Global distribution of the lithosphere-asthenosphere boundary: a new look

Hamza, Valiya M.; Vieira, None Fábio

doi:10.5194/se-3-199-2012

Cited by 34 publications

(34 citation statements)

References 54 publications

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“…The value of 18 mW/ m 2 has been found to be the best-fitting average Moho heat flow for these regions (Jaupart & Mareschal, 2007). However, the study by Hamza & Vieira (2012) shows a much higher mantle heat flow, varying from 20-40 mW/ m 2 on continents to more than 40 mW/m 2 in offshore areas ( fig. 7 in Hamza & Vieira, 2012).…”

Section: Mantle Heat Flowmentioning

confidence: 95%

“…However, the study by Hamza & Vieira (2012) shows a much higher mantle heat flow, varying from 20-40 mW/ m 2 on continents to more than 40 mW/m 2 in offshore areas ( fig. 7 in Hamza & Vieira, 2012). According to Turcotte & Schubert (2002), the average continental mantle heat flow is 28 mW/m 2 , and according to Allen & Allen (2013) it is 30 mW/m 2 .…”

Section: Mantle Heat Flowmentioning

confidence: 99%

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Radiogenic heat production in the crust from inversion of gravity and magnetic data

Hokstad¹,

Tašárová²,

Clark³

et al. 2017

NJG

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Understanding heat flow and its lateral variability is important for petroleum prospecting. We present a methodology and workflow for estimation of radiogenic heat production in the crust and heat flow from geophysical data. The surface heat flow is determined by three main components: heat from Earth's interior, heat produced in the crust, and heat produced in the sediments. To estimate the crustal heat contribution, we have developed a statistical inversion approach. We first estimate density and susceptibility by inversion of crustal gravity and magnetic anomalies. Then we compute the radiogenic heat production in the crystalline crust by Bayesian rock-physics inversion of density and susceptibility. We demonstrate the proposed methodology with two case examples. In the first example, we compute radiogenic heat production from density and susceptibility measured on rock samples from onshore Norway. The estimated average value of the radiogenic heat production in the rock samples is about 2 µW/m³, with uncertainty of ± 0.5 µW/m³. The second example is from the greater Barents Sea, where we applied a full workflow including a large-scale lithospheric modelling to estimate the mantle heat flow, 3D gravity and magnetic inversion, and rock-physics inversion. The average heat production in the Barents Sea crust is about 1.5 µW/m³. The predicted heat production and heat flow are in good agreement with results presented by other authors.

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Section: Mantle Heat Flowmentioning

confidence: 95%

Section: Mantle Heat Flowmentioning

confidence: 99%

Radiogenic heat production in the crust from inversion of gravity and magnetic data

Hokstad¹,

Tašárová²,

Clark³

et al. 2017

NJG

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“…The thickness according to Hamza and Vieira (2012) has a pronounced peak of 280 km in Poland and also shows decreasing values from east to west with no distinct change in the gradient except a kind of plateau with about 180 km in northwestern Denmark. Except the decrease in lithospheric thickness from east to west, there is no other similar feature when compared to our GIA-model results.…”

Section: Figurementioning

confidence: 98%

Lithosphere and upper-mantle structure of the southern Baltic Sea estimated from modelling relative sea-level data with glacial isostatic adjustment

2014

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Abstract. During the last glacial maximum, a large ice sheet covered Scandinavia, which depressed the earth's surface by several 100 m. In northern central Europe, mass redistribution in the upper mantle led to the development of a peripheral bulge. It has been subsiding since the begin of deglaciation due to the viscoelastic behaviour of the mantle. We analyse relative sea-level (RSL) data of southern Sweden, Denmark, Germany, Poland and Lithuania to determine the lithospheric thickness and radial mantle viscosity structure for distinct regional RSL subsets. We load a 1-D Maxwell-viscoelastic earth model with a global ice-load history model of the last glaciation. We test two commonly used ice histories, RSES from the Australian National University and ICE-5G from the University of Toronto.Our results indicate that the lithospheric thickness varies, depending on the ice model used, between 60 and 160 km. The lowest values are found in the Oslo Graben area and the western German Baltic Sea coast. In between, thickness increases by at least 30 km tracing the Ringkøbing-Fyn High. In Poland and Lithuania, lithospheric thickness reaches up to 160 km. However, the latter values are not well constrained as the confidence regions are large. Upper-mantle viscosity is found to bracket [2-7] × 10 20 Pa s when using ICE-5G. Employing RSES much higher values of 2 × 10 21 Pa s are obtained for the southern Baltic Sea. Further investigations should evaluate whether this ice-model version and/or the RSL data need revision. We confirm that the lower-mantle viscosity in Fennoscandia can only be poorly resolved.The lithospheric structure inferred from RSES partly supports structural features of regional and global lithosphere models based on thermal or seismological data. While there is agreement in eastern Europe and southwest Sweden, the structure in an area from south of Norway to northern Germany shows large discrepancies for two of the tested lithosphere models. The lithospheric thickness as determined with ICE-5G does not agree with the lithosphere models. Hence, more investigations have to be undertaken to sufficiently determine structures such as the Ringkøbing-Fyn High as seen with seismics with the help of glacial isostatic adjustment modelling.

