Late Devonian carbon isotope chemostratigraphy: A new record from the offshore facies of South China

• Published in: Global and planetary change 2019-11, Vol.182, p.103024, Article 103024
• Main Authors: Zhang, Xinsong, Joachimski, Michael M., Over, D. Jeffrey, Ma, Kunyuan, Huang, Cheng, Gong, Yiming
• Format: Article
• Language: English
• Subjects: Bio-events; Famennian; Frasnian; Plants; Stable carbon isotopes; Tectonics
• ISSN: 0921-8181; 1872-6364
• DOI: 10.1016/j.gloplacha.2019.103024

We present a new biostratigraphically constrained carbon isotope record from the Lali section (South China) to document perturbations in the Late Devonian carbon cycle. Positive carbon isotope excursions (CIEs) are most important components of the Late Devonian long-term carbon isotope cycle: Frasnes (+2‰), Middlesex (+1‰), Lower Kellwasser (+3‰), Upper Kellwasser (+3‰) and Upper annulata (+1‰) events, as well as a small positive CIE (+1‰) in the Famennian expansa-aculeatus zones were recorded. It is noteworthy that no significant carbon isotope shifts are found for the Rhinestreet, Nehden, Condroz and Enkeberg events. The Late Devonian long-term carbon isotope curve from South China is in agreement with contemporaneous world-wide trends in Euramerica (Europe and North America) and Gondwana. Global data suggests a higher Famennian δ13Ccarb baseline (about +2.5 ‰) than that of the Frasnian (about +1‰). Previous studies have related the positive CIE to ocean anoxia, but its ultimate driver remains unclear. Other interpretations include the spread of land plants or increased tectonic activity, but these explanations are questionable due to the relative short durations of the CIEs compared to long-term processes of plant evolution and plant cover extension as well as tectonic movements. •The Late Devonian long-term carbon isotope curve in South China is in accord with contemporaneous world-wide trends.•Numerous Late Devonian bio-events are characterized positive carbon isotope excursions.•The Famennian δ13Ccarb baseline (about +2.5 ‰) is higher than in the Frasnian (about +1 ‰).•Ocean anoxia, spread of land plants and global tectonics may contribute to carbon isotope excursions.