Heat flow, gravity and structure of the Abitibi belt, Superior Province, Canada: Implications for mantle heat flow

Guillou, Laurent; Mareschal, Jean‐Claude; Jaupart, Claude; Gariépy, Clément; Bienfait, G.; Lapointe, Raynald

doi:10.1016/0012-821x(94)90054-x

“…The results from these methods help constrain and improve the tectonic interpretations obtained from other methods by providing information on crustal composition and thickness (through modelling). Results show a general increase of Bouguer gravity anomaly and crustal heat flux from east (Grenville) to west (Kapuskasing), whereas the mantle heat flux stays relatively constant across the different provinces and subprovinces of the southeastern Canadian Shield (10-14 mW·m -2 ; Guillou et al 1994).…”

Section: Geophysical Coveragementioning

confidence: 97%

Teleseismic studies of the lithosphere below the Abitibi-Grenville Lithoprobe transect

Rondenay¹,

Bostock²,

Hearn³

et al. 2000

Rev. Can. Sci. Terre

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Abstract:In the past decade, the Abitibi-Grenville Lithoprobe transect has been the site of numerous geological and geophysical surveys oriented towards understanding the lithospheric evolution of the southeastern Superior and adjoining Grenville provinces. Among the different geophysical methods that have been employed, earthquake seismology provides the widest range of information on the deep structures of the upper mantle. This paper presents a review of studies, both complete and ongoing, involving teleseismic datasets that were collected in 1994 and 1996 along the transect. A complete shear-wave splitting analysis has been performed on the 1994 dataset as part of a comparative study on electrical and seismic anisotropies. Results suggest a correlation between the two anisotropies (supported by xenolith data) and favour a lithospheric origin for the seismic anisotropy. The two anisotropies are believed to represent the fossilized remnants of Archean strain fields in the lithospheric roots of the Canadian Shield. Preliminary splitting results for the 1996 experiment suggest that the S-wave azimuthal anisotropy may be depth dependent and laterally varying. Ongoing receiver function analysis and traveltime inversion studies provide velocity models of the crust and upper mantle beneath the study area. Preliminary receiver function results reveal the presence of an S-velocity increase at -90-100 km depth which appears to be laterally continuous over 200 km. Traveltime inversion models indicate the presence of an elongate, low-velocity anomaly beneath the southern portion of the 1996 array which strikes obliquely to major geological structures at the surface (e.g., Grenville Front). Preliminary interpretation relates this anomaly to the same process (e.g., fixed mantle plume, continental rifting) responsible for the emplacement of the Monteregian Hills igneous province.Résumé : Au cours de la dernière décennie, de nombreuses campagnes géologiques et géophysiques ont été effectuées le long de la traverse Abitibi-Grenville du projet Lithoprobe, dans le but de comprendre l'évolution lithosphérique de la partie sud-est de la Province du Supérieur et de la Province de Grenville. Parmi les différentes méthodes géophysiques employées, la sismologie passive est sans doute celle qui procure le plus d'informations sur les structures profondes du manteau supérieur. Cet article passe en revue les études, complétées et en cours, s'appuyant sur les données télésismi-ques enregistrées en 1994 et en 1996, le long de la traverse. Une analyse complète de biréfringence des ondes S a été effectuée sur les données de 1994, dans le cadre d'une étude comparative entre l'anisotropie électrique et sismique. Les résultats obtenus suggèrent une corrélation entre les deux anisotropies (observation supportée par l'analyse de xénoli-thes), et favorisent une anisotropie sismique d'origine lithosphérique. Les deux anisotropies semblent associées à des champs de déformation archéens fossilisés dans les racines lithosphériques du Bouclier canadien...

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“…2a. Gravity and heat-flow surveys (Antonuk and Mareschal 1992;Guillou et al 1994) complete the main geophysical coverage of the study area. The results from these methods help constrain and improve the tectonic interpretations obtained from other methods by providing information on crustal composition and thickness (through modelling).…”

Section: Geophysical Coveragementioning

confidence: 99%

Teleseismic studies of the lithosphere below the Abitibi-Grenville Lithoprobe transect

