Xie Shucheng

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Xie
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Shucheng
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  • Preprint
    Uncovering the spatial heterogeneity of Ediacaran carbon cycling
    ( 2016-12) Li, Chao ; Hardisty, Dalton S. ; Luo, Genming ; Huang, Junhua ; Algeo, Thomas J. ; Cheng, Meng ; Shi, Wei ; An, Zhihui ; Tong, Jinnan ; Xie, Shucheng ; Jiao, Nianzhi ; Lyons, Timothy W.
    Records of the Ediacaran carbon cycle (635 to 541 million years ago) include the Shuram excursion (SE), the largest negative carbonate-carbon isotope excursion in Earth history (down to -12 ‰). The nature of this excursion remains enigmatic given the difficulties of interpreting a perceived extreme global decrease in the δ13C of seawater dissolved inorganic carbon (DIC). Here, we present carbonate and organic carbon isotope (δ13Ccarb and δ13Corg) records from the Ediacaran Doushantuo Formation along a proximal-to-distal transect across the Yangtze Platform of South China as a test of the spatial variation of the SE. Contrary to expectations, our results show that the magnitude and morphology of this excursion and its relationship with coexisting δ13Corg are highly heterogeneous across the platform. Integrated geochemical, mineralogical, petrographic, and stratigraphic evidence indicates that the SE is a primary marine signature. Data compilations demonstrate that the SE was also accompanied globally by parallel negative shifts of δ34S of carbonate-associated sulfate (CAS) and increased 87Sr/86Sr ratio and coastal CAS concentration, suggesting elevated continental weathering and coastal marine sulfate concentration during the SE. In light of these observations, we propose a heterogeneous oxidation model to explain the high spatial heterogeneity of the SE and coexisting δ13Corg records of the Doushantuo, with likely relevance to the SE in other regions. In this model, we infer continued marine redox stratification through the SE but with increased availability of oxidants (e.g., O2 and sulfate) limited to marginal near-surface marine environments. Oxidation of limited spatiotemporal extent provides a mechanism to drive heterogeneous oxidation of subsurface reduced carbon mostly in shelf areas. Regardless of the mechanism driving the SE, future models must consider the evidence for spatial heterogeneity in δ13C presented in this study.
  • Article
    An interlaboratory study of TEX86 and BIT analysis of sediments, extracts, and standard mixtures
    (John Wiley & Sons, 2013-12-20) Schouten, Stefan ; Hopmans, Ellen C. ; Rosell-Mele, Antoni ; Pearson, Ann ; Adam, Pierre ; Bauersachs, Thorsten ; Bard, Edouard ; Bernasconi, Stefano M. ; Bianchi, Thomas S. ; Brocks, Jochen J. ; Carlson, Laura Truxal ; Castaneda, Isla S. ; Derenne, Sylvie ; Selver, Ayca Dogrul ; Dutta, Koushik ; Eglinton, Timothy I. ; Fosse, Celine ; Galy, Valier ; Grice, Kliti ; Hinrichs, Kai-Uwe ; Huang, Yongsong ; Huguet, Arnaud ; Huguet, Carme ; Hurley, Sarah ; Ingalls, Anitra ; Jia, Guodong ; Keely, Brendan ; Knappy, Chris ; Kondo, Miyuki ; Krishnan, Srinath ; Lincoln, Sara ; Lipp, Julius S. ; Mangelsdorf, Kai ; Martínez-Garcia, Alfredo ; Menot, Guillemette ; Mets, Anchelique ; Mollenhauer, Gesine ; Ohkouchi, Naohiko ; Ossebaar, Jort ; Pagani, Mark ; Pancost, Richard D. ; Pearson, Emma J. ; Peterse, Francien ; Reichart, Gert-Jan ; Schaeffer, Philippe ; Schmitt, Gaby ; Schwark, Lorenz ; Shah, Sunita R. ; Smith, Richard W. ; Smittenberg, Rienk H. ; Summons, Roger E. ; Takano, Yoshinori ; Talbot, Helen M. ; Taylor, Kyle W. R. ; Tarozo, Rafael ; Uchida, Masao ; van Dongen, Bart E. ; Van Mooy, Benjamin A. S. ; Wang, Jinxiang ; Warren, Courtney ; Weijers, Johan W. H. ; Werne, Josef P. ; Woltering, Martijn ; Xie, Shucheng ; Yamamoto, Masanobu ; Yang, Huan ; Zhang, Chuanlun L. ; Zhang, Yige ; Zhao, Meixun ; Sinninghe Damste, Jaap S.
    Two commonly used proxies based on the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) are the TEX86 (TetraEther indeX of 86 carbon atoms) paleothermometer for sea surface temperature reconstructions and the BIT (Branched Isoprenoid Tetraether) index for reconstructing soil organic matter input to the ocean. An initial round-robin study of two sediment extracts, in which 15 laboratories participated, showed relatively consistent TEX86 values (reproducibility ±3–4°C when translated to temperature) but a large spread in BIT measurements (reproducibility ±0.41 on a scale of 0–1). Here we report results of a second round-robin study with 35 laboratories in which three sediments, one sediment extract, and two mixtures of pure, isolated GDGTs were analyzed. The results for TEX86 and BIT index showed improvement compared to the previous round-robin study. The reproducibility, indicating interlaboratory variation, of TEX86 values ranged from 1.3 to 3.0°C when translated to temperature. These results are similar to those of other temperature proxies used in paleoceanography. Comparison of the results obtained from one of the three sediments showed that TEX86 and BIT indices are not significantly affected by interlaboratory differences in sediment extraction techniques. BIT values of the sediments and extracts were at the extremes of the index with values close to 0 or 1, and showed good reproducibility (ranging from 0.013 to 0.042). However, the measured BIT values for the two GDGT mixtures, with known molar ratios of crenarchaeol and branched GDGTs, had intermediate BIT values and showed poor reproducibility and a large overestimation of the “true” (i.e., molar-based) BIT index. The latter is likely due to, among other factors, the higher mass spectrometric response of branched GDGTs compared to crenarchaeol, which also varies among mass spectrometers. Correction for this different mass spectrometric response showed a considerable improvement in the reproducibility of BIT index measurements among laboratories, as well as a substantially improved estimation of molar-based BIT values. This suggests that standard mixtures should be used in order to obtain consistent, and molar-based, BIT values.