Advances in aspects of the application of magnetotellurics for mineral exploration
Notice bibliographique
Résumé
Summary world in the Earth-ionosphere waveguide. The physical T he high-frequency magnetotelluric method, audio-MT dramatically both diurnally and seasonally, and with solar (AMT), is currently being widely used for mining exploration, activity. The ionospheric layers are formed of particles that especially in Canada. However, there are st ill some aspects are electrically charged and that attenuate EM waves. The regarding its implementation that need to be considered. diurnal variation in attenuation is due the lower conductivity These range from signal detection and processing to response of the atmosphere at night because of the smaller aerosol function analysis to appreciation of three-dimensional effects. c ontent (no sun activity). This results in higher penetration of T he main natural electromagnetic source at the range of Sudbury (northern Ontario) and in northern Germany, we frequencies covered by mining scale MT, audio- frequencies have studied this diurnal variation of the magnetic field of 10 Hz - 20 kHz, is the global system of lightning. Due to amplitude at audio frequencies (Figure 1). The daytime and the physical characteristics of the Earth's ionosphere and nig httime amplitudes can vary by 2 to 3 orders of magnitude, atmosphere, there is a minimum in the electromagnetic which explains reports from several studies of an increase in spectrum around 1,000-3,000 Hz, which is exactly the signal-to-noise ratio during nighttime AMT acquisition. frequency range that is first sensitive to the presence of a typical conducting body. Some ore deposit exploration is being carried out in areas where there is existing mining activity, thus the data can be seriously affected by noise. The classical processing schemes are based on either the Fourier or the windowed Fourier transforms, and these methods do not readily separate noise from signal. The application of the wavelet transform offers an analysis of the time series at the frequency and time domains simultaneously. One of the main problems during the interpretation stage of MT data is the detection and removal of galvanic distortion effects caused by near-surface inhomogeneities. In mining exploration there is the additional problem that the targets are complicated 3D structures, and thus the classical 3D/2D decomposition schemes fail. For this reason a new 3D/3D algorithm has been designed. T arget bodies are usually complex in geometry and are strongly conductive, requiring full 3D interpretation of the data. Different structures can be inductively coupled adding a new difficulty to this geophysical method. We have undertaken analyses to check the validity of 2D interpretations over 3D regional structures. In this paper we describe our efforts in these four aspects of MT exploration. Secondly, we have verified a seasonal variation in amplitude. Source field structure
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».