始新世—渐新世气候转变研究进展

始新世—渐新世（E—O）气候转变（34 Ma前后）是新生代气候演化过程中最显著的变冷事件之一,标志着地球气候由“温室”进入“冰室”。这一转变伴随着地球环境的一系列重大变化,对于研究新生代气候变冷的驱动机制、区域气候对全球重大气候事件的响应方式、重大气候事件对生态环境及生物演替的影响等具有重要意义。近年来地质记录和气候模拟在E—O转变研究上取得了一系列重要进展：①不同纬度区的地质记录揭示出这一转变伴随着全球性的显著降温,指示其触发因素是全球性的;②气候模拟研究揭示出大气CO2浓度降低及与之联系的全球碳循环变化是导致这一转变的主因,否定了传统认为的环南极流形成导致E—O气候变冷的假说;③深海沉积记录揭示出这一转变过程持续400～500 ka,表现为全球降温和南极冰盖形成先后两阶段变化;④海—陆气候记录的对比初步揭示出陆地区域的干旱化可能主要与全球降温（对应于E—O转变的第一阶段）相关。当前对E—O气候转变的研究还存在地质记录分辨率不够高、模拟结果与地质记录不完全吻合、陆地记录相对较少等方面的不足。更精确的大气CO2浓度和温度的重建、更多高分辨率海—陆气候记录的研究以及古气候数值模拟的改进有望进一步揭示出E—O转变过程中气候系统各要素的变化特征和相互关系,为更深入认识这一转变的驱动机制提供依据。     

Tectono-sedimentary evolution of the External Liguride units (Northern Apennines,Italy): insights in the pre-collisional history of a fossil ocean-continent transition zone

Abstract

In the Northern Apennines, the External Liguride (EL) units are interpreted as derived from the domain that joined the Ligure–Piemontese oceanic basin to the Adriatic plate continental margin. The EL units can be divided into two different groups according to the lithostratigraphic features of the basal complexes underlying the Upper Cretaceous–Lower Tertiary carbonate flysch (e.g. Helminthoid flysch). The first group includes the western successions characterized by Santonian–Campanian sedimentary melanges where slide blocks of lherzolitic mantle, gabbros, basalts, granulites, continental granitoids are represented. The second group is represented by the eastern successions where the Cenomanian–Campanian basal complexes mainly consist of sandstones and conglomerates where the mafic and ultramafic rocks are scarce or completely lacking. Their original substrate is represented by the Middle Triassic to Lower Cretaceous, mainly platform carbonate deposits, found as slices at the base of the eastern successions.

The stratigraphic features shown by the basal complexes allow the reconstruction of their source area that is assumed to be also representative for the pre-Upper Cretaceous setting. The proposed reconstruction suggests the occurrence in the EL domain of two distinct domains. The eastern domain was characterized by a thinned and faulted continental crust belonging to the Adriatic continental margin. The western domain was instead floored by subcontinental mantle associated with lower and upper continental crust, representing the ocean–continent transition. This setting is interpreted as the result of the opening of the Ligure–Piemontese oceanic basin by passive rifting, mainly developed by simple shear, asymmetric extension of the continental crust. © 2001 Éditions scientifiques et médicales Elsevier SAS     

断层带流体对断层强度和强震孕育的影响

大量研究表明,流体在断层弱化中起着非常重要的作用.在地壳浅部脆性域,自由水通过流体孔隙压力减小断层有效正压力,从而降低断层摩擦强度;在地壳深部,矿物中的微量结构水弱化岩石流变强度.另外,流体-岩石相互作用等化学过程,如长石水解反应,对断层强度的影响也非常显著.断层深部流体通过物理作用与化学作用影响着岩石的变形机制,从而影响断层力学性质与地震孕育和发生.断层内部流体孔隙压力周期性变化是断层带脆-塑性转化、裂缝张开与愈合等的直接体现,这种变化控制着断层强度与强震周期性发生现象.     

