Potential source rocks in the Ropianka Formation of the Magura Nappe (Outer Carpathians, Poland) – geochemical and foraminiferal case study

Abstract

Abstract:To optimize exploration for new hydrocarbon accumulations in the Polish Outer Carpathians, it is necessary to concentrate attention on identification of hydrocarbon accumulations of the "shale-gas" type. Results of recently completed analysis suggested new such possible targets in the Magura Basin, preserved in the Outer Carpathian Magura Nappe. Analysis of the preliminary results of paleoenvironmental and geochemical studies of these shales is the subject of this paper. Micropaleontological and geochemical study was conducted on the 300 m thick Świątkowa Member, the uppermost part of the Ropianka Formation located in the external, northernmost Siary Zone. This member is composed of thin-and medium-bedded sandstones interbedded by green, brown, black and dark-gray shales. Poor and changeable oxygenation is reflected in the composition of foraminiferal assemblages. A negative correlation between the TOC content and numbers and diversity of foraminifera is observed. The paleogeographic position and paleoenvironment assessment indicates that the Siary Zone fulfills certain conditions for organic productivity and preservation during the deposition of the Ropianka Formation.

Acta Geologica Polonica

“…Bubík et al (1999) (1960) from Mora via. The common occurrence of Caudammina excelsa was noticed in the Magura Nappe from Lower Paleocene deposits (Waśkowska et al 2018), from Campanian-Maastrichtian (Malata 2002) and from Maastrichtian-Lower Paleocene deposits (Malata et al 1996). Olszewska (1980) and Bąk (2004) indi cate similar asemblages from other Outer Carpa thian areas.…”

“…Hanzlíková (1983) draws attention to the stratigraphic significance of Placentammina pla centa and described the Placentammina placenta dominated assemblages from the Moravian Paleo cene. Beckmann et al (1982) and Waśkowska et al (2018) found assemblages rich in these taxa in the Paleocene, whereas Geroch (1960) and Bąk (2004) Samples taken from the thin-bedded complex between the Biotite Sandstone and Shale and the Mutne Sandstone Member (complex II) contain rich and diversified assemblages. Taking into account the occurrence of biostratigraphical markers, they refer to the upper part of Rzehakina inclusa Zone of Early Maastrichtian-Maastrichtian/Paleocene age.…”

“…Geroch (1960), Jurkiewicz (1967), Beckmann et al (1982, Hanzlíková (1983) and Bąk (2004). The occurrence of a high number of Caudammina in Lower Paleocene deposits in the Magura Nappe is common; particularly abundant are Caudammina ovulum (Jurkiewicz 1967;Waśkowska et al 2018) and Caudammina excelsa (Malata et al 1996). Because of the high number of Caudammina, the Danian deposits from the Subsilesian Nappe were described as a Caudammina association (Waśkowska-Oliwa 2008).…”

The Upper Cretaceous variegated shales in the Ropianka Formation of the Magura Nappe (Outer Carpathians) – age and lithostratigraphic position

“…The foraminiferal as sem blages of the Farony Shale cor respond to the as sem blages from the Cre ta ceous part of the Ropianka and Jaworzynka for ma tions of the Magura Nappe. As sem blages with nu mer ous Caudammina gigantea (acme assem blages) were no ticed ear lier by Blaicher (1958), Sikora and ¯ytko (1960), Bieda et al (1963), Jednorowska (1966, 1975, Geroch et al (1967), Malata (1981Malata ( , 2002, Malata and Oszczypko (1996), Oszczypko et al (1990Oszczypko et al ( , 2005, Stráník et al (2000), Waoekowska (2021), Waoekowska et al (2021), in creased numbers of Caudammina ovulum (Grzybowski) with nu mer ous Caudammina gigantea Geroch were de scribed by Sikora and ¯ytko (1960), Malata (1981) and Oszczypko et al (2005), and Saccammina-Placentammina rich as sem blages were no ticed by Jednorowska (1968) and Waoekowska et al (2018Waoekowska et al ( , 2021. The spe cies found in the Farony Shale are truly cos mo pol i tan, and as seen in a re cent study of DWAF from an IODP site in the Tas man Sea (Kaminski et al, 2021).…”

“…It can be a pre rog a tive to be long to the same fa cies. In the sam ple, 21/FAR-2/20 Cau dammina excelsa (Dyl¹¿anka) is pres ent, which is an other fea ture of the Placentammina-Saccammina acme (Waoekowska et al, 2018;Waoekowska, 2021).…”