Carbon and oxygen isotopes in the Frasnian–Famennian section of the Kuznetsk basin (southern West Siberia)

Abstract

The first detailed isotope-geochemical study of carbonate deposits has been performed in the Lower Famennian stratotype section of the northwestern Kuznetsk Basin (Kosoy Utyos), which was localized in the middle latitudes of the Northern Hemisphere in the Late Devonian. The δ13Ccarb, δ13Corg, and δ18O variation curves were constructed for the section deposits. Geochemical and petrographic studies of carbonates allowed allocation of samples that underwent postsedimentation alteration and exclude them from further interpretation. Compared with coeval sections in the other world’s regions, the Kosoy Utyos section is characterized by higher δ13Ccarb values, up to 5.4‰, whereas the maximum value in subequatorial area sections is 4‰. The isotope shift amplitude of the studied section reaches 4.6‰, which is 1.5‰ higher than those in other regions. The δ18O values are 3‰ lower than the ones of the world’s coeval sections. The results obtained show that δ13C and δ18O variation trends differ from those of coeval subequatorial sections. The high shift amplitude and maximum δ13Ccarb values in the Kosoy Utyos section are due to the shallow-water carbonate sedimentation environments on the Siberian continental shelf and, probably, the lower temperatures of waters in the middle latitudes as compared with the subequatorial areas.

Biochemostratigraphy of the Upper Frasnian in the Namur–Dinant Basin, Belgium: Implications for a global Frasnian–Famennian pre-event

“…7a-c). The δ O values of the studied shells are depleted relative to those of their modern (~ 0‰ VPDB) counterparts (Brand et al, 2003) due to the fact that the Paleozoic ocean waters were significantly depleted in 18 O compared with modern oceans but the fossil values are generally within the range documented for the global middle Devonian, particularly around Late Frasnian, in South China, Siberia, Europe and N. America Buggisch, 1993, 1996;Chen et al, 2002;Yudina et al, 2002;Joachimski et al, 2004;da Silva and Boulvain, 2008;Ma et al, 2008;Izokh et al, 2009).…”

“…Buggisch, 1993, 1996;Chen et al, 2002;Yudina et al, 2002;Joachimski et al, 2004;da Silva and Boulvain, 2008;Ma et al, 2008;Izokh et al, 2009). Although some studies utilized well preserved low-Mg calcitic brachiopod shells and phosphatic conodonts (e.g., Joachimski et al, 2004), others involved frequently whole-rock samples of variable degrees of preservation, and at times low-resolution sampling (big sampling intervals), which likely masked some significant variations around the boundary.…”

Climate instability and tipping points in the Late Devonian: Detection of the Hangenberg Event in an open oceanic island arc in the Central Asian Orogenic Belt

“…Many of these study sites have been strongly influenced by increased sedimentation from the rising Appalachian Mountains. Additional studies have been conducted in locations that would presumably not be affected by the Appalachian/Variscan Orogenic Events, but all are associated with sediments derived from the cratonic blocks of Indochina (Hara et al, 2010 andKönigshof et al, 2012), South China (Zheng et al, 1993, Chen et al, 2005, Gharaie et al, 2007, Chen et al, 2013, Komatsu et al, 2014and Whalen et al, 2015, Australia (Stephens andSumner, 2003 andGeorge et al, 2014), Russia/Siberia (Gutak et al, 2008, Izokh et al, 2009and Tagarieva, 2013 and northern Africa . In contrast, only one study has unequivocally shown the presence of a Late Devonian anoxia event in an open oceanic setting far from continental-derived sediments: Carmichael et al (2014) have documented the Kellwasser Event using multiple geochemical proxies within the Central Asian Orogenic Belt (CAOB), which therefore required an overhaul of the established models for ocean anoxia.…”

Carbon isotopic evidence for the associations of decreasing atmospheric CO2level with the Frasnian‐Famennian mass extinction

“…Δ 13 C is often used as reliable paleo‐ p CO 2 barometer [ Cramer and Saltzman , 2007; Young et al , 2008], because the isotopic difference between carbonate and organic matter is dominated by photosynthetic fractionation, which partly depends on the concentration of dissolved CO 2 in seawater [e.g., Popp et al , 1989; Freeman and Hayes , 1992; Hayes et al , 1999]. Unfortunately, most previous studies focused separately on the changes of inorganic and organic carbon isotope [ McGhee et al , 1986; Joachimski and Buggisch , 1993; Wang et al , 1996; Racki et al , 2002; Xu et al , 2003; Buggisch and Joachimski , 2006; Izokh et al , 2009], few examined the variations of Δ 13 C. Even the few Δ 13 C data seem to change geographically [ Joachimski , 1997; Chen et al , 2005]. In the Baisha and Fuhe sections from south China, Δ 13 C shows high‐frequency vibrations around the F‐F boundary [ Chen et al , 2005], but it is suggested that there is no obvious change in Europe [ Joachimski et al , 2002].…”