苏门答腊岛(印尼)成矿带的岩浆作用和源区及其对比

本文介绍了苏门答腊岛上两个成矿带(即铜-金矿成矿带和锡矿成矿带)的矿产分布,岩浆岩的岩石类型和地球化学特征。根据本研究课题在巴东地区岩石化学资料,本文总结了铜-金矿成矿带含矿母岩的地球化学特征,探讨其岩浆岩成因和源区。同时,将其锡矿成矿带岩浆岩的岩石类型和地球化学-大地构造环境与其相邻地体进行对比。研究结果表明:西苏门答腊地体的铜-金矿成矿带的含矿母岩为SI-型埃达克质花岗岩,形成于活动大陆边缘(ACM)火山弧构造环境,其岩浆物质主要来源于俯冲洋壳板片局部熔融叠加上弱的地幔楔熔融-混染作用(MASH)。而东苏门答腊地体‘锡岛’和"暹缅马苏"地体的锡矿带含矿母岩为过铝质(S-型)花岗岩类,其形成构造环境为碰撞带的弧后盆地和陆内裂谷,物质源区来自地壳重熔和岩浆分异。地球化学资料表明,该两地体具有共同的深部岩浆源区。     

The climate-population nexus in the East African Horn: Emerging degradation trends in rangeland and pastoral livelihood zones

Increasing climate variability and extreme weather conditions along with declining trends in both rainfall and temperature represent major risk factors affecting agricultural production and food security in many regions of the world. The rangelands of Ethiopia, Kenya, and Somalia in the East African Horn remain one of the world's most food insecure regions, yet have substantially increasing human populations predominantly dependent on pastoralist and agro-pastoralist livelihoods. We identify regions where substantial rainfall decrease between two periods interrupted by the 1998 El Nino event (1981–2012) in the East African Horn is coupled with human population density increases. Vegetation in this region is characterized by a variable mosaic of land covers, generally dominated by grasslands necessary for agro-pastoralism, interspersed by woody vegetation. Recent assessments indicate that vegetation degradation is occurring, adversely impacting fragile ecosystems and human livelihoods. Using AVHRR and MODIS vegetation products from 1981 to 2012, we observe changes in vegetation patterns and productivity over the last decade across the East African Horn. We observe vegetation browning trends in areas experiencing reduced main-growing season precipitation; these areas are also concurrently experiencing increasing population pressures. We also found that the drying precipitation patterns only partially statistically explain the vegetation browning trends, indicating that other factors such as population pressures and land use changes might be responsible for the observed declining vegetation condition. Furthermore, we show that the general vegetation browning trends persist even during years with normal rainfall conditions such as 2012, pointing to potential long-term degradation of rangelands on which approximately 10 million people depend. These findings may have implications for current and future regional food security monitoring and forecasting as well as for mitigation and adaptation strategies in a region where population is expected to continue increasing against a backdrop of drying climate trends and increased climatic variability.     

大青山地区金地球化学特征

大青山地区出露地层主要是侏罗系中统兰旗组安山岩、安山质角砾熔岩、凝灰岩等;侵入岩为晚侏罗世二长花岗岩;断裂发育,岩石蚀变强烈。金地球化学特征表明,金主要富集在侏罗系中统兰旗组火山岩中。金的原生晕、次生晕异常特征和分布表明,破碎蚀变岩带就是金矿化蚀变带。通过野外地质调查已在三道盘—马家窝铺的安山岩和二长花岗岩中发现了5条金矿化带和29条金银矿脉。实践证明,在大青山地区进行金矿普查运用地球化学方法是有效的。     

Macrofaunal involvement in the sublittoral decay of kelp debris: the detritivore community and species interactions

The fauna associated with sea-bed accumulations of decomposing Laminaria saccharina has been studied by year-round SCUBA diving at two sites in the Clyde Sea area. Seasonal changes in density of 64 species are reported. In the autumn, large quantities of kelp are detached by storms. This weed carries with it to the sea bed a large part of its normal fauna. Additional species settle onto the weed from the plankton whilst others migrate onto it from the surrounding sea bed. Peak densities of associated species were recorded in autumn. Litter bag experiments in situ showed that, except during the summer, weed is lost from sea-bed accumulations at a faster rate when macrofaunal animals are excluded. The macrofauna therefore inhibits decomposition. The relative importance of interactive cropping by three macrodetritivores, Psammechinus miliaris (Echinodermata), Platynereis dumerilii (Polychaeta) and Gammarus locusta (Amphipoda) was studied by in situ containment of different species combinations. The presence of Gammarus with Psammechinus resulted in less weed being lost than when Psammechinus was isolated. This is because Gammarus selectively crops rotting weed, retarding frond disintegration by microbes. Platynereis retards microbial colonization of frond tissues ruptured during its feeding by repeated cropping of the same region. Weed would decompose very rapidly were it not for macrofaunal cropping. Macroalgal decay thus differs profoundly from that of vascular plants.     