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“…(e) Estimates to the depth of the lithosphere-asthenosphere boundary (LAB). Contoured are those of the spherical harmonic model of Hamza and Vieira (2012), and the circles are those of Artemieva (2006), both based on thermal arguments (depth to 1300°C from Artemieva's model TC1). The diamonds are the petrologically derived ones of Snyder and Grütter (2010) based on analyses of xenoliths brought to the surface in kimberlites.…”

Section: Lithosphere-asthenosphere Depth Estimatesmentioning

confidence: 99%

“…2e. The contoured LAB depth estimates for Canada come from the spherical harmonic global model of Hamza and Vieira (2012) (Perry et al 2010, andpersonal communication, 2013) (squares). The SHF data were contoured using GMT Smith 1991, 1998) Gripp and Gordon's (2002) model (red arrows), from GPS (blue and green arrows) and DORIS (black arrows) observations (see text for details).…”

Section: Lithosphere-asthenosphere Depth Estimatesmentioning

confidence: 99%

The electrical resistivity of Canada’s lithosphere and correlation with other parameters: contributions from Lithoprobe and other programmes

et al. 2014

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Over the last 30 years, through Lithoprobe and other programmes, modern, high-quality magnetotelluric (MT) measurements probing deep into the lithosphere and underlying asthenosphere have been made at over 6000 sites across Canada in all provinces and territories, except Nova Scotia. Some regions are well covered, particularly Alberta, southern British Columbia, and western Ontario, whereas others remain poorly covered, such as Quebec and large swaths of Nunavut. Prior publications from individual studies have added significantly to the wealth of Canada's geoscience knowledge, and have demonstrated that MT can contribute significantly to understanding of the tectonic processes that have shaped Canada. However, to date no continent-scale maps of lithospheric electrical parameters have been constructed from the extensive MT database. Herein we review the contributions made by the MT components of Lithoprobe, and present new continental-scale maps of various electrical parameters at crustal and upper mantle depths for the whole of Canada. From those maps, combined with regional estimates of temperature, we develop derivative information on petrological-geophysical properties, including predictions of temperature and water content. We find that at 100 km depth the Canadian Shield is cold and dry, and the Cordillera is warmer but mostly dry, i.e., little water is present in the peridotite. Exceptions are beneath the Prairies, the Wopmay Orogen, and northeast Nunavut where there does appear to be water in the nominally anhydrous minerals. Also, southwest British Columbia appears colder than the rest of the Cordillera due to the subducting Juan de Fuca plate. In contrast, at 200 km depth almost all of Canada is dry.Résumé : Au cours des trente dernières années, grâce à Lithoprobe et à d'autres programmes, des mesures magnétotelluriques (MT), modernes et de grande qualité, ont été prises à plus de 6000 sites à travers le Canada, dans toutes les provinces et territoires sauf en Nouvelle-Écosse; ces mesures sondaient profondément dans la lithosphère et l'asthénosphère sous-jacente. Certaines régions sont bien couvertes, surtout l'Alberta, le sud de la Colombie-Britannique et l'ouest de l'Ontario, alors que d'autres sont mal couvertes, par exemple le Québec et de grandes parties du Nunavut. Des publications antérieures, basées sur des études individuelles, ont grandement contribué à enrichir les connaissances géoscientifiques canadiennes et elles ont démontré que les mesures MT peuvent grandement contribuer à la compréhension des processus tectoniques qui ont formé le Canada. Toutefois, à ce jour, aucune carte des paramètres électriques lithosphériques, à l'échelle du continent, n'a été construite à partir de la vaste base de données MT. Dans le présent article, nous revoyons les contributions des composantes MT de Lithoprobe et nous présentons de nouvelles cartes à l'échelle du continent de divers paramètres électriques aux profondeurs de la croûte et du manteau supérieur pour l'ensemble du Canada. À partir de ces cartes, ...

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Global distribution of the lithosphere-asthenosphere boundary: a new look

Cited by 34 publications

References 54 publications

Radiogenic heat production in the crust from inversion of gravity and magnetic data

Radiogenic heat production in the crust from inversion of gravity and magnetic data

Lithosphere and upper-mantle structure of the southern Baltic Sea estimated from modelling relative sea-level data with glacial isostatic adjustment

The electrical resistivity of Canada’s lithosphere and correlation with other parameters: contributions from Lithoprobe and other programmes

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