Composition-related microstructures in zinc-bearing carbonate assemblages from Broken Hill,New South Wales

Summary Analytical transmission electron microscopy has been used to investigate two zincian dolomites occurring as overgrowths on calcite from the oxidized zone of the ore bodies at Broken Hill, New South Wales. Particular attention has been focussed on the nature of the microstructures, and any correlations between microstructure and local composition, especially zinc content. The possible occurrence of tiny amounts of the zinc dolomite, minrecordite, has also been explored.The most notable features in the zincian dolomite are fine-scale distributions of ribbonlike calcitic second phase, growth bands, and modulated microstructures (strong modulations in diffraction contrast). Their occurrence is correlated with calcium in excess of stoichiometric requirements, but is not directly influenced by zinc content. The associated calcites are low in zinc, but they also exhibit carbonate second phase, which is thought to be dolomitic although giving no detectable order (b-type) reflections. Long-exposure electron diffraction patterns, however, revealed the presence of diffuse c-type superstructure reflections, which are thought to arise from smaller volumes in which Ca and Mg cations are ordered, for which a model is proposed.

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Zusammensetzungsabhängige Mikrogefüge in Zn-haltigen Karbonat-Vergesellschaftungen von Broken Hill, New South Wales

Zusammenfassung Analytische Transmissionselektronenmikroskopie wurde benutzt um zwei Zn-haltige Dolomite zu untersuchen, die als Überzüge von Calcit aus der Oxidationszone der Erzkörper von Broken Hill, New South Wales, auftraten. Besondere Aufmerksamkeit wurde der Art der Mikrogefüge und möglichen Korrelationen zwischen Mikrogefüge und der lokalen Zusammensetzung, vor allem dem Zn-Gehalt, gewidmet. Dem möglichen Auftreten von geringen Mengen des Zn-Dolomit, Minrecordit, wurde ebenfalls nachgegangen.Die bemerkenswertesten Erscheinungen im Zn-haltigen Dolomit sind feine bandartige Verteilung einer calcitischen Phase, Wachstumsbänder und modulierte Strukturen (starke Modulationen im Beugungskontrast sichtbar). Ihr Auftreten ist mit über das stöchiometrische Verhältnis hinaus vorhandenem Ca korreliert; es ist aber vom Zn-Gehalt nicht direkt beeinflußt. Die mitvergesellschafteten Calcite haben einen niedrigen Zn-Gehalt, zeigen aber eine weitere Karbonatphase. Diese wird für dolomitsch gehalten, obwohl keine entsprechenden Ordnungsreflexe (b-Reflexè) nachweisbar waren. Sehr lange belichtete Elektronenbeugungs-Aufnahmen zeigen jedoch diffuse c-Typ-Über-struktur-Reflexe. Diese sind wahrscheinlich auf kleine Bereiche beschränkt, in dener die Ca und Mg Kationen geordnet sind, wofür ein Modell vorgeschlagen wird.

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With 10 Figures     

Wetting Induced Deformation of Soils Triggering Landslides in Pakistan

Geotechnical and Geological Engineering - Shallow and deep seated landslides in natural slopes are often induced by rainfall. The cause of the failure is usually considered to be due to the...     

辽东半岛复州湾剖面寒武系第二统光合作用生物膜建造的核形石

作为一种经常大于鲕粒的包覆颗粒类型,核形石以其不平滑的圈层被解释为微生物成因,区别于成因存在较大争议的鲕粒,而且常与鲕粒和其他类型的碳酸盐颗粒相互共生;作为一种在围绕着生物碎屑和非生物碎屑核心的序列式纹层化作用过程中形成的球形或假球型生物沉积构造,核形石还常常单独产出和分布,所以又被解释为微生物碳酸盐岩,或者被归为球状叠层石。在辽东半岛寒武系第二统碱厂组和馒头组之中,厘米级别大小的核形石密集发育在三级层序的顶部,成为一种时间特化的相。另外,以下重要特征将辽东半岛寒武系第二统的核形石特征化,包括:(1)与凝块和微凝块共生;(2)多为球状和椭球状;(3)由不均一的非纹层状致密泥晶和微亮晶构成;(4)核形石皮层以及核形石间凝块中发育特别的蓝细菌鞘钙化化石等。尽管穿越成岩作用过滤器去解释古代核形石复杂的形成机理存在着巨大的挑战,也尽管形成这些核形石的复杂生物膜钙化作用细节需要更加深入地研究才能得到更好地了解,但是,辽东半岛第二统碱厂组和馒头组核形石中直接的微生物化石证据,尤其是核形石内较为丰富的钙化蓝细菌鞘化石,使其成为一个了解光合作用生物膜建造核形石的典型实例。     

