Mid-Ludfordian coeval carbon isotope, natural gamma ray and magnetic susceptibility excursions in the Mielnik IG-1 borehole (Eastern Poland)—Dustiness as a possible link between global climate and the Silurian carbon isotope record

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

“…Of potential utility for constraining the stratigraphic position of the interval investigated in the present study is the positive stable CIE recognized globally in the Ludfordian (Wenzel and Joachimski 1996;Bickert et al 1997;Kaljo et al 1997;Azmy et al 1998;Wigforss-Lange 1999;Wenzel et al 2000;Saltzman 2001;Calner 2005b;Martma et al 2005;Kaljo and Martma 2006;Jeppsson et al 2007;Kaljo et al 2007;Lehnert et al 2007;Eriksson and Calner 2008;Barrick et al 2010;Kozłowski and Munnecke 2010;Munnecke et al 2010;Cramer et al 2011;Loydell and Frýda 2011;Kaljo et al 2012;Kozłowski and Sobień 2012;Manda et al 2012). The beginning of the excursion coincides with an abrupt decrease in abundance of Polygnathoides siluricus, shortly before its Last Appearance Datum (LAD) (Martma et al 2005;Kaljo and Martma 2006;Jeppsson et al 2007;Lehnert et al 2007;Eriksson and Calner 2008).…”

“…3). Surface exposures in Podolia represent shallow-water carbonate facies developed on a vast epeiric platform, which extended basinward into the shelf facies recognized today in the subsurface of Poland (Teller 1997;Kozłowski and Sobień 2012), Baltic countries (Kaljo 1970;Kaljo et al 1997;Martma et al 2005), as well as in Sweden (Samtleben et al 2000;Calner et al 2006).…”

“…The beginning of the excursion coincides with an abrupt decrease in abundance of Polygnathoides siluricus, shortly before its Last Appearance Datum (LAD) (Martma et al 2005;Kaljo and Martma 2006;Jeppsson et al 2007;Lehnert et al 2007;Eriksson and Calner 2008). The peak interval is constrained within the O. snajdri zone (coeval with the top of the Neocucullograptus kozlowskii zone), and in many sections there is lithological evidence for a sub-stratigraphic (contained entirely within one biozone) gap or even erosion (Kaljo et al 1997;Calner 2005b;Lehnert et al 2007;Eriksson and Calner 2008;Kozłowski and Munnecke 2010;Loydell and Frýda 2011;Kaljo et al 2012;Kozłowski and Sobień 2012). The position of the falling limb of the excursion is less consistent.…”

“…The Ludfordian (Upper Silurian) stage was the time of the most pronounced positive stable carbon isotope excursion (CIE) in the Phanerozoic, known as the Lau excursion (Wenzel and Joachimski 1996;Bickert et al 1997;Wigforss-Lange 1999;Calner et al 2004;Martma et al 2005; Kaljo and Martma 2006;Jeppsson et al 2007;Kaljo et al 2007; Lehnert et al 2007;Eriksson and Calner 2008;Barrick et al 2010;Kozłowski and Munnecke 2010;Munnecke et al 2010;Cramer et al 2011;Loydell and Frýda 2011;Jeppsson et al 2012;Kaljo et al 2012;Kozłowski and Sobień 2012). Very good geochemical, biostratigraphical, and paleoecological documentation exists for the Lau excursion, and it is often used as a model to study positive CIEs, which are widely used as chemostratigraphic markers and as indicators of perturbations of the global carbon cycle (Jeppsson 1990;Aldridge et al 1993;Bickert et al 1997;Jeppsson and Aldridge 2000;Munnecke et al 2003;Calner 2005a;Melchin and Holmden 2006;Cramer and Saltzman 2007a, b;Fanton and Holmden 2007;Calner et al 2008;Małkowski et al 2009;Kozłowski and Sobień 2012).…”

“…Very good geochemical, biostratigraphical, and paleoecological documentation exists for the Lau excursion, and it is often used as a model to study positive CIEs, which are widely used as chemostratigraphic markers and as indicators of perturbations of the global carbon cycle (Jeppsson 1990;Aldridge et al 1993;Bickert et al 1997;Jeppsson and Aldridge 2000;Munnecke et al 2003;Calner 2005a;Melchin and Holmden 2006;Cramer and Saltzman 2007a, b;Fanton and Holmden 2007;Calner et al 2008;Małkowski et al 2009;Kozłowski and Sobień 2012). Studies of recent and sub-fossil carbonate sediments indicate that sea-level forcing, restricted circulation and laterally variable sediment composition can significantly influence the d 13 C carb values, leading to amplification of positive excursions in carbonate platform interiors during flooding intervals (Immenhauser et al 2003;Swart and Eberli 2005;Swart 2008;Gischler et al 2009;Oehlert et al 2012).…”