Geophysical methods for mapping Quaternary sediment thickness: Application to the Saint-Lary basin (French Pyrenees)

This study aims at mapping the sediment infill thickness in the Saint-Lary basin (Aure valley, French Pyrenees). For this purpose, we combine passive seismic and gravity surveys. The resonance frequencies of the sediment body are retrieved from seismic ambient measurements, while the gravimetric survey shows negative residual anomaly of about −3 mGal in the basin. Both methods reveal unexpected but consistent bedrock shape. The southern Saint-Lary basin appears deeper than its northern part, with maximal infill thickness of about 300 m and 150 m, respectively. Valley cross sections show regular and smooth “U”-shape in the southern Saint-Lary basin, in contrast to an irregular and asymmetric pattern in the northern basin. This basin shape may be related to Quaternary fluvio-glacial carving processes especially controlled by a regional fault (the Soulan fault), variations in bedrock hardness, and preferential ice flow paths.     

Visualization experiments of iron precipitates: Application for in-situ arsenic remediation

Laboratory experiments were carried out to acquire more insight and understanding of the phenomena associated with the in-situ arsenic remediation. Visualization techniques are the most informative for the detection of Fe(II) while flowing in soils. Green Rust (GR) was considered as representative of in-situ iron precipitates. In a visualization flat cell, the change in color of GR to orange, due to oxidation, was monitored by a digital camera and the images were analyzed giving the spatial and temporal distribution of Fe(II). Moreover, both oxygen and pH changes in time were recorded in two sections along the flow direction in the cell. The measured and calculated concentration profiles were compared and the actual reaction rates were predicted. The reaction rate constants measured in this study, under flowing conditions, are in a good agreement with the values obtained from batch experiments reported in the literature.     

Use of backpropagation neural network for landslide monitoring: a case study in the higher Himalaya

Static and dynamic rock slope stability analyses were performed using a numerical discontinuum modelling technique for a 700-m high rock slope in western Norway. The rock slope has been investigated by the Geological Survey of Norway (NGU), which has been carrying out rock slide studies for the county Møre and Romsdal in western Norway. The purpose of numerical modelling was to estimate the volume of the rock mass that could potentially slide under static and dynamic forces. This estimation was required to assess the run-up heights (tsunami) in a fjord that could potentially be caused by the rockslide. Three cases have been simulated for predicting the behaviour of the rock slope. First, an initial static loading is applied in the numerical model to simulate the prevailing rock mass conditions at the site. Second, saturated and weathered joint conditions are modelled by reducing the residual friction angle along the discontinuities of the rock mass. In doing so, the model simulates the effect of degradation of discontinuities in the rock slope. Third, a dynamic loading, based on peak ground accelerations expected in the area, is applied to simulate dynamic earthquake conditions.

These numerical studies have provided some useful insights into the deformation mechanisms in the rock slope. Both sliding and rotation of blocks start to occur once the residual friction angle along the discontinuities is reduced and when the region is shaken by a strong earthquake. The results indicate that, due to variations in the inclination of discontinuities, the entire slope does not become unstable and that down-slope sliding and rotation of blocks occur mainly on the top layers of the slope. Within the range of parameter values considered for this study, it is unlikely that the whole rock slope can be destabilised. The study provides an illustration of how the geo-mechanical properties of a rock mass can be integrated in a discontinuum rock slope model, which is used for predicting the behaviour of the slope under existing environmental and earthquake conditions. This model has helped not only to better understand the dynamics of the rockslide but also to estimate the potential rock volume that can become unstable when subjected to static and dynamic loads.     

Inverse method applied to a sand wedge: Estimation of friction parameters and uncertainty analysis

We examine the fundamental mechanism of frontal accretion in a sand wedge from the occurrence of a forward thrust ramp evolving into a fault-bend fold to the jump of deformation to a new frontal ramp ahead. We use inverse problem theory to extract quantitative information on friction parameters from the systematic comparison of experimental observations and theoretical predictions. The observables are locations, dips and lifetime of thrust ramps, hinge and associated compression. The experimental values (observed data) are cast into statistical models describing the error bars. The theory of limit analysis provides calculated data, requiring five parameters : material density, friction coefficient of the décollement plane, friction coefficient of the bulk material, and the variation of friction with slip on the ramp as well as the distance for this variation. The misfit between observed data and calculated data is determined for all physically admissible values of the parameters. Values yielding a small misfit are interpreted as highly probable. The mean misfit per observable is within their error bars and therefore application of the theory reproduces the observables. Bulk and décollement friction coefficient values with high probability are compared to independent measurements. The inversion also reveals systematic discrepancies: the frictional weakening on the ramps is overestimated, while the force is underestimated, the calculated thrust sheet is longer than observed and the calculated jump to a second ramp occurs earlier than observed. These conclusions allow us to identify necessary improvements for the experimental set-up and of the theoretical assumptions.     

