Geochemistry of boron in the ultrabasics of Nuggihalli schist belt,Karnatak state,India

Contents of boron (ppm), magnesia (%) and silica (%) of thirty samples of basic and ultrabasic rocks and 8 samples of serpentinites from Nuggihalli schist belt have been determined by spectrochemical, E.D.T.A. and colorimetric methods respectively. From the analytical data it is found that boron in serpentinites and ultrabasic rocks has higher clarks. The increase of boron in serpentinites and ultrabasic rocks is suggestive of allometamorphism. From the geochemical and statistical investigations it appears that there exists a correlation between the content of boron and magnesia in the basic and ultrabasic rocks and in serpentinites. Boron content in brown serpentinite is less than in platy serpentinite.     

储层岩石周期性电渗流特性的微观机制

以双电层电位理论和电渗流动的动量方程为基础,结合储层岩石平行毛管束模型,推导出岩石孔隙内周期性电渗流的解析式,揭示了储层中电渗效应的微观机制,分析了非密闭储层岩石中宏观电渗Darcy速度及密闭储层中电渗压力系数频散特性的影响因素．数学模拟结果表明:储层岩石孔隙中,周期性电渗流速度剖面在频率较高时呈“波浪”状;孔隙度越大,电渗Darcy速度模值越大,其相位也越大,而电渗压力系数数值越小．储层岩石的溶液浓度越小或阳离子交换量越大,电渗Darcy速度模值和电渗压力系数数值越大,但对电渗Darcy速度的相位没有影响．     

Fluid flow,relative permeabilities and capillary pressure curves through heterogeneous porous media

There is a growing interest in fluid flow through rocks which show a large range, or heterogeneity, in pore sizes (from order tens of nanometres up to a hundred microns) which lead to small porosities and permeabilities. Digital imagery of these rocks yield under-resolved pore structures or a gray-scale sample. In this work we use the gray-scale lattice Boltzmann (LB) method to determine flow of two, immiscible fluids through such three-dimensional porous media. The method yields transient and equilibrium flow fields from which we determine relative permeability and capillary pressure curves. The method is applied to real digital rock data to extract flow properties through the sample. Both single phase and multiphase LB simulations are carried out. We find low permeabilities (of the order of milli-Darcy) together with large residual saturations (between 50–75%), indicative of a rock sample which has void regions remote from each other, i.e. either disconnected or connected by very narrow pore throats.     

The geology of the manganese ore deposits of talwara,district Banswara,Rajasthan

Talwara (23° 34′: 74° 22′) is a small Manganese-producing locality in the district of Banswara, Rajasthan. From the Banswara Town, Talwara can be reached by a motorable road. In the past, the Manganese ores of the locality have drawn very little attention of the geologists. The ores of Manganese, being associated exclusively with the Aravalli limestone of Rajasthan, occur in the form of scattered masses occupying solution cavities, fissures, etc., in limestone. Aravalli quartzites, conglomerates, phyllites and slates also occur in the vicinity of Talwara. The white limestone with a mosaic structure is of common occurrence and is composed of calcite and dolomite with some magnetite. The impurer varieties of limestone are characterised by the presence of tremolite, hornblende and quartz with a little of biotite. Schistosity is developed only in a calc-amphibole rock having alternating bands of hornblende and limestone. Crush-breccia is noticed occurring in association with manganiferous limestone at a distance of about 2 miles west of Talwara. This breccia might have originated due to severe local crushing of the country-rock. The limestones seemed to be a product of low-grade metamorphism of a calcareous sediment. Fresh ores are generally hard and cavernous but on weathering they become softer and soily. Fragments of unreplaced limestone are occasionally present in the ore-bodies. This limestone has also been replaced by the Manganese ores to a greater or lesser extent, depending on the structural characters of the host rock. The ores are composed largely of massive and colloform cryptomelane. Pyrolusite forms an insignificant part of the ores. There are two generations of cryptomelane, of which, the earlier colloform one is veined by the later generation of cryptomelane. There are also examples of pseudomorphous replacement of limestone by cryptomelane. Most of the pyrolusite was derived from the supergene alteration of cryptomelane. From their nature and mode of occurrence the Manganese ores are classified as outcrop secondary ores formed in cavities in crystalline limestones belonging to the less metamorphosed type of Dharwar.     

