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Chicoutimi, Canada

Richard S.K.,University of Quebec at Chicoutimi | Richard S.K.,555 Boulevard Of Luniversite | Chesnaux R.,University of Quebec at Chicoutimi | Rouleau A.,University of Quebec at Chicoutimi | And 3 more authors.
Hydrogeology Journal | Year: 2014

Field evidence of hydraulic connections between a bedrock aquifer and an overlying granular aquifer in the Canadian Shield (Grenville Province) is presented. This issue is rarely considered and investigated despite its important hydraulic and chemical consequences and its widespread occurrence worldwide. The methodology employed is based on complementary field tests conducted at specific experimental sites instrumented both in the rock and in the overlying deposits. One of the bedrock sites revealed a natural hydraulic connection with the overlying granular aquifer caused by the weathered surface of the uppermost bedrock. Another site revealed an artificial hydraulic connection between the bedrock and the granular aquifer created by an improperly sealed casing. A regional study showed that hydraulic connections yield an erroneous interpretation of the true hydraulic properties of the tested aquifer. The detection of hydraulic connections is therefore essential to properly define well-capture areas and contamination conditions. It is recommended to practitioners that pumping tests be performed as well as hydrochemical comparisons of each existing aquifer unit. Falling-head permeability tests are also helpful in verifying the quality of the seal at the bedrock-casing contact. More effective procedural controls and better well-construction practices are necessary to reduce the risks of cross-contamination induced by defective seals. © 2014 Springer-Verlag Berlin Heidelberg. Source


Fraser K.A.,555 Boulevard Of Luniversite | Fraser K.A.,University of Quebec at Chicoutimi | St-Georges L.,University of Quebec at Chicoutimi | Kiss L.I.,University of Quebec at Chicoutimi | Chiricota Y.,University of Quebec at Chicoutimi
Proceedings of the 4th International Conference on Particle-Based Methods - Fundamentals and Applications, PARTICLES 2015 | Year: 2015

Numerical simulation of complex industrial processes has become increasingly common in recent years. Depending on the nature of the industrial application, multiple types of physical phenomena may need to be considered as well as the interaction of multiple disjoint bodies. This paper is focused on industrial applications with large plastic deformation. Such processes are typically not well treated by finite element (FE) methods. For this reason, the smoothed particle hydrodynamics method (SPH) is used. In this work, we introduce a robust and straightforward thermo-mechanical contact algorithm for multi-physics SPH simulations in 3D. Source


Trepanier S.,555 Boulevard Of Luniversite | Trepanier S.,Redevance Auriferes Osisko Ltd. | Mathieu L.,555 Boulevard Of Luniversite | Daigneault R.,University of Quebec at Chicoutimi | Faure S.,555 Boulevard Of Luniversite
Computers and Geosciences | Year: 2016

This study proposes an artificial neural networks-based method for predicting the unaltered (precursor) chemical compositions of hydrothermally altered volcanic rock. The method aims at predicting precursor's major components contents (SiO2, FeOT, MgO, CaO, Na2O, and K2O). The prediction is based on ratios of elements generally immobile during alteration processes; i.e. Zr, TiO2, Al2O3, Y, Nb, Th, and Cr, which are provided as inputs to the neural networks. Multi-layer perceptron neural networks were trained on a large dataset of least-altered volcanic rock samples that document a wide range of volcanic rock types, tectonic settings and ages. The precursors thus predicted are then used to perform mass balance calculations. Various statistics were calculated to validate the predictions of precursors' major components, which indicate that, overall, the predictions are precise and accurate. For example, rank-based correlation coefficients were calculated to compare predicted and analysed values from a least-altered test dataset that had not been used to train the networks. Coefficients over 0.87 were obtained for all components, except for Na2O (0.77), indicating that predictions for alkali might be less performant. Also, predictions are performant for most volcanic rock compositions, except for ultra-K rocks. The proposed method provides an easy and rapid solution to the often difficult task of determining appropriate volcanic precursor compositions to rocks modified by hydrothermal alteration. It is intended for large volcanic rock databases and is most useful, for example, to mineral exploration performed in complex or poorly known volcanic settings. The method is implemented as a simple C++ console program. © 2016 Published by Elsevier Ltd. Source


