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

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 parts per thousand), Middlesex (+ parts per thousand), Lower Kellwasser ( + 3 parts per thousand), Upper Kellwasser ( + 3 parts per thousand) and Upper annul= (+ 1 parts per thousand) events, as well as a small positive CIE (+ 1 parts per thousand) 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 (delta)13C(carb) baseline (about + 2.5 parts per thousand) than that of the Frasnian (about +1 parts per thousand). 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.