Venez partager notre savoir-faire. IOS Services Géoscientifiques offrira trois présentations orales à la Réunion Conjointe AGU-CGU-GAC-MAC au Palais des Congrès de Montréal, Québec, du 4 au 7 mai 2015. Réjean Girard présentera deux conférences : « XRF-portatif : Un outil décisionnel et un exemple d'application sur un succès d'exploration : La Découverte de Ressources Sirios sur le projet aurifère Cheechoo », le mercredi à 11 h 15 et « Le contrôle de la qualité : Une attitude essentielle pour les professionnels de la géoscience », le jeudi à 9 h 15. Également, Valérie Lecomte présentera « Caractérisation du partitionnement des métaux dans les sols par cartographies de distribution des éléments chimiques à l’aide d’un microscope électronique à balayage MEB-EDS-SDD : Applications en géochimie d'exploration et en environnement », le mardi à 11 h 45. (Résumés disponibles en anglais ci-dessous)

IOS tiendra aussi un kiosque dans la salle des exposants pour répondre à toutes vos questions et vous en apprendre plus sur nos dernières innovations.

La Réunion Conjointe est une plateforme unique pour tous les scientifiques et chercheurs du Canada et des États-Unis afin de se retrouver dans un contexte amical. Avec plus de 2000 participants, la conférence couvre tout le spectre des sciences de la Terre et de l’Espace, tout en étant suffisamment petite pour offrir une forte collaboration. En plus d’un programme scientifique élaboré, les conférenciers pourront participer à des excursions, formations et ateliers portant sur plusieurs sujets qui seront suscités l’innovation et les discussions. (traduction libre : http://ja.agu.org/2015/)

Au plaisir de vous rencontrer à Montréal!

Résumés:

HH-XRF : A decision tool for exploration success, the example from Sirios' gold Cheechoo project

Hand held X-ray fluorescence analyzer (HHXRF) were made available to mineral exploration industry about 10 years ago, and then regarded as high-tech toy for gizmo lovers, trigging dreams of exploration efficiency. However, when properly used, HH-XRF analysers are powerful decision making tools. As example, a HH-XRF has been used in the course of a humus geochemistry program where provided quick analyses, although of lesser quality, prior that sample being to submitted for conventional ICP-MS assaying. Although definitively less sensitive and accurate, HHXRF detected reliably the presence of the main pathfinder elements for gold, such as arsenic, tungsten and cobalt. Obtaining fast results enabled Sirios Resources to convey an effective prospecting program upon the detected anomaly within the same summer. HH-XRF lead to the discovery of the first gold bearing occurrence on their Cheechoo project located in James Bay, northern Québec. All the significant anomalies were subsequently confirmed by ICP-MS analysis after Na-pyrophosphate digestion. Anomalies were related to minutely disseminated pyrite, arsenopyrite and scheelite in subjacent bedrock, barely distinguishable by the naked eyes, and grams per ton gold grades. Although HHXRF has not detected subtleties, it proved effective to detect the major signatures, and saved almost a year in the exploration cycle. A review of the analytical results and reliability, with inter-elements and inter-methods comparison will be presented. The Cheechoo project host a broad low-grade gold mineralization hosted within an Archean tonalite near Goldcorp's Eleonore mine, a context interpreted as a reduced intrusion hosted deposit. This type of mineralization is notorious for being difficult to detect.

Quality control : An indispensable mindset in professional geosciences

Implementation of a quality control program (QAQC) in exploration and mining project is a compulsory requirement in regard of NI 43-101 regulation. The necessity of this requirement is easy to understand considering the capital requirement of any of these projects, the inacceptable failure rate and the general lack of understanding of the consequences of errors by geoscientists. Brief review of NI-43-101 technical reports indicates that for most geoscientists, QAQC is merely synonymous of assays control. However, the rigorousness of data acquisition and verification is a process which needs to encompass any data acquisition, from drill core description to structural measurement. As example, calculating a resource, the ultimate geologist professional act, requires the multiplication of a volume, a density and a grade. While any NI 43-101 report describe extensively the controls on assays, description of the controls on density measurements are near inexistent. Error propagation needs to be understand, as well as the consequences of total error build-up on the decision making process. Thus, quality control shall be a mindset to any geoscientist, and shall be implemented to all level of data acquisition. Geoscientist must be educated regarding how errors are generated, both by human and machine, and how to test for and quantify these. Examples of catastrophic failures caused by minute errors will be presented.

Metals partitioning in soils by scanning electron microscopy (SEM-EDX) mapping of the elements distribution: applications for geochemical exploration and environmental sciences

Soils are composed of a mixture of components that play roles in metals binding: humic substances, oxides, carbonates, charcoal, detritals etc. Deportation of trace metals between these components is still not well documented and expected to depend on variety of environmental factors. Conventional analysis methods, such as partial or sequential extractions, provide information on metals abundance related to specific components, but are likely not as selective as indicated. The current objective is to determine the metal's binding sites in anomalous soils at the microscopic scale, mostly using scanning electron microscopy (SEM) with a backscattered electron detector (BSE) and last generation energy dispersive spectrometer (EDS-SDD). The experiment was carried out on a collection of soils from sites known to show various natural or anthropogenic metal enrichments. The mapping of chemical elements distribution allowed locating different metals phases and precipitation sites, even if metals were in trace amount. High magnification imaging and microanalyses were performed to characterize the nature of the chemical signal (organic matter, oxides, clays, residual minerals, etc.). Results show, for example, that copper in humic soil dominantly precipitates on organic matter up to a saturation point, where it start precipitation as distinct authigenic sulfides, and in a lesser extent to accumulates in iron and manganese oxides. Each metal has its own distinctive behavior. For the mineral exploration industry, knowledge of the metals partitioning and dispersion mode shall improve the deconvolution of the signal in order to locate their source and discriminate true from false anomaly. In regard of environmental sciences, a better comprehension of the metals binding sites will help to anticipate the associated risk and it shall provide important information to design the appropriate decontamination or remediation methods.