Assessing the vulnerability of social–environmental system from the perspective of hazard,sensitivity, and resilience: a case study of Beijing,China

Despite a recent increase in the number of vulnerability analyses there has been relatively little discussion of vulnerability assessment of social–environment system, especially when they face multiple hazards. In this study, we developed an applicable and convenient method to assess vulnerability of social–environment system at a regional scale. Vulnerability is quantified by measuring three critical elements (i.e. hazards, sensitivity, and resilience) through some key variables. The results showed that vulnerability is high in Miaofeng Mountain in Mengtougou District, the hills of Pinggu County and the riparian zones of the lower courses of the Beiyun and Yongding Rivers; but low in the city of Beijing and the southwestern part of the Fangshan District. Areas of very high, high, medium, and low-vulnerability account for 6.19, 25.48, 33.06, and 35.27% of the total area, respectively. The degree of vulnerability decreases in a northwest direction in mountainous areas and declines from watercourses to riparian zones along a lateral direction in the plain. Some adaptive strategies are also proposed.     

Paleozoic granitoid magmatism of the eastern part of the Central Asian Fold Belt and formation of large ore deposits

Evidence on the Paleozoic granitoids of the eastern part of the Central Asian Fold Belt (CAFB) was analyzed. A tectonic chart of orogenic belts was compiled. Sketch maps were constructed for the geodynamic settings of the formation of Paleozoic granitoids and the extensiveness of their occurrence. Two types of deep controlling structures were distinguished: zones of lithospheric faults and plumes, including the newly recognized Jiamusi-Bureya plume. It was sown that the distribution of large and superlarge Paleozoic ore deposits is related to these structures, primarily to plumes. Sites promising for large and superlarge deposits related to the Paleozoic granitoid magmatism were determined in the Russian Far East.     

三维地震资料波阻抗反演技术及其应用

利用高纵向分辨率的测井资料与连续观测的地震资料进行波阻抗反演,可以大大提高三维地震资料对地下地质情况的研究程度。以山西常村矿为例,介绍了波阻抗反演在目的层位追踪、薄层辨别、断点断距的确定、陷落柱的解释以及冲刷无煤带的圈定等方面的应用。实例表明波阻抗反演地震剖面比常规地震剖面具有明显的优势,特别是在薄层的分辨率能力上,波阻抗反演表现的尤为突出,如在该区波阻抗反演剖面上,不仅能够分辨15#煤层的三个分层,同时对6#、9#、12#薄煤层也有清晰的反映。     

The Paleo－Environmental Significance of Sr and Ca Contained in Acid－Soluble Fraction of Plateau Loess Deposits in Xining Basin

The Xining Basin,located on northeastern Qinghai-Xizang Plateau,is adjacent to the Qaidam Bsim and Gobi-desert.Therefore,thick,integrated deposits of loess or paleo-sol sequence were well developed.As is well known,there is much paleo-environmental information recorded in loess and plaeo-sol.So if we deal with paleo-environmental index from different an gles ,especially from loess geochemistry,some important and detailed paleo-environmental evolutional information will be acquired.Based on this,the authors determined the contents of Sr and Ca contained in acid-soluble fraction from the bottom to the top of the Panzishan section.This section was obtained through making a well about 17 m in depth,including S1 paleo-sol that was developed during the last interglacial period.According to the results,it is found that variations in contents of Sr and Ca are well correlated with conversion of loess and paleo-sol.In loess deposits,the contents of Sr and Ca are higher than those in paleo-sol deposits.It is known that loess was deposited under cold-dry climate conditions and paleo-sol was developed during warm-humid climate episodes.It is concluded that due to their mobile behaviors,under cold-dry climate conditions,Sr and Ca are stagnant during weak weathering,but under warm-humid climate conditions,Sr and Ca are easily leached and transported in aqueous solution.Therefore,they can be utilized as indicatiors of climate changes.Moreover,variations in contents of Sr and Ca are more sensitive than susceptibility.The mobile behaviors of Sr and Ca contained in acid-soluble fraction can serve as a new quantitative index to evaluate paleo-environmental changes on the plateau.     

