Pahoehoe–a′a transitions in the lava flow fields of the western Deccan Traps,India-implications for emplacement dynamics,flood basalt architecture and volcanic stratigraphy

Unlike pahoehoe, documentation of true a′a lavas from a modern volcanological perspective is a relatively recent phenomenon in the Deccan Trap (e.g. Brown et al., 2011, Bull. Volcanol. 73(6): 737–752) as most lava flows previously considered to be a′a (e.g. GSI, 1998) have been shown to be transitional (e.g. Rajarao et al., 1978, Geol. Soc. India Mem. 43: 401–414; Duraiswami et al., 2008 J. Volcanol. Geothermal. Res. 177: 822–836). In this paper we demonstrate the co-existence of autobrecciation products such as slabby pahoehoe, rubbly pahoehoe and a′a in scattered outcrops within the dominantly pahoehoe flow fields. Although volumetrically low in number, the pattern of occurrence of the brecciating lobes alongside intact ones suggests that these might have formed in individual lobes along marginal branches and terminal parts of compound flow fields. Complete transitions from typical pahoehoe to ‘a′a lava flow morphologies are seen on length scales of 100–1000 m within road and sea-cliff sections near Uruli and Rajpuri. We consider the complex interplay between local increase in the lava supply rates due to storage or temporary stoppage, local increase in paleo-slope, rapid cooling and localized increase in the strain rates especially in the middle and terminal parts of the compound flow field responsible for the transitional morphologies. Such transitions are seen in the Thakurwadi-, Bushe- and Poladpur Formation in the western Deccan Traps. These are similar to pahoehoe–a′a transitions seen in Cenozoic long lava flows (Undara ∼160 km, Toomba ∼120 km, Kinrara ∼55 km) from north Queensland, Australia and Recent (1859) eruption of Mauna Loa, Hawaii (a′a lava flow ∼51 km) suggesting that flow fields with transitional tendencies cannot travel great lengths despite strong channelisation. If these observations are true, then it arguably limits long distance flow of Deccan Traps lavas to Rajahmundry suggesting polycentric eruptions at ∼65 Ma in Peninsular India.     

冲积性河流河床冲淤调整对洪水泥沙过程的响应——以黄河游荡型河段为例

为研究冲积性河流造床机理,基于能量耗散原理分析河床调整与水沙过程（变异特性）间的关系十分必要。以黄河游荡型河段为例,利用实测资料分析和平面二维水沙数值模拟方法,进行了各种洪水泥沙条件下河流冲淤规律的探讨。研究发现平滩面积、河相系数与径流泥沙特征值间存在的关联性映射出冲积性河流能量关系中的制约机制;不同洪水泥沙过程的河床冲刷强度变化具有阶段性,主槽累积刷槽效应与洪水泥沙过程有密切响应关系;高效输沙的洪水过程通过塑造最适宜的河床断面形态,能实现最佳输沙效率与主槽的最大冲刷。在不同漫滩洪水条件中,综合系数Φ最大时的洪水过程具有最大累积刷槽效应,因此对应流量可作为黄河下游漫滩洪水的调控指标。     

Terminal Pleistocene change in mammal communities in southeastern Washington State,USA

Small mammal communities in western North America experienced declines in taxonomic richness across the late Pleistocene to Holocene transition (PHT), a recent natural global warming event. One community also experienced a decline in evenness and others replaced one species with a congener. Variability in response of small mammal communities to PHT warming is apparent. At the presently arid and xeric Marmes site in the Columbia Basin of southeastern Washington State, megafauna were absent by about 13,000 cal yr BP, evenness of small mammals declined about 11,700 cal yr BP and again about 11,400 cal yr BP whereas richness declined about 11,400 cal BP. Regional faunal turnover was, however, minimal among small-bodied taxa. Local mammal communities are depauperate as a result of megafaunal extinctions and subsequent decreases in small-mammal richness and evenness. The latter chronologically corresponds with a decrease in primary productivity driven by increasing warmth and aridity. More faunas must be studied in order to fully document the range of variability in the responses of mammalian communities to PHT warming. Documentation of patterns in those responses will facilitate understanding and enhance predictive accuracy with respect to responses of mammalian communities to modern global warming.     

大陆坡脚确定原则与方法

大陆坡脚是大陆边缘的一个重要地形特征,是沿海国扩展其大陆架权利和划定其200海里以外大陆架外部界限的基础,也是大陆架界限委员会审议沿海国划界案时特别关注的重要技术参数。《联合国海洋法公约》第76条大陆架制度的制定源于典型的被动大陆边缘。但由于全球大陆边缘的多样性和复杂性,特别是后期构造活动、沉积作用对大陆边缘的改造与影响,海底地形地貌异常复杂多变,导致大陆坡脚的识别非常困难。加上各沿海国为获得最大范围的外大陆架,对大陆坡脚的相关规定进行有利于自己的解释,使得大陆坡脚的确定成了外大陆架划界中一个颇具争议的热点问题。本文基于对《联合国海洋法公约》和《大陆架界限委员会科学和技术准则》对大陆坡脚的规定,结合不同类型大陆边缘的地质特征和各沿海国划界实践,对陆坡基部区的确定、坡度变化最大之点的选取以及相反证明规则的适用性等问题进行了探讨。     

