Mykolaiv Sands in Opole Mi nor and be yond : sed i men tary fea tures and bi otic con tent of Mid dle Mio cene ( Badenian ) sand shoals of West ern Ukraine

The Mykolaiv Sands are a huge lithosome of Mid dle Mio cene (Badenian) age, ac com mo dated within the Fore-Carpathian Ba sin in the West ern Ukraine. Typ i cally de vel oped in the area of Opole Mi nor, it spreads across ad ja cent re gions of Opole to cover an area of about 1300 km. The var ied sed i men tary struc tures and ubiq ui tous bur rows, in di cate their de vel op ment as a stack of sand shoals or re lated bod ies, up to a few tens of metres thick, some of which tem po rarily reached sea level. Amidst the shoals, storm scours in ter mit tently formed chan nel-like infills, some with re sid ual lags at the base. The re versed den sity strat i fi ca tion and/or an in creas ing grav ity gra di ent in volved mass move ments, some of which may have been trig gered by seis mic shocks fo cused at the shore or the ad ja cent hin ter land of Podolia and Volhynia. Spe cial at ten tion is paid to the di verse fos sils, all taphonomically fil tered (ar agon ite shells and chitinous car a paces be ing lost), but which lo cally are mass-ag gre gated. They typ ify par tic u lar sand sets/bod ies, to form allochthonous as sem blages, some mem bers of which (the cirripedes Scalpellum and Creusia, the shark Hemipristis, the ray Myliobatis) are newly rec og nized in the Ukrai nian part of the Fore-Carpathian Ba sin. The oth ers en rich con sid er ably the fau nal con tent of the Mid dle Mio cene (Badenian) Paratethyan bas ins, ei ther in terms of tax o nomic di ver sity, or the eco-taphonomy of se lected taxa (the star fish Astropecten, di verse echinoids). The whole fau nal con tent of the Mykolaiv Sands may owe its pro fuse de vel op ment to the global Mid dle Mio cene Cli ma tic Op ti mum of early Badenian age.