Shallow and deep aquifer hydrochemistry and chemical variability of water quality at Shariatpur district, Bangladesh

Water quality and hydrochemistry of Shariatpur district were evaluated in terms of hydrochemical composition and some important physico-chemical parameters. The groundwater of the study area is good for drinking, domestic as well as for irrigation purposes. Among the major ions, shallow tube well waters give higher concentration of Ca²⁺ which ranges from 24 to 260 mg/L. The deep tubewell waters show higher concentration of Na⁺ which varies from 74 to 582 mg/L during dry season. Among the trace elements most of the shallow aquifer samples show higher concentration of Fe²⁺, Mn²⁺ and As. Concentration of Fe²⁺ varies from 0.655 to 18.8 mg/L, and Mn²⁺ from trace to 0.868 mg/L during dry period. Hydrochemical analyses reveal significant seasonal variation in water quality of shallow aquifer. Both the shallow aquifer and the surface water of the study area are predominantly of Ca–Mg–HCO₃ type, while the deep aquifer water is mainly of Na–K–Cl–SO₄ type with slight inclination to Ca–Mg–HCO₃ type. The study area is suitable for groundwater development if comprehensive and holistic approaches towards water resource management are taken into consideration.     

The early phase of multiple proto-stellar system emerging from collapse of molecular cloud under various initial thermal states

We report on the short timescale intensity fluctuations of PSR B1133+16 and PSR B1237+25 due to scintillation at 1.54 GHz. The structure functions of intensity fluctuations are constructed and the linear fittings are applied to the structure regime in log–log plots to get the slope values. The slope of the SFs for PSR B1237+25 are less than that of PSR B1133+16, and both of them are much less than 2. For PSR B1133+16, the slope values agree very well with a Kolmogorov spectrum predicted value 5/3, whereas PSR B1237+25 not. We investigate the dynamic spectrum and obtain its auto-correlation function (ACF). Scintillation parameters are obtained by fitting to the autocorrelation function of the dynamic spectrum. The observed diffractive interstellar scintillation (DISS) timescales agree well with the observations and are consistent with some expected values, but the observed de-correlation frequency bandwidths are much less than predicted ones. The expected refractive interstellar scintillation (RISS) timescales are also estimated by using our derived diffractive scintillation parameters. They are consistent with the timescales of slow pulse intensity fluctuations. We proposed that the short timescale of pulse intensity variations caused by the DISS are modulated by the slow variations due to the effects of RISS.     

Conversion between solid and beam element solutions of finite element method based on meta-modeling theory: development and application to a ramp tunnel structure

In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. The proposed method is rigorous and efficient compared to a typical conversion method which merely computes surface integration of solid element nodal stresses to obtain cross-sectional forces. The meta-modeling theory ensures the rigorousness of proposed method by defining a proper distance between beam element and solid element solutions in a function space of continuum mechanics. Results of numerical verification test that is conducted with a simple cantilever beam are used to find the proper distance function for this conversion. Time history analysis of the main tunnel structure of a real ramp tunnel is considered as a numerical example for the proposed conversion method. It is shown that cross-sectional forces are readily computed for solid element solution of the main tunnel structure when it is converted to a beam element solution using the proposed method. Further, envelopes of resultant forces which are of primary importance for the purpose of design, are developed for a given ground motion at the end.     

Planck absolute entropy of a rotating BTZ black hole

In this paper, the Planck absolute entropy and the Bekenstein–Smarr formula of the rotating Banados–Teitelboim–Zanelli (BTZ) black hole are presented via a complex thermodynamical system contributed by its inner and outer horizons. The redefined entropy approaches zero as the temperature of the rotating BTZ black hole tends to absolute zero, satisfying the Nernst formulation of a black hole. Hence, it can be regarded as the Planck absolute entropy of the rotating BTZ black hole.     

