Not-So-Boring Bass: C-Isotope Stratigraphy and Facies Analysis of the Mesoproterozoic Bass Formation, Grand Canyon, Az

Characteristics of the carbon cycle in late Mesoproterozoic: Evidence from carbon isotope composition of paired carbonate and organic matter of the Shennongjia Group in South China

“…1150 Ma (Li et al, 2013;Wang et al, 2013;Du et al, 2015). A similar negative shift has been observed in other locations, although the magnitude is larger than the one observed here (see below for details, Azmy et al, 2001;Bartley et al, 2007;Lathrop, 2018).…”

“…1200 Ma based on the zircon U-Pb age of bentonite deposits cropping out in the lower Yemahe Formation (Li et al, 2013). The highest δ 13 Ccarb values observed in the middle Wenshuihe Formation, around +5‰, are similar to that reported in the contemporaneous strata (~1200 Ma), e.g., the Bass Formation in the Grand Canyon Supergroup, USA (Lathrop, 2018), the Raipur Group in the Chattisgarh basin (Patranabis-Deb et al, 2016) and the Lakheri limestone in the Vindhyan basin, India (Gilleaudeau et al, 2018).…”

“…9D). This positive shift has been observed in India (Maheshwari et al, 2009;Patranabis-Deb et al, 2016), Siberia (Bartley et al, 2007), and Laurentia (Beeunas and Knauth, 1985;Moon, 2015;Lathrop, 2018). Therefore, such 13 C-enriched carbonates also occur in the Yemahe and Wenshuihe formations of the Shennongjia Group (this work; Tian et al, 2018;Zou et al, 2019), thereby suggesting a possibly global phenomenon.…”

“…(e.g., Whelan et al, 1990;Knoll et al, 1995;Kah et al, 1999Kah et al, , 2012Bartley and Kah, 2004;Bartley et al, 2007;Maheshwari et al, 2009;Gilleaudeau and Kah 2013;Lathrop, 2018;Paula-Santos et al, 2021).…”

“…Thus, the  13 Ccarb and  13 Corg are widely used as indicators for the fraction of organic carbon burial [forg, forg = Fbo/(Fbo + Fbc), where Fbo is the flux of organic carbon burial, and Fbc represents the flux of carbonate burial], which is then used to infer the oxidation state of the Earth's surface environments (Hayes et al, 1999;Bartley and Kah, 2004). It has been observed that the  13 Ccarb values increase substantially from ~0‰ in the early Mesoproterozoic to ~+4‰ in the late Mesoproterozoic (Kah et al 1999;Bartley and Kah, 2004;Kah et al, 2012;Silva-Tamayo et al, 2018;Lathrop, 2018;George et al, 2019;Paula-Santos et al, 2021). These moderately positive  13 Ccarb values are generally attributed to elevated rates of organic carbon burial.…”