affect the migration process of geogas are far from enough. On the other hand, appropriate mathematical theory models have not been set up yet. ②In China, there are currently few accurate and practical physical models for geogas prospecting to carry out controllable and repetitive series experiments as well as theoretical studies. It is essential that an appropriate physical model should be established timely in order to provide an experimental platform and a kind of technical assistance for the mechanism study of geogas prospecting. ③To achieve the aim of popularizing the geogas prospecting in the uranium exploration area, the research of trapping solution and sampling and measuring methods should be further developed and the methods of rapid geogas in-site measuring which are suitable for various geologic structures of uranium deposits should be made reasonably to cater to the need of rapid and accurate field measurement. 相似文献
130.
中国大陆显生宙俯冲型、碰撞型和复合型片麻岩穹窿(群) 总被引:6,自引:2,他引:6
片麻岩穹窿(gneiss dome)是中下地壳热动力学过程产生的、与岩浆作用(或混合岩化作用)密切相关的穹窿状构造。片麻岩穹窿大部分是地壳深层次变动的产物,在世界范围内几乎出露在所有的折返造山带中,反映了所在地区地壳的大幅度抬升。片麻岩穹窿核部主要是无或弱岩浆组构的花岗岩体和高级变质岩(例如混合岩),边部是具有岩浆组构的花岗片麻岩,幔部由来自地壳深部的高级片岩和片麻岩组成。片麻岩穹窿的形成经历从垂直上升的地壳流导致的岩浆上涌的挤压收缩机制到岩浆体侵位的顶部伸展机制的转化过程。根据片麻岩穹窿的岩石组合、组构特征、成因机制和大地构造背景以及片麻岩穹窿与地壳流关系的分析,结合中国大陆典型片麻岩穹窿的研究,提出中国大陆显生宙的片麻岩穹窿和片麻岩穹窿群可以划分为与大洋岩石圈板片俯冲增生与随后的折返造山相关的"俯冲型"片麻岩穹窿(群),如秦岭片麻岩穹窿;与陆陆碰撞折返造山有关的"碰撞型"片麻岩穹窿(群),如北喜马拉雅拉轨岗日片麻岩穹窿(群)和松潘甘孜雅江片麻岩穹窿(群);与俯冲和碰撞的叠合作用有关的"复合式"片麻岩穹窿(群),如帕米尔空喀山片麻岩穹窿和东冈底斯林芝片麻岩穹窿(群)。 相似文献