Confidence bands for quantile function under random censorship

Some new confidence bands are established for the quantile function from randomly censored data. The method does not require estimation of the density function. As an application, we construct bands for the quantile function of the length of fractures in the granitic plutons near Lac du Bonnet, Manitoba, where an Underground Research Laboratory is being built for the nuclear waste disposal program in Canada.Geological Survey of Canada Contribution Number 10386.Research partially supported by an NSERC Canada Grant.Research done while at Carieton University, supported by NSERC Canada and EMR Canada Grants of M. Csörg.     

Hydrogeochemistry of the Purana formations of eastern Madhya Pradesh in India

The Raipur and Indravati series comprising the Purana formations of Chhattisgarh consist of conglomerates, orthoquartzites, sub-arkoses, shales, limestones and dolomites. The lithofacies in these have considerable lateral variations. Both Mahanadi and Indravati basins are saucer-shaped with centripetal dips; the arenaceous rocks along the fringes have dips up to 15°, while the younger rocks in the centre are almost horizontal. In carbonate rocks, karst is developed on a regional scale with sinkholes of higher topographic areas linked with resurgences of low relief areas. Groundwater in the above formations occurs generally under water table condition, but in karstic limestone also under confined condition. The chemical relationship of groundwater circulating in the various lithofacies are plotted in the trilinear diagrams after Piper. Groundwater within depths of 92m has carbonate hardness (Secondary alkalinity) exceeding 50 per cent with the chemical properties dominated by alkaline earths and weak acids. The cations and anions in water from similar lithofacies of Mahanadi and Indravati basins are distributed in the same field of the trilinear diagram with almost similar scatter of ions suggesting thereby a similar geochemical environment. The quality of groundwater is within permissible limits for irrigation and domestic purposes, while softening of water from temporary bicarbonate hardness may be necessary for certain specific industries. Expansion of groundwater recharge by increasing the ‘area of spreading’ of flood water of the Mahanadi basin and application of the technique in the Indravati basin will enrich the soils. Prevention of disposal of industrial wastes underground, especially in karstic regions will be a primary step in pollution control.     

裂缝三级摩擦因数及影响因素研究(以砂岩（颗粒胶结体）为例)

讨论摩擦面的摩擦因数模型．认为砂岩的摩擦因数分为砂粒球面摩擦因数、微裂纹平面摩擦因数、凸凹构成的裂缝摩擦因数3个层次,分别代表3类不同的成因,3个层次的耦合是真实岩石摩擦因数的决定因素．岩石摩擦因数是在砂粒球面材料摩擦因数基础上,经过后两种形式的放大而形成岩石的宏观摩擦因数．裂纹表面凸起的平均角度或者分形维数是影响岩石摩擦因数分异的最大影响因素,而颗粒排布模式导致的分异相对小得多．颗粒接触的静摩擦因数大于动摩擦因数的成因与颗粒的平均接触角度有关．     

冀中坳陷古近系沙河街组三段中亚段岩相古地理

冀中坳陷古近系始新统沙河街组三段中亚段地层全区广泛分布,在钻井、岩心和地震资料等定性和定量资料基础上,运用灰色关联分析方法得到的各单因素关联主因子,优选出5类与沉积相域展布有关的影响因素:地层厚度、粗碎屑岩含量、细碎屑岩含量、红色泥岩含量及暗色泥岩含量.在此基础上,采用单因素分析多因素综合作图法,编制了各层序格架下的岩相古地理图.冀中坳陷古近系沙三中亚段主要发育的沉积相,包括冲积扇、河流、(扇)辫状河三角洲、近岸湖底扇及湖泊.研究结果表明:沙三中亚段主要发育大型冲积扇河流-(扇)辫状河三角洲湖泊沉积体系,并处在冀中坳陷始新统早期的湖盆断陷扩张深陷期沉积这一演化阶段.     