Numerical modelling of clast rotation during soft-sediment deformation: a case study in Miocene delta deposits

A numerical model for a rotated clast in a sedimentary matrix is presented, quantifying the deformation in associated soft-sediment deformation structures. All the structures occur in a southwards prograding deltaic sequence within the Miocene Ingering Formation, deposited at the northern margin of the Fohnsdorf Basin (Eastern Alps, Austria). Debris flow and pelitic strata contain boudins, pinch-and-swell structures, ptygmatic folds, rotated top-to-S reverse faults and rigid clasts, developed under different stress conditions within the same layers. The deformation around a 24×10 cm trapezoid-shaped rigid clast, resembling the δ-clast geometry in metamorphic rocks, has been modelled using a 2D finite element modelling software. Under the chosen initial and boundary conditions the rotational behaviour of the clast mainly depends on the proportions of pure and simple shear; best fitting results were attained with a dominantly pure shear deformation (~65–85%), with stretching parallel and shortening normal to the bedding. In this specific model set-up, the initial sedimentary thickness is reduced by 30%, explained by stretching due to sediment creeping and compaction. The high amount of pure shear deformation proposed is compatible with the observed layer-parallel boudinage and pinch-and-swell structures. Rotated faults and ptygmatic folds were caused by the minor component of bedding-parallel simple shear.     

From well-test data to input to stochastic continuum models: effect of the variable support scale of the hydraulic data

The question of how well the true underlying hydraulic conductivity statistics of heterogeneous media are captured by well tests is addressed. The hydraulic conductivity value and the corresponding support volume associated with a theoretical well are correlated, causing a bias in the statistics derived from well-test analyses. Statistics derived from numerically simulated well tests are compared with the known underlying conductivity statistics and the results indicate an under-prediction by simulations at higher hydraulic conductivities. The deviation starts at about mean conductivity and can be as large as an order of magnitude, with the conductivity in the vicinity of the well defining the upper boundary. In other words, the conductivity value interpreted from the well test cannot be larger than the value that the well test first encounters. Consequently, for data in this simulation exercise, the standard deviation, if only determined for the upper range of the conductivity values, would be underestimated by a factor of 1.6–2. While this specific range is likely to depend on the scale and degree of the underlying heterogeneity as well as the duration of the test, the results should be indicative of a more general behaviour and are likely to occur in other heterogeneous data as well.

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Resumen Se plantea la pregunta de qué tan bien son representadas en las pruebas de pozo, las estadísticas reales de conductividad hidráulica subyacente de medios heterogéneos. Son correlacionados el valor de conductividad hidráulica y el volumen de apoyo correspondiente asociado con un pozo teórico, causando una distorsión en las estadísticas derivadas del análisis de la prueba de pozo. Las estadísticas derivadas de las pruebas de pozo simuladas numéricamente son comparadas con las estadísticas de conductividad subyacente conocidas, y los resultados indican una sub-predicción por las simulaciones hechas con conductividades hidráulicas más altas. La desviación empieza casi con la conductividad media y puede ser tan grande como un orden de magnitud, con la conductividad en la vecindad del pozo definiendo el límite superior. En otras palabras, el valor de conductividad interpretado a partir de la prueba del pozo no puede ser más grande que el valor que la prueba de pozo encuentre primero. Por consiguiente, para los datos en este ejercicio de simulación, la desviación estándar, si solamente fue determinada para el rango superior de los valores de conductividad, se subestimaría en un factor de 1.6–2. Mientras es probable que este rango específico dependa de la escala y del grado de la heterogeneidad subyacente, así como de la duración de la prueba, los resultados deben ser indicativos de un comportamiento más general y son probables también de ocurrir en otros datos heterogéneos.

