Sedimentology of resedimented carbonates: Facies and geometrical characterisation of an upper Cretaceous calciturbidite system in Albania

Carbonate turbidite systems are not as well studied as their siliciclastic counterparts, resulting in a lack of knowledge on their vertical and lateral organisation. Thus, a preliminary detailed sedimentological study was undertaken in the upper Cretaceous limestones of Albania, which have been described as brecciated limestones and, more recently, as calciturbidites. The sedimentological study of three outcrops (Piluri, Vanister and Muzina) allows the definition of different lithologies grading from fine- to coarse-grained sequences representing the calciturbidites, intercalated with debris flow deposits and thick slumped levels. The thin-section examination of several facies defined in the field shows a dominance of mud-rich microfacies with variable granulometry, texture (mainly wackestone to packstone and floatstone), and the mixing of bioclastic and lithoclastic grains from both shallow-water (intertidal/infratidal) and deep-water settings (slope/basin). The microfacies description and fauna determination support the gravity origin of these calciclastic limestones. According to previous studies of the Ionian Basin and the surrounding platforms, the upper Cretaceous calciturbidite system could be reasonably linked to regional tectonic instabilities in relation to the beginning of the convergence between the Africa and Eurasian plates. The lateral and vertical organisation of these carbonate gravity deposits favours a depositional model over the apron model and that these deposits were fed by material derived from either the Apulian or the Kruja platform, through faulted shelf breaks.

► Sedimentology and petrography of Upper Cretaceous calciturbidites in Albania. ► Facies and microfacies classifications of calciturbidites, debris-flow and slumps. ► Tectonism appears as the main triggering factor of the gravitary system. ► Regional tectonic instability is linked to African and Eurasian plate convergence. ► Field study favours the depositional model of slope/base of slope apron.