@article{fdi:010061918,
  title = {{T}hermo-mechanical modeling of lower crust exhumation-{C}onstraints from the metamorphic record of the {P}alaeoproterozoic {E}burnean orogeny, {W}est {A}frican {C}raton},
  author = {{G}anne, {J}{\'e}r{\^o}me and {G}erbault, {M}uriel and {B}lock, {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he aim of this paper is to explore the link between the metamorphic record of a {P}alaeoproterozoic 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 {B}irimian {P}rovince (2.2-2.0 {G}a) of the {W}est {A}frican {C}raton. {M}etamorphic data collected in {B}urkina {F}aso, southwest {G}hana and eastern {S}enegal suggests a {P}alaeoproterozoic {B}irimian crust dominated by moderate apparent geothermal gradients of 20-30 degrees {C}/km ({M}2a), which fit a purely conductive thermal crustal regime. {T}his produced greenschist- to amphibolite-facies metamorphic assemblages that developed during the {E}burnean orogeny (similar to 2.1 {G}a), associated with regional shortening and granitoid intrusions. {T}he {M}2a gradient is superimposed on an early thermal regime ({M}1: <10-15 degrees {C}/km) that produced high-{P} greenschist- to blueschist-facies metamorphic assemblages. {M}1 most likely recorded an earlier thermal history in the volcano-sedimentary basins where the protolith of the metamorphic terrains formed. {W}hether {M}1 is related to distributed burial associated with sediment accumulation or early subduction-related tectonics remains an open question, not directly addressed here. {T}hermo-mechanical models were built based on the assumption of an initial crust made up of a succession of volcanic island arcs emplaced on top of a basement dominated by {C}a{O}-rich {T}onalite-{T}rondhjemite-{G}ranodiorite suites ({TTG}s), and tectonically paired with sedimentary basins. {F}rom the results of these thermo-mechanical models, we propose a mechanism of burial, heating and exhumation of meta-sediments through the {B}irimian crust controlled by simultaneous folding/shortening and gravitational instabilities in the juvenile crust. {W}e postulated here the pre-existence of thick sedimentary basins (depth 15 km) in the {B}irimian orogenic crust to model the late-stage exhumation of meta-sediments, collected in the thermal aureole of {C}a{O}-poor granitoids, and which record elevated metamorphic pressures ({P} > 6-8 kbar). {A}t around 25 km depth, {TTG}s reached appropriate {PT} conditions to start melting. {T}he buoyant and low-viscosity partially molten material, comprising a fraction of {C}a{O}-poor melt and residual material, then ascended through the overlying sediments. {I}t entrained upwards lower crustal material as well as the surrounding sediments. {T}his scenario explains the important breaks in metamorphic conditions observed in the {B}irimian province between the thin slivers (<2 km thick) of high-pressure rocks ({P} > 8 kbar) preserved in the thermal aureoles of granites and the adjacent synforms of greenstones, which consist of low-grade metasediments ({P} < 6 kbar; {T} < 450 degrees {C}). {T}his scenario is in agreement with a significant recycling of the {TTG}s in the genesis of {C}a{O}-poor granitoid melts. {W}e discuss the implications of our results for the tectono-metamorphic and mechanical evolution of {P}alaeoproterozoic orogenies.},
  keywords = {{P}alaeoproterozoic orogenies ; {H}igh-pressure rocks ; {E}xhumation ; {T}hermo-mechanical model ; {W}est {A}frican {C}raton ; {AFRIQUE} {DE} {L}'{OUEST}},
  booktitle = {},
  journal = {{P}recambrian {R}esearch},
  volume = {243},
  numero = {},
  pages = {88--109},
  ISSN = {0301-9268},
  year = {2014},
  DOI = {10.1016/j.precamres.2013.12.016},
  URL = {https://www.documentation.ird.fr/hor/fdi:010061918},
}