Vukmanovic Z.,University of Western Australia | Vukmanovic Z.,CSIRO | Reddy S.M.,University of Western Australia | Reddy S.M.,Curtin University Australia | And 5 more authors.
Lithos | Year: 2014

Komatiite-hosted nickel sulphides from the Yilgarn Craton (Australia) consist of two main sulphide phases: pyrrhotite (Fe7S8) and pentlandite ((Fe,Ni)9S8); two minor sulphide phases: chalcopyrite (CuFeS2) and pyrite (FeS2) and trace arsenides. Samples of massive sulphides from three deposits with diverse deformation and metamorphic histories (the Silver Swan, Perseverance and Flying Fox deposits) have been studied by electron backscatter diffraction and laser ablation inductively coupled plasma mass spectrometry and nano-scale secondary ion mass spectrometry. These ore bodies were selected to investigate the relationship between microstructures and mineral trace element chemistry in three dominant sulphide species in each deposit. In all three samples, pyrrhotite preserves a strong evidence of crystal plasticity relative to both pentlandite and pyrite. The trace element composition of pyrrhotite shows significant variation in specific elements (Pb, Bi and Ag). This variation correlates spatially with intragrain pyrrhotite microstructures, such as low angle and twin boundaries. Minor signatures of crystal plasticity in pyrite and pentlandite occur in the form of rare low angle boundaries (pentlandite) and mild lattice misorientation (pyrite). Trace element compositions of pentlandite and pyrite show no correlation with microstructures. Variations in pyrrhotite are interpreted as a result of intragrain diffusion during the syn- and post-deformation history of the deposit. Intragrain diffusion can occur either due to bulk diffusion, dislocation-impurity pair diffusion, or by "pipe diffusion", i.e. along fast diffusion pathways at high and low angle, and twin boundaries. This contribution examines three different diffusion models and suggests that dislocation-impurity pair diffusion and pipe diffusion are the most likely processes behind increased trace element concentration along the microstructures in pyrrhotite. The same phenomenon is observed in samples from three different deposits that experienced widely different metamorphic conditions, implying that the final disposition of these elements reflects a post peak-metamorphic stage of the geological history of all three deposits. © 2013 Elsevier B.V. Source


Richard S.K.,University of Quebec at Chicoutimi | Richard S.K.,555 Boulevard Of Luniversite | Chesnaux R.,University of Quebec at Chicoutimi | Rouleau A.,University of Quebec at Chicoutimi | And 3 more authors.
Hydrogeology Journal | Year: 2014

Field evidence of hydraulic connections between a bedrock aquifer and an overlying granular aquifer in the Canadian Shield (Grenville Province) is presented. This issue is rarely considered and investigated despite its important hydraulic and chemical consequences and its widespread occurrence worldwide. The methodology employed is based on complementary field tests conducted at specific experimental sites instrumented both in the rock and in the overlying deposits. One of the bedrock sites revealed a natural hydraulic connection with the overlying granular aquifer caused by the weathered surface of the uppermost bedrock. Another site revealed an artificial hydraulic connection between the bedrock and the granular aquifer created by an improperly sealed casing. A regional study showed that hydraulic connections yield an erroneous interpretation of the true hydraulic properties of the tested aquifer. The detection of hydraulic connections is therefore essential to properly define well-capture areas and contamination conditions. It is recommended to practitioners that pumping tests be performed as well as hydrochemical comparisons of each existing aquifer unit. Falling-head permeability tests are also helpful in verifying the quality of the seal at the bedrock–casing contact. More effective procedural controls and better well-construction practices are necessary to reduce the risks of cross-contamination induced by defective seals. © 2014, Springer-Verlag Berlin Heidelberg. Source

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