Zr/Hf ratio as an indicator of fractionation of rare-metal granites by the example of the Kukulbei complex,eastern Transbaikalia

The concept of granitic melt fractionation as the main process in the concentration of rare elements in granites calls for the development of a reliable method to determine the evolutionary sequences of granite series. We propose to use for this purpose a zirconium-hafnium indicator, the Zr/Hf weight ratio in granitic rocks (Zaraisky et al., 1999, 2000). By the example of three classic regions of rare-metal deposits, eastern Transbaikalia, central Kazakhstan, and Erzgebirge (Czech Republic and Germany), it was empirically shown that the Zr/Hf ratio of granites decreases during the fractional crystallization of granite magmas in the sequence granodiorite → biotite granite → leucogranite → lithium-fluorine granite. The reason is the higher affinity of Hf compared with Zr to a granite melt. This implies that the crystallization and settling of accessory zircon will cause the progressive enrichment of Hf relative to Zr in the residual melt. As a result, the Zr/Hf ratio decreases regularly in the series of sequential phases of granite intrusion related to a single magma chamber from granodiorite to biotite granite, leucogranite, and Li-F granite (from 45-30 to 10-2). Our experimental investigations supported the preferential enrichment of haplogranite melt in Hf and zircon crystals in equilibrium with melt in Zr (T= 800°C and P = 1 kbar). The Zr/Hf indicator was tested by the example of the wellknown Kukulbei rare-metal granite complex of eastern Transbaikalia (J3), which is unique in the degree of fractionation of initial granite melt with the formation of three phases of granite emplacement and vein derivatives. An important feature of the complex is its “short” differentiation trend. It was supposed that the granite magma of the first phase is parental, and the later phases forming small intrusive bodies in large massifs of biotite granites of the first phase are sequential products of its crystallization differentiation in a magma chamber. The biotite granites of the first phase are barren. The leucocratic granites of the second phase are accompanied by tin-tungsten greisen deposits (e.g., Spokoininskoe), and the upper part of cupola-like stocks of Li-F amazonite granites of the third phase host apogranite-type tantalum deposits (Orlovka, Etyka, and Achikan). In addition to three granite phases, the Kukulbei complex includes dikes of ongonites, elvans, amazonite granites, and chamber miarolitic pegmatites. All of the granitic rocks of the complex have similar isotopic ages of 142± 0.6 Ma. The Zr/Hf ratio decreases systematically from phase 1 (40–25), to phase 2 (20–10), and phase 3 (10–2). The ongonites, elvans, and pegmatites have similar Zr/Hf ratios (15-5), falling between the ranges of leucocratic muscovite granites and Li-F granites. Compared with other granite series, the granitic rocks of the Kukulbei complex show specific petrographic and geochemical features: they are strongly enriched in Rb, Li, Cs, Be, Sn, W, Mo, Ta, Nb, Bi, and F but depleted in Mg, Ca, Fe, Ti, P, Sr, Ba, V, Co, Ni, Cr, Zr, REE, and Y. From the early to late intrusion phases, the degree of enrichment and depletion in these element groups increases regularly. This is accompanied by a significant decrease (from 40 to 2) in Zr/Hf, which can be used as a reliable indicator of genetic relations, degree of fractionation, and rare-metal potential of granites. Granites with Zr/Hf values lower than 25 are promising for prospecting for Sn, W, Mo, and Be greisen deposits, whereas the formation of Ta deposits requires Zr/Hf values lower than 10.     

安徽月山岩体的锆石SHRIMP U-Pb定年及其意义

月山岩体是长江中下游成矿带中安庆-贵池矿集区内月山矿田中最重要的中酸性侵入岩体.本文对月山岩体主要岩石--闪长岩进行了锆石SHRIMP U-Pb定年,得到年龄值为138.7±0.5Ma,表明岩体形成于早白垩世.该结果与铜陵等地的高钾钙碱性中酸性侵入岩的形成时代类似,但早于月山矿田内的花岗质岩体和庐枞盆地、宁芜盆地中的岩浆岩.在综合区内已有的岩石学、地球化学和成矿年代学资料的基础上,认为月山矿田内的铜金铁成矿作用与月山岩体的形成有着密切的成因联系,二者在时间上是一个连续的过程,皆发生于燕山期,成岩成矿作用过程发生于区域挤压-拉张过渡的构造背景.     

