Conditions of the accumulation of organic matter and metals in the bottom sediments of the Chukchi Sea

The chemical composition of bottom sediments in the Chukchi and, partly, East Siberian Seas was studied. In the south and west of the Chukchi Sea, a zone has been detected with the accumulation of sediments rich in organic carbon, an increased background content and anomalies of sulfophile metals (Mo, Zn, Hg, Ag, Au), iron-group metals (V, Ni, Co), and some PGE (Ru, Pt). This zone is confined to the neotectonic active system of rift troughs extending from the Bering Strait and eastern Chukchi Peninsula to the continental slope, where it is bounded by the Cenozoic Charlie rift basin of the Canadian hollow. The geochemical features of the carbon-enriched sediments evidence that they formed under oxygen-deficient conditions and, sometimes, in suboxic and anoxic environments near endogenic water and gas sources. The high carbon and metal contents suggest that the very fine-grained sediments in the rift troughs of the Chukchi Sea are a possible analog of some types of ancient highly carbonaceous sediments belonging to black shales.     

黑龙江西北部小古里河过钾质基性、超基性火山岩的发现

本文报道了黑龙江省五大连池裂谷带北端出露的一套超基性、基性的过钾质火山岩,通过详细的野外调查,确认了火山岩的喷发顺序,肯定了火山岩从基性岩向超基性岩的演变以及它们的K2O、TiO2含量不断提高的事实。在此基础上作者对超基性-过钾质岩石的岩浆成因提出了初步认识,认为它们不是岩浆结晶分异作用的产物,而是在裂谷演化构造背景下的一次独立的深源岩浆事件。本文将小古里河的过钾质火山岩和乌干达及意大利等世界上著名的钾质火山岩进行了比较。     

The design process in rock engineering

Summary The engineering design process, often systematically used in other branches of engineering, such as mechanical or architectural engineering, is seldom applied in rock engineering. While it is sometimes claimed that rock excavations are actually designed, little attention is paid to the engineering design philosophy. This paper emphasizes the need for a systematic design process in rock engineering and shows that the rock engineer can no longer claim that engineering practice mandates empiricism and rule of thumb methods. The engineering design process is described and the design approaches for rock engineering are outlined.     

Phase differentiation of matter in the sedimentary process

The paper is dedicated to the problem of material differentiation in the sedimentation zone, in mud sediments at the diagenesis stage, and at deep levels of the sedimentary cover during catagenesis. The role of academician N.M. Strakhov in substantiating the recent concept of phase differentiation and its significance for understanding ore genesis is emphasized.     

Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal

This paper describes current knowledge about the nature of and potential for thermo–hydro–mechanical–chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress–strain curve for Avro granite from the Swedish Äspö Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a ‘wall-block model’ and a ‘near-field model’. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress–strain curve for rock and for modelling the EDZ.     

Impact of geochemical barriers on the accumulation of heavy metals in urban soils

Based on multidimensional statistical models that connect the levels of contents of heavy metals and metalloids in the soils of the Eastern Administrative Okrug of Moscow with landscape and anthropogenic factors, a comparative estimation of the capacity of the complex geochemical barriers in the surface layers of urban and background soils is carried out. The share of heavy metals fixed in the urban soils due to the technogenous transformation of their physical and chemical properties, which amounted to 40–50% of the total content for Bi, Pb, Cd, Sb, As, and up to 26–30% for Zn and Cu, is calculated. The growth in the content of Bi, Sb, As, Cu, Pb, and Zn in urban soils is caused by an increase in the quantity of iron and manganese oxides. The increase in the content of Sb, As, and Pb is related to organic matter; and the rise in Bi, Cd, and Cu has resulted from the increasing amounts of the silt and clay particles in the soils, which indicates the leading role of sorption geochemical barriers. Cu, Zn, and Cd also accumulate on alkaline barriers.     

Distribution of radioactive isotopes in rock and ore of Arkhangelskaya pipe from the Arkhangelsk diamond province

The contents of radioactive elements and the uranium isotopic composition of kimberlite in the Arkhangelskaya pipe at the M.V. Lomonosov deposit and of nearby country rocks have been studied. A surplus of ²³⁴U isotope has been established in rocks from the near-pipe space. The high γ = ²³⁴U/²³⁸U ratio is controlled by the geological structure of the near-pipe space. A nonequilibrium uranium halo reaches two pipe diameters in size and can be regarded as a local ore guide for kimberlite discovery. The rocks in the nearpipe space are also characterized by elevated or anomalous U, Th, and K contents with respect to the background.     

Creep in rock as a stochastic process

The heterogeneous character of rock suggests the use of statistical mechanics for the formulation of models of plasticity and creep. A stochastic creep model which allows for large variations in strength and size of the involved rock mass is outlined. The model, which is analogous to a previously developed concept for clastic materials, is shown to account rather well for typical creep behaviour of rock at moderate stresses and temperatures. Thus, it yields the often observed linear relation between the creep strain and the logarithm of time.     

