The Ediacaran succession occurs at the southwestern slope of the East European Platform from the Black Sea to the Lublin-Podlasie Basin. It includes a black shale interval in Ukraine represented by the Kalus Beds which may have hydrocarbon source rock potential. Coeval organic-rich rocks are known to have sourced commercial accumulations of oil and gas in different parts of the world. In western Ukraine and NW Moldova, the thickness of the Kalus shales exceeds 90 m. These strata crop out locally near the border of the Ukrainian Shield and dip in the southwestern direction towards the Teisseyre-Tornquist zone, reaching the depths of over 4000 m. This paper presents a study of hydrocarbon source rock potential of the Kalus Beds and is based on the results of organic geochemical and mineralogical investigations. The organic-rich Kalus Beds are represented by clay-rich siltstone in which quartz (38–66%) and mica (8–19%) prevail over clay minerals. They also contain a significant amount of feldspar (4–11%) and chlorite (4–12%). The clay fraction is represented by illite, chlorite, kaolinite and illite-smectite. Mixed-layered clay minerals are distributed at burial depths of up to 150 m. Kaolinite occurs in a wider range of depths, but below 3800 m clay minerals are represented exclusively by chlorite and illite. Such a proportion of mineral components of the analysed beds and the grain size of quartz indicate their high brittleness and thus suitability for efficient hydraulic fracturing. The total organic carbon content in the Kalus shales varies between 0.1 and 0.89 wt%, exceeding 0.5 wt% in some parts of the study area, and thus these strata can be considered as a low-quality potential hydrocarbon source rock. The maturation level of the Kalus Beds clearly depends on the depth of burial. These rocks are immature till a depth of 100 m. Generation windows for oil and gas occur within depth ranges from 100 to 2200 m and from 2200 to 3800 m, respectively. At greater depths these rocks are overmature. In the main part of the study area, the organic-rich Kalus Beds have significant thickness and are matured to the level of oil and gas windows and hence might generate hydrocarbons and contribute to the development of the petroleum system in the region.
Aseeva, E. A. 1988. Iskopaemye ostatki vendskikh talofitov [Fossil remains of Vendian talophytes]. In Biostratigrafiya i paleogeograficheskie rekonstruktsii dokembriya Ukrainy [Biostratigraphy and Palaeogeographic Reconstructions of the Precambrian of Ukraine], pp. 81–102. Naukova Dumka, Kiev [in Russian].
Bratslavskiy, P. F., Shevchenko, O. M., Kuzmenko, L. S. & Veklych, U. M. 2008. Derzhavna geologichna karta Ukrainy mashtabu 1: 200 000. Podilska seria. Arkush M-35- XXVIII (Mogyliv-Podilsk) [State Geological Map of Ukraine at a Scale of 1:200 000. Podillya Series. Sheet M-35- XXVIII (Mogyliv-Podilsk)]. UkrDGRI, Kiev [in Ukrainian].
Burtner, R. L. & Warner, M. A. 1986. Relationship between illite/smectite diagenesis and hydrocarbon generation in Lower Cretaceous Mowry and Skull Creek Shales of the Northern Rocky Mountain area. Clays and Clay Minerals, 34, 390–402.
https://doi.org/10.1346/CCMN.1986.0340406
Chebanenko, I. I., Vishnyakov, I. B. & Vlasov, B. I. 1990. Geotektonika Volyno-Podolii [Geotectonics of Volyno-Podolia]. Naukova Dumka, Kiev, 244 рр. [in Russian].
Clause 2016. PyXRD: A Model for the Simulation of 1-Dimensional X-Ray Diffraction Patterns of Disordered Layered Minerals. Software Manual. Boston, USA, 48 pp.
Craig, J., Thurow, J., Thusu, B., Whitham, A. & Abutarruma, Y. (eds). 2014. Global Neoproterozoic petroleum systems: The emerging potential in North Africa. Geological Society London Special Publications, 326, 1–25.
https://doi.org/10.1144/SP326.1
Curtis, J. B. 2002. Fractured shale-gas systems. AAPG Bulletin, 86, 1921–1938.
https://doi.org/10.1306/61EEDDBE-173E-11D7-8645000102C1865D
Decker, A. D., Coates, J. M. & Wicks, D. E. 1992. Stratigraphy, gas occurrence, formation evaluation and fracture characterization of the Antrimshale, Michigan Basin. GRI Topical Report, No. GRI-92/0258, 153 pp.
