2025-09-10 中国科学院(CAS)
Paleogeographic location of the Hule-1 core in the Jiangnan region, South China. (Image by NIGPAS)
＜関連情報＞
- https://english.cas.cn/newsroom/research_news/earth/202509/t20250910_1054313.shtml
- https://www.sciencedirect.com/science/article/abs/pii/S0031018225005127
中国南方江南斜面におけるオルドビス紀（フロイアン-サンドビアン期）の高解像度炭素同位体層序：δ13CorgにおけるMDICEの初の完全記録とその地球規模的意義 High resolution Ordovician (Floian-Sandbian) carbon isotope stratigraphy from the Jiangnan slope, South China: The first complete record of the MDICE in δ13Corg and its global significance
Xiaocong Luan, Mikael Calner, Fangyi Gong, Oliver Lehnert, Guanzhou Yan, Yuchen Zhang, Zhutong Zhang, Rongchang Wu
Palaeogeography, Palaeoclimatology, Palaeoecology Available online: 25 August 2025
DOI:https://doi.org/10.1016/j.palaeo.2025.113227
Highlights
- Detailed litho-, bio- and chemostratigraphy on the Middle–Late Ordovician in Jiangnan slope, South China;
- The most complete MDICE in δ13Corg data recorded worldwide so far;
- Inferring more pronounced perturbation of the global carbon cycle during the Darriwilian Age.
Abstract
The Middle Darriwilian Isotopic Carbon Excursion (MDICE) is one of the globally recognized positive excursions in carbon isotope chemostratigraphy, but mainly documented by δ13Ccarb data in previous research. In this paper, new stable organic carbon isotope data (δ13Corg) are presented from the Hule-1 core from the southern Anhui Province of southern China. The core constitutes an Ordovician siliciclastic succession deposited in the upper Jiangnan slope. The Ordovician graptolite biostratigraphy of this area is already well established, and ranges from the Baltograptus deflexus Zone (Floian) to the Nemagraptus gracilis Zone (Sandbian). Based on the well-constructed graptolite biostratigraphy, a low-amplitude positive excursion of middle–late Darriwilian age within the Hulo Formation is confidently identified as the MDICE. The excursion has an amplitude of ca. 1.1‰ starting from the value of −28.0‰ near the base of this formation, reaching a peak at −26.9‰ in the middle, and decreasing to −28.5‰ in its upper part. Therefore, it reveals to our knowledge the globally best preserved and most complete δ13Corg record of MDICE hitherto. Our data elucidate the stratigraphic significance of the MDICE also in deeper depositional environments and as a tool for correlation across different lithofacies belts. The inferred perturbation of the global carbon cycle during this time interval was presumably more pronounced than previously thought, confirming that the Darriwilian was a critical time slice in terms of environmental and biosphere changes.