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Résumé Nous posons ici la question de savoir dans quelle mesure les statistiques de la conductivité hydraulique des milieux hétérogènes pourrait être révélée par des essais de puits. La valeur de la conductivité hydraulique et le volume capté correspondant sont corrélés, créant un biais dans l’analyse des statistiques dérivées des essais de puits. Les statistiques en provenance de simulations numériques d’essais de puits sont comparées avec les statistiques de conductivités connues et les résultats indiquent une sous-évaluation par les simulations, pour les conductivités hydrauliques les plus élevées: la déviation commence à partir de la valeur moyenne de la conductivité et peut atteindre la magnitude d’un ordre de grandeur en considérant la conductivité mesurée au voisinage du puits. Autrement dit, la valeur de la conductivité interprétée via l’essais de pompage ne peut être plus importante que les premières valeurs rencontrées. Par conséquence, pour les données de cet exercice de simulation, la déviation standard sera sous-estimée d’un facteur compris entre 1.6–2 pour les valeurs les plus élevées. Tandis que l’échelle spécifique de valeurs est dépendante de l’échelle et du degré de l’hétérogénéité souterraine, de même que de la durée du test, les résultats pourraient être indicatifs d’un comportement plus général et seraient sans doute observables dans d’autres cas de données hétérogènes.

     

Determination of aquifer roof extending under the sea from variable-density flow modelling of groundwater response to tidal loading: case study of the Jahe River Basin,Shandong Province,China

The main task of studies on salt-water intrusion into coastal confined aquifers is to predict the position of the fresh- salt-water interface, which can be determined from the length of the aquifer roof extending under the sea. Records of groundwater level affected by tides can be used to infer hydrological conditions and determine hydraulic parameters of an aquifer extending under the sea. In this paper, a three-dimensional, variable-density groundwater flow model has been developed to determine the equivalent roof length of an aquifer extending under the sea from the tidal-effected data of groundwater level in the Jahe River Basin, Shandong Province, China. The seaward boundary is obtained by converging hydraulic head fluctuations observed in drill holes with calculated values, and the aquifer parameters in the extending zone are estimated. The impacts of aquifer roof length and aquifer parameters on the fluctuation of tidal groundwater are studied. It is concluded that the length of the aquifer roof extending under the sea should correspond with certain aquifer parameters in the extrapolation zone. Therefore, the seaward boundary determined from tidal-effect information is the equivalent boundary in hydrodynamic characteristics rather than the true boundary of the confined aquifer

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Resumen El principal objetivo de los estudios sobre intrusiones de agua salada en acuíferos costeros confinados es predecir la posición de la interfase agua dulce-agua salada, la cual puede determinarse a partir de la longitud del techo del acuífero que se extiende por debajo del mar. Los registros de niveles de agua subterránea afectados por las mareas puede utilizarse para inferir las condiciones hidrológicas y determinar los parámetros hidráulicos de un acuífero que se extiende por debajo del mar. En este artículo se ha desarrollado un modelo de flujo tri-dimensional de agua subterránea de densidad variable para determinar la longitud del techo equivalente de un acuífero que se extiende por debajo del mar a partir de datos, afectados por la marea, de niveles de agua subterránea en la Cuenca del Río Jahe, Provincia Shandong, China. El límite hacia el océano se obtiene por convergencia de fluctuaciones de presiones hidráulicas observadas en pozos con valores calculados, y se estiman los parámetros del acuífero en la zona extendida. Se estudian los impactos de la longitud del techo del acuífero y los parámetros del acuífero en la fluctuación del agua subterránea afectada por las mareas. Se concluye que la longitud del techo del acuífero que se extiende por debajo del mar debería corresponder con ciertos parámetros del acuífero en la zona de extrapolación. Por lo tanto, el límite hacia el océano determinado a partir de información de efectos de marea es el límite equivalente en características hidrodinámicas más que el límite real del acuífero confinado.

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Résumé Les sujets principaux des études dinstrusion saline dans les aquifères confinés en zone côtière sont la prédiction de la position de linterface entre leau salée et leau fraîche, qui peut être déterminée à partir de lextention du toit de laquifère sous la mer. Les enregistrements des niveaux des eaux souterraines influencés par les marées peuvent être utilisés pour préciser les conditions hydrologiques et déterminer les paramètres hydrauliques dun aquifère possédant une extension sous la mer. Dans cet article, un modèle tridimensionnel comprenant des eaux souterraines de densité variable a été développé pour déterminer la longueur équivalente du toit dun aquifère qui sétend sous la mer à partir des données concernant les effets de marée sur les eaux souterraines dans le bassin de la rivière Jahe, dans la province de Shandong, Chine. La limite de salinité est déterminée en faisant converger les fluctuations des hauteurs piézométriques avec les valeurs calculées, et les paramètres de laquifère sont estimés dans la zone sétendant sous la mer. Lincidence de la longueur de laquifère sous la mer sur les fluctuations des niveaux est étudiée. On en conclut que la longueur du toit de laquifère sous la mer peut correspondre à certains aquifères paramètres dans la zone dextrapolation. Par conséquent, la limite de salinité déterminée à partir des effets de marée est léquivalent dune limite hydrodynamique plutôt que la véritable limite de laquifère.

