RT Journal Article
T1 Insights on the crustal evolution of the West African Craton from Hf isotopes indetrital zircons from the Anti-Atlas belt
A1 Abati Gómez, Jacobo
A1 Aghzer, Abdel Mouhsine
A1 Gerdes, Axel
A1 Ennih, Nasser
AB The Lu-Hf isotopic composition of detrital zircons has been used to investigate the crustal evolution ofthe northern part of the West African Craton (WAC). The zircons were separated from six samples ofsiliciclastic sedimentary rocks from the main Neoproterozic stratigraphic units of the Anti-Atlas belt,from the Sirwa and Zenaga inliers. The data suggest that the north part of the WAC formed during threecycles of juvenile crust formation with variable amount of reworking of older crust. The younger groupof zircons, with a main population clustering around 610 Ma, has a predominant juvenile character andevidences of moderate mixing with Paleoproterozoic and Neoarchean crust, which supports that mostigneous and metamorphic rocks where zircons originally crystallized were formed in an ensialic magmaticarc environment. The group of zircons in the age range 1.79–2.3 Ga corresponds to the major crustforming event in the WAC: the Eburnian orogeny. The isotopic data indicate that the provenance areashould represent a crustal domain that was separated from a mantle reservoir at ∼2050–2300 Ma, andfurther evolved with a time-integrated 176Lu/177Hf of ∼0.01, characteristic of continental crust. The evolutionof the Eburnian orogeny is, consequently, compatible with new crust formation in an island arcenvironment, the transition to a continental arc setting and a final continent–continent collision. TheLower Paleoproterozoic and Neoarchean evolution (2.3–2.75 Ga) includes a group of detrital zircon agesthat has not been identified up to now in the igneous or metamorphic rocks of the north WAC basement.Their Hf isotopic signature points to reworking of mainly juvenile Neoarchean crust with some Meso- toPalaearchean contributions. The significance of these ages is uncertain: they can represent a tectonothermalevent not discovered yet in the Reguibat Shield or the zircons can be far traveled from an unknownsource.
PB Elsevier Science B.V., Amsterdam
SN 0301-9268
YR 2012
FD 2012
LK https://hdl.handle.net/20.500.14352/44173
UL https://hdl.handle.net/20.500.14352/44173
LA eng
DS Docta Complutense
RD 25 abr 2025