Unstable kinetic Alfvén wave in partially ionized plasma

The stability of kinetic Alfven waves is discussed for a partially ionized plasma with a flux of ionizing electrons which balance the plasma particle losses. Accidental electromagnetic perturbations are shown to be unstable due to the energy change of ionizing electrons.     

Palaeosurfaces and major valleys in the area of the Kjǿlen Mountains,southern Norway - consequences of uplift and climatic change

Protected area management in Norway is undergoing institutional changes with the implementation of management models aimed at increased public participation. At the same time tourism enterprises are increasing in number within the protected areas. Greater levels of interaction with stakeholders place new demands on lead institutions in terms of communication, transparency, involvement, and power sharing. A governance perspective was used to examine some facets of the interaction between a local council managing a national park in Norway and tourism companies using the park for their operations. The main objective was to assess how the tourism sector perceives the cooperation and interface with the management institution. Semi-structured interviews were used, together with a framework of United Nations Development Programme principles of good governance: legitimacy and voice, direction, performance, accountability, and fairness. The results showed rather negative evaluations by the tourism sector, and operators expressed views, implying that the current management model fails to achieve most of the principles of good governance. Although based on a one-sided view by one group of stakeholders, the study suggests that lack of access to important processes and decisions, perceived bias towards traditional conservation, neglect of cultural heritage, and undue restrictions on access could have serious implications for developing an effective management model.     

Has the Problem of a Permanent El Nio been Resolved for the Mid-Pliocene?

The mid-Pliocene, the most recent warm geological period, is thought to be indicative of the fate of the Earth's climate under global warming. Earlier evidence has suggested that permanent El Nio-like conditions existed in the mid-Pliocene, though the concept of a permanent El Nio remains controversial. Here, the authors analyzed Nio 3.4 SST in pre-industrial and mid-Pliocene simulations with the low-resolution version of the Norwegian Earth System Model (NorESM-L). The simulated mid-Pliocene Nio3.4 SST, with a smaller standard deviation, indicated that a weaker ENSO existed in the mid-Pliocene relative to the pre-industrial experiment. Compared with earlier modeling studies, our simulations show that the problem of ENSO's standard deviations in the mid-Pliocene remains unresolved, although the mean and the period of ENSO in the mid-Pliocene have been resolved by earlier geological and modeling studies.     

京津冀地区霾成因机制研究进展与展望

为满足当前对京津冀地区霾研究和控制的迫切要求,本文梳理了近年来京津冀地区霾的长期变化特征、天气学特征、污染物来源等相关研究成果,发现:从2000年以后,京津冀地区的霾日数呈现出了下降趋势;北京细颗粒物(PM2.5)质量浓度也在总体上呈现下降的趋势,但2013年年均质量浓度仍高达89.5μg m–3,约为我国空气质量标准的3倍(35μg m–3),京津冀空气污染的形势依然严峻;近年来京津冀地区的霾污染事件频发可以归因为不利天气条件与大量污染物人为排放的共同作用;大量的研究表明,区域输送对京津冀地区霾事件的形成和维持有不可忽视的影响;京津冀地区的大气污染不再局限于一时一地,针对重污染天气的预警以及应急控制应该以区域预报为基础实现区域联动;京津冀地区独特的地理环境条件加上城市群的快速发展,形成的局地大气环流也会对局地的污染过程产生重大的影响;大气边界层内气象要素的变化对重污染发生具有显著贡献。京津冀地区的污染控制需要城市群的联动应对治理。     

Composition and origin of the Çaldağ oxide nickel laterite,W. Turkey

The Çalda? nickel laterite deposit located in the Aegean region of W. Turkey contains a reserve of 33 million tons of Ni ore with an average grade of 1.14% Ni. The deposit is developed on an ophiolitic serpentinite body which was obducted onto Triassic dolomites in the Late Cretaceous. The deposit weathering profile is both laterally and vertically variable. A limonite zone, which is the main ore horizon, is located at the base of the profile. A hematite horizon is located above the limonite, which in the south of the deposit is capped by Eocene freshwater limestones and in the north by a siliceous horizon. The deposit is unusual in lacking a significant saprolite zone with little development of Ni-silicates. The boundary between the limonite zone and serpentinite below is sharp with a marked decrease in concentrations of MgO from 13 to 1 wt.% over a distance of 2 mm representing the ‘Mg discontinuity’. Ni concentrations within goethite, the main ore mineral, reach a maximum of ~3 wt.% near the base of the limonite zone. Silica concentrations are high throughout most of the laterite with up to 80 wt.% silica in the upper portion of some profiles. The combination of a serpentinite protolith and a high water table at Çalda?, in association with an aggressive weathering environment in a tropical climate, resulted in the formation of an oxide-dominated deposit. The precipitation of silica may coincide with a change in climate with silica precipitation linked to an increase in seasonality. Additional variations within profile morphology are attributed to transportation during and after laterite development as a result of faulting, pocket type laterite formation and slumping, each of which produces a contrasting set of textural and geochemical features.     