     

Control of rheological stratification on rifting geometry: a symmetric model resolving the upper plate paradox

Numerical experiments reproduce the fundamental architecture of magma-poor rifted margins such as the Iberian or Alpine margins if the lithosphere has a weak mid-crustal channel on top of strong lower crust and a horizontal thermal weakness in the rift center. During model extension, the upper crust undergoes distributed collapse into the rift center where the thermally weakened portion of the model tears. Among the features reproduced by the modeling, we observe: (1) an array of tilted upper-crustal blocks resting directly on exhumed mantle at the distal margin, (2) consistently oceanward-dipping normal faults, (3) a mid-crustal high strain zone at the base of the crustal blocks (S-reflector), (4) new ocean floor up against a low angle normal fault at the tip of the continent, (5) shear zones consistent with continentward-dipping reflectors in the mantle lithosphere, (6) the mismatch frequently observed between stretching values inferred from surface extension and bulk crustal thinning at distal margins (upper plate paradox). Rifting in the experiment is symmetric at a lithospheric scale and the above features develop on both sides of the rift center. We discuss three controversial points in more detail: (1) weak versus strong lower crust, (2) the deformation pattern in the mantle, and (3) the significance of detachment faults during continental breakup. We argue that the transition from wide rifting towards narrow rifting with a pronounced polarity towards the rift center is associated with the advective growth of a thermal perturbation in the mantle lithosphere.     

Quantitative Integration of High-Resolution Hydrogeophysical Data: A Novel Approach to Monte-Carlo-Type Conditional Stochastic Simulations and Implications for Hydrological Predictions

Geophysical techniques can help to bridge the inherent gap that exists with regard to spatial resolution and coverage for classical hydrological methods. This has led to the emergence of a new and rapidly growing research domain generally referred to as hydrogeophysics. Given the differing sensitivities of various geophysical techniques to hydrologically relevant parameters, their inherent trade-off between resolution and range, as well as the notoriously site-specific nature of petrophysical parameter relations, the fundamental usefulness of multi-method surveys for reducing uncertainties in data analysis and interpretation is widely accepted. A major challenge arising from such endeavors is the quantitative Integration of the resulting vast and diverse database into a unified model of the probed subsurface region that is consistent with all available measurements. To this end, we present a novel approach toward hydrogeophysical data integration based on a Monte-Carlo-type conditional stochastic simulation method that we consider to be particularly suitable for high-resolution local-scale studies. Monte Carlo techniques are flexible and versatile, allowing for accounting for a wide variety of data and constraints of differing resolution and hardness, and thus have the potential of providing, in a geostatistical sense, realistic models of the pertinent target parameter distributions. Compared to more conventional approaches, such as co-kriging or cluster analysis, our approach provides significant advancements in the way that larger-scale structural information contained in the hydrogeophysical data can be accounted for. After outlining the methodological background of our algorithm, we present the results of its application to the integration of porosity log and tomographic crosshole georadar data to generate stochastic realizations of the detailed local-scale porosity structure. Our procedure is first tested on pertinent synthetic data and then applied to a field dataset collected at the Boise Hydrogeophysical Research Site. Finally, we compare the performance of our data integration approach to that of more conventional methods with regard to the prediction of flow and transport phenomena in highly heterogeneous media and discuss the Implications arising.     

湖南某钨矿成矿规律探讨

在系统研究本区区域地质背景、矿区地质特征和矿床地质特征的基础上,通过对本区花岗岩岩石化学、微量元素等研究,确定花岗岩性质,并总结控矿地质条件,为矿山地质工作提供重要的依据。     

The Development of a new Numerical Modelling Approach for Naturally Fractured Rock Masses

