In Selina quarry the Lower Cretaceous succession (Upper Barremian–Upper Albian) of 27 m thick deposits with two subaerial surface exposures are studied. The mineral composition, conditions of origin of the clay sediments were determined. XRD analyses revealed that illite and mixed layered-I-S, in lower part with less (30-40%) and higher part with more (70%) illite component, are main constituents. Other minerals that are found are calcite, gypsum, jarosite and potassium feldspar. The modal analysis of the heavy mineral fraction revealed the presence of opaque minerals (pyrite, markazite and goethite) and titanite, zircon, turmaline, garnet, biotite, epidote, while in the light fraction calcite, dolomite and muscovite were found. It can be assumed that the starting material of the volcanic origin was subsequently altered. Microfacies and micropaleontological analyses have identified 10 microfacies types that suggest depositional carbonate platform environments, and the identified microfossil assemblage (benthic foraminifers and algae) indicating stratigraphic range of the Late Baremian–Late Albian. Considering on the obtained results the first subaerial surface exposure is the regional exposure of he Late Aptian–Early Albian, while the second surface exposure of Late Albian is caused by deposition during oscillating transgression.