Mineralogy and chemical composition of the clay fraction of Neogene shales from the Surma Group in the Bengal basin,Bangladesh

Mineralogical and chemical investigations (<2μm clay separates) of shale samples from the Neogene-age Surma Group obtained from four wells (Habiganj-11, Shahbazpur-1, Titas-11, Titas-15) in the Bengal basin, Bangladesh, were carried out in order to reveal the clay mineral composition as reservoir exploration and exploitation requires a good understanding of the clay minerals. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-Ray fluorescence spectrometry (XRF). Mineralogically, the sub-surface Surma Group shales comprise predominantly quartz, plagioclase, illite, chlorite, kaolinite, with lesser amounts of K-feldspar, dolomite and smectite, and minor to trace amounts of calcite, siderite and pyrite. The chemical composition of the <2 μm clay separates also suggests an illite and chlorite-rich composition. With increasing burial depth, the Surma Group shales are enriched in illite. The gradual decreasing of the smectite clays with depth and ultimate disappearance at greater depths (≥ 3000 m) may have been responsible for the presence of the diagenetic illite. Based on the mineralogical composition it is most likely that the illite-chlorite associations together with quartz and feldspar were predominantly detrital in origin and thus reflect the presence of a rapidly-rising source terrain not subjected to intense weathering.     

Citizens as sensors: the world of volunteered geography

In recent months there has been an explosion of interest in using the Web to create, assemble, and disseminate geographic information provided voluntarily by individuals. Sites such as Wikimapia and OpenStreetMap are empowering citizens to create a global patchwork of geographic information, while Google Earth and other virtual globes are encouraging volunteers to develop interesting applications using their own data. I review this phenomenon, and examine associated issues: what drives people to do this, how accurate are the results, will they threaten individual privacy, and how can they augment more conventional sources? I compare this new phenomenon to more traditional citizen science and the role of the amateur in geographic observation.     

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.     

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.     

Structural improvement of age-hardened gypsum-treated bauxite red mud waste using readily decomposable phyto-organics

Several years (7) after incidental lithification by added gypsum, the effect of crushing and phyto-organics on some physical properties of red mud wastes (RMW) was examined under laboratory conditions. It was hypothesized that mechanically breaking up the hardened masses would increase their permeability. However, on the contrary, crushing these rock-hard masses into <2-mm particles did not increase permeability. A phyto-organic treatment on the other hand greatly improved permeability of the crushed entities such that infiltration rates increased from 0 to 10 cm/h. After 24 weeks of incubation, the structure of the newly formed phyto-organically treated gypsum-hardened RMW aggregates was also substantially improved over that of the controls, as a >3-fold increase in resistance to disintegration during wet sieving was exhibited by the phyto-organically treated samples. The increase in water infiltration by combining crushing with phyto-organic applications was ascribed to a decrease in particle dispersion, creating more stable clay clusters, which in turn stabilized channels and pores. Conversely, it was concluded that the singular crushing of gypsum-hardened bauxite waste in the waste dumps is potentially wasteful and ineffective.     

淮河流域水文随机方法的径流图化(英文)

Theoretical difficulties for mapping and for estimating river regime characteristics in a large-scale basin remain because of the nature of the variable under study: river flows are related to a specific area, i.e. the drainage basin, and are hierarchically organized in space through the river network with upstream-downstream dependencies. Another limitation is there are not enough gauge stations in developing countries. This presentation aims at de-veloping the hydro-stochastic approach for producing choropleth maps of average annual runoff and computing mean discharge along the main river network for a large-scale basin. The approach applied to mean annual runoff is based on geostatistical interpolation proce-dures coupled with water balance and data uncertainty analyses. It is proved by an applica-tion in the upstream at Bengbu in the Huaihe River Basin, a typical large-scale basin in China. Hydro-stochasitic approach in a first step interpolates to a regular grid net and in a second step the grid values are integrated along rivers. The interpolation scheme includes a con-straint to be able to account for the lateral water balance along the rivers. Grid runoff map with 10 km × 10 km resolution and the discharge map along the river with the 1 km basic length unit are the main results in this study. This kind of statistic approach can be widely used be-cause it avoids the complexity of hydrological models and does not depend on the meteoro-logical data.     

Analysis of solar radiation on the surface estimated from GWNU solar radiation model with temporal resolution of satellite cloud fraction

Preliminary analysis with a solar radiation model is generally performed for photovoltaic power generation projects. Therefore, model accuracy is extremely important. The temporal and spatial resolutions used in previous studies of the Korean Peninsula were 1 km × 1 km and 1-h, respectively. However, calculating surface solar radiation at 1-h intervals does not ensure the accuracy of the geographical effects, and this parameter changes owing to atmospheric elements (clouds, aerosol, ozone, etc.). Thus, a change in temporal resolution is required. In this study, one-year (2013) analysis was conducted using Chollian geostationary meteorological satellite data from observations recorded at 15-min intervals. Observation data from the intensive solar site at Gangneung-Wonju National University (GWNU) showed that the coefficient of determination (R²), which was estimated for each month and season, increased, whereas the standard error (SE) decreased when estimated in 15-min intervals over those obtained in 1-h intervals in 2013. When compared with observational data from 22 solar sites of the Korean Meteorological Administration (KMA), R² was 0.9 or higher on average, and over- or under-simulated sites did not exceed 3 sites. The model and 22 solar sites showed similar values of annual accumulated solar irradiation, and their annual mean was similar at 4,998 MJ m^?2 (3.87 kWh m^?2). These results show a difference of approximately ± 70 MJ m^?2 (± 0.05 kWh m^?2) from the distribution of the Korean Peninsula estimated in 1-h intervals and a higher correlation at higher temporal resolution.     

