Tags

Type your tag names separated by a space and hit enter

Integrated carbon, sulfur, and nitrogen isotope chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial gradient, ocean redox oscillation, and fossil distribution.
Geobiology. 2017 07; 15(4):552-571.G

Abstract

The Ediacaran Doushantuo Formation in South China is a prime target for geobiological investigation because it offers opportunities to integrate chemostratigraphic and paleobiological data. Previous studies were mostly focused on successions in shallow-water shelf facies, but data from deep-water successions are needed to fully understand basinal redox structures. Here, we report δ13 Ccarb , δ13 Corg , δ34 Spyr , δ34 SCAS , and δ15 Nsed data from a drill core of the fossiliferous Lantian Formation, which is a deep-water equivalent of the Doushantuo Formation. Our data confirm a large (>10‰) spatial gradient in δ13 Ccarb in the lower Doushantuo/Lantian formations, but this gradient is probably due to the greater sensitivity of carbonate-poor deep-water sediments to isotopic mixing with 13 C-depleted carbonate cements. A pronounced negative δ13 Ccarb excursion (EN3) in the upper Doushantuo/Lantian formations, however, is spatially consistent and may be an equivalent of the Shuram excursion. δ34 Spyr is more negative in deeper-water facies than in shallow-water facies, particularly in the lower Doushantuo/Lantian formations, and this spatial pattern is interpreted as evidence for ocean redox stratification: Pyrite precipitated in euxinic deep waters has lower δ34 Spyr than that formed within shallow-water sediments. The Lantian Formation was probably deposited in oscillating oxic and euxinic conditions. Euxinic black shales have higher TOC and TN contents, but lower δ34 Spyr and δ15 Nsed values. In euxinic environments, pyrite was predominantly formed in the water column and organic nitrogen was predominantly derived from nitrogen fixation or NH4+ assimilation because of quantitative denitrification, resulting in lower δ34 Spyr and δ15 Nsed values. Benthic macroalgae and putative animals occur exclusively in euxinic black shales. If preserved in situ, these organisms must have lived in brief oxic episodes punctuating largely euxinic intervals, only to be decimated and preserved when the local environment switched back to euxinia again. Thus, taphonomy and ecology were the primary factors controlling the stratigraphic distribution of macrofossils in the Lantian Formation.

Authors+Show Affiliations

Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. Department of Geosciences, Virginia Tech, Blacksburg, VA, USA.Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA.Department of Geological Sciences, Indiana University, Bloomington, IN, USA.State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong, China.State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.Department of Geosciences, Virginia Tech, Blacksburg, VA, USA.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28063179

Citation

Wang, W, et al. "Integrated Carbon, Sulfur, and Nitrogen Isotope Chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial Gradient, Ocean Redox Oscillation, and Fossil Distribution." Geobiology, vol. 15, no. 4, 2017, pp. 552-571.
Wang W, Guan C, Zhou C, et al. Integrated carbon, sulfur, and nitrogen isotope chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial gradient, ocean redox oscillation, and fossil distribution. Geobiology. 2017;15(4):552-571.
Wang, W., Guan, C., Zhou, C., Peng, Y., Pratt, L. M., Chen, X., Chen, L., Chen, Z., Yuan, X., & Xiao, S. (2017). Integrated carbon, sulfur, and nitrogen isotope chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial gradient, ocean redox oscillation, and fossil distribution. Geobiology, 15(4), 552-571. https://doi.org/10.1111/gbi.12226
Wang W, et al. Integrated Carbon, Sulfur, and Nitrogen Isotope Chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial Gradient, Ocean Redox Oscillation, and Fossil Distribution. Geobiology. 2017;15(4):552-571. PubMed PMID: 28063179.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Integrated carbon, sulfur, and nitrogen isotope chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial gradient, ocean redox oscillation, and fossil distribution. AU - Wang,W, AU - Guan,C, AU - Zhou,C, AU - Peng,Y, AU - Pratt,L M, AU - Chen,X, AU - Chen,L, AU - Chen,Z, AU - Yuan,X, AU - Xiao,S, Y1 - 2017/01/06/ PY - 2016/07/06/received PY - 2016/12/07/accepted PY - 2017/1/8/pubmed PY - 2018/3/13/medline PY - 2017/1/8/entrez KW - Ediacaran Period KW - Lantian Formation KW - South China KW - carbon isotopes KW - nitrogen isotopes KW - sulfur isotopes SP - 552 EP - 571 JF - Geobiology JO - Geobiology VL - 15 IS - 4 N2 - The Ediacaran Doushantuo Formation in South China is a prime target for geobiological investigation because it offers opportunities to integrate chemostratigraphic and paleobiological data. Previous studies were mostly focused on successions in shallow-water shelf facies, but data from deep-water successions are needed to fully understand basinal redox structures. Here, we report δ13 Ccarb , δ13 Corg , δ34 Spyr , δ34 SCAS , and δ15 Nsed data from a drill core of the fossiliferous Lantian Formation, which is a deep-water equivalent of the Doushantuo Formation. Our data confirm a large (>10‰) spatial gradient in δ13 Ccarb in the lower Doushantuo/Lantian formations, but this gradient is probably due to the greater sensitivity of carbonate-poor deep-water sediments to isotopic mixing with 13 C-depleted carbonate cements. A pronounced negative δ13 Ccarb excursion (EN3) in the upper Doushantuo/Lantian formations, however, is spatially consistent and may be an equivalent of the Shuram excursion. δ34 Spyr is more negative in deeper-water facies than in shallow-water facies, particularly in the lower Doushantuo/Lantian formations, and this spatial pattern is interpreted as evidence for ocean redox stratification: Pyrite precipitated in euxinic deep waters has lower δ34 Spyr than that formed within shallow-water sediments. The Lantian Formation was probably deposited in oscillating oxic and euxinic conditions. Euxinic black shales have higher TOC and TN contents, but lower δ34 Spyr and δ15 Nsed values. In euxinic environments, pyrite was predominantly formed in the water column and organic nitrogen was predominantly derived from nitrogen fixation or NH4+ assimilation because of quantitative denitrification, resulting in lower δ34 Spyr and δ15 Nsed values. Benthic macroalgae and putative animals occur exclusively in euxinic black shales. If preserved in situ, these organisms must have lived in brief oxic episodes punctuating largely euxinic intervals, only to be decimated and preserved when the local environment switched back to euxinia again. Thus, taphonomy and ecology were the primary factors controlling the stratigraphic distribution of macrofossils in the Lantian Formation. SN - 1472-4669 UR - https://www.unboundmedicine.com/medline/citation/28063179/Integrated_carbon_sulfur_and_nitrogen_isotope_chemostratigraphy_of_the_Ediacaran_Lantian_Formation_in_South_China:_Spatial_gradient_ocean_redox_oscillation_and_fossil_distribution_ L2 - https://doi.org/10.1111/gbi.12226 DB - PRIME DP - Unbound Medicine ER -