Pyroclastic Flow Hazard at Volcán Citlaltépetl

Volcán Citlaltépetl (Pico de Orizaba) with an elevation of 5,675 m is the highest volcano in North America. Its most recent catastrophic events involved the production of pyroclastic flows that erupted approximately 4,000, 8,500, and 13,000 years ago. The distribution of mapped deposits from these eruptions gives an approximate guide to the extent of products from potential future eruptions. Because the topography of this volcano is constantly changing computer simulations were made on the present topography using three computer algorithms: energy cone, FLOW2D, and FLOW3D. The Heim Coefficient (), used as a code parameter for frictional sliding in all our algorithms, is the ratio of the assumed drop in elevation (H) divided by the lateral extent of the mapped deposits (L). The viscosity parameter for the FLOW2D and FLOW3D codes was adjusted so that the paths of the flows mimicked those inferred from the mapped deposits. We modeled two categories of pyroclastic flows modeled for the level I and level II events. Level I pyroclastic flows correspond to small but more frequent block-and-ash flows that remain on the main cone. Level II flows correspond to more widespread flows from catastrophic eruptions with an approximate 4,000-year repose period. We developed hazard maps from simulations based on a National Imagery and Mapping Agency (NIMA) DTED-1 DEM with a 90 m grid and a vertical accuracy of ±30 m. Because realistic visualization is an important aid to understanding the risks related to volcanic hazards we present the DEM as modeled by FLOW3D. The model shows that the pyroclastic flows extend for much greater distances to the east of the volcano summit where the topographic relief is nearly 4,300 m. This study was used to plot hazard zones for pyroclastic flows in the official hazard map that was published recently.     

植被发育斜坡非饱和带大孔隙

在气候温湿的滑坡灾害易发区,根系通道、动物通道、干裂缝、管道及团聚体间的结构性孔隙等大孔隙普遍存在于斜坡非饱和带中.采用微观观察、化学分析和现场试验方法并结合相关学科的研究成果,分析大孔隙界定、大孔隙类型和主控因素、大孔隙三维空间结构及大孔隙时效稳定.不同测量方法的差异和大孔隙密度时空变异性是目前大孔隙定义缺乏统一性的原因.大孔隙尺寸不能作为唯一标准界定大孔隙,必须考虑其三维几何形态.多因素控制大孔隙的成因和类型,其中根系通道、裂缝和结构性孔隙对优先流有显著贡献.需从三维几何学和拓扑学方面进一步研究大孔隙三维结构.枯枝落叶层是大孔隙抵御环境因素扰动的重要屏障,但大孔隙域与周围基质域水量交换对大孔隙时效稳定是不利的.深入研究以上问题对植被发育斜坡优先流模型的改进和发展是重要的.     

江苏省开发区土地集约利用的分层线性模型实证研究

本文构建了分层线性模型以揭示不同层次因素对工业用地集约利用的影响。研究表明,开发区土地集约度的差异有63.96%是开发区本身的差异造成的,有36.04%是区域之间的差异造成的;开发区成立年限、开发区入驻企业数量和开发区土地政策强度在区域之间存在明显的变异,开发区区位和开发区级别对开发区土地集约度的关系不依赖于区域环境的变化;区域工业产值和区域城市化率两个变量对开发区成立年限和开发区土地集约度的正向关联影响不显著;区域工业产值会强化开发区入驻企业数量和开发区土地集约度之间的正向关联,而区域城市化率则弱化了开发区入驻企业数量和开发区土地集约度之间的正向关联;开发区土地政策强度和开发区土地集约度之间的正向关系受区域工业产值的影响不大,而区域城市化率会强化开发区土地政策强度和开发区土地集约度之间的正向关系;区域层次变量解释了18.18%的开发区入驻企业数量与开发区土地集约度之间的相关,解释了11.27%的开发区土地政策强度与开发区土地集约度之间的相关。     

Outside the boundary - Land use changes in the surroundings of urban nature reserves

The importance of the landscape surrounding a protected area for sustaining its values is frequently discussed in conservation literature. Studies on the interactions of urbanisation and nature conservation at the global scale suggest that protected nature attracts urbanisation, and that this in turn might negatively impact the area. However, studies specifically addressing such land use dynamics at city scale are largely missing. In this study we examine the change in proportion of built up area in two zones (500 m and 1000 m) surrounding 15 urban nature reserves in southern Sweden. By using comprehensive maps from the last 50 years, we compared the zones to the overall urbanisation in the cities to reveal discrepancies in land use surrounding the nature reserves. We found that the amount of built up area in the buffer zones surrounding nature reserves followed the same trend as the corresponding cities and this relation was stable over time, although the positive relationship was not significant. The establishment of nature reserves had no detectable effect on surrounding land use, however two distinguished groups of reserves were identified with either more or less built up area in buffers zones compared to cities. These differences were related to specific local drivers such as land ownership, land use history and nature reserve location. In contrast to earlier studies at global scale, our study did not show that nature reserves attract urbanisation. Instead, we stress that the great variety of contextual factors at the city scale makes quantitative analysis of this kind extremely difficult. However, a general neglect from planning and nature conservation agencies to recognise nature reserves’ dependence on the surrounding landscape configuration could be detrimental to sustain their values in the long-term. Hence we suggest that zones surrounding nature-protected areas should be planned and managed according to local land use history and current landscape conditions to enable and enhance necessary cross-boundary interactions.