Bulletin du Service Géologique de l'Algérie
Volume 34, Numéro 1, Pages 93-118
2026-06-30
Granulite-facies Metamorphism In The Hoggar (south Algeria): A Review Of Uht And Ht Metamorphism During The Paleoproterozoic And The Neoproterozoic.
Authors : Doukkari Sid Ali . Ouzegane Khadidja . Harouz Chakib . Arab Amar .
Abstract
The Hoggar Shield in southern Algeria preserves a complex record of high- to ultrahigh-temperature (HT to UHT) metamorphism that provides valuable insights into lower crustal processes during the Paleoproterozoic and Neoproterozoic orogenic events. In the In Ouzzal terrane, early interpretations emphasized the preservation of Archean metamorphism, inferred from ca. 2.5 Ga granitic magmatism. However, recent studies combining petrology, thermodynamic modeling, and geochronology (e.g., Ouzegane et al., 2003; Aït Djafer et al., 2009; Doukkari et al., 2018) have demonstrated that a pervasive Paleoproterozoic overprint associated with the Eburnean orogeny (ca. 2.0–1.9 Ga) erased most Archean signatures. This event involved extreme crustal heating, with UHT conditions locally exceeding 1000 °C, recorded by assemblages such as sapphirine–quartz and orthopyroxene–sillimanite–spinel. Similarly, in the Central Hoggar, early models described the region as a relatively stable metacraton only weakly affected by the Pan-African orogeny. However, more recent structural, petrological, and geochronological data (Ouzegane et al., 2023, 2025; Bettioui et al., 2022) have shown that the Pan-African event caused deep reworking of the LATEA domain, including widespread HT metamorphism, crustal melting, and the emplacement of granitoids between 635 and 580 Ma. These findings reflect a major reinterpretation of the metamorphic evolution of the Hoggar, shifting the paradigm from one of tectonic stability to dynamic, multi-orogenic reactivation of the lower crust. Current research efforts now focus on constraining the duration and thermal evolution of these HT and UHT events to better understand the geodynamic processes that sustained such extreme conditions in the Precambrian crust.
Keywords
Granulite-facies, Hoggar, Paleoproterozoic, Neoproterozoic.
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