面向乡村振兴的农村居民点用地结构转型研究

农村居民点作为乡村地域功能的空间反映,其内部用地功能结构随着经济社会发展发生剧烈变动,“转型”正成为当前中国农村居民点用地结构发展的主要特征。本文以乡村振兴战略需求为切入点,在阐明农村居民点用地结构转型内涵的基础上,依据“过程-类型-机制-优化”的研究思路系统剖析农村居民点用地结构转型规律,将农村居民点用地结构转型研究与乡村振兴战略需求相结合。研究认为,基于农村居民点内部典型地类间组合关系的演变过程,其转型可划分为外向非农化、内生乡村化和空心衰败化三种类型。城镇化、乡村工业化和以乡村振兴战略为主的农业农村现代化通过改变城乡间人口、土地、资本和技术等要素流动和资源配置效率进而影响着居民点转型的方向和结果;同时,合理、有序的农村居民点用地结构也可为乡村振兴的具体实施提供空间基础。未来应以乡村振兴战略需求为导向,从类型转换、效率提升和制度保障等角度优化居民点用地结构转型,以期在理论上创新和完善农村居民点用地转型与优化的研究范式,实践上为村庄规划和乡村振兴提供科技支撑。     

欧洲经济地理学区域创新政策研究进展

区域创新政策对创新驱动增长和经济结构转型升级至关重要。20世纪90年代以来,基于对新古典主义经济学“空间中性”的创新政策的反思,欧洲经济地理学提出“基于空间”的区域创新政策,至今已被欧盟委员会和经济合作与发展组织等组织所采用。本文对这一时期欧洲经济地理学区域创新政策的发展背景、主要任务、理论基础和政策建议等方面进行梳理,研究发现：第一,欧洲经济地理学区域创新政策的主流框架有3个,分别是区域创新系统、精明专业化和可持续转型地理理论;第二,3个框架各有侧重,区域创新系统侧重解决系统失灵问题,精明专业化聚焦优先发展领域的选择问题,可持续转型地理理论则强调转型失灵问题;第三,针对上述问题,3个框架均给出“基于空间”的区域创新政策建议,其中,区域创新系统和精明专业化是基于区域资源禀赋差异的视角,可持续转型地理理论则从技术的空间粘性角度出发。最后,提出中国经济地理学未来区域创新政策研究的几个重点研究方向。     

Energy globalization of China: Trade,investment, and embedded energy flows

Journal of Geographical Sciences - China is in a critical period of transforming from the oil and gas era to the renewable energy era. To better understand the process of energy interaction between...     

The case for Japanese—Russian joint implementation in implementing the Kyoto Protocol

The Doha Amendment allows surplus Assigned Amount Units (AAUs) to be carried over from the first commitment period, but limits their use for offsetting emission growth beyond commitment levels. Amendment 7ter simultaneously ‘shaves’ AAU allocation to a level equivalent to the average 2008–2010 emissions for countries that pledged a growth target under the second commitment period of the Kyoto Protocol. This means that economies in transition (EITs) are not allocated headroom for growth, and makes their commitments starkly different from their original pledges. The ‘bubble’ arrangement within the EU adds uncertainty to whether new Member States will avoid the ‘shaving’ of 7ter due to their pooled target. This would put Annex I EITs into an unequal position as a result of the Doha Amendment.     

Low-carbon societies: a challenging transition for an attractive future

The Low-Carbon Society (LCS) research project (Strachan et al., 2008a) is examined for its insights about the scale, nature and timing of the deployment of low-carbon technologies. In addition to ‘carbon price only’ policies, other incentives and demand-side efforts are needed in order to embed climate policies into broader development approaches. The question of what constitutes transition pathways is considered. Fundamental institutional, individual and social changes are needed to accompany economic and technological change as energy is embedded in overall development patterns. The cost assessment of decarbonization policies may be too optimistic if it is only considered as the final outcome of a LCS, and if the inevitable hindrances and setbacks along the transition pathway are disregarded. The significance of transition costs is highlighted, together with their causes: social and short- and medium-term economic costs and adjustments in macroeconomic dynamics. Although the overall welfare costs of LCS are likely to be smaller than the benefits (including the co-benefits), a clear and realistic understanding of potential transition difficulties is necessary in order to define the robust policy mix needed to underpin it.     

高原季节转换时期大气环流变化特征

利用1961～ 2007年NCEP/NCAR的再分析逐日资料,分析高原主体上空大气环流的季节变化和受到高原影响的东亚大型环流系统的季节变化,以此证明本文得到的“高原普适性划分方法”的合理性.得到的初步结论概括如下：高原主体上空的位势高度、风场、高空温度、降水的季节变化和高原普适性季节划分方法划分的高原四季变化一致,高原南亚高压、副热带高压、副热带西风急流的三个特征指数季节变化和高原普适性季节划分方法划分的高原四季变化一致,这些结论都说明高原普适性季节划分方法划分的高原四季是合理的;风场季节率（500hPa、100hPa）显著区随高度升高向赤道靠近,风场季节率的变化主要和东亚季风的变化有关,大气环流系统季节率的显著说明了大气环流的季节变化,同时也证明了高原普适性季节划分方法的合理性.