Fluid flow, alteration and mineralisation associated with theemplacement of the Lycian nappes (SW Turkey)

Abstract

Associated with the emplacement of the Lycian nappes, SW Turkey, Cretaceous limestones were thrusted over an ophiolitic mélange in their front zone. Miocene flysch formed immediately in front of these nappes and were overthrusted by the Lycian nappes. Petrographic and stable isotope evidence demonstrates that fluid circulation in the allochthonous limestones was rock-buffered and restricted. The thrust contact between the ophiolitic melange and the overlying limestones is characterised by an alteration with hematitisation, dolomitisation, silicification and intense calcite veining. Although this alteration indicates an upward fluid flux from the ophiolitic melange, the stable isotopic composition of the calcite veins in the altered zone does not reflect a major migration across the thrust fault. In contrast, extensive ferroan calcite veins developed in the flysch deposits as the result of the expulsion of seawater trapped in the pores during thrusting and/or sedimentation.