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Elsevier, Precambrian Research, (243), p. 88-109, 2014

DOI: 10.1016/j.precamres.2013.12.016

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Thermo-mechanical modeling of lower crust exhumation-Constraints from the metamorphic record of the Palaeoproterozoic Eburnean orogeny, West African Craton

Journal article published in 2014 by Jérôme Ganne, Muriel Gerbault ORCID, S. Block
This paper is available in a repository.
This paper is available in a repository.

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Abstract

The aim of this paper is to explore the link between the metamorphic record of a Palaeoproterozoic orogeny and its thermo-mechanical evolution, in order to discuss the burial and exhumation processes of moderate- to high-pressure volcano-sedimentary rocks (6–8 to >10 kbar) in the Birimian Province (2.2–2.0 Ga) of the West African Craton. Metamorphic data collected in Burkina Faso, southwest Ghana and eastern Senegal suggests a Palaeoproterozoic Birimian crust dominated by moderate apparent geothermal gradients of 20–30 °C/km (M2a), which fit a purely conductive thermal crustal regime. This produced greenschist- to amphibolite-facies metamorphic assemblages that developed during the Eburnean orogeny (∼2.1 Ga), associated with regional shortening and granitoid intrusions. The M2a gradient is superimposed on an early thermal regime (M1: <10–15 °C/km) that produced high-P greenschist- to blueschist-facies metamorphic assemblages. M1 most likely recorded an earlier thermal history in the volcano-sedimentary basins where the protolith of the metamorphic terrains formed. Whether M1 is related to distributed burial associated with sediment accumulation or early subduction-related tectonics remains an open question, not directly addressed here.