Spatial microsimulation modeling for residential energy demand of England in an uncertain future

High quality infrastructure is crucial to economic success and the sustainability of society. Infrastructures for services, such as transport, energy, and water supply, also have long lead times, and therefore require effective long-term planning. In this paper, we report on work undertaken as part of the UK Infrastructure Transitions Research Consortium to construct long-term models of demographic change which can help to inform infrastructure planning for transport, energy, and water as well as IT and waste. A set of demographic microsimulation models (MSM), which are spatially disaggregate to the geography of UK Local Authorities, provides a high level of detail for understanding the drivers of changing patterns of demand. However, although robust forecasting models are required to support projections based on the notion of ‘predict-and-provide,’ the potential for behavioral adaptation is also an important consideration in this context. In this paper, we therefore establish a framework for linkage of a MSM of household composition, with behavior relating to the consumption of energy. We will investigate variations in household energy consumption within and between different household groups. An appropriate range of household types will be defined through the application of decision trees to consumption data from a detailed survey produced by the UK Department of Energy and Climate Change. From this, analysis conclusions will be drawn about the impact of changing demographics at both household and individual level, and about the potential effect of behavioral adjustments for different household groups.     

灰色马尔可夫理论在地震预测方面的研究

以陕南地区汶川地震余震资料数据为实例,提出灰色马尔可夫模型对地震进行预测.利用传统的GM(1,1)模型对数据进行拟合和初步预测,运用马尔可夫模型的状态区间和状态转移矩阵对初步预测值进行修正,并对下一组地震数据进行预测.结果表明,模型预测精度高,预测值与实际值接近,可以作为今后地震预报的辅助手段.     

“Forever Hmong”: Ethnic Minority Livelihoods and Agrarian Transition in Upland Northern Vietnam

This article examines how ethnic minority Hmong farmers have adapted to, circumnavigated, or resisted state-sponsored agrarian change and other interventions in the northern Vietnam uplands over the past twenty years. Based on longitudinal research with Hmong informants, I examine to what extent their livelihood strategies have led to wealth creation or differentiation. The article highlights the most important transformations, as farmers conceive and voice them, to Hmong agrarian livelihoods over this period, the importance of longitudinal fieldwork to help unravel endogenous wealth definitions, and the complex impacts of state interventions on ethnic minority ways of making a living.     

Distance Decay Values And Shopping Center Size

The question of what lies ahead is of particular concern for Latin Americanists. The last decade has witnessed a serious erosion of both the popularity of their specialty, and an equally troublesome reduction in employment opportunities. This paper uses Association of American Geographers (AAG) data bases to document the age-gender structure of contemporary Latin Americanist geographers, and projects likely compositional changes through the end of the century.     

Spatiotemporal index for analyzing controls on snow climatology: application in the Colorado Front Range

Mountain snowpacks are important water supplies that are susceptible to climate change, yet snow measurements are sparse relative to snowpack heterogeneity. We used remote sensing to derive a spatiotemporal index of snow climatology that reveals patterns in snow accumulation, persistence, and ablation. Then we examined how this index relates to climate, terrain, and vegetation. Analyses were based on Moderate Resolution Imaging Spectroradiometer eight-day snow cover from 2000 to 2010 for a mountain watershed in the Colorado Front Range, USA. The Snow Cover Index (SCI) was calculated as the fraction of years that were snow covered for each pixel. The proportion of SCI variability explained by independent variables was evaluated using regression analysis. Independent variables included elevation, northing, easting, slope, aspect, northness, solar radiation, precipitation, temperature, and vegetation cover. Elevation was the dominant control on SCI patterns, due to its influence on both temperature and precipitation. Grouping SCI values by elevation, we identified three distinct snow zones in the basin: persistent, transitional, and intermittent. The transitional snow zone represents an area that is sensitive to losing winter snowpack. The SCI can be applied to other basins or regions to identify dominant controls on snow cover patterns and areas sensitive to snow loss.     

转型期社区医疗服务多元供给模式——以广州市天河区为例

以广州市统计局提供的第六次人口普查数据作为人口统计数据源,以天河区卫生局提供的社区医疗机构数据作为社区医疗服务研究数据源,以广州市天河区作为研究案例,总结出社区医疗服务存在政府供给、单位制供给、集体经济供给、社会力量供给4种模式。各供给模式均具有受卫生局领导、政府部门监管和作为城市医疗体系的基础等一系列共性,同时在供给主体、服务对象、筹资与财务管理和人事管理等方面存在差异性,形成相互补充的多元模式共存体系,社区医疗服务的准公共物品属性、社会经济体制转型与城乡二元体制、居民的多元化需求和不同供给主体的利益诉求综合作用是多元模式共存的机制。只有充分利用多元模式供给主体、全方位协调机制要素、进行合理的制度设计,才能更好地促进社区医疗服务均等化,同时为其他城市公共服务供给提供参考借鉴。