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Jean-Paul Liégeois
Earth Sciences
Geodynamics and mineral resources
Geodynamics and mineral resources
Publication details
Bouzeguella-Talmat, S., Bonin, B., Ouabadi, A. & Liégeois, J.P. 2014. ‘Pétrographie, minéralogie et conditions de cristallisation de la série TTG du batholite composite de l’Amsel (Hoggar central, Algérie), témoin d’un mélange de magmas’. Bulletin du Service Géologique d'Algérie 25: 243-272. Editions du Service géologique de l'Algérie. ISSN: 1010-9366. (PR).
Article in a scientific Journal / Article in a Journal
Located in the Laouni terrane (LATEA metacraton), the Pan-African Amsel composite batholith crosscuts a high-grade metamorphic Paleoproterozoic basement (2150-2060 Ma) and was emplaced along a dextral strike-slip shear-fault.
Two granitoid suites were identified, a TTG suite in the north and a granitic suite in the south.
The TTG suite is made up of amphibole biotite granodiorite mingled with amphibole tonalite, engulfing MMEs and crosscut by aplitic dykes. The granodiorite displays a granular texture and the following paragenesis: plagioclase – quartz ± amphibole – biotite – K feldspar– zircon – titanite – ilmenite – magnetite – opaques. The MMEs display a doleritic foliated texture and the following paragenesis: plagioclase ± amphibole ± quartz – biotite ± K feldspar– zircon – apatite – allanite – ilmenite – opaques.
The granodiorite crystallized at 778 ± 25°C, while MMEs crystallized at 820-773 ± 25°C. Amphibole crystallized in granodiorite at a pressure of 437-386 MPa and in MMEs at 745-255 MPa. Except a pristine dioritic enclave, MMEs correspond to different stages and/or various degrees of the mixing process. The ultimate stage is represented by the Oued Ezerzer peraluminous biotite granodiorite. Similar pressures obtained for both MMEs and their host rock suggest that mixing occurred at 405-411 MPa, under low ƒO2 conditions and at a temperature of crystallization of 778 ± 25°C, corresponding to emplacement at 15 km depth.