EVOLUTION OF THE RIONI BASIN, EASTERN BLACK SEA, OFFSHORE GEORGIA, FROM THE CRETACEOUS TO THE PLIOCENE

Located in the Eastern Black Sea, offshore the Republic of Georgia, the Rioni Basin is in the western part of a foreland basin system called the Trans-Caucasus Basin which includes, the Kartli Basin in the center and the Kura Basin in the East.The Rioni basin was initiated during the opening of Trans-Caucasus basin due to back-arc rifting in Late Jurassic to Paleocene, and experienced compressional tectonics during the closure of the Northern Neo-Tethys Ocean from Early Eocene to Pliocene. It contains a late Jurassic anhydrite and two important source rock shale units: a) the Mid-Late Eocene Kura Formation, and b) the Oligo-Miocene Mykop Formation.

Although many researchers have studied the Rioni basin with respect to its source rock and oil and gas potential, there is no published comprehensive geological research on the structural and tectonics evolution of the basin history from its inception in Late Jurassic to present. We have interpreted a 3D seismic volume along with 14 2D seismic lines from the offshore Rioni basin to better understand structural development of the basin. Horizons were marked on the Lesa-9 well located on the offshore line 078815, which was then correlated to Line AGC-2017. The horizons located were the top of Pontian (violet), top of Meotian (yellow), top of Upper Sarmatian (pink), top of Cretaceous (blue), and base of Cretaceous (green). Cross correlation with other lines in the Rioni basin shows that the geology of the Rioni basin is highly faulted and complex. It is difficult to correlate these stratigraphic horizons from line to line and even within a single line, it is often difficult to correlate across the whole line.

Our initial interpretation of the 2D and 3D data suggest that along with thrusting, we have salt and shale diapirism and associated structural features within the Rioni basin. We are now working on delineating the salt diapirs from the shale diapirs using velocity modeling.