Effect of pretreatment of the electrokinetic properties of quartz

Effects of various commonly used pretreatments such as desliming, ultrasonic scrubbing and leaching with dilute nitric, hydrofluoric and sodium hydroxide solutions on the electrokinetic properties of quartz in aqueous solutions are reported. The study showed that treatments with various reagents often used in mineral processing research in the past to clean minerals can affect, sometimes severly, the electrokinetic properties of quartz. The change in these properties during subsequent aging is also found to be governed by the type of treatment used. This study also shows the need in mineral research for standardization of mineral preparation techniques in order that the discrepancy in data reported for surface properties in literature can be minimized.     

A review of theories of mechanisms of induced seismicity

Theories of the physical processes leading to the stimulation of seismic activity by underground explosions, fluid injection, and reservoir impoundment are summarized. In all cases, the materials must be pre-stressed to a substantial fraction of their breaking strength in order for seismicity to be induced. Stress concentrations due to the presence of old faults or to inhomogeneities in the material properties play an important role in localizing induced seismicity.

For the few cases for which data are available, the stimulation of earthquakes by fluid injection in bore holes is adequately explained by a Coulomb-Mohr failure criterion and the concept of effective pressure in a water-filled porous mechanism. Reservoir-related earthquakes are most likely due to the same mechanism, but, in view of the low injection pressures, additional physical or chemical effects of the water on the materials may play an important role. There may be a weakening of the materials in old fault zones by the introduction of water or static fatigue in silicate rocks due to stress corrosion.     

Causes of salinization of the Gulf of Taganrog

Using the database of automatic hydrometeorological stations, installed in the Don RIver delta and Taganrog Bay seashore, the sources of the anomalois scale water negative surge and salinization of the Azov Sea under conditions of low river flow in 2015–2016 are studied. The new schemes of stratification and advection of salty sea waters in the Don River mouth under different weather conditions, water discharge and levels are given.     

鄂尔多斯盆地延长组长7富铀烃源岩铀的赋存状态

鄂尔多斯盆地晚三叠世延长组长7段是一套深湖相富铀烃源岩,铀含量很高,其矿物学特点是富含胶磷矿、草莓状黄铁矿、有机质等.通过光片、扫描电镜、电子探针、能谱分析、α放射性照相等研究方法,分析了长7段富铀烃源岩中铀的赋存状态,结果表明铀除了以类质同象赋存于胶磷矿中,以及以吸附态赋存于黄铁矿和有机质中以外,还在长7富铀烃源岩中...     

国际水文地质学家协会进展

国际水文地质学家协会成立于1956年。1985年资深的中国专家出席了第17届和18届国际水文地质大会,自那时以来,越来越多的中国代表出席了该学会的学术会议。中国分会于1987年建立,并组织相关活动。中国的协会成员近年来不断增加。国际水文地质大会曾在中国举办两次,第21届大会于1988年在桂林市举行,第34届大会于2006年在北京举行。多年来,在我国每年都举行水文地质学和地下水科学学术会议。协会主办的《Hydrogeology Journal》期刊编委会中有很多中国和华裔学者,中国分会负责论文摘要的中文翻译。协会的图书系列在我国广泛传播,促进了中国地下水科学的发展。该协会近期提出了水文地质战略系列,已经发布的九个专题分别是:生态系统与地下水、能源与地下水、粮食安全与地下水、全球变化与地下水、人类健康与地下水、城市与地下水、联合国2030年可持续发展目标、采矿业与地下水,以及气候变化适应地下水,指导了地下水资源和水文地质科学的发展。     

深基坑边坡支护方式的现状

根据目前国内边坡支护工作中的主要方式,将深基坑边坡支护按其结构的受力状态和支护的作用原理进行分类,详细论述了各种深基坑边坡支护方式的机制和适用条件,对今后岩土工程的实际工作具有一定的参考作用。     

