Kinematics and Age of the Orogen‐Perpendicular Shkoder‐Peja Normal Fault in North Albania Constrained by Fault‐Slip Data, Raman Spectroscopy and K‐Ar Fault‐Gouge Dating

Abstract The Shkoder‐Peja Normal Fault (SPNF) is the largest orogen‐perpendicular fault on the Balkan Peninsula, separating the Dinarides fold‐and‐thrust belt in the north from the Hellenides in the south. It has accommodated orogen‐parallel extension during clockwise oroclinal bending of the Hellenic segment and juxtaposes Adriatic shelf successions in its footwall against obducted ophiolites in its hanging wall. Despite its length of at least 100 km, it is still an improperly understood fault. In this study, we combine results of geological mapping of a c. 13 km swath along the fault segment in Northern Albania with fault‐slip data, Raman spectroscopy of carbonaceous matter (RSCM) and K‐Ar dating of fault gouges to better constrain its kinematics and age. Our results provide evidence of top‐to‐the SSE extension across the SPNF, post‐dating Eocene nappe stacking and truncating nappe‐internal folds within the footwall. Illite crystallinity and RSCM data suggest that epizonal versus anchizonal conditions were reached in the footwall and hanging wall units, respectively. K‐Ar dates of various grain size fractions (2–6, <2 and <0.2 μm) from fault gouges yielded ages between 47 and 106 Ma. Since these ages overlap with the minimum depositional ages of the stratigraphically youngest unit in the footwall, they are interpreted as mixed detrital and authigenic illite ages. Modeled ages for a pure authigenic illite fraction range between c. 34.4 and 6.2 Ma. As minimum temperatures of c. 100°C are required for the formation of authigenic illite, younger or even still ongoing fault activity at lower temperatures is likely.