Metamorphic Domes in Northern Tunisia: Exhuming the Roots of Nappe Belts by Widespread Post-Subduction Delamination in the Western Mediterranean
Metadata
Show full item recordAuthor
Booth Rea, Guillermo; Gaidi, Seifeddine; Ruano Roca, Patricia; Azañón Hernández, José Miguel; Galve Arnedo, Jorge PedroEditorial
Advancing Earth and sciences(AGU)
Date
2023-05-23Referencia bibliográfica
Booth Rea, G., Gaidi, S., Melki, F., Marzougui, W., Ruano, P., Nieto, F., et al. (2023). Metamorphic domes in Northern Tunisia: Exhuming the roots of nappe belts by widespread post-subduction delamination in the Western Mediterranean. Tectonics, 42, e2022TC007467. [https://doi. org/10.1029/2022TC007467]
Sponsorship
Ministerio de Ciencia e innovación PID2019- 107138RB-I00; P18-RT-3632 of the Junta de Andalucia,; Erasmus Mundus External Cooperation Window and by Scientific Cooperation Agreement 0534 between the Office National des Mines (ONM); The Tunis el Manar University and the Group for Relief and Active Processes Analysis (ARPA) from the University of Granada; Tunisian Company of Petroleum Activities (ETAP); Universidad de Granada / CBUAAbstract
Cenozoic extension in the Western Mediterranean has been related to the dynamics of back-arc
domains. Although, in most of its orogenic belts extension propagated into the fore-arc nappe domains. Here
we revisit the structure, metamorphism and radiometric ages of the Tunisian Tell, where HP/LT rocks (350°C at
0.8 GPa), were exhumed by the sequential activity of extensional detachments after heating and decompression
(410°C–440°C at 0.6–0.3 GPa) in a plate convergent setting. Normal faults thinning the Tunisian Tell detached
at two different crustal levels. The shallower one cuts down into the Atlas Mesozoic sequence, involving Tellian
Triassic evaporites in the hanging-wall forming halokinetic structures in the Mejerda basin late Miocene.
The deeper-detachment bounds metamorphic domes formed by marbles and metapsammites from the Atlas
domain. Illite crystallinity on Triassic rocks shows epizonal to anchizonal values, at deep and intermediate
structural depths of the Tell-Atlas nappe belt, respectively. New U-Pb 49.78 ± 1.28 Ma rutile ages from Tellian
metabasites, together with existing phlogopite 23–17 Ma K-Ar ages in Atlas marbles from the footwall of the
deepest detachment, indicate a polymetamorphic evolution. The Tell rocks underthrusted the Kabylian flysch
in the early Eocene. Further, early Miocene shortening thrusted the metabasites over lower-grade sediments,
producing HP/LT metamorphism and ductile stretching at the base of the Atlas belt. The exhumation of
midcrustal roots of Western Mediterranean nappe belts after tectonic shortening is a common feature related
to tearing at the edges of the subduction systems and inboard delamination of their subcontinental lithospheric
mantle.