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Jurassic facies units and environmental changes on the northeastern margin of the Adriatic Carbonate Platform (Sošice, Žumberak Mt., Croatia)

The Jurassic carbonate succession of the Sošice section (Žumberak Mt.) can be divided into eight facies units whose sedimentary features suggest platform to basin transition. The first three Lower Jurassic facies units consist of numerous coarsening-upward cycles that were deposited on the shallow carbonate platform of the Adria microplate as a consequence of periodic changes of sea-bottom conditions around the fair-weather wave-base. Due to late Early Jurassic extensional tectonics in the Neo-Tethyan region, the Adria microplate disintegrated and several smaller platforms came into being, the Adriatic carbonate platform was one of them. The separation of the Adriatic carbonate platform was followed by the simultaneous opening of the Dinaridic branch of the Neo-Tethys on its northeastern side, resulting in extensional faulting that played a major role in the development of next four successive facies units. These were formed during the late Early Jurassic to Late Jurassic. By that, the first two were deposited on the platform upper foreslope, while the other two were formed in the toe-of-slope environment. As the platform margin gradually shifted southwestward as a consequence of progressive extensional faulting, the basin area spread over the sunken part of the platform and platform slope, when the last facies unit of basin realm was formed during the Jurassic/Cretaceous transitional period. Acknowledgements: This work represents a part of the BSc Thesis of the second author and was supported by the Ministry of Science, Education and Sports of the Republic of Croatia, through the Project No. 119-1191152-1171

Jurassic; facies units; Adriatic carbonate platform; platform to basin transition; Sošice; Žumberak Mt.; Croatia

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