Pdf: http://rogov.zwz.ru/crimea/13-dec2010/krajewski%20crimea%20mt.pdf

The following paper presents the results of study on Upper Jurassic (Kimmeridgian-Tithonian)-Lower Cretaceous (Lower Berriasian) sediments in the southwestern part of the Crimean Mts. (Yalta and Ay-Petri massifs, southern Ukraine). This is the first study in this region based upon microfacies analysis. In both the Yalta and the Ay-Petri massifs 16 sequences in total were examined and sampled for the purposes of microfacies analysis, and identification of depositional environments. The studied sediments represent the Kimmeridgian, Tithonian and the Lower Berriasian. The presence of Oxfordian sediments mentioned in the literature has not been confirmed. In the studied sequences several facies varieties were recorded, representing three main stages of the Crimean carbonate platform: (i) platform slope (Kimmeridgian-Tithonian), (ii) platform margin reefs, ooidal shoals and internal platform facies (Tithonian), and (iii) open/restricted internal platform (Tithonian-Lower Berriasian). The sequences are dominated by sediments deposited in shallow subtidal environments. Moreover, numerous depositional gaps are observed along with erosional episodes and beds of siliciclastic deposits composed of material supplied from the adjacent land. In the Ay-Petri Massif depositional environments evolved into a vast platform-margin reef complex built mostly by sponges, algae, corals, microbialites and microencrusters. Ooidal-bioclastic shoals were common. The Yalta Massif is domi- nated by the internal platform sediments developed mostly as pelitic oncoidal facies. In the following chapters the author discusses development, stratigraphy and interpretation of studied sediments, in reference to the older, traditional concepts and in relation to the recent developments. The influence of tectonics on currently observed facies distribution is analysed together with the relation of the Yalta and the Ay-Petri carbonate massifs to their basement. Furthermore, some selected aspects of the existence of coral reefs in the study area and of the role of microencrusters as important reef-builders are discussed. Finally, the remarks are presented on the problems of reef complexes in both the Crimean and the Caucasus Mts.

thanks to Marcin Krajewski for pdf