Bulletin du Service Géologique de l'Algérie
Volume 34, Numéro 1, Pages 55-75
2026-06-30
A Review Of The Hoggar Eclogites (south Algeria)
Authors : Arab Amar . Ouzegane Khadidja . Doukkari Sidali .
Abstract
The high-pressure eclogites of the Hoggar massif (Central and Western Hoggar, Algeria) record a complex Neoproterozoic tectono-metamorphic history tied to the Pan-African orogeny. These eclogites occur as lenses within diverse host rocks across several terranes (Egéré-Aleksod, Tighsi, Tassendjanet, Sérouenout) and preserve peak eclogite-facies mineral assemblages dominated by garnet, omphacite, quartz, and rutile, with retrograde symplectites marking subsequent decompression and hydration events. Thermobarometric and pseudosection analyses indicate peak conditions commonly in the range of ~19–22 kbar and ~650–750 °C, reached along a generally clockwise P–T path with near-isothermal decompression during exhumation, consistent with subduction of both oceanic and continental rift-related mafic crust followed by rapid uplift and transpression during continental collision. Geochemical signatures suggest basaltic protoliths derived from rift-shoulder settings during late Neoproterozoic extension, while isotopic and U–Pb zircon ages cluster around 680–620 Ma, recording eclogite-facies crystallization and syn-collisional exhumation. Field relationships and structural data highlight these eclogitic rocks as markers of deep crustal processes within the Tuareg Shield, representing remnants of subducted lithosphere that were later overprinted by high-temperature metamorphism and tectonic reworking. The recently obtained dataset underscores the role of the Hoggar eclogites in deciphering the dynamics of Pan-African subduction-collision cycles and Gondwana assembly in northern Africa.
Keywords
Hoggar, eclogites, P-T-t path, geochemistry, U-Pb zircon ages
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