Seawater carbon and strontium isotope variations through the late Ediacaran to late Cambrian in the Tarim Basin

Abstract

This is a repository copy of Seawater carbon and strontium isotope variations through the late Ediacaran to late Cambrian in the Tarim Basin.

Carbon Isotope Stratigraphy of the Cambrian System in the Eastern Tarim Basin, China

“…5). Such large negative excursions of δ 13 C carb and δ 13 C org also exist in the bottom black shales or dolostones of the Yurtus Formation in the western Tarim Basin, with a nadir δ 13 C carb value of −12.4‰ and a nadir δ 13 C carb value of −36.5‰ (Yao et al, 2011;Su et al, 2020;Zhang et al, 2020c;Zhang et al, 2022). Not restricted to the Tarim Block, this negative excursion of δ 13 C carb at the base of the Cambrian has also been recognized in South China (Ishikawa et al, 2008;Li et al, 2009;Jiang et al, 2012), Siberia (Brasier and Sukhov, 1998;Kouchinsky et al, 2007), Laurentia (Narbonne et al, 1994;Corsetti and Hagadorn, 2000), West Africa (Maloof et al, 2005), Mongolia (Brasier et al, 1996;Smith et al, 2016) and West Asia (Amthor et al, 2003).…”

Record of the Late Paleozoic Ice Age From Tarim, China

“…In this case, the infiltration of meteoric water with continental weathering products enriched in isotopically light CO 2 might have resulted in the lower δ 13 C values than those in the back-reef and bank reef in the lower member of Kangkelin Fm. After removing these samples with high Mn/Sr and Mg/Ca ratios, the low-correlation coefficient observed in this study between δ 18 O with δ 13 C, Mn/Sr, and Mg/Ca excludes the possibility of significant diagenetic processes for the range in the isotope data ( Figure 5; Grossman, 2012;Y. Zhang et al, 2020).…”

“…Here, we selected cut-offs for our studied samples during our prescreening: samples that clearly deviate from the main data group (Mn/Sr > 5, Mg/Ca > 0.1, and δ 18 O < −10‰) are considered as not representing primary seawater signals (Y. Zhang et al, 2020).…”

“…In addition, the Mn/Sr and Mg/Ca ratios would increase when carbonate rocks experienced a high degree of diagenetic alteration. Thus, cross‐plots of δ 18 O with δ 13 C, and Mn/Sr and Mg/Ca ratios are considered useful diagnostic tools of alteration of water‐rock interaction (Banner & Hanson, 1990; Brand & Veizer, 1980, 1981; Y. Zhang et al., 2020). Here, we selected cut‐offs for our studied samples during our prescreening: samples that clearly deviate from the main data group (Mn/Sr > 5, Mg/Ca > 0.1, and δ 18 O < −10‰) are considered as not representing primary seawater signals (Y. Zhang et al., 2020).…”

“…In contrast to δ 13 C, the δ 18 O data of bulk carbonate can be overprinted during diagenesis given the abundant oxygen in underground water. Therefore, Kaufman and Knoll (1995) and Qie et al (2015) 10.1029/2020GC009237 with δ 13 C, and Mn/Sr and Mg/Ca ratios are considered useful diagnostic tools of alteration of water-rock interaction (Banner & Hanson, 1990;Brand & Veizer, 1980, 1981Y. Zhang et al, 2020).…”