Döbelin, N. & Kleeberg, R. 2015. Profex: a graphical user interface for the Rietveld refinement program BGMN. Journal of Applied Crystallography, 48, 1573–1580.
https://doi.org/10.1107/S1600576715014685
Dolenko, G. N., Rizun, B. P., Senkovskij, Y. N., Chizh, Y. I., Medvedev, A. P. & Bojchuk, M. V. 1984. Geologiya i neftegazonosnost´ Volyno-Podol´skoj plity[Geology and Oil- and Gas-Bearing Potential of the Volyn-Podolsk Plate]. Naukova Dumka, Kiev, 106 рр. [in Russian].
Frank-Kamenetskij, V. A. 1983. Rentgenografiya osnovnykh tipov porodoobrazuyushchikh mineralov (sloistye i karkasnye silikaty) [Radiography of the Main Types of Rock-Forming Minerals (Layered Silicates and Skeleton Silicates]. Nedra, Leningrad, 359 pp. [in Russian].
Gnidets, V. P., Grigorchuk, K. G., Polukhtovych, B. M. & Fedyshyn, V. O. 2002. Litohenez devonskykh vidkladiv Prydobrudzkoho prohynu (paleookeanohrafiya, sedymentatsiyna tsyklichnist, formuvannya porid-kolektoriv) [Lithogenesis of Devonian Deposits of Dobrogea Foredeep (Palaeooceanography, Sedimentary Cyclicity, Reservoir Rocks’ For- mation)]. UkrDGRI, Lviv, 85 pp. [in Ukrainian, with English abstract].
Gnilovskaya, M. B. 1979. Vendotenidy [Vendotenides]. In Paleontologiya verkhnedokembrijskikh i kembrijskikh otlozhenij Vostochno-Evropejskoj platformy[Palaeontology of the Upper Precambrian and Cambrian Deposits of the East European Platform], pp. 39–48. Nauka, Moscow [in Russian].
Gnilovskaya, M. B., Ishchenko, A. A., Kolesnikov, Ch. M., Korenchuk, L. V. & Udal´tsov, A. P. 1988. Vendotenidy Vostochno-Evropejskoj platformy[Vendotenides of the East European Platform]. Nauka, Leningrad, 143 рр. [in Russian].
Gureev, Y. A. 1988. Besskeletnaya fauna venda [Skeletonless fauna of the Vendian]. In Biostratigrafiya i paleogeograficheskie rekonstruktsii dokembriya Ukrainy [Biostrati- graphy and Palaeogeographic Reconstructions of the Precambrian of Ukraine], pp. 65–80. Naukova Dumka, Kyiv [in Russian].
Ishchenko, А. А. 1983. K kharakteristike vendskoj vodoraslevoj flory Pridnestrovya [On the characteristics of the Vendian algal flora of the Dnister area]. In Stratigrafiya i formatsii dokembriya Ukrainy [Stratigraphy and Precambrian Formations of Ukraine], pp. 181–206. Naukova Dumka, Kyiv [in Russian].
Jarvie, D. M., Hill, R. J., Pollastro, R. M., Wavrek, D. A., Claxton, B. L. & Tobey, M. H. 2003. Evaluation of unconventional natural gas prospects in the Barnett Shale: fractured shale gas model. In European Association of International Organic Geochemists Meeting, Kraków, Poland, September 8–12, Book of Abstracts, Part II, pp. 3–4. Society of Research on Environmental Changes “Geosphere”.
Khizhnyakov, A. V. 1963. Geologicheskoe stroenie i perspektivy neftegazonosnosti Lvovskogo paleozojskogo progiba [Geological structure and oil and gas prospects of the Lvov Paleozoic trough]. In Geologiya i neftegazonosnost´ territorii USSR [Geology and Oil- and Gas-Bearing Potential of the Territory of the Ukrainian SSR], pp. 189–202. Gostoptekhizdat, Moscow [in Russian].