Reaction of zoning of garnet

Compositional zoning of garnet in metamorphic or igneous rocks preserves evidence of the equilibration history of the sample and can be interpreted in terms of a growth-fractionation, diffusion-exchange, or diffusion-reaction model. Diffusion zoning is usually assumed to result from exchange reactions between garnet and other phases as the partitioning coefficient varies in response to changing environmental conditions, primarily temperature. However, in many natural environments where garnet grew originally in divariant equilibrium with other phases, changing conditions can promote continuous or “divariant” reactions and consequent compositional shifts of phases that can be much greater in some systems showing these reactions than those related to the small changes of partitioning. Diffusional zoning related to overstepping of these continuous reactions must be related to incongruent reaction and necessitates formulation of a kinetic diffusion-reaction model involving moving phase boundaries as well as solid-state diffusion. Three samples containing zoned garnets from the metamorphic aureole around the Ronda ultramafic intrusion in southern Spain are used to illustrate two possible models of diffusion-reaction processes. The examples are particularly informative because the reactions are demonstrably irreversible and evidence of the reaction system is preserved. Partitioning data indicates that compositions of product phases are not in equilibrium with the original garnet and do not vary with extent of reaction; therefore, exchange reactions with garnet were not possible and garnet changed composition only by incongruent reaction. After a small amount of reaction, Mg/Fe of the rim composition approaches a value apparently in equilibrium with product phases, but the garnets are zoned inward to the original garnet composition preserved in the interior. Grossularite content is approximately constant and spessartite content variable but small, thus, the rim composition of pyrope or almandine is assumed to be fixed by the external reaction process and is taken as a boundary condition in the following models. The zoning profile of pyrope or almandine component between the fixed rim and core compositions (assumed to extend to ∞) is described in semiinfinite, half-space models appropriate for large garnets with narrow rims. The first model corresponds to a reaction system in which all garnet compositions are metastable (case 1) and zoning depends on the independent variables of the diffusion constant, velocity of the interface between garnet and matrix, and time. The second model, corresponding to systems in which the initial garnet composition is metastable but an equilibrium composition is stable (case 2), depends on the independent variables diffusion constant, time, and a function of reaction compositions. In case 1 the consumption velocity is assumed constant and a steady state zoning profile is reached at large time, whereas, in case 2, the velocity decreases with the concentration gradient and steady state is not possible. The models were tested using a reaction time estimated from cooling models of the aureole, mass of garnet consumed, determined petrographically, and phase compositions. The two cases are somewhat independent in that different parameters are independent variables. The estimate of the diffusion constant of 10^?18±2 cm²/sec (assumed to be a mutual or binary coefficient for almandine and pyrope) is considered reasonable for the temperature range of reaction (probably 600–900° C), and the two models are consistent considering the probable error and possible real temperature differences. It is obvious that details of the metamorphic reaction system must be known to successfully apply diffusion models. Kinetic models, involving consumption or growth of the phase as well as diffusion are probably necessary when dealing with natural rocks. Several possible and interesting complications, such as cross coupling between components, can be investigated if more data were available. Experimental determination of diffusion constants allow natural reaction rates to be estimated by this method. Diffusion zoning is an important consideration that could increase the efficiency of experimentation with chemically recalcitrant phases.     

济阳坳陷车镇凹陷古近系沙河街组遗迹化石Macaronichnus(通心粉管迹)及其沉积环境

济阳坳陷车镇凹陷古近系沙河街组发现的Macaronichnus segregatis(分离通心粉管迹)是一种直到微弯曲形状的层内进食潜穴,个体较小,不分枝,长一般7～8 mm,直径1～3 mm,与前人发现的化石在个体大小上存在着差异。它主要出现于四类环境：①三角洲平原河道间低地,②三角洲、扇三角洲前缘远端砂坝和浊积扇的中扇到外扇,③潮湿气候条件下的浅湖,④周期性干旱气候条件下的滨浅湖。不同沉积环境中产出的Msegregatis都分布于粉砂质泥岩中。通过分析各沉积环境的水动力条件和水体化学性质以及Msegregatis的形成过程,可得出以下结论：①Msegregatis出现的水动力条件中等,水体能量过高或过低,都不适宜其生成;②Msegregatis出现的水体化学性质介于贫氧与富氧之间;③Msegregatis是在沉积物沉积后还未固结时由食沉积物生物活动造成的,衬壁的出现反映了软基底性质。     

The value of measurements of density in the study of dolerites

The value of density measurements in the study of differentiated dolerite sills is discussed. It is shown that density measurements correspond closely with the results of chemical and modal analyses. There is a considerable statistical fluctuation in measured values of the density from relatively close specimens, and a similar fluctuation is to be expected in the results of chemical or modal analyses. Because of their speed, it is possible to make a large number of density measurements and take mean values over fifty foot intervals to indicate trends.