Micromechanical analysis of the failure process of brittle rock

The failure process of brittle rock submitted to a compression state of stress with different confining pressures is investigated in this paper based on discrete element method (DEM) simulations. In the DEM model, the rock sample is represented by bonding rigid particles at their contact points. The numerical model is first calibrated by comparing the macroscopic response with the macroscopic response of Beishan granite obtained from laboratory tests. After the validation of numerical model in terms of macroscopic responses, the failure process of the DEM model under unconfined and confined compression is studied in micro‐scale in detail. The contact force network and its relation to the development of micro‐cracks and evolution of major fractures are studied. Confining pressure will prohibit the development of tensile cracks and hence alter the failure patterns. An in‐depth analysis of micro‐scale response is carried out, including the orientation distribution and probability density of stress acting on parallel bonds, the effect of particle size heterogeneity on bond breakage and the evolution of fabric tensor and coordination number of parallel bond. The proposed micromechanical analysis will allow us to extract innovative features emerged from the stresses and crack evolution in brittle rock failure process. Copyright © 2014 John Wiley & Sons, Ltd.     

Petrogenesis of ultramafic-mafic to felsic plutonic rock associations from southern portion of Chhotanagpur Gneissic Complex in Central India: A multi-stage crust-mantle interaction process

A granite-granodiorite-gabbro-ultramafic rock association occurs in the southern sector of Chhotanagpur Gneissic Complex in Central India. Field relations show mingling and mixing of mafic and granodioritic magmas along the contacts of the intrusives. Petrographic studies, coupled with analyses of phase compositions and bulk rock major and trace element compositions favor origin of mafic magma from partial melting of sub-continental hybridized lithospheric mantle and subsequent two stage emplacement. Initial ponding of mafic magma at basal crust elevated the geothermal gradient so as to cause partial melting of lower crustal materials and generation of granodioritic melt. Simultaneous emplacement of granodioritic and mafic magmas tapped from basal crustal reservoir at mid-crustal depth resulted in restricted mingling-mixing along the contacts of the contrasting magma types locally producing rocks of dioritic composition. The mode of evolution of this cogenetic mafic-felsic association, when combined with available geochronological data, has important implications in demarcation of the extent of Grenvellian orogen that resulted in amalgamation of the Southern Crustal Province of India (SCP) with the Bundelkhand Craton or Northern Crustal Province (NCP).     

Heavy metals accumulation in plants growing in ex tin mining catchment

The degree of contamination by heavy metals (arsenic, copper, lead, tin and zinc) in soil and transfer to plants has been studied. Specimens of plant species from five locations in an area of 10 × 10 m were sampled with their corresponding soils. Thirty six plant species including two shallow water aquatic plants were identified. Soil and plant specimens were analyzed by using inductively coupled plasma optical emission spectrometry. It was found that metal concentration in soil was highly variable while concentration of metals in plants directly depends on the concentration of metals it was rooted. Roots showed highest metal concentration followed by leaves, shoots and flowers. Bioconcentraion factor and translocation factor were calculated, representing Cyperus rotundus L. as a potential tin-hyperaccumulator plant, previously not reported in literature. Plant Species Imperata cylindrica, Lycopodium cernuum, Melastoma malabathricum, Mimosa pudica Linn, Nelumbo nucifera, Phragmites australis L., Pteris vittata L. and Salvinia molesta, were metal accumulator while Acacia podalyriaefolia G. Don, Bulb Vanisium, Dillenia reticulate King, Eugenia reinwardtiana, Evodia roxburghiania Hk. f. clarke, Gleichenia linearis, Grewia erythrocarpa Ridl., Manihot esculenta Crantz, Paspalum conjugatum Berguis, Passiflora suberosa, Saccharum officinarum, Stenochlaena palustris (Burm.) Bedd. and Vitis trifolia Linn. were tolerated plant species. All other studied plants were excluders. Identified plant species could be useful for revegetation and erosion control in metals contaminated ex-mining sites. Morphological changes such as reduction in size, change in color and deshaping have also been observed in plant species with high metal values.     

大河超基性岩带岩体的含矿性

大河超基性岩带岩体大多呈透镜状、脉状产出,可分为南（S）北（N）两个岩带,北带又进一步划分为N-Ⅰ、N-Ⅱ亚带;N-Ⅰ亚带岩体总体属铁质超基性岩,N-Ⅱ亚带和S带中的岩体为偏镁质的超基性岩。岩带已发现有铬、镍矿体,但铬的矿化弱、矿体规模小;镍在岩带中矿化普遍,随岩体中MgO质量分数升高,镍的矿化强度也相应增加,并伴有钻、铂族等有益组分。