Kosakowski, P., Radkovets, N., Rauball, J. & Zakrzewski, A. 2017. Occurrence and burial and thermal history of the Ediacaran strata (W-SW Ukraine and Moldova). In 79th EAGE Conference & Exhibition, Paris, France, pp. 101–105. European Association of Geoscientists & Engineers.
https://doi.org/10.3997/2214-4609.201700619
Kruglov, С. С. & Tsypko, A. K. 1988. Tektonika Ukrainy [Tectonics of Ukraine]. Nedra, Moscow, 254 pp. [in Russian].
Krupsky, Y. Z., Kurovets, I. M., Senkovsky, Y. M., Mikhailov, V. A., Chepil, P. M., Drygant, D. M., Shlapinsky, V. E., Koltun, Y. V., Chepil, V. P., Kurovets, S. S. & Bodlak, V. P. 2014. Netradytsiyni dzherela vuhlevodniv Ukrayiny [Non-traditional sources of hydrocarbons of Ukraine]. In Knyha 2, Zakhidnyy naftohazonosnyy rehion [Book 2, Western Oil and Gas Region]. Nika-Tsentr, Kyiv, 400 pp. [in Ukrainian].
Makhnach, A. S. & Veretennikov, N. V. 2003. Korrelyatsiya stratigraficheskikh skhem venda Belarusi i drugikh rajonov Vostochno-Evropejskoj platformy [Correlation of the Vendian stratigraphic schemes of Belarus and other regions of the East European Platform]. In Stratigrafiya i paleontologiya geologicheskikh formatsij Belarusi [Stratigraphy and Palaeontology of Geological Formations of Belarus], pp. 174–182. Institut geologicheskikh nauk NAN Belarusi, Minsk [in Russian].
Moore, D. M. & Reynolds, R. C., Jr. 1997. X-Ray Diffraction and the Identification and Analysis of Clay Minerals. Oxford University Press, Oxford, New York, 378 pp.
Palij, V. M. 1976. Ostatki besskeletnoj fauny i sledy zhiznedeyatel´nosti iz otlozhenij verkhnego dokembriya i nizhnego kembriya Podolii [Remains of skeletonless fauna and traces of life activity from the sediments of the Upper Precambrian and Lower Cambrian of Podolia]. In Paleontologiya i stratigrafiya verkhnego dokembriya i nizhnego paleozoya yugo-zapada Vostochno-Evropejskoj platformy [Paleontology and Stratigraphy of the Upper Precambrian and Lower Palaeozoic of the Southwest of the East European Platform], pp. 63–77. Naukova Dumka, Kyiv [in Russian].
Paszkowski, M., Budzyń, B., Mazur, S., Sláma, J., Środoń, J., Millar, I. L., Shumlyanskyy, L., Kędzior, A. & Liivamägi, S. 2021. Detrital zircon U-Pb and Hf constraints on provenance and timing of deposition of the Mesoproterozoic to Cambrian sedimentary cover of the East European Craton, part II: Ukraine. Precambrian Research, 40, 106–282.
https://doi.org/10.1016/j.precamres.2021.106282
Peters, K. E., Walters, C. C. & Moldowan, J. M. 2007. The Biomarker Guide. Vol. 2: Biomarkers and Isotopes in Petroleum Systems and Earth History, 2nd Edition. Cambridge University Press, New York, 704 pp.
Poprawa, P., Radkovets, N. & Rauball, J. 2018. Ediacaran-Paleozoic subsidence history of the Volyn-Podillya- Moldavia basin (W and S Ukraine, Moldavia, NE Romania). Geological Quarterly, 62, 459–486.
https://doi.org/10.7306/gq.1418
Radkovets, N. 2016. Lower Devonian lithofacies and palaeoenvironments in the southwestern margin of the East European Platform (Ukraine, Moldova and Romania). Estonian Journal of Earth Sciences, 65, 200–2013.
https://doi.org/10.3176/earth.2016.18
Radkovets, N., Kotarba, M. & Wójcik, K. 2017a. Source rock geochemistry, petrography of reservoir horizons and origin of natural gas in the Devonian of the Lublin and Lviv basins (SE Poland and western Ukraine). Geological Quarterly, 61, 569–589.
https://doi.org/10.7306/gq.1361
Radkovets, N., Rauball, J. & Iaremchuk, I. 2017b. Silurian black shales of Western Ukraine: petrography and mineralogy. Estonian Journal of Earth Sciences,66, 161–173.