The density in a moderately thick tholeiite sheet normally increases linearly from the lower contact to a maximum several hundred feet above it, and then decreases to a minimum at the most silicic region which usually occurs several hundred feet below the upper contact. For a sheet of uniform thickness, the variation of density with depth appears to be roughly the same at all points. The density remained constant in a horizontal tunnel at a constant height above the lower contact, but irregular changes in density, possibly associated with changes in level of the roof or flow can occur, and a remarkable case of a rapid horizontal variation in density is discussed in some detail.     

Results of Marine Radioecological Study of Fjords of Western Spitsbergen

The patterns of the distribution of technogenic radionuclides ¹³⁷Cs and ⁹⁰Sr in the water mass and bottom deposits of three fjords of Western Spitsbergen (Isfjorden and its arms Grønfjorden and Billefjorden) were studied. The hydrological processes affecting migration of radionuclides in these water bodies were described. It was shown that the ice sheet of the archipelago that accumulates atmospheric precipitation is a source of radioactive contamination of the marine environment of the coast. Technogenic isotopes were accumulated during nuclear weapon testing in the second half of the twentieth century. The current climatic changes strengthen the role of glaciers in the contamination of arctic seas. It was noted that extrema of the ¹³⁷Cs and ⁹⁰Sr specific activity is mainly concentrated in the areas of glacier runoff discharge.

     

含矿岩浆通道对于岩浆铜镍硫化物矿床找矿工作的意义

“深部熔离-贯入式”岩浆铜镍硫化物矿床具有矿化比例极高、岩体岩相分带及矿体产状与原地分异、熔离机制不协调的特征.我国对这类矿床深部勘探策略和方法的研究相对滞后,尚未开展深部找矿工作.本文以金川矿床为重点,系统总结和归纳其地质特征和成矿有利部位,对比了与之成因类似的加拿大Voisey＇s Bay超大型岩浆Gu-Ni-Co硫化物矿床的成功勘探经验,阐述了这类矿床沿岩浆通道找矿的前景和巨大潜力.以金川矿床为实例,提出了这类矿床沿含矿岩浆通道开展深部找矿的策略和方法.     

A review of the stratigraphy of Marwar Supergroup of west-central Rajasthan

The lithostratigraphy, depositional environment and age of the Marwar Supergroup have been reviewed in the light of report of δ¹³C depletion recorded in the carbonates of the Bilara Group (middle part of Marwar Supergroup) and discovery of trilobite-like trace fossils from the ·Red bedsŽ of Nagaur Group (upper part of Marwar Supergroup). The δ¹³C depletion observed in Bilara carbonates is not a result of glaciation rather due to rapid burial and poor water circulation in the low energy water of the protected basin. Secondly, the trace fossils are, in fact, traces of notostracan crustaceans found in shallow fluvial and shallow lacustrine environment. The present paper also records a spiral, burrowing trace-fossil, possibly Gyrolithes, from a cross-bedded sandstone of the Jodhpur Group.     

采场底板突水机理的跨层拱结构模型

开采华北型煤田受底板承压水威胁的煤炭资源,必须对底板围岩的破坏规律有所认识。为了弄清底板岩层的活动规律,利用实验室大型非线性三维计算机数值模拟,对煤层底板应力分布特征进行了研究。发现采场底板存在跨层拱结构,并指出跨层拱是承载地应力和水压的承载结构;通过理论计算,得出了跨层拱最大主应力的计算公式,据此可以得出底板岩层裂隙产生的位置,该成果可对华北型煤田受承压水威胁矿井的回采工作面宽度设计提供参考。      

