The Neoproterozoic Hüttenberg δ13C anomaly: Genesis and global implications

Huan Cui, Alan Kaufman, Yongbo Peng, Xiao-Ming Liu, Rebecca Plummer, Elizabeth Lee

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23 Citations (Scopus)
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Abstract

The Neoproterozoic Hüttenberg Formation in northeastern Namibia records a remarkable δ13Ccarb positive excursion with a sustained plateau of values up to +12‰ (i.e., the Hüttenberg anomaly). High-resolution chemostratigraphic analyses of drill core samples spanning the upper Elandshoek and Hüttenberg formations reveal multiple new observations: (1) overall high but oscillatory δ13Ccarb values; (2) δ18Ocarb values ranging from −8‰ to −2‰; (3) significant enrichment of 13C in organic carbon and a broad co-variation between δ13Ccarb and δ13Corg; (4) a profound negative excursion in δ34Spyrite from +30‰ to −10‰; (5) an overall inverse δ13C–δ34S relationship; and (6) 87Sr/86Sr values down to 0.7074 in limestone samples. The new data suggest that the Hüttenberg anomaly records dynamic fluctuations in marine redox conditions, which may include an oxygenation event during the height of the δ13Ccarb positive excursion and a deoxygenation event at its termination. The δ34Spyrite negative excursion suggests the buildup of the marine sulfate reservoir, likely due to enhanced pyrite oxidation during the oxygenation event. The δ34Spyrite increase at the end of the Hüttenberg anomaly may result from a seawater sulfate concentration drawdown towards pre-anomaly conditions. On one hand, the Hüttenberg anomaly may reflect restricted basin signals that are deviated from the Ediacaran open ocean; on the other hand, the Ediacaran Hüttenberg anomaly, together with the Cryogenian δ13Ccarb positive excursions, suggests a stepwise pattern of the Neoproterozoic Oxygenation Event. Both local and global environmental factors may have contributed to the Hüttenberg anomaly. The Hüttenberg anomaly therefore represents a local enhancement of global oxygenation signals. Our data support the emerging view that the Neoproterozoic Oxygenation Event may have facilitated the evolution of early life at that time.
Original languageEnglish
Pages (from-to)242-262
Number of pages21
JournalPrecambrian Research
Volume313
DOIs
Publication statusPublished - 1 Aug 2018

Keywords

  • Carbon cycle
  • Chemostratigraphy
  • Hüttenberg anomaly
  • Namibia
  • Neoproterozoic
  • Positive excursion
  • Sulfur isotopes

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