Structural complexity inferred from anisotropic resistivity: Example from airborne EM and compilation of historical resistivity/induced polarization data from the gold-rich Canadian Malartic district, Québec, Canada

This paper is © 2019 Society of Exploration Geophysicists. The posting is available free of charge and its use is subject to the SEG terms and conditions: https://seg.org/Terms-of-UseStructurally complex zones within orogenic terranes typically correspond to areas where there is interference between multiple fold generations and are known to be favorable pathways for fluid flow because of their higher permeability. In the Canadian Malartic district, gold anomalies have been linked with zones of structural complexity that have been quantified by outcrop bedding orientation measurements and calculation of bedding variance maps. In this work, historical apparent resistivity and induced polarization data in the Canadian Malartic district were reprocessed and combined with new surveys to create a compilation of inverted chargeability and resistivity, which were then interpreted together with airborne electromagnetics and outcrop structural data. The results indicate chargeability anomalies, up to five times the background value, associated with the sulfide mineral content in monzodioritic dikes that are thickened in folds and hydrothermally altered. Although the airborne apparent half-space resistivity is mostly sensitive to conductive surficial cover, the inverted ground resistivity method is sensitive to deeper structure and likely represents bedrock signal at depths greater than 25 m. Inverted ground resistivity exhibits strong anisotropy in areas of subvertical bedding, where measured resistivities can vary by up to a factor of two, over the same location, depending on whether the survey lines are perpendicular or parallel to the strike of bedding. This result is observed at scales of 50 cm up to 100 m. Analysis of inverted ground resistivity together with bedding variance indicates a strong correlation between structurally complex zones with high bedding variance and a decrease in resistivity at depths greater than 25 m. This suggests that in places where the presence of disseminated gold cannot be directly detected, or where the outcrop exposure is limited due to overburden cover, geophysical data may still succeed in identifying structural complexity zones that could potentially host mineralization.Natural Sciences and Engineering Research Council of Canada and the Canada Mining Innovation Council (NSERC-CMIC Mineral Exploration Footprints Project Contribution 178

Integrated Multi-Parameter Exploration Footprints of the Canadian Malartic Disseminated Au, McArthur River-Millennium Unconformity U, and Highland Valley Porphyry Cu Deposits: Preliminary Results from the NSERC-CMIC Mineral Exploration Footprints Research Network

Mineral exploration in Canada is increasingly focused on concealed and deeply buried targets, requiring more effective tools to detect large-scale ore-forming systems and to vector from their most distal margins to their high grade cores. A new generation of ore system models is required to achieve this. The Mineral Exploration Footprints Research Network is a consortium of 70 faculty, research associates, and students from 20 Canadian universities working with 30 mining, mineral exploration, and mining service providers to develop new approaches to ore system modelling based on more effective integration and visualization of multi-parameter geological-structural-mineralogical-lithogeochemical-petrophysical-geophysical exploration data. The Network is developing the next generation ore system models and exploration strategies at three sites based on integrated data visualization using self-consistent 3D Common Earth Models and geostatistical/machine learning technologies. Thus far over 60 footprint components and vectors have been identified at the Canadian Malartic stockwork-disseminated Au deposit, 20–30 at the McArthur-Millennium unconformity U deposits, and over 20 in the Highland Valley porphyry Cu system. For the first time, these are being assembled into comprehensive models that will serve as landmark case studies for data integration and analysis in the today’s challenging exploration environment

Effects of chronic low-level copper exposure on ultrastructure of the olfactory system in rain bow trout (Oncorhynchus mykiss)

This study investigated the effects of a chronic exposure to a low level of copper on cell populations of the olfactory system in yearling rainbow trout. Fish were sacrificed after 15, 30 and 60 days of copper exposure. Transmission electron microscopy was used to describe the sequence of subcellular changes occurring in three tissues, the sensory epithelium, the olfactory nerve and the olfactory bulb. Data show that a 15-day exposure to 20 pg/l of copper causes specific degeneration of al1 mature receptor cells as well as numerous immature neurons. Moreover, degenerating receptor cells exhibited morphological features of a cell death by apoptosis. After 30 days, and more specifically after 60 days of exposure, numerous clusters of cells were observed in the basa1 region of the epithelium, suggesting a great mitotic activity in this area. In parallel, an increased number of maturing receptor cells and goblet cells were observed, but no fully mature neurons were noted even after 60 days of exposure. In both the olfactory nerve and the olfactory bulb, the number of degenerating axons and terminals, which was high at 15 days, decreased with time and some process of glomerular reinnervation was detected after 60 days. A reactive hypertrophy of supporting, ensheathing and astrocytic cells was also observed in exposed fish, which demonstrates that these cell types are actively involved in the process of tissue scarring. Even though some signs of neurona1 regeneration were reported during the time-course of exposure, indicating some fish acclimation, results raise the question of the olfactory function during such environmental stress

Mélange à quatre ondes en bord de bande d'un cristal photonique 1D

International audienc

Mélange à quatre ondes en bord de bande d'un cristal photonique 1D

Nous présentons ici une expérience de mélange à quatre ondes pour la caractérisation de non-linéarités optiques du troisième ordre dans des cristaux photoniques 1D. Nous avons montré que la structuration du matériau permettait d'augmenter l'efficacité des processus non-linéaires grâce aux propriétés de localisation de la lumière en bord de bande interdite du cristal photonique

opesci/devito: Devito-3.4

Release notes Preliminary support for MPI (no changes to user code requested) Support for staggered grids Improved compilation technology Improved Operator autotuning More powerful DSL (e.g., take derivatives of entire expressions such as (u+v).dx) More efficient pickling Misc bug fixes New modeling examples based on the elastic wave equation New examples describing aspects of the compilation technologyRelease notes Preliminary support for MPI (no changes to user code requested) Support for staggered grids Improved compilation technology Improved Operator autotuning More powerful DSL (e.g., take derivatives of entire expressions such as (u+v).dx) More efficient pickling Misc bug fixes New modeling examples based on the elastic wave equation New examples describing aspects of the compilation technology3.