@article{fdi:010064679,
  title = {{P}etrological and geochronological constraints on lower crust exhumation during {P}aleoproterozoic ({E}burnean) orogeny, {NW} {G}hana, {W}est {A}frican {C}raton},
  author = {{B}lock, {S}. and {G}anne, {J}{\'e}r{\^o}me and {B}aratoux, {L}enka and {Z}eh, {A}. and {P}arra-{A}vila, {L}. {A}. and {J}essell, {M}ark and {A}illeres, {L}. and {S}iebenaller, {L}uc},
  editor = {},
  language = {{ENG}},
  abstract = {{N}ew petrological and geochronological data are presented on high-grade ortho- and paragneisses from northwestern {G}hana, forming part of the {P}aleoproterozoic (2.25-2.00{G}a) {W}est {A}frican {C}raton. {T}he study area is located in the interference zone between {N}-{S} and {NE}-{SW}-trending craton-scale shear zones, formed during the {E}burnean orogeny (2.15-2.00{G}a). {H}igh-grade metamorphic domains are separated from low-grade greenstone belts by high-strain zones, including early thrusts, extensional detachments and late-stage strike-slip shear zones. {P}aragneisses sporadically preserve high-pressure, low-temperature ({HP}-{LT}) relicts, formed at the transition between the blueschist facies and the epidote-amphibolite sub-facies (10.0-14.0kbar, 520-600 degrees {C}), and represent a low (similar to 15 degrees {C}km(-1)) apparent geothermal gradient. {M}igmatites record metamorphic conditions at the amphibolite-granulite facies transition. {T}hey reveal a clockwise pressure-temperature-time ({P}-{T}-t) path characterized by melting at pressures over 10.0kbar, followed by decompression and heating to peak temperatures of 750 degrees {C} at 5.0-8.0kbar, which fit a 30 degrees {C}km(-1) apparent geotherm. {A} regional amphibolite facies metamorphic overprint is recorded by rocks that followed a clockwise {P}-{T}-t path, characterized by peak metamorphic conditions of 7.0-10.0kbar at 550-680 degrees {C}, which match a 20-25 degrees {C}km(-1) apparent geotherm. {T}hese {P}-{T} conditions were reached after prograde burial and heating for some rock units, and after decompression and heating for others. {T}he timing of anatexis and of the amphibolite facies metamorphic overprint is constrained by in-situ {U}-{P}b dating of monazite crystallization at 2138 +/- 7 and 2130 +/- 7{M}a respectively. {T}he new data set challenges the interpretation that metamorphic breaks in the {W}est {A}frican {C}raton are due to diachronous {B}irimian basins' overlying a gneissic basement. {I}t suggests that the lower crust was exhumed along reverse, normal and transcurrent shear zones and juxtaposed against shallow crustal slices during the {E}burnean orogeny. {T}he craton in {NW} {G}hana is made of distinct fragments with contrasting tectono-metamorphic histories. {T}he range of metamorphic conditions and the sharp lateral metamorphic gradients are inconsistent with hot orogeny' models proposed for many {P}recambrian provinces. {T}hese findings shed new light on the geodynamic setting of craton assembly and stabilization in the {P}aleoproterozoic. {I}t is suggested that the metamorphic record of the {W}est {A}frican {C}raton is characteristic of {P}aleoproterozoic plate tectonics and illustrates a transition between {A}rchean and {P}hanerozoic orogens.},
  keywords = {anatectic dome ; collision ; exhumation ; {P}aleoproterozoic ; {W}est {A}frican ; {C}raton ; {AFRIQUE} {DE} l'{OUEST} ; {GHANA}},
  booktitle = {},
  journal = {{J}ournal of {M}etamorphic {G}eology},
  volume = {33},
  numero = {5},
  pages = {463--494},
  ISSN = {0263-4929},
  year = {2015},
  DOI = {10.1111/jmg.12129},
  URL = {https://www.documentation.ird.fr/hor/fdi:010064679},
}