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U–Pb dating of the end of the Pan-African orogeny in the Tuareg shield: the post-collisional syn-shear Tioueine pluton (Western Hoggar, Algeria) |
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| Authors: | J L Paquette R Caby M T Djouadi J L Bouchez |
| Institution: | a Magmas et Volcans, UMR 6524 CNRS, Université Blaise-Pascal, 5 rue Kessler, F-63038 Clermont-Ferrand, France b Laboratoire de Tectonophysique, ISTEEM et UMR 5568, Université de Montpellier II, Place E. Bataillon, F-34095 Montpellier, France c Pétrophysique et Tectonique, UMR 5563, Université Paul-Sabatier, 38 rue des Trente-six Ponts, F-31400 Toulouse, France |
| Abstract: | The Tioueine pluton intrudes the Neoproterozoic series of the Iskel terrane, located in the Tuareg shield, western Hoggar. The consistency of the internal structures as well as the nature and organization of the associated microstructures demonstrate that the Tioueine pluton was emplaced syn-kinematically while N–S strike–slip shear zones were active. The syn-tectonic emplacement of the Tioueine massif implies that this pluton, although belatedly crystallized, entirely belongs to the concept of post-collisional magmatism. In order to date precisely the late Pan-African tectono-metamorphic event in the studied area, an U–Pb age of 523±1 Ma was obtained from abraded zircons of a late quartz–syenite from the Tioueine pluton. This early Cambrian age is younger than the other plutons of the Tuareg shield, which were mainly emplaced between 630 Ma and 580 Ma. This dating also shows that the Tuareg shield was not a single coherent block at 525 Ma, but rather an amalgam of active terranes moving each other along major shear zones. Finally, the Tioueine massif represents probably the final welding of the Tuareg shield assembly of terranes and consequently the end of the post-collisional orogenic episode in the whole Pan-African belt. |
| Keywords: | Pan-African orogeny U–Pb zircon dating Taourirt plutons Granite |
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