Rondenay¹,

Bostock²,

Hearn³

et al. 2000

View full text Add to dashboard Cite

Abstract:In the past decade, the Abitibi-Grenville Lithoprobe transect has been the site of numerous geological and geophysical surveys oriented towards understanding the lithospheric evolution of the southeastern Superior and adjoining Grenville provinces. Among the different geophysical methods that have been employed, earthquake seismology provides the widest range of information on the deep structures of the upper mantle. This paper presents a review of studies, both complete and ongoing, involving teleseismic datasets that were collected in 1994 and 1996 along the transect. A complete shear-wave splitting analysis has been performed on the 1994 dataset as part of a comparative study on electrical and seismic anisotropies. Results suggest a correlation between the two anisotropies (supported by xenolith data) and favour a lithospheric origin for the seismic anisotropy. The two anisotropies are believed to represent the fossilized remnants of Archean strain fields in the lithospheric roots of the Canadian Shield. Preliminary splitting results for the 1996 experiment suggest that the S-wave azimuthal anisotropy may be depth dependent and laterally varying. Ongoing receiver function analysis and traveltime inversion studies provide velocity models of the crust and upper mantle beneath the study area. Preliminary receiver function results reveal the presence of an S-velocity increase at -90-100 km depth which appears to be laterally continuous over 200 km. Traveltime inversion models indicate the presence of an elongate, low-velocity anomaly beneath the southern portion of the 1996 array which strikes obliquely to major geological structures at the surface (e.g., Grenville Front). Preliminary interpretation relates this anomaly to the same process (e.g., fixed mantle plume, continental rifting) responsible for the emplacement of the Monteregian Hills igneous province.Résumé : Au cours de la dernière décennie, de nombreuses campagnes géologiques et géophysiques ont été effectuées le long de la traverse Abitibi-Grenville du projet Lithoprobe, dans le but de comprendre l'évolution lithosphérique de la partie sud-est de la Province du Supérieur et de la Province de Grenville. Parmi les différentes méthodes géophysiques employées, la sismologie passive est sans doute celle qui procure le plus d'informations sur les structures profondes du manteau supérieur. Cet article passe en revue les études, complétées et en cours, s'appuyant sur les données télésismi-ques enregistrées en 1994 et en 1996, le long de la traverse. Une analyse complète de biréfringence des ondes S a été effectuée sur les données de 1994, dans le cadre d'une étude comparative entre l'anisotropie électrique et sismique. Les résultats obtenus suggèrent une corrélation entre les deux anisotropies (observation supportée par l'analyse de xénoli-thes), et favorisent une anisotropie sismique d'origine lithosphérique. Les deux anisotropies semblent associées à des champs de déformation archéens fossilisés dans les racines lithosphériques du Bouclier canadien...

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“…Crustal models are generated by varying the Moho heat flux, the thicknesses of the lithological units, their densities and heat production rates. In the Abitibi belt of the Superior Province, only a limited number of models meet the constraints of both gravity and heat flux data, with values of Q m lying between 7 and 15 mW m −2 [Guillou et al, 1994].…”

Section: Appendix C: Variations Of the Moho Heat Fluxmentioning

confidence: 99%

“…Thus, surface heat flux variations can only be due to changes of crustal heat production, which can be related to other geophysical data on crustal structure. Gravity data have been used to further constrain lateral variations of crustal structure [Guillou et al, 1994]. Crustal models are generated by varying the Moho heat flux, the thicknesses of the lithological units, their densities and heat production rates.…”

Section: Appendix C: Variations Of the Moho Heat Fluxmentioning

confidence: 99%

Low heat flux and large variations of lithospheric thickness in the Canadian Shield

Lévy¹,

Jaupart²,

Mareschal³

et al. 2010

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[1] Ten new heat flux determinations have been made using measurements in 22 mining exploration boreholes located at latitudes higher than 51°N in the Canadian Shield. They provide data in poorly sampled regions near the core of the North American craton where one expects the lithosphere to be thickest. The new heat flux values are all smaller than 34 mW m −2 and are among the lowest recorded so far in the shield. For all the new sites, there is no relationship between heat flux and heat production in surface rocks. In the Canadian Shield, heat flux variations occur at wavelengths <100 km and are mostly of crustal origin. Local averages in two 250 × 250 km windows located on Archean areas at high latitudes on either side of James Bay are 29 mW m −2 and 31 mW m −2 , the lowest values found so far at this scale in the Canadian Shield. S wave traveltime delays derived from tomographic models provide the additional constraints needed to resolve differences of deep lithospheric thermal structure. There is no significant correlation between average surface heat flux and traveltime delays within the Canadian Shield, confirming that variations of the surface heat flux are mostly of crustal origin. Traveltime delays cannot be explained by variations in crustal heat production only and require variations of heat supply to the lithosphere and/or radiogenic heat production in the lithospheric mantle. These variations are associated with changes of lithospheric thickness that may be as large as 80 km. The heat flux at the base of the Superior lithosphere is constrained to be 11 ± 2 mW m −2 .

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Heat flow, gravity and structure of the Abitibi belt, Superior Province, Canada: Implications for mantle heat flow

Cited by 73 publications

References 37 publications

Teleseismic studies of the lithosphere below the Abitibi-Grenville Lithoprobe transect

Teleseismic studies of the lithosphere below the Abitibi-Grenville Lithoprobe transect

Teleseismic studies of the lithosphere below the Abitibi-Grenville Lithoprobe transect

Low heat flux and large variations of lithospheric thickness in the Canadian Shield

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