The Dobrotiv Formation (Miocene) in the Boryslav-Pokuttya and Sambir nappes of the Ukrainian Carpathians: a record of sedimentary environmental change in the development of the Carpathian Foredeep Basin

Abstract

The late Early Miocene Dobrotiv Formation, a 700–800-m-thick unit, was deposited in a subsiding platform margin, which become involved in the marginal part of the Outer Eastern Carpathian accretionary wedge. The sedimentary succession from the Sloboda Conglomerate up to the Dobrotiv Formation records a transition from alluvial fan through fan-delta to deltaic deposits, followed by the fluvial plain-channel facies of the Stebnyk Formation. The deltaic deposits are mud-dominated, with poorly developed thickening-up packets of beds. Efficient sediment accumulation was balanced by subsidence caused by subsurface loading. Emerged parts of the deltaic sedimentary system include tetrapod footprints and raindrop imprints. The general absence of mudcracks in the Dobrotiv Formation suggests a humid climate. Deposits of the Sloboda, Dobrotiv and Stebnyk formations form fining- and thinning-upwards clastic wedge successions along the Ukrainian Carpathians