Paired carbonate and organic carbon isotope variations of the Ediacaran Doushantuo Formation from an upper slope section at Siduping, South China

Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China

“…(D) Reconstructed redox architecture during the deposition of the upper Doushantuo Formation. Sedimentology Zhu et al, 2013) and chemostratigraphy Wang et al, 2016) suggest that the Doushantuo Formation at Jiulongwan section was deposited in an intra-shelf environment, while the Zhongling section were deposited in an outer-shelf environment. The euxinic conditions on the platform were largely restricted in intra-shelf lagoonal settings , rather than an open shelf environment .…”

“…Please refer to the supplementary material for detailed field and petrographic observations. The variable expression of the δ 13 C negative excursion in the uppermost Doushantuo Formation across the basin Lu et al, 2013;Cui et al, 2015;Wang et al, 2016) hampers our interpretation of its origin and global implications (Fig. 8A, J).…”

“…A pronounced negative δ 13 C excursion in the uppermost Doushantuo Formation in the Yangtze Gorges area of South China is widely regarded as an equivalent of the Shuram Excursion (Jiang et al, 2007;McFadden et al, 2008;Lu et al, 2013;Tahata et al, 2013;Wang et al, 2016;Xiao et al, 2016). However in outer-shelf environment, this excursion is only expressed by a few negative δ 13 C data points (Zhou and Xiao, 2007;Zhu et al, 2007;Li et al, 2010).…”

“…Our revised correlation is also consistent with the progressive shallowing in water depth on the basis of independent sedimentological observation in the outer-shelf sections, where an increasing proportion of intraclasts and oolites relative to fine-grained phases are deposited Cui et al, 2015). The missing EN3b and EN3c in the outer-shelf sections may be due to either a basin-wide unconformity Zhu et al, 2013;Wang et al, 2016), or the diachronous nature of the lithologic boundary between Doushantuo and Dengying formations . If our basin-scale correlation for the Doushantuo Formation is correct, the strongly 13 C-depleted authigenic signatures revealed from the uppermost Doushantuo Formation at Zhongling could immediately precedes EN3, or could be time-equivalent to EN3a at the Jiulongwan section, suggesting a potential linkage between methane oxidation, sea level regression, and the onset of the Shuram Excursion (Bjerrum and Canfield, 2011).…”

Acanthomorphic acritarchs of the Doushantuo Formation from an upper slope section in northwestern Hunan Province, South China, with implications for early–middle Ediacaran biostratigraphy

“…The lower and middle Ediacaran ($635-551 Ma) Doushantuo Formation is dominated by organic-rich siliciclastics and carbonate rocks, whereas upper Ediacaran strata consist of Dengying Formation dolostone deposited in shallow water facies and Liuchapo Formation siliceous rocks deposited in slope and basinal facies (Cao et al, 1989). While the thickness and lithology vary in different depositional facies, the Doushantuo Formation in slope/basinal facies (e.g., the Siduping section in Hunan Province and the Wuhe section in Guizhou Province, as well as the Lantian Formation in southern Anhui Province) can be easily correlated with the Doushantuo Formation in the Yangtze Gorges area (i.e., Jiulongwan section) (Jiang et al, 2007;Wang et al, 2016Wang et al, , 2017aYuan et al, 2011). This correlation is further supported by numerous C and Sr isotope chemostratigraphic studies (Jiang et al, 2007;Lu et al, 2013;Wang et al, 2016;Zhu et al, 2007Zhu et al, , 2013.…”