High-energy sedimentary events in lagoonal successions of the Upper Silurian of Podolia, Ukraine

Abstract

Three Late Silurian carbonate proWles of the Malynivtsy and Skala Formations from Podolia (western Ukraine) are discussed in terms of sedimentation dynamics. Their common feature is the appearance of thick, stromatoporoid-rich beds within Wne-grained peritidal deposits. These intercalations are composed of fossils typical of oVshore sedimentary environments. In the most spectacular case, a channel, several tens of metres wide and inWlled with stromatoporoids, is incised in a peritidal cyclic complex. The successions investigated exhibit sedimentary features that are diagnostic of onshore redeposition. Independently of the scale of the recorded sedimentary events, the onshore redeposition was caused by factors with energy levels exceeding those of average storms, probably by hurricanes or even tsunami waves. The dynamic nature of some of the stromatoporoid beds has to be taken into account when constructing the curves illustrating bathymetrical and facies development of the Silurian succession of Podolia. The genesis of lens-shaped stromatoporoid beds, elongated depending on their origin, either parallel or perpendicular to the facies belts, should be considered an important factor in reconstructions of the depositional architecture of sedimentary hydrocarbon collectors.

Recent studies on the Silurian of the western part of Ukraine

“…Points i-iv listed above and discussed in the following chapters of this paper summarize the results of the studies published in the authors' consecutive papers (Skompski et al 2008;Łuczyński et al 2009. Our understanding of the nature of the high-energy sedimentary events and of their impact on the facies record of the Silurian successions of Podolia evolved slightly during these years, and this is also presented here.…”

Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine)

“…The continuing rapid increase in sea level has caused a retrogradational facies shift, cannibalistic disintegration of the previously deposited sediments and, finally, high dynamic deposition of the upper bio/lithoclastic limestone/dolomite complex. In this stage of the platform's development, the appearance of tidal channels (Konovka village (9) section; but also other Upper Silurian sections in Podolia (Skompski et al 2008)) is a most expected feature. In consequence, it appears that the extremely shallow-water parts of the platforms, identified as tidal plains, have a surprisingly large growth potential.…”

“…Our earlier studies (Skompski et al 2008;Łuczyński et al 2009, 2014 have revealed that part of these beds, particularly those in the higher part of the Silurian succession, are in fact represented by sediments composed of material redeposited shoreward and derived from open marine regions. One can assume that some of the stromatoporoid biostromes on Gotland are of a similar origin (compare, Kershaw 1990).…”

Facies development and sequence stratigraphy of the Ludfordian (Upper Silurian) deposits in the Zbruch River Valley, Podolia, western Ukraine: local facies overprint on the δ13Ccarb record of a global stable carbon isotope excursion

“…11). In spite of the facies model of Einasto et al (1986), where the Silurian carbonate platform of Podolia is treated as rimmed, it is assumed here that a carbonate ramp is a more appropriate model due to the very low-relief and spatial discontinuity of the biostromes and reef mounds and the epeiric character of the Podolian part of the basin (compare Eriksson and Calner 2008;Skompski et al 2008). The first recognizable element of stratal architecture is the sequence boundary (SB) marking the top of the Isakivtsy Fm.…”