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TitreFeasibility of virtual source reflection seismology using interferometry for mineral exploration: a test study in the Lalor Lake volcanogenic massive sulphide mining area, Manitoba, Canada
AuteurCheraghi, S; Craven, J; Bellefleur, G
SourceGeophysical Prospecting vol. 63, 2015 p. 833-848, https://doi.org/10.1111/1365-2478.12244
Année2015
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140205
ÉditeurEuropean Association of Geoscientists and Engineers
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1111/1365-2478.12244
Mediapapier; en ligne; numérique
Formatspdf
ProvinceManitoba
SNRC63K/16
Lat/Long OENS-100.1667 -100.1000 54.9000 54.8500
Sujetsgisements minéraux; activités minières; exploitation souterraine; modèles; données sismiques; prospection minière; techniques de cartographie; gîtes sulfureux
Illustrationslocation maps; geological sketch maps; graphs; cross-sections
ProgrammeDeveloppements methodologie, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
Approximately 300 hours of ambient noise data were recorded on a grid of receivers covering an area of 4 km2 over the Lalor Mine, Canada, to test the capability of seismic interferometry to image ore deposits in the crystalline rock environment. Underground mining activities create the main source of ambient noise in the area. Alongside the ambient noise survey, a larger three-dimensional active-source seismic survey was also acquired and used to evaluate the interferometry results. Power spectral density calculations show random ambient noise with a frequency range of 2 Hz - 35 Hz. A beamforming analysis identified body waves arriving from the west -northwest (pointing towards the mine) and surface waves propagating from the northeast. The calculated virtual shot gathers retrieved by cross-correlating ambient noise at all receivers were processed following both two-dimensional and three-dimensional approaches using a sequence similar to the one applied to the active-source three-dimensional data. The dip-moveout stacked section reveals a number of events similar to those observed on the processed active seismic sections. In particular, the passive seismic interferometry method is capable to partly image shallowly dipping reflections but did not produce convincing images of steeply dipping reflections. Dip-moveout stacked sections obtained with different cross-correlation time windows indicate that the strength and number of reflections generally increase with longer noise records. However, a few reflections at depth show reduced coherency with longer noise time windows. The passive seismic interferometry results over the Lalor mining area are encouraging, but image quality of the passive survey is lower than the acquired active three-dimensional survey at the area. Future ambient noise surveys with longer offsets, shorter receiver spacing, and wider azimuth distribution are needed in crystalline rock environment to address the potential of the method for mineral exploration.
Résumé(Résumé en langage clair et simple, non publié)
Nous avons étudié la possibilité d¿utiliser le bruit sismique ambiant pour générer des images de la sous-surface du gisement VMS de Lalor, Manitoba. Le bruit ambiant provient des activités minières et du village de Snow Lake situé à environ 8 km du site. Cette approche teste la complémentarité potentielle aux coûteux levés de sismique réflexion qui requièrent une source sismique anthropogénique à la surface. Les images tirées du bruit ambiant sont comparées avec les images sismiques conventionnelles disponibles dans la région et les résultats sont encourageants.
GEOSCAN ID295169