Miospore stratigraphy of Lower and early Middle Devonian deposits from Tidikelt, Central Sahara, Algeria

Abstract

The Tidikelt region forms an outstanding area for subsurface Lower Devonian stratigraphy in the central Algerian Sahara. Sediments from five boreholes have revealed abundant and diverse assemblages of miospores, acritarchs, chitinozoa, scolecodont and microplant remains. The miospores are moderately well preserved. Three new miospore species ( Dibolisporites saharansis nov. sp. Hassan Kermandji, Acinosporites conatus nov. sp. Hassan Kermandji and Scylaspora tidikeltense nov. sp. Hassan Kermandji) are described. Miospore assemblages vary through the regressive and transgressive sequences. Seven miospore assemblage biozones, including six new miospore assemblage biozones ( Scylaspora tidikeltense–Perotrilites microbaculatus, Dictyotriletes emsiensis–Emphanisporites spinaeformis, Apiculiretusispora arenorugosa–Camptozonotriletes caperatus, Verrucosisporites polygonalis–Dictyotriletes subgranifer, Emphanisporites annulatus–Geminospora svalbardiae, Hystricosporites microancyreus–Grandispora protea, Calyptosporites velatus–Rhabdosporites langii) are proposed for the Lower and early Middle Devonian rocks of Tidikelt Plateau. The combined use of distinctive, wide distribution cosmopolitan and Gondwanan forms as biozonal and species characteristics permits accurate subdivision, dating and correlation of Tidikelt successions with other similar miospore zones of the Lower Devonian of Europe, Canada and other parts of Gondwana plate. The miospore data provide new explanations to stratigraphic relationships of regional rock units, sedimentary cycles and stratigraphic hiatus. The miospore biozones are proposed as a provincial biozonation, which may also be applied to other Palaeozoic rocks of similar miospore content.