1 In sti tute of Ge ol ogy and Geo chem is try of Com bus ti ble Min er als of the NAS of Ukraine, Naukova 3a, 79060 Lviv, Ukraine Radkovets, N., 2015. The Si lu rian of southwest ern mar gin of the East Eu ro pean Plat form (Ukraine, Moldova and Ro ma nia): lithofacies and palaeoenvironments. Geo log i cal Quar terly, 59 (1): 105-118, doi: 10.7306/gq.1211 Si lu rian strata, stretch ing along the west ern mar gin of the East Eu ro pean Plat form from the Bal tic to the Black Sea, rep re sent a

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... o ten tial tar get for both con ven tional and un con ven tional hy dro car bon ex plo ra tion. Dis tri bu tion of the black shale fa cies, pro spec tive for shale gas, and the reef fa cies, pro spec tive for oil, has been stud ied in re spect of palaeoenvironments. The Silu rian se quence has been in ves ti gated in the ter ri tory of Ukraine (Volyn-Podillyan Plate, Dobrogean Foredeep) and cor related with the data on Moldova and Ro ma nia (Moldovian Plat form). The oc cur rence of Si lu rian strata, their thick ness, and petrographic and lithological char ac ter is tics al lowed re con struct ing the dis tri bu tion of open-shelf, reef and la goonal fa cies. The reef fa cies mi grated dur ing the Wen lock-Mid dle Pridoli, shift ing to wards the open sea and back to wards the shore, and there fore has been termed a mi grat ing reef fa cies. Cor re spond ingly, the bound ary be tween the open-shelf and reef fa cies was shift ing. The fa cies dis tri bu tion was con trolled by the transgressive-re gres sive cy cles, which caused the fluc tu a tions of the shelf wa ter depth in dif fer ent time in ter vals of the Si lu rian. The shelf wa ter depth of about 100 m, where the top of the ox ygen-min i mum layer im pinged on the sea bot tom, was the boundary between the open-shelf facies, represented by organic-rich sediments, and the reef build ups.