GEOSCAN, résultats de la recherche


TitreElastic finite-difference modeling of volcanic-hosted massive sulfide deposits: A case study from Half Mile Lake, New Brunswick, Canada
AuteurBellefleur, G; Malehmir, A; Müller, C
SourceGeophysics vol. 77, no. 5, 2012 p. WC25-WC36,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110270
Documentpublication en série
Mediapapier; en ligne; numérique
Lat/Long OENS-66.5000 -66.0000 47.5000 47.2500
Sujetsgîtes volcanogènes; sulfures; gisements minéraux; ondes P; ondes transversales; ondes sismiques; modèles; établissement de modèles; géologie économique; géophysique
Illustrationslocation maps; profiles
ProgrammeDeveloppements methodologie, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
We present elastic finite-difference modeling results over a geologically realistic 2D representation of the Half Mile Lake volcanic-hosted massive sulfide deposit, New Brunswick, Canada. The model is constrained by geologic information from surface mapping and boreholes, whereas petrophysical properties are provided by wireline logging data acquired in two boreholes intersecting different parts of the deposit. We analyzed the P-P, P-S, S-P, and S-S responses of the lower and deep mineralized zones and assessed some compositional effects by substituting massive sulfides with gabbro properties in the model. Finitedifference modeling results predict complex scattering signature associated with the lower and deep sulfide zones. Both zones scattered back P-P, P-S, S-P, and S-S waves generally having strongest amplitudes in the stratigraphy down-dip direction. The P-S, S-P, and S-S scattered waves, if properly recorded
on multicomponent data, represent useful signal that could help the targeting of deep sulfide mineralization. Finite-difference simulations further reveal phase-reversals on P-P wavefields scattered at the lower and deep zones. The phase reversals are not observed for gabbro inclusions, suggesting that this signature could be used to discriminate gabbro units from sulfide mineralization. The finite-difference simulation successfully reproduces any events of the VSP data, in particular P-S and S-S events on the radial component and P-P and S-P events on the vertical component. Comparison with 3D data is rather poor and only shows weak correlation with P-P events from the lower and deep zones. Despite the poor correlation, a prestack time migrated S-P section displays an amplitude anomaly at the
location of the deep zone, suggesting that S-P waves were recorded on the 3D data, although this survey was acquired with explosive sources and vertical geophones.