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

Abstract

ABSTRACT:Łuczyński, P., Kozłowski, W. and Skompski, S. 2015. Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine). Acta Geologica Polonica, 65 (3), 297-318. Warszawa.The term "re-flooding window" was recently proposed as a time-interval connected with the transgressive stage of present day peri-reefal development. In the analysis presented here, a fossil record of a re-flooding window has been recognized. Nine Late Silurian carbonate sections exposed on the banks of the Dnister River in Podolia (Ukraine) have been correlated base on bed-by-bed microfacies analysis and spectral gamma ray (SGR) measurements. Correlated were sections representing settings ranging from the inner part of a shallow-water carbonate platform to its slope, through an organic buildup. The reconstructed depositional scenario has been divided into six development stages, with the first three representing a regressive interval and the latter three a transgressive interval of the basin's history. The re-flooding window has been identified at the beginning of a transgressive part of the succession. Surprisingly, it is characterized by an extremely fast growth of a shallow, tide-dominated platform and by deposition of calciturbiditic layers in a more basinal area. The interpreted succession is a small-scale model illustrating the reaction of carbonate depositional sub-environments to sea level changes and determining the facies position of the stromatoporoid buildups within the facies pattern on a Silurian shelf. The use of SGR analyses in shallow water, partly high-energy, carbonate facies, both for correlation purposes and for identifying depositional systems, is a relatively new method, and thus can serve as a reference for other studies of similar facies assortment.

Coexistence of algae and a graptolite-like problematicum: a case study from the late Silurian of Podolia (Ukraine)

“…According to LoDuca and Brett (1997), the appearance of an algal assemblage, defined as the 'Medusaegraptus epibole', is concomitant with a similar Konservat-Lagerstätten and synchronised with a shallowing episode on the 6 th order sea-level curve, chronostratigraphically correlated with the upper part of the Gorstian. The stratigraphic position of the investigated Ukrainian section is more or less analogous in the sense of the sea level curve (Predtechenskij et al 1983;Łuczyński et al 2015), and similar in the chronostratigraphical sense. However, a more precise correlation is impossible due to the lack of sufficient biostratigraphic data.…”

“…In the investigated layer of marly shales with the algal assemblage, other fossils are rare and dominated by leperditicopid arthropods, Campylites-type tubes, bivalves, relatively numerous gastropods, and rare fragments of eurypterids. The layer is best traceable in the vicinity of a bioherm (for precise location see Łuczyński et al 2015;Text-fig. 2A, B herein), and several tens of meters south and north of it.…”

Exploring Icehouse Cyclicity Pattern and Seawater Dynamics on an Ancient Carbonate Platform With Nd Isotopes (Carboniferous, Southern Kazakhstan)

“…There is a consensus that Carboniferous sedimentary cyclicity is related to glacial episodes in Gondwanaland and is highly likely to have been forced by glacio‐eustatic sea‐level oscillations (e.g., Ahern & Fielding, 2019; Crowell, 1978) whereas the facies successions within each cycle were primarily controlled by sedimentation rates and subsidence regime of carbonate platforms (Walkden, 1987). The Gondwanan ice sheet was highly sensitive to orbitally forced variations in solar insolation; resultant sea‐level oscillations had an approximate 100 ka periodicity (Crowley et al., 1993; V. P. Wright & Vanstone, 2001), but much longer estimates have also been discussed (see Skompski, 1996; Smith & Read, 2001; Tucker, 2003). There is also a debate over the exact timing of the Carboniferous glaciations (Isbell et al., 2003) as well as the scale and rapidity of the sea‐level fluctuations (for review, see Rygel et al., 2008).…”

“…Cyclic sedimentary successions are characteristic of late Mississippian to mid-Pennsylvanian shallow-water carbonate platforms and shelves (Veevers & Powell, 1987). They have been identified in pure carbonate successions (e.g., Chen et al, 2019;Gallagher & Somerville, 2003;Huang et al, 2020;Zempolich et al, 2002), mixed clastic-carbonate environments (e.g., Dvorjanin et al, 1996;Moore, 1957;Skompski, 1996;Smith & Read, 2000), and siliciclastic basins (Jirásek et al, 2018). The cycles are generally a few to over 30 m thick and characteristically exhibit shallowing-upward sequences, composed principally of subtidal sediments and capped by subaerial exposure surfaces (Walkden, 1987).…”

New data on red Visean calcareous algae of the Dnipro-Donetsk Depression: systematic composition and facial confinement

“…Berchenko, V.I. Yefimenko, O.A.Sukhov (Berchenko, 1985, 1988, Berchenko, Yefimenko, 1994, Skompski, 1996, Berchenko, Sukhov, 2013 In general, these authors published a number of works related to the study of fossil algae of the DDD, elucidation of their stratigraphic significance and facies timing. The work by O.I.…”