Upper Turonian-Santonian slope limestones of the Islands of Premuda, Ist and Silba (Adriatic Coast, Croatia)

Abstract

Upper Turonian-Santonian limestones at three island locations (Ist, Silba and Premuda) in the southwestern part of the Adriatic carbonate platform, record slope deposition based on their sedimentological and palaeontological characteristics. These Upper Cretaceous successions consist of three vertically superimposed lithotypes: (1) pelagic mudstonespackstones, (2) laminated pelagic wackestones-packstones, and (3) bioclastic floatstones-rudstones to packstonesgrainstones with fossils of shallow marine organisms. According to the proximity of the shallow water carbonate platform interior the depositional setting of the slope deposits could be identified as relatively more proximal or distal. The proximal part is characterized by non laminated pelagic limestones with resedimented bioclastic limestones, while the more distal parts have both laminated and nonlaminated pelagic limestones with rare resedimented bioclastic limestones. The resedimented bioclastic limestones represent slope apron deposits. Locally, at Premuda Island, the slope apron includes blocks of laminated pelagic limestones. The depositional environments of the Ist and Premuda profiles could be interpreted as of more distal origin, while those of the Silba profile represents a more proximal part of the slope.