Summary. An approach for modelling fractured rock masses has been developed which has two main objectives: to maximise the quality of representation of the geometry of existing rock jointing and to use this within a loading model which takes full account of this style of jointing. Initially the work has been applied to the modelling of mine pillars and data from the Middleton Mine in the UK has been used as a case example. However, the general approach is applicable to all aspects of rock mass behaviour including the stress conditions found in hangingwalls, tunnels, block caving, and slopes. The rock mass fracture representation was based on a combination of explicit mapping of rock faces and the synthesis of this data into a three-dimensional model, based on the use of the FracMan computer model suite. Two-dimensional cross sections from this model were imported into the finite element computer model, ELFEN, for loading simulation. The ELFEN constitutive model for fracture simulation includes the Rotating Crack, and Rankine material models, in which fracturing is controlled by tensile strength and fracture energy parameters. For tension/compression stress states, the model is complemented with a capped Mohr-Coulomb criterion in which the softening response is coupled to the tensile model. Fracturing due to dilation is accommodated by introducing an explicit coupling between the inelastic strain accrued by the Mohr-Coulomb yield surface and the anisotropic degradation of the mutually orthogonal tensile yield surfaces of the rotating crack model. Pillars have been simulated with widths of 2.8, 7 and 14 m and a height of 7 m (the Middleton Mine pillars are typically 14 m wide and 7 m high). The evolution of the pillar failure under progressive loading through fracture extension and creation of new fractures is presented, and pillar capacities and stiffnesses are compared with empirical models. The agreement between the models is promising and the new model provides useful insights into the influence of pre-existing fractures. Further work is needed to consider the effects of three-dimensional loading and other boundary condition problems.     

综合地球物理方法在高放废物处置场址特性评价中的应用

本介绍了地球物理方法在我国高放废物处置库场址特性评价中的作用，即查明研究区内断裂的位置，宽度，倾向，倾角及其含水性和确定预选区内花岗岩底板的埋深，此项研究成果显示了该方法在我国干旱地区的深部地质环境及水资源分布研究中的有利应用前景。     

三维可视化及物探新技术在矿山接替资源勘查中的应用——以铜陵狮子山矿田为例

在矿山发现和勘查过程中往往积累了大量地质、物探等资料,随着地质体三维可视化和物探新处理方法的发展,利用这些方法对已有资料进行深度挖掘与开发可以提炼出新的有利找矿的信息,避免工作量的重复投入,可为矿山接替资源勘查提供有力的技术支持.本研究以铜陵狮子山矿田为例,收集了其勘探阶段积累下来的地质钻探及物探资料,采用地质体三维可视化建模技术对这些资料进行了二次处理,建立了冬瓜山铜矿的三维矿床模型.在可视化环境下,分析了矿体与各成矿地质要素之间的关系,结合新处理方法对已有重磁资料再处理获取的信息,圈定出了寻找同类矿床的靶区一前冲靶区,并采用EH-4等物探方法进行了验证,通过钻探验证表明,采用三维可视化、物探处理新方法对已有资料进行深度挖掘与开发,不但可以为矿山接替资源勘查提供找矿信息,还能节约大量时间和资金.     

Installation of a vertical slurry wall around an Italian quarry lake: complications arising and simulation of the effects on groundwater flow

Slurry walls are non-structural barriers that are constructed underground to impede groundwater flow or manage groundwater control problems. The study area is in the Piemonte plain (Italy), close to the River Po. Quarrying works carried out below the piezometric surface created two big quarry lakes. The local groundwater system is characterized by a lower semi-confined aquifer, which is overlain by a semi-permeable bed of clayey peat (aquitard) and an upper unconfined aquifer. Locally, the peat fades away and the granulometry of this horizon becomes silty sandy. A planned enlargement of the quarry will increase the size and depth of the quarry lakes. So the aquitard bed between the two aquifers will be damaged, creating a mixing rate of groundwater. Such a procedure would not be compatible with the presence of two municipal wells upstream from the quarries. Consequently, the installation of a vertical diaphragm (slurry wall) is recommended to separate the aquifers and to act as a filter for the groundwater flowing from the unconfined to the semi-confined aquifer. To predict the consequences caused by the installation of the vertical diaphragm separating the unconfined aquifer and the semi-confined one, a specifically adjusted finite-difference model was used. The model showed a maximum rising of the water table equal to 12 cm, just upstream of the diaphragm and for a distance of about 100 m, and a maximum lowering of 2 cm just downstream of the diaphragm. However, the slurry wall would not cause any change in the piezometric head in the area where there are municipal wells and, hence, will not have any negative effect on the functionality of the municipal wells. Moreover, the migration of water from the unconfined aquifer through the vertical diaphragm will stimulate a series of attenuation and auto-depuration processes of eventual contaminants. These processes are due to the higher crossing time that the groundwater flow takes to go through the vertical barrier (t _a = 96.5 days, whereas for the horizontal semi-permeable layer t _a = 9.6 days). So, the vertical diaphragm can be a resolutive element, representing a mediation and separation factor between the unconfined and the semi-confined aquifers along the border of the quarrying areas, and a protective barrier for the water quality of the quarry lake and the semi-confined aquifer.     

