the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 09 Mar 2026
Paleozoic-Mesozoic Terrestrial Total Organic Carbon and Organic Carbon Isotope Database
Abstract. Studies of the terrestrial carbon cycle commonly rely on geochemical proxies such as total organic carbon (TOC) and the organic carbon isotopic composition (δ13Corg). However, terrestrial TOC and δ¹³Corg data are widely dispersed across the literature and lack a unified compilation, limiting large‑scale synthesis and cross‑comparison. Here, we present a global, standardized dataset of TOC and δ13Corg measurements derived exclusively from terrestrial sedimentary facies: Paleozoic-Mesozoic Terrestrial Total Organic Carbon and Organic Carbon Isotope Database (PM-TOCI). The dataset compiles 66,587 individual data points (49,016 TOC and 17,571 δ13Corg) from 619 publications, spanning the Devonian to Cretaceous (419–66 Ma). Each entry is accompanied by 34 standardized metadata fields, covering geographic information, stratigraphic age, lithology, and depositional facies, thereby enabling consistent filtering, comparison, and reuse across spatial and temporal scales. This dataset is intended to facilitate future data-driven studies of terrestrial organic carbon accumulation, paleoclimate variability, source-rock assessment, and long-term carbon cycle dynamics, as well as the link between carbon cycle and biotic evolution. The dataset is openly accessible at https://doi.org/10.5281/zenodo.18163858 (Tian et al., 2026).