A single domain grain model for the low-field constricted hysteresis loops of some basaltic rocks

Basaltic rocks contain magnetic grains oriented randomly in a nonmagnetic matrix. Experimental studies of low-field hysteresis of such rocks have shown partially and totally constricted hysteresis loops for some specimens. A possible origin of these constricted loops on the basis of interacting single domain behaviour is suggested.     

裂缝孔隙介质中二相驱动问题的交替方向有限元方法及理论分析

考虑裂缝孔隙介质中二相驱动问题的数值方法及理论分析。对压力方程采用混合有限元方法,对裂缝和岩块系统上的饱和度方程采用交替方向有限元方法,证明了交替方向有限元格式具有最优Ｌ２模和Ｈ１模误差估计。     

Gradient-consistent non-linear model of the generation of ultrasound in the propagation of seismic waves

The equations of the propagation of weak non-linear waves are obtained by a detailed analysis of the gradient-consistent micropolar model of a granular continuous medium. The high-frequency mode of oscillation is associated with ultrasonic waves, and the low-frequency mode is associated with the usual seismic waves in rocks. The evolution equations that include the case of long-wave-short-wave resonance are obtained by an asymptotic consideration. This resonance corresponds to the case of the generation of ultrasound (noise) by travelling seismic waves.     

Numerical calculation of salt leaching from rocks in the presence of head-driven flow

A numerical procedure is proposed for solving the problem of leaching of water-soluble salts from multilayer rocks in the presence of a head-driven flow, allowing for the interaction of seepage and desalinisation processes. The results of a numerical experiment are reported.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 61, pp. 47–53, 1987.     

Digital Rock Physics: A case study of carbonate rocks

Digital Rock physics is a numerical framework applying image-based methods to determine effective material properties of rock. It is possible to find several of these methods in the literature, but we focused mainly in micro X-Ray Computed Tomography (µXRCT) to acquire the digital rock samples. After scanning the 3-D microstructure, morphological filters and numerical simulations were performed to characterize the samples. In particular carbonate rocks present a mismatch in numerical results compared to laboratory experiments. The elastic parameters, the P- and S-wave moduli, respectively,are overestimated when compared to ultrasonic measurements in the laboratory. We describe possible causes of this mismatch and propose a new segmentation technique to improve the correlation between numerical simulations and laboratory data. Furthermore, the workflow proposed for the characterization of carbonate rocks has been applied to different digitized samples from different sources, and a data driven material law has been found that fits better experimental results than the lower Hashin-Shtrikman bound. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Topological indices: their nature,mutual relatedness,and applications

During the last two decades a large number of numerical graph invariants (topological indices) have been defined and used for correlation analysis in theoretical chemistry, pharmacology, toxicology, and environmental chemistry. However, no systematic study has been undertaken to determine to what extent these indices are correlated with each other. In the present paper we have carried out a principal component analysis (PCA) of 90 topological parameters derived from 3692 distinct chemicals taken from an environmental database consisting of nearly nineteen thousand compounds. The PCA using the correlation matrix resulted in 10 principal components (PC's) with eigenvalues greater than 1. These ten PC's explained over 92% of the variance in the standardized data. The first four PC's explained over 78% of the variance and the interpretations of these four PC's is given in terms of the chemical structures at the extremes of these PC's.     

Global existence for a 1D parabolic–elliptic model for chemical aggression in permeable materials

We prove the global existence and uniqueness of smooth solutions to a nonlinear system of parabolic–elliptic equations, which describes the chemical aggression of a permeable material, like calcium carbonate rocks, in the presence of acid atmosphere. This model applies when convective flows are not negligible, due to the high permeability of the material. The global (in time) result is proven by using a weak continuation principle for the local solutions.     

Modeling cadmium accumulation in radish,carrot, spinach and cabbage

Heavy metals like cadmium and arsenic have serious health consequences and ecosystem impacts. Due to various factors including the disposal of municipal and industrial wastes, application of fertilizers, atmospheric deposition and discharge of wastewater on land, has resulted in increase in the concentration of heavy metals in the soil. Crops and vegetables grown on such soil accumulate heavy metals, which leads to phyto-toxicity. For understanding and managing precious natural resources, mathematical models are increasingly being used. This paper describes a dynamic macroscopic numerical model for heavy metal transport and its uptake by vegetables in the root zone. The model is applied for simulating cadmium uptake by radish (Raphanus sativus), carrot (Daucos carota), spinach (Spinacia oleracea) and cabbage (Brassica oleracea) by using measured field data. The governing non-linear partial differential equations are solved numerically by an implicit finite difference method using Picard’s iterative technique and the source code is written in MATLAB.     