Chromium speciation in oxide-type compounds: application to minerals,gems, aqueous solutions and silicate glasses

Cr K-edge XANES spectra were obtained for a variety of Cr-bearing model compounds containing Cr(II), Cr(III), Cr(IV), Cr(V) and Cr(VI), in which the Cr-site symmetry is D4h, Oh and Td. The centroid position of the pre-edge feature is a better indicator of the Cr valence than the edge position. In Cr-rich oxides, higher-energy transitions must be excluded in order to refine a robust valence for Cr. The pre-edge for chromates is not unique and varies as a function of the CrO₄ ^2? moiety distortion, which is often related to Cr-polymerization (monochromate vs. dichromate). Both the analogy with the Mn K-pre-edge information and ab initio FEFF calculations of the pre-edge feature for Cr(III) and Cr(VI) confirm the experimental trends. This methodology is applied to the Cr K-edge pre-edge feature collected in gems (emerald, spinel and ruby), the layered minerals fuchsite and kämmererite, two Cr-bearing aqueous solutions and a set of sodo-calcic silicate glasses used for bottling sparkling white wine. In emerald and fuchsite, the Cr-site is differently distorted than its ruby or spinel counterpart. In a Cr(III)-bearing aqueous solution and sodo-calcic glass, no evidence for Cr(III) with Td and C3v symmetry is detected. However, minor amounts of chromate moieties (most likely monomeric) are detected in a glass synthesized in air. Preliminary spectra for the wine bottle glass suggest that only trace amounts of chromates might possibly be present in these glasses.     

塔中地区志留系碎屑锆石测年及其地质意义

志留系是塔里木盆地第一套砂岩储层广泛分布的沉积盖层,其沉积来源与成因对志留纪构造演化及周边造山带的研究具有重要意义。塔中地区3个志留系样品的碎屑锆石LA?ICP?MS U?Pb定年研究表明,志留系具有比较集中的二期物源年龄：南华纪中期、古元古代中期。碎屑锆石测定的年龄表明塔中志留系物源均来自前寒武纪,塔中东部源区方向的塔南隆起基底在奥陶纪已隆升成为蚀源区。大量的新元古代中期锆石年龄表明塔里木板块在新元古代时期可能与Rodinia超大陆具有相似的聚合与裂解演化史。     

潍北-莱州湾凹陷郯庐断裂带新生代走滑特征

横切潍北-莱州湾凹陷郯庐断裂带的地震反射剖面和断裂带内的凹陷断层、沉积相和油气特征,直接或间接显示了郯庐断裂带的延伸、运动性质和活动时限。郯庐断裂带在海域和陆上的几何形态及其组合基本一致,根据切过断裂带的剖面和平面上断层的组合特征,判断其为兼具垂直位移的走滑运动断层系。走滑断裂带的活动控制着凹陷内同构造沉积以及构造样式,表明郯庐断裂带的活动时限具分段性,相当于渤海湾盆地孔店组(E1?2k)-沙四段(E2?3s4)沉积期(古新世-早始新世)-孔店组-沙二段(E2?3s2)沉积期(古新世-始新世)-孔店组-沙一段(E2?3s1)(古新世-渐新世)沉积时期,走滑拉分活动由南向北迁移; 活动方式也由古新世-早始新世的左旋走滑活动,被早始新世之后的右旋走滑活动所替代。     

从多系统年代学(Multi-System Geochronology)透视云开地块古生代-中生代的构造演化

云开地块位于华南板块南缘,经历了麻粒岩-高角闪岩相的高级变质作用,是华南地区为数不多的高级变质地体。研究表明,云开地块在古生代到中生代经历了复杂的构造演化过程,分别记录了早古生代末期、早中生代、晚中生代早期和晚中生代晚期的构造影响。这些构造事件在多系统年代学图上具有很好的表现,系统地揭示了云开地块的地质演化历史。     

Brittle Rock Failure in the Steg Lateral Adit of the Lötschberg Base Tunnel

Summary  During the crossing of brittle rock formations at the L?tschberg base tunnel, failure phenomena have been observed both at the tunnel face and at the walls. A detailed analysis has been undertaken to explain these behaviours, based on the recent developments of Canadian research on brittle failure mechanisms. At the tunnel walls, a very good agreement is found between the calculated and observed damage and between two prediction methods, i.e. a semi-empirical failure criterion and elastic calculations with the “brittle Hoek-Brown parameters.” Near the face, due to the 3D nature of the stress conditions, some limitations of these approaches have been highlighted, and the growth of wall failure has been analysed. This research allowed a better understanding of the brittle rock mass behaviour at the L?tschberg base tunnel and showed that brittle failure processes dominate the behaviour of deep, highly stressed excavations in massive to moderately jointed rock. It also illustrates where improvements to the adopted approaches are required.