LITHOFACIES FEATURES AND ACCUMULATING CONDITIONS OF MIDDLE DEVONIAN BASAL LAYERS OF DOBRUDJA FOREDEEP

The main purpose of this work is to identify lithofacies features and sedimentation conditions of basal thickness of Eifelian deposits within Biloliskyi block of Dobrudja Foredeep. Methods include lithological interpretation of geological and geophysical materials, lithofacies and sedimentological analyses. Features of lithofacies zonality of Early Eifelian deposits have been determined. It has been shown that argillaceous sulphate sediments are mostly within Sariyarsko-Zhovtoyarska and Saratsko-Balabanivska anticlinal zones and carbonate sediments are in depressions. The reconstructions of environments of their sedimentation have been done, which showed irregular character of spatial age-specific development of formations of different facial zones of sulphate carbonate shelf. The supra-littoral territory was occupied by Sariyarsko-Zhovtoyarska and Saratsko-Balabanivska uplifts and bordered with rather narrow zones of littoral and upper sublittoral. The main part of Tuzlivska and Alibeiska depressions occupied lower sublittoral. Wedge-out of horizons of upper sublittoral with biostrome in the arch uplifts has been displayed. Scientific novelty. For the first time lithofacies zonality of Early Eifelian deposits and their environments have been done. Practical significance. Displayed wedge-out of horizons with biostrome in the arch uplifts may indicate non-anticlinal nature of hydrocarbon traps in Middle Devonian deposits, thus some corrections should be done in practice of oil and gas searching of this region.