Late Wenlock carbon isotope excursions and associated conodont fauna in the Podlasie Depression, eastern Poland: a not‐so‐big crisis?

Abstract

The middle Silurian ‘big crisis’ refers to a graptolite extinction event and faunal turnover at the onset of a double‐peaked positive carbon isotope excursion. The crisis has been proposed to affect conodonts, giving rise to a sophisticated palaeoecological model of their stepwise extinction, known as the Mulde Event. However, the impact of the event on conodont faunas outside Gotland and the Silurian Baltic Basin remains unknown. Here, it is examined in the Widowo IG‐1 core (E Poland). The middle Silurian succession in this core represents foreshoal, shoal, and lagoonal settings on a tropical carbonate ramp on the shelf of the Eastern European Craton. Three positive δ13Ccarb excursions have been identified; the two upper excursions correlate with the Mulde isotope anomaly and with two global eustatic regressions. Conodont species proposed to be affected by the extinction event either were not observed or ranged through the extinction interval. Changes in their frequencies are best explained by the sequence stratigraphic architecture of the late Wenlock strata in the Widowo IG‐1 core. The little impact of the ‘big crisis’ may reflect facies homogeneity across the studied interval, supporting the hypothesis that the late Wenlock conodont turnover in epicontinental settings was primarily driven by eustatically controlled facies shifts. Copyright © 2015 John Wiley & Sons, Ltd.

A record of Late Ordovician to Silurian oceanographic events on the margin of Baltica based on new carbon isotope data, elemental geochemistry, and biostratigraphy from two boreholes in central Poland

“…Strata in the subsurface of Poland have been surveyed in detail by petroleum exploration companies (see summary by Kiersnowski and Dyrka, 2013). Although data from many of these sections remain proprietary, our results benefit from the context established by published geochemical and biostratigraphic work from the boreholes Bartoszyce IG-1 (Porębska et al, 2004), Widowo IG-1 (Jarochowska and Munnecke, 2015), Wilków-1 (Smolarek et al, 2017), and upper Silurian deposits at Mielnik IG-1 (Kozłowski and Sobieo, 2012).…”

“…Carbon isotope studies have led to the identification of the positive excursions associated with the upper Homerian Mulde Event in the Widowo IG-1 borehole (Jarochowska and Munnecke, 2015) and at Bartoszyce IG-1, where a positive shift in isotopes is reported in both δ 13 C carb and δ 13 C org records (Porębska et al, 2004) Older strata have not received the same amount of attention bestowed on wellconstrained sections in Ukraine (Kaljo et al, 2007), Lithuania (Kaljo et al, 1998), Estonia (Cramer et al, 2010;Munnecke and Männik, 2009), and Gotland (Bickert et al, 1997;Samtleben et al, 2000;Munnecke et al, 2003;Calner et al, 2004). The elemental geochemistry and stable isotope data from Grabowiec-6 and Zwierzyniec-1 offer a new opportunity to…”

“…The chronostratigraphy is from Melchin et al (2012). Teller, 1997;Jarochowska and Munnecke, 2015). The position of E 23° 25' 56.795") and Zwierzyniec-1 (N 50° 44' 14.013", E 23° 07' 24.570") are labelled by shaded circles along with other borehole localities (white circles) that have been studied in earlier published work.…”

Utility of organic carbon isotope data from the Salina Group halite (Michigan Basin): A new tool for stratigraphic correlation and paleoclimate proxy resource

“…Most CIEs range 2‰ to 4‰ δ 13 C carb relative to background values, with the Lau event ranging 7‰ to 12‰. Comparisons of these CIEs with small-scale extinction and recovery events exhibit variable degrees of correlation, suggesting that no single repetitive set of paleo climatic circumstances and/or controlling mechanism can explain these events (Munnecke et al, 2010;Noble et al, 2012;Cooper et al, 2014;Jarochowska and Munnecke, 2015;Trotter et al, 2016).…”

Graptolite turnover and δ13Corg excursion in the upper Wenlock shales (Silurian) of the Holy Cross Mountains (Poland)

“…A twin-peaked positive carbon isotope excursion has been documented globally in the upper Wenlock. Such carbon isotope excursions of this age are documented: in Baltica (Samtleben et al 1996;Wenzel & Joachimski 1996;Bickert et al 1997;Kaljo et al 1997Kaljo et al , 1998Kaljo et al , 2007Samtleben et al 2000;Porębska et al 2004;Martma et al 2005;Calner et al 2006bCalner et al , 2012Jarochowska et al 2014Jarochowska et al , 2016aJarochowska et al , 2016bRadzevičius et al 2014cJarochowska & Munnecke 2016;Makhnach et al 2018); Laurentia (Saltzman 2001;Noble et al 2005;Cramer et al 2006;Lenz et al 2006;Sullivan et al 2016); Avalonia (Corfield et al 1992;Marshall et al 2012;Blain et al 2016;Fry et al 2017); Timan (Shebolkin & Männik 2014); Perunica (Frýda & Frýdová 2014, 2016; and Gondwana (Vecoli et al 2009). Thus, most of the stable carbon isotopic data are from the Baltica, Laurentia and Avalonia paleocontinents.…”