The late Cretaceous-Eocene instability of the Apulian passive margin in Albania (Kruja carbonate platform) and its impacts on sedimentation

A detailed sedimentological analysis (facies F1--F15) and a precise biostratigraphy of the Lower Cretaceous, Upper Cretaceous (CsB1--CsB7 biozones), Paleocene and Eocene are established for the shallow-water carbonates in the Kruja platform (Kulmaka massif), located along the Apulian passive margin of Albania. Two distinct periods of evolution were recognized : (1) a period of pre-Santonian stability leading to neritic inner platform sedimentation, despite the regression close to the end of the Cenomanian followed by the deepening during the Turonian recorded on other platforms of the Apulian domain; (2) a period of instability, during Upper Santonian-Upper Eocene interval, causing in "the western zone" major hiatus (16--47 Ma, and locally 60 Ma) and Eocene polygenic breccias, whereas the neritic sedimentation continued in "the eastern zone" with moderate fluctuations. This instability has also been reported for the same period in the Gavrovo platform (Greece), similar to the Kruja platform, reflecting a regional feature. This instability is attributed to strike-slip movements along NNW-SSE faults between the Kruja-Gavrovo platform and the Ionian Basin following the collision of Apulian and European plates at the Cretaceous-Eocene times. Two erosional phases are proposed for the Kulmaka massif (Kruja platform), during Upper Santonian-Upper Eocene interval. Following Upper Santonian time, strike-slip movements generated horst and grabben structures in the inner cretaceous platform and caused erosion of the cretaceous series in "the western zone" that produced up to 450 m thick slope breccias in the Ionian Basin. This instability induced a differentiation of sedimentary conditions across-strike of the platform since the Upper Maastrichtian time : pelagic in "the western zone" and neritic external platform in "the eastern zone". During Paleocene and Middle-Upper Eocene times, the second phase generated new hiatus, identified throughout the Kruja-Gavrovo platform, and polygenic breccias in "the western zone" of Kulmaka massif. The difference in sedimentation between these two zones of the massif is preserved during the Middle-Upper Eocene time. Finally, the Oligocene flysch, resulting from a major distensive event of the Alpine orogeny, cover unconformably the carbonate platform.