A detailed taxonomical study was carried out for the identification of encrusting micro- organisms. Among these microencrusters, Perturbatacrusta leini, Iberopora bodeuri, Calcistella jachenhausenensis, and Pseudorothpletzella schmidi have been taxonomically revealed for the first time in Turkey. Within the biostratigraphic frame of the I. nalti Formation consisting of Mesoendothyra izjumiana zone ( Kimmeridgian), Calcistella jachenhausenensis zone ( Lower Tithonian- Upper Tithonian) and Protopeneroplis ultragranulata zone ( Upper Tithonian- Berriasian), carbonate sedimentation occurred in five depositional environments comprising slope, fore- reef, reef, back- reef and lagoonal environments. The majority of the reefal deposits of the I. nalti carbonates can be classified as coral- microbial- microencruster boundstones, which frequently occur in association with back- reef and fore- reef deposits within the Kimmeridgian- Berriasian interval. A shallowing and a subsequent deepening of water depth in the Berriasian have been revealed by the examination of stacking patterns and vertical evolution of the microfacies. Based on the observed microfacies and general features of micro- encrusting organisms, it is concluded that I. nalti carbonates share many similarities with the reefal carbonate deposits of Intra- Tethyan domain in terms of microfacies types and microencruster content.