Provenance,weathering, and paleoenvironment of the Upper Cretaceous Duwi black shales,Aswan Governorate,Egypt

The mineralogy and geochemistry of the Upper Cretaceous Duwi black shales of Nile Valley district, Aswan Governorate, Egypt, have been investigated to identify the source rock characteristics, paleoweathering, and paleoenvironment of the source area. The Duwi Formation consists mainly of phosphorite and black shales and is subdivided into three members. The lower and upper members composed mainly of phosphorite beds intercalated with thin lenses of gray shales, while the middle member is mainly composed of gray shale, cracked, and filled with gypsum. Mineralogically, the Duwi black shales consist mainly of smectite and kaolinite. The non-clay minerals are dominated by quartz, calcite, phosphate, dolomite, feldspar, with little gypsum, anhydrite, iron oxides, and pyrite. Based on the CIA, PIA, and CIW values (average?=?84, 94, 95, respectively), it can be concluded that the litho-components of the studied shales were subjected to intense chemical weathering and reflect warm/humid climatic conditions in the depositional basin. The provenance discrimination diagram indicates that the nature of the source rocks probably was mainly intermediate and mafic igneous sources with subordinate recycled sedimentary rocks (Nubia Formation). Geochemical characteristics indicate that the Duwi black shales in Nile Valley district were deposited under anoxic reducing marine environments.     

Estimation of Block Sizes for Rock Masses with Non-persistent Joints

Summary  Discontinuities or joints in the rock mass have various shapes and sizes. Along with the joint orientation and spacing, the joint persistence, or the relative size of the joint, is one of the most important factors in determining the block sizes of jointed rock masses. Although the importance of joint persistence on the overall rock mass strength has long been identified, the impact of persistence on rock strength is in most current rock mass classification systems underrepresented. If joints are assumed to be persistent, as is the case in most designs, the sizes of the rock blocks tend to be underestimated. This can lead to more removable blocks than actually exist in-situ. In addition, a poor understanding of the rock bridge strength may lead to lower rock mass strengths, and consequently, to excessive expenditure on rock support. In this study, we suggest and verify a method for the determination of the block sizes considering joint persistence. The idea emerges from a quantitative approach to apply the GSI system for rock mass classification, in which the accurate block size is required. There is a need to statistically analyze how the distribution of rock bridges according to the combination of joint orientation, spacing, and persistence will affect the actual size of each individual block. For this purpose, we generate various combinations of joints with different geometric conditions by the orthogonal arrays using the distinct element analysis tools of UDEC and 3DEC. Equivalent block sizes (areas in 2D and volumes in 3D) and their distributions are obtained from the numerical simulation. Correlation analysis is then performed to relate the block sizes predicted by the empirical equation to those obtained from the numerical model simulation. The results support the concept of equivalent block size proposed by Cai et al. (2004, Int. J. Rock Mech. Min. Sci., 41(1), 3–19).     

Bristen granite: a highly differentiated,fluorite-bearing A-type granite from the Aar massif,Central Alps,Switzerland

Bristen granite is a body of fine-grained leucogranite occurring in the Gotthard rail base tunnel in the Central Alps. During construction of the tunnel, Bristen granite (Brgr) has been drilled along a 600 m long section. The aplite-granite belongs to the suite of Variscan granitoid intrusions of the Aar massif and contains a variety of accessory minerals typical of highly differentiated granites. Rock forming fluorite, partly enriched in yttrium (Y) and rare earth elements (REE), is intergrown with the late Y- and REE-bearing carbonate mineral synchysite. The granite contains a variety of Ti- and Y-REE-niobates, thorite, and zircon. Compared with the calc-alkaline central Aar granite (cAgr), Bristen granite is strongly depleted in Ti, P, Mg, Sr, and Ba and shows a remarkable enrichment in incompatible elements such as Rb, Th, U, Nb, Y, HREE and F. Bristen granite is the most evolved granitoid rock of the Aar massif. The composition of Brgr is typical of post-collisional reduced (ferroan) A-type granites. The Brgr melt formed in the lower crust and crystallized from a highly differentiated melt at the cotectic point in the quartz-feldspar system close to 100 MPa and 700 °C. The Brgr intruded as a small isolated stock pre-Variscan gneisses with sharply discordant contacts. The primary igneous host of Nb, Ta, Y, U, Th and REE is biotite in addition to minor amounts of allanite, and zircon. The presence of Y-REE-fluorite, synchysite, parisite and Y- and Ti-niobates and other REE-minerals can be related to reaction of igneous biotite and primary fluorite with hydrothermal fluids. The reaction is associated with alpine metamorphism, because Y-bearing fluorite and synchysite have been reported from Alpine fissures. The transformation of primary biotite to chlorite and muscovite released the heavy metal oxides under lower greenschist facies conditions that formed the Alpine diagnostic mineral stilpnomelane at about 300 °C.