2D rotation of rigid inclusions in confined bulk simple shear flow: a numerical study

We have used incompressible Navier–Stokes in 2D finite element modelling to investigate rigid inclusion rotation under confined bulk simple shear flow. Confinement is defined as the ratio (S) between the channel width (H) and the inclusion's least axis (e₂)(S=H/e₂). The numerical results show that (i) inclusion rotation is strongly influenced by S and, when the confinement is effective, aspect ratio (R) and shape also play an important role. (ii) Back rotation is limited because inclusions reach a stable equilibrium orientation (_se). (iii) There is also an unstable equilibrium orientation (_ue), which defines an antithetic rotation field with _se, and both _se and _ue depend on S, and inclusion R and shape.     

An analysis of the infer-aquifer recharge for a deep-seated aquifer system tapped by a wellfield

Operation of a wellfield tapping a deep-seated aquifer system depends upon the recharge from outside the aquifer system under the condition of exploitation. This kind of replenishment, however, is not learned until the wellfield is in operation and a quarry-pumping test is often needed in the investigation of the wellfield. A deep-seated confined aquifer consisting of Ordovician carbonates occurs in the Chezhoushan Syncline crossing the border of Tianjin and Hebei in northern China. The Ordovician aquifer is believed to receive recharge through leakage from the overlying Quaternary aquifer only in the northeastern part of the syncline. The Ninghebei wellfield is planned to produce 100,000 m³/day of groundwater from the Ordovician aquifer for water supply. A three-dimensional transient numerical model was established based on a hydrogeologic survey, especially a quarry-pumping test conducted in 2003. The model was calibrated with the water-level data of the quarry-pumping test and used to predict the future water-level changes that might result from the three proposed exploitation scenarios. A 20 year predictive simulation results indicate that hydraulic heads decline rapidly in the early months, decline slowly in the following years and reach a steady state in the late period with a maximum drawdown of 52.09 m under the maximum total withdrawal rate of 120,000 m³/day from the Ordovician aquifer, and that the infer-aquifer recharge through leakage from the Quaternary aquifer can balance the withdrawal rate.     

An index to represent lateral variation of the confidence of experts in a 3-D geological model

A Confidence Index is proposed that expresses the confidence of experts in the quality of a 3-D model as a representation of the subsurface at particular locations. The Confidence Index is based on the notion that the variation of the height of a particular geological surface represents general geological variability and local variability. The general variability comprises simple trends which allow the modeller to project surface structure at locations remote from direct observations. The local variability limits the extent to which borehole observations constrain inferences which the modeller can make concerning local fluctuations around the broad trends. The general and local geological variability of particular contacts are modelled in terms of simple trend surfaces and variogram models. These are then used to extend measures of confidence that reflect expert opinion so as to assign a confidence value to any location where a particular contact is represented in a model. The index is illustrated with an example from the East Midlands region of the United Kingdom.     

Improvement in the interpretation of stress measurements by use of the overcoring method: development of a new approach

Determination of the state of the initial stresses in a rock formation is still one of the most important and complex problems in geotechnics. The over-coring method of measuring the stresses is one of the measurement methods most frequently used in geotechnics. It has been shown to be highly suitable for measuring the stresses in “hard and sound” rocks. However, applied to rocks which have a partialy elastic behaviour the method comes up against many problems the biggest of which are: (1) the non-elastic behaviour of the rock; and (2) the presence of natural fractures or those caused by the overcoring operation. These problems make it impossible to obtain correct deformation measurements which can be interpreted in terms of stresses. To overcome these problems, a new method has been developed based on the use of the deformations recorded at the start of the overcoring tests this method is the subject of the present article.     

The Role of a Detachment Fault in the Spatial Distribution of Ore-Bearing Paleofluid Flows in the Central Kolyma Region: A Nonconventional Approach to Predictive Metallogenic Modeling

Geology of Ore Deposits - The Central Kolyma region is the main gold-bearing part of the Verkhoyansk–Kolyma fold-and-thrust belt. Analysis of the developed geodynamic models of fold and...