Petrology and geochemistry of the Texenna ophiolites, northeastern Algeria: Implications for the Maghrebian flysch suture zone

This study presents the first geochemical, mineralogical and petrological data on mafic ultramafic rocks of Texenna (Lesser Kabylia, north-eastern Algeria) with aim constraining their tectonic setting in context Maghrebide belt. The magmatic-sedimentary complex comprises serpentinite, metabasites (metagabbro, metadolerite metabasalt pillow-lava structures), oceanic metasediments (radiolarite calcschists). Serpentinites consist mainly mesh textures large bastites lizardite, Cr-spinels altered to “ferritchromit” chlorite, chrysotile chlorite veins. Their features are very similar those serpentinites collected from seafloor. Pillow-lava metabasalts contain mineral assemblages albite, epidote, actinolite titanite, and, despite metamorphism, have preserved many microstructures (former glassy, variolitic spherulitic zones; former devitrification spherulites gas vesicles; pseudomorphs after phenocrysts microliths). Metadolerites metagabbros sometimes magmatic plagioclase, but generally transformed into an assemblage calcic amphiboles, epidote a typical static greenschist-facies hydrothermal metamorphism crust. Some deformation conditions phengite-bearing is linked emplacement ophiolites current during orogeny. Geochemically, whole-rock compositions indicate harzburgite protolith, while tholeiitic show N-MORB signature for pillow lavas T-MORB E-MORB affinities intrusive (metadolerites metagabbros). These results demonstrate time that belongs true ophiolitic slice sedimentary cover Maghrebian Flysch domain was deposited over rather than thinned continental analogies other Western Mediterranean region, indicating they represent remnants ancient lithosphere western Tethys (i.e., Ocean) formed between Africa Iberia Middle-Late Jurassic.