Coal resources of the Sonda coal field, Sindh Province, Pakistan

Approximately 4.7 billion t of original coal resources, ranging from lignite A to subbituminous C in rank, are estimated to be present in the Sonda coal field. These resources occur in 10 coal zones in the Bara Formation of Paleocene age. The Bara Formation does not out crop in the area covered by this report. Thin discontinuous coal beds also occur in the Sonhari Member of the Laki Formation, of Paleocene and Eocene age, but they are unimportant as a resource of the Sonda coal field.The coal resource assessment was based on 56 exploratory drill holes that were completed in the Sonda field between April 1986 and February 1988. The Sonda coal field is split into two, roughly equal, areas by the southwestward flowing Indus River, a major barrier to the logistics of communications between the two halves. As a result the two halves, called the Sonda East and Sonda West areas, were evaluated at different times by slightlydifferent techniques; but, because the geology is consistent between the two areas, the results of both evaluations have been summarized in this report. The resource estimates for the Sonda East area, approximately 1,700 million t, were based on the thickest coal bed in each zone at each drill hole. This method gives a conservative estimate of the total amount of coal in the Sonda East area. The resource estimates for the Sonda West area, approximately 3,000 million t, were based on cumulative coal bed thicknesses within each coal zone, resulting in a more liberal estimate. In both cases, minimum parameters for qualifying coal were a thickness of 30 cm or greater and no more than 50% ash; partings thicker than 1 cm were excluded. The three most important coal zones in the Sonda field are the Inayatabad, the Middle Sonda and the Lower Sonda. Together, these three coal zones contain 50% of the total resources. Isopachs were constructed for the thickest coal beds in these three coal zones and indicate large variations in thickness over relatively small distances. Coal beds in the Sonda coal field were difficult to correlate because of poor core recovery in some intervals and abrupt lateral thinning and thickening. Most coal zones are separated by 5–10 m of interburden, although in some places the interburden between zones is over 100 m thick. More closely spaced drill holes should clarify and significantly improve coal zone correlations in the Bara Formation.Coal resources in the Sonda coal field were calculated for three reliability categories; measured, indicated, and inferred. The most reliable estimates are those for the measured category. Measured coal resources are approximately 91 million t, or about 2% of the total resource; indicated resources are 681 million t, or about 14% of the total; and inferred resources, the least reliable resource category, are 3,931 million t, or 84% of the total resources. The distribution of resources by reliability category is due to the relatively wide spacing (approximately 5 km) between core holes.Analyses of 90 coal samples, on an as-received basis, indicate average ash and sulfur contents of 13.7% and 3.6%, respectively, and a range in rank from lignite A to subbituminous C. Calorific values for these samples range from 6,000 to 8,000 Btu/lb (1 Btu = 1055J; 1 lb = 4536 kg).     

P-wave minimum 1D velocity model for central and northern Pakistan

Journal of Seismology - We present a P-wave minimum 1D velocity model for central and northern Pakistan along with station delays. The velocity model and appropriate station delays are obtained...     

Sugarcane waste straw biochar and its effects on calcareous soil and agronomic traits of okra

Biochar has been considered a safe soil additive to enhance soil fertility and agronomic traits of different crops. This study was conducted to explore the impacts of sugarcane waste straw biochar on soil characteristics and some agronomic traits of okra. The experiment was carried out with four treatments, i.e., control, sugarcane waste straw biochar (10 ton ha^?1), farmyard manure (FYM, 10 ton ha^?1), and chemical fertilizers (NPK; 120:100:80 kg ha^?1) having three replications of each treatment. Soil samples were tested for texture, bulk density, particle density, pH, electrical conductivity (EC), organic matter content, nitrate nitrogen (NO₃-N), and extractable-P. The sugarcane waste straw biochar was characterized for plant major nutrient elements. The impact of various treatments was observed on soils and agronomic traits of okra like plant height, fruit size, fruit length, and yield of okra. Results revealed that sugarcane waste straw biochar expressed higher EC value and noticeable amounts of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and magnesium (Mg). The sugarcane waste straw biochar, in comparison with FYM and NPK, significantly improved the NO₃-N, extractable-P, OM and EC of the calcareous soil, and reduced the soil bulk density. Furthermore, plant growth and yield parameters were significantly improved under biochar application over the control, FYM and NPK. Overall, sugarcane waste straw biochar proved to be a good alternative to conventional organic and inorganic fertilizers under calcareous soil conditions.