https://doi.org/10.3176/earth.2017.14
Radkovets, N., Kosakowski, P., Rauball, J. & Zakrzewski, A. 2018. Burial and thermal history modelling of the Ediacaran succession in Western and SW Ukraine and Moldova. Journal of Petroleum Geology, 41, 85–106.
https://doi.org/10.1111/jpg.12694
Radzivil, A. Y., Shulha, V. F., Ivanova, A. V., Machulina, S. O., Verhelska, N. V., Aleksandrova, A. V. & Zaytseva, L. B. 2012. Etapy utvorennya vuhletsevykh formatsiy v heolohichnykh strukturakh Ukrayiny [Stages of Formation of Carbon Formations in Geological Structures of Ukraine]. LAT & K, Kyiv, 215 pp. [in Ukrainian].
Sokolov, B. S. 1997. Ocherki stanovleniya venda [Essays on the Formation of the Vendian]. Nauchnoe izdatel´stvo KMK, Moskva, 142 pp. [in Russian].
Shul´ga, V. F., Zdanovskij, A., Zajtseva, L. B., Ivanova, A. V., Ivanina, A. B., Korol´, N. D., Kotasova, A., Kotas, A., Kostik, I. E., Lelik, B. I., Miger, T., Manichev, V. I., Matrofajlo, M. N., Ptak, B., Savchuk, V. S., Sedaeva, G. M. & Stepanenko, Y. G. 2007. Korrelyatsiya karbonovykh uglenosnykh formatsij L’vovsko-Volynskogo i Lyublinskogo bassejnov [Correlation of the Carboniferous Coal-Bearing Formation of the Lviv-Volyn and Lublin Basins]. National Academy of Sciences of Ukraine, Institute of Geological Sciences and Polish State Geological Institute, Upper Silesian Branch, Kiev, 427 pp. [in Russian, with English summary].
Trushkevych, R. T. & Shvay, L. P. 1998. Formuvannya pokladiv nafty i hazu u zakhidnomu rehioni [Formation of oil and gas deposits in the western region]. Naftova i hazova promyslovist, 4, 7–9 [in Ukrainian].
Vashchenko, V. O., Turchynova, S. M., Turchynov, I. I. & Poliha, G. G. 2007. Derzhavna geologichna karta Ukrainy mashtabu 1:200 000. Karpatska seria. Arkush M-35-XXV (Ivano-Frankivsk) [State Geological Map of Ukraine at a Scale of 1:200 000. Carpathian Series. Sheet M-35-XXV (Ivano-Frankivsk)]. UkrDGRI, Kyiv [in Ukrainian].
Vecoli, M. 2013. The palaeobiology and geochemistry of Precambrian hydrocarbon source rocks. Marine and Petroleum Geology, 40, 1–47.
https://doi.org/10.1016/j.marpetgeo.2012.09.011
Velikanov, V. Y. 1985. Opornyj razrez venda Podolii [Basic Vendian section of Podolia]. In Vendskaya Sistema [Vendian System], pp. 35–66. Nauka, Moscow [in Russian].
Velikanov, V. Y. 2011. Ukrayinskyy hipostratotyp Vendskoyi systemy [Ukrainian hypostratotype of the Vendian system]. Geologichnyi zhurnal, 1, 42–49 [in Ukrainian, with English abstract].
https://doi.org/10.30836/igs.1025-6814.2011.1.139324
Velikanov, V. Y., Aseeva, E. A. & Fedonkin, M. A. 1983. Vend Ukrainy [Vendian of Ukraine]. Naukova Dumka, Kiev, 164 pp. [in Russian].
Zelizna, S. T., Plaksa, Y. P. & Filts, D. I. 1971. Bituminologichne doslidzhennya mynkovetskykh vidkladiv Prydnistrovia [Bituminological study of the Mynkivtsi deposits of the Dnister area]. Geologiya i geokhimiya goryuchykh kopalyn, 25, 79–86 [in Ukrainian].
Zevin, L. S. & Zavyalova, L. L. 1974. Kolichestvennyj rentgenograficheskij fazovyj analiz [Quantitative X-ray Phase Analysis]. Nedra, Moscow, 183 pp. [in Russian].