Schools in Southampton: A Quantitative Approach to School Location,Closure and Staffing

Between 1965 and 1976 the number of children born in the UK decreased by about one third. The fall in the number of births was followed by a fall in the number of children on roll in compulsory education, which resulted in many schools being closed. This paper examines the dynamics of falling rolls in the city of Southampton. Multidimensional scaling techniques are used to explore the social characteristics of the schools proposed for closure. The paper examines also the consequences of the exercise of parental choice of school. It is shown that social dynamics and staffing rules based on constant pupil/teacher ratios remove resources from the schools that are most in need of them.     

Instability in a delay-PDE model of earthquake occurrence

Summary Ductile deformation prior to brittle fracture in rocks causes fracture to take place with a time delay after the critical stress for fracture is reached, in the presence of an increasing load stress. We discuss the stability of a stochastic model of interactive earthquake occurrence under the influence of time delays resulting from the ductile process. A threshold for oscillatory behavior is found for large enough coupling and discrete time delays. The system is stable if the time delays are spread over a broad time interval, even for large coupling.     

The combination of collocation,finite difference,and multigrid methods for solution of the two‐dimensional wave equation

In this article, we apply compact finite difference approximations of orders two and four for discretizing spatial derivatives of wave equation and collocation method for the time component. The resulting method is unconditionally stable and solves the wave equation with high accuracy. The solution is approximated by a polynomial at each grid point that its coefficients are determined by solving a linear system of equations. We employ the multigrid method for solving the resulted linear system. Multigrid method is an iterative method which has grid independently convergence and solves the linear system of equations in small amount of computer time. Numerical results show that the compact finite difference approximation of fourth order, collocation and multigrid methods produce a very efficient method for solving the wave equation. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008     

A study of the vestigial records of cosmic rays in lunar rocks using a thick section technique

An experimental technique has been developed for systematic measurements of fossil tracks along selected planes cut from grains and rocks. With controlled etching, the technique allows successive revelation of tracks in different minerals in the same section, a typical sequence being olivine, anorthite, clinopyroxene. It thus becomes possible to study precisely the cosmic ray track density variations over dimensions much greater than those of individual crystals. The technique also provides accurate information on the relative recording characteristics of different minerals present in a rock and cosmic ray tracks can be studied with a minimum interference of tracks due to spontaneous fission of uranium and transuranic elements. Continuous chains of sections, each section measuring approximately 1 cm., have been cut along several different planes in fifteen rocks from Mare Tranquillitatis, Oceanus Procellarum and Fra Mauro region. The cosmic ray track measurements from these sections have provided dramatic evidence for a number of processes affecting lunar rocks. The statistical, and non-uniform nature of erosion by micrometeorite bombardment can be seen in sections intersecting exposed surface which show regions of very steep track density gradients interspersed with eroded regions having lower track densities. The thick section technique permits determination of the energy spectrum of VH nuclei from track density gradients that extend over distances limited only by the dimensions of the rock, and, more important, in samples of identical orientation. The latter is particularly important in higher energy regions (deeper within the rock) where variations in crystal orientation cause track density differences of the same order as real changes in the gradient. Also in the near surface regions of rocks where low energy particles produce steep track density gradient, the thick section method has proved indispensable since it permits accurate depth determinations not possible in the spot sampling procedure. In this paper the technique of studying track profiles in thick sections is described. Although developed primarily for studying lunar samples, the thick section technique is also useful for similar studies in meteorites, particularly for gas-rich meteorites containing irradiated grains. In contrast to single grain studies, thick sections preserve the grain boundaries and permit accurate depth—density measurements. In addition thick section studies have revealed occasional large uniformly irradiated lithic fragments which would not have been possible to discover by spot sampling methods.