Evaluation of impact of industrial effluents on intertidal sediments of a creek

A large amount of material in the form of industrial effluents and urban sewage containing metal contaminants directly enters Dudh creek. Metals on entering the creek tend to settle at the bottom and become part of the sediments. The distribution of metals with depth reflects changes in their supply as well as diagenetic modifications with time. In the present study, an attempt has been made to understand the impact of waste discharged from Tarapur Maharashtra Industrial Development Corporation on Dudh creek. Two cores were collected, one close to the creek mouth and the other in the inner part of the creek. Sediment component, organic carbon and metal (vanadium, copper, nickel, lead, zinc, manganese, iron and aluminium) analyses were carried out on the two cores. The variation in the distribution of sediment components with depth reflects changes in hydrodynamic condition of the creek over the years. Increase in concentration of most of the metals in the upper part of the cores indicates additional input in recent years. The core collected in the inner part of the creek showed higher metal and organic carbon concentration as compared to the downstream core. This was very well supported by distribution of points on an isocon plot. Enrichment factor and index of geoaccumulation were used to find the extent of pollution in sediments of the creek. Correlation and R-mode factor analysis have also been computed to understand the association and source of metal input in sediments of Dudh creek.     

Address of the retiring President of the International Association of Sedimentologists: Differences in size distributions of populations of particles among sands of various origins

This address reminisces and reflects on a subject in which I have been involved for more than twenty years: the effect of depositional processes on various parameters of the size-frequency distribution of sands. Movements of air and water generally separate particles by their sizes; the distribution of sizes relates to (1) the availability of different sizes of particles in a parent material, (2) processes operating where the sediments are deposited, particularly the competency of flow, and (3) concentrations of particles in suspension. Differences in size-frequency distributions among sands correlate with various origins, that is with their terminal depositional environments. Reminiscences in this address express my personal experience, both its up and downs, in advocating the study of this relationship, particularly in applying the method of moments on the basis of the concept that one statistical function expresses the characteristics of the population of particles. This address re-emphasizes some points made in previous studies (Friedman, 1961, 1962b, 1967) on the interrelationship between textural parameters and depositional processes for beach, dune, and river sands and then complements and supplements data which have not been presented before. These new data are grouped on scatter plots for sands of various origins. Finally, this address displays on maps regional trends of process-induced changes in size distributions of populations of particles in sands of four different settings: (1) a beach-dune setting, as exemplified by Padre Island, Texas, on the shores of the Gulf of Mexico; (2) a point-bar setting in the Arkansas River of Oklahoma; (3) a continental shelf-slope setting in the Gulf of Mexico off Louisiana, Mississippi, and Alabama; and (4) a continental shelf setting of the western Atlantic Ocean off New Jersey. This address concludes with the observation that the distribution of particles in sands will be influenced by the conditions that determine what happens in the depositional environment, hence statistical parameters that define the size-frequency distribution may be related to formative process.     

震后沟道泥石流启动条件——松散堆积体雨中失稳的水力学机制分析

5.12地震导致大规模的松散崩滑物质堆积于沟道,极大的增加了震后降雨型沟道泥石流爆发的概率。然而,灾后特殊的物源条件和成灾环境改变了传统沟道泥石流的形成机制,给震后沟道泥石流的防治工作带来了巨大的困难。为此,以水文学为基础,在构建松散堆积体潜水位变化水文学模型的前提下,借助水力学理论,分析了沟道堆积体内水力随潜水位变化的规律和特征,研究作用在单元条块堆积体上静水压力和动水压力的计算方法。在合理分段沟道松散堆积体的前提下,基于无限边坡理论完成了对各段堆积体下滑力、基底抗滑力及剩余下滑力的表达构建。结合算例解析了震后降雨条件下堆积体失稳的力学机制。分析表明,震后沟道松散堆积体失稳启动并泥石流化是流域降雨作用下堆积体内潜水位不断抬升、水力环境不断劣化的结果。流域大、沟道窄、堆积深、导水系数小、沟床缓的堆积体因较高的潜水位更易在降雨中失稳,且失稳模式因条块间剩余下滑力差异而分为整体推移启动及解体牵引启动两类。     

Assessment of Liquefaction Potential of the Sediments of Chandigarh Area

Assessment of the liquefaction potential is one of the important aspects for earthquake hazard assessment. Liquefaction in the sediments during earthquake events may cause significant ground deformation, which in turn, may lead to significant structural damages to civil or engineering structures, further leading to loss of life and property. Liquefaction in sediments occurs in specific geological and geoenvironmental conditions under the influence of a certain level of earthquake shaking.In this paper an assessment of the liquefaction potential of the sediments present in and around Chandigarh has been made. The sub-surface disposition and geotechnical properties of the sedimentary units mapped and depth wise probed by drilling 24 shallow boreholes prima facie indicates susceptibility of interlayed sequence to liquefaction. The conditioning factors and geoenvironmental conditions essential for occurrence of liquefaction have been integrated and analysed to determine potential areas for liquefaction around the Union Territory of Chandigarh with respect to different levels of ground acceleration values expected in the area due to earthquake events.     

