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In a complex tectonic setting, the Jurassic isolated outcrop of the Tuburnic area (Ghar Dimaou region, NW Tunisia) is considered to be the unique witness of Upper Jurassic successions from the Northern Tunisia-Algeria bordering area. The scarcity of seismic data and lack of direct datations along continuous and complete transects can allow only punctual comparisons and/ or random correlations within the South-Tethyan Margin of Tunisia and Algeria. This paper aims to update the biostratigraphy of the Upper Tithonian series of this key section on the basis of a high resolution biozonation, using calpionellids as precise biomarkers. All the calpionellid zones and subzones are identified in two sections of the Tuburnic area (NW Tunisia), one of them being described here for the first time. In both sections, the genus Chitinoidella is mentioned and the accompanying and/ or relaying hyaline calpionellid species are illustrated here for the first time. Neither the Kimmeridgian units of previous works nor their Middle-Upper Berriasian calpionellid-bearing sequences were identified. Within the whole Jurassic Tuburnic section, at least the upper part of the characteristic radiolarian-bearing biosiliceous levels, previously correlated with mimetic deposits from the Jedidi Formation of the “Tunisian Trough” (Bajocian-Callovian), are directly dated here by calpionellids as lowermost Upper Tithonian in age (Chitinoidella Zone). Long-distance correlations of the study sections with recently well-dated series from NE Algeria lead us to consider the Tuburnic area’s geodynamic setting as part of a pelagic resistant block’s southern edge. This extends from the Algerian Kabylia foreland of Northern Constantine to the Babors palaeogeographic domain. SE-NW correlations with coeval well-dated sections from Northern Tunisia allow us to consider the study section as part of the Northern Tunisia trough edge, progressively open to the Tethyan influences. A synthesis from both correlations transects, in Algeria and Tunisia, provide a basis from which to propose a regional geodynamic model.
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