怀柔应急水源地可持续供水与水源涵养研究

怀柔应急水源地自运行以来一直续采至今,由于连续干旱和多年的超设计规模运行,导致区内水文地质条件发生了较大变化,为保证其"应急供水"的能力,具备随时启动供水的功能,结合南水北调水源进京的机遇,从资源回补涵养和供水系统的热备运行两方面开展研究工作。在综合分析区域水文地质条件和研究多年地下水动态变化规律的基础上,利用地下水数值模型对怀柔应急水源地在不同开采条件下的回补方式和效果进行模拟,拟定了南水北调进京后区域水资源人工回补方案及应急水源地的热备运行方案,并模拟预测了水源地热备运行和地下水涵养效果,为怀柔应急水源地可持续供水提供科学依据。分析结果表明:南水北调水源进京后,怀柔应急水源地可采用夏季高峰集中供水与日常保压相结合的"集中开采"方案和日常"稳压开采"方案。     

Isotope evidence for quantifying river evaporation and recharge processes in the lower reaches of the Yellow River

Evaporation and recharge are important hydrological processes in the water cycle. However, accurately quantifying these two processes of river remains to be difficult due to their spatial heterogeneity and the limitations of traditional methods. In this study, a more reliable method of stable isotopes of δ ¹⁸O and δ ²H based on the Rayleigh distillation equation and mass conservation was used to estimate the evaporation and recharge of the rivers in the lower reaches of the Yellow River, North China Plain. Comprehensive sampling campaigns including 30 surface water samples from 10 rivers, 33 groundwater samples from domestic and observation wells, and two Yellow River water samples were conducted. The results showed that the evaporation proportion of the rivers based on δ ¹⁸O and δ ²H both averaged 14.4%. The evaporation proportions in each river did not completely follow a linear increasing trend along the flow path. This phenomenon could be mainly explained by the different proportions of recharge from groundwater and Yellow River water. With closer to the Yellow river, evaporation of the rivers decreased while the recharge by the Yellow River increased. Regression equations based on δ ¹⁸O, δ ²H, and their average revealed that the evaporation proportion respectively increased by 1.02, 0.79, and 0.90% with the increase in the distance to the Yellow River per 10 km. On the contrary, the recharge proportion decreased by 7.68, 5.51, and 6.59%, respectively. In addition, using δ ¹⁸O rather than δ ²H was more reliable in studying the spatial influence of the Yellow River on evaporation and recharge. Sensitivity analysis showed that the evaporation model was most sensitive to isotopic composition, rather than to air temperature or relative humidity. The results of this study provide insights into the determination of river hydrological processes and the management of water resources.     