Characteristics of Sources of Oils of Romashkino Field by Composition of Saturated and Aromatic Biomarkers

Composition of saturated biomarkers revealed the presence of at least two sources of oils of the Romashkino field with the monotypic conditions. All the studied oils are characterized by presence of a large number of components—anoxia testifiers in the photic layer of sedimentation basin in the fractions of aromatic compounds. These are products full or partial hydrogenation, cyclization and degradation of polyene compounds. Total content of this group of compounds is measured in these fractions for the first time. It is shown that the total content of the anoxia testifiers is high. Thus the specific characteristic of oil source rocks is defined—their formation in the conditions of existence of anoxia in the photic layer during the entire accumulation time of initial organic matter, and the thickness of the layer infected with hydrogen sulphide was significant. On the basis of composition and content of the anoxia testifiers it is shown that the hydrogenation of initial polyenes prevailed in diagenesis over the processes of cyclization.     

青藏高原中部地面蒸发量观测计算与特征分析

青藏高原中部地区地面蒸发过程主要发生于５－１０月，７月蒸发最为剧烈。与其它因子相比较，地面蒸发量与水面蒸发量相关关系最好，与潜在蒸发量相关关系次之。下垫面条件对地面蒸发量影响很大，冻结与冻结地表面蒸发量可相关２－３倍。与更为干旱的高原西部的天山地区的研究成果相比，该区稀量蒸发能力的指标的实际蒸发量均要高出许多。     

Radiogeochemical studies of the features of radionuclide distribution at the sites of dumping of radioactive wastes of the Novaya Zemlya Archipelago

This paper presents the results of the studies performed from aboard the R/V Akademik Boris Petrov of the Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, in 2002–2004 aimed at surveying the sites of dumping of potentially dangerous objects in Stepovoy, Abrosimov, and Tsivol’ka bays of the Kara Sea. These studies coupled the instrumental facilities of acoustic survey with the visual examination of the objects recovered and also included sampling of the bottom sediments and near-bottom water in the vicinity of the objects and away from them. Subsequently, the samples collected were analyzed using direct gamma spectrometry and radiochemical concentrating selected radionuclides. This allowed us to obtain a statistically reliable database on the specific concentrations of radionuclides (cesium, strontium, cobalt, and plutonium) in the water column and in the bottom sediments. In selected parts of Stepovoy and Abrosimov bays, at the sites where containers were located, local areas with contaminated bottom sediments were registered in the immediate vicinity of the objects, in which significant concentrations of Cs-137 were detected. We also carried out experiments with the samples of the collected bottom sediments on the determination of the kinetic parameters of sorption in the sediment-solution system using the method of radioactive indicators. Taking into account the hydrological conditions, the results obtained allow one to explain particular features of radioactivity distribution in selected aquatic areas. Based on a comparison between the results of the studies performed in 1992–1994 and 2002–2004, we estimated the dynamics of the changes in the mean level of specific concentrations of radionuclides in the regions of the location of sunken objects in shallow-water bays of the Novaya Zemlya Archipelago. The registration of elevated concentrations of corrosive elements in the surface layers of the bottom sediments in these zones suggests a necessity of a multidisciplinary study consisting of regular repeated measurements at reference points in different areas aimed at before-the-fact prevention of possible leakages of radioactive substances from the sunken objects, which might result in a significant contamination of the environment. Original Russian Text ? O.V. Stepanets, L.A. Kodina, A.N. Ligaev, A.P. Borisov. G.Yu. Solov’eva, 2006, published in Geokhimiya, 2006, No. 12, pp. 1315–1324.