Heavy metals distribution in agricultural topsoils in urban area

Intensive urbanisation of the Croatian capital of Zagreb has led to a situation where very good agricultural soils, developed mostly on Pleistocene eolian sediments and alluvial and proluvian Holocene sediments are entrapped within urban and suburban areas. Therefore the influence of urban and industrialised environments on the accumulation of metals in agricultural topsoils has been investigated. On an area of 860 km² of the wider Zagreb region, 331 samples were taken according to a regular 1ǵ km square mesh. Samples were dissolved in aqua regia and analysed for Cd, Cu, Fe, Mn, Ni, Pb and Zn with flame atomic aqua regia absorption spectroscopy. The following concentration ranges have been determined: Cd 0.25-3.85 mg kg^-1 (average 0.66 mg kg^-1), Cu 4.30-183 mg kg^-1 (average 20.8 mg kg^-1), Fe 5.8-51.8 g kg^-1 (average 27 g kg^-1), Mn 79.2-1282 mg kg^-1 (average 613 mg kg^-1), Ni 0.70-282 mg kg^-1 (average 49.5 mg kg^-1), Pb 1.50-139 mg kg^-1 (average 25.9 mg kg^-1), and Zn 15.2-277 mg kg^-1 (average 77.9 mg kg^-1). Visualisation of the spatial data is made by the aid of GIS, and selected maps of the heavy metal concentrations in topsoils are displayed. Statistical multivariate analysis was carried out for quantitative study and data were processed by means of R-mode factor analysis, applying the varimax-raw rotational technique. F1, which grouped Cd, Pb, Cu, Zn and partially Ni, is characterized as a factor with strongly scattered anthropogenic influence. The elements in F2, Fe, Mn and partially Ni are mainly of geogenic, i.e. pedogenic, origin. The variations in concentrations of the investigated elements are thus of both natural and anthropogenic origins. The variations in the main soil constituents, particularly Fe and Mn, are determined primarily by the composition of different regolithic substrates of the fluvial origin in recent pedogenesis. High concentrations of nickel are also related to morphogenetic characteristics of the wider region, primarily basic and ultrabasic magmatic rocks of the surrounding mountain range. It is, however, assumed that the anomalous nickel concentrations in the vicinity of the highway and the airport are of anthropogenic origin, i.e. caused by fuel combustion. Copper is characterized by strongly scattered anthropogenic influence, which is related particularly to uncontrolled solid waste disposals or discharges of liquid waste from households or agricultural enterprises. With Zn, Pb and Cd, there are two possible ways of diffuse pollution. The Sava River, which drains the area and feeds the abundant Quaternary aquifer spreading below the major part of the investigated agricultural areas, has been exposed to intensive pollution by mining, industry and cities in the recent history. The part of the area with the highest determined concentrations of Zn, Pb and Cd was repeatedly flooded as recently as the previous decade; therefore, the recent sedimentation of the river deposits exposed to pollution is a very probable cause of the accumulation of metals in this until recently inundation area. The other way is atmospheric deposition of particles from urban sources (industrial emission, traffic, waste disposals, heating plants, etc.). In addition to agricultural enterprises, several economically important, but ecologically risky, facilities are situated in the vicinity of the water-protection area. The area is intersected by a very busy ring road, while a marshalling yard, the city dump, pharmaceutical and chemical industry, the district-heating plant and the airport are all located in close proximity. The geochemical maps show a clear relationship between human activities and metal concentration gradients.     

Stratigraphy and geochemistry of pillow basalts within the ophiolitic mélange of the Izmir–Ankara–Erzincan suture zone: implications for the geotectonic character of the northern branch of Neotethys

The Izmir-Ankara-Erzincan suture zone of Turkey is a broad zone of ophiolitic mélange containing numerous fragmented blocks ranging in age from Triassic to Cretaceous. Stratigraphic sequences for various mélange units are compared, together with the geochemistry of associated basaltic pillow lavas of Cretaceous age. A review of geochemical data for the pillow lavas demonstrate: (a) a dominant group of alkalic basalts with enriched incompatible elements, variable Zr/Y and Zr/Nb ratios, and (b) a range of tholeiitic basalts with slightly depleted to mildly enriched (normalized) rare earth patterns, (La/Yb)_N 0.4-3.0, and generally low Zr/Y ratios. The alkalic basalts can be chemically matched to Pacific Ocean seamounts, although the close association of red radiolarites and cherts suggests that many basalts represent the margins of such structures, rather than the main seamount edifice. Nd-Sr isotope data are typical for ocean island basalts and represent an admixture of a dominant EM-1 source and a depleted MORB-like source. Enhanced δ¹⁸O compositions are a consequence of submarine alteration and not crustal contamination. Tholeiitic compositions have affinities with both N- and E-type MORB, although most are probably representative of tholeiitic ocean islands. Overall the basalts are mainly representative of structures built on the ocean floor, rather than the oceanic crust itself, being scraped off the subducting crust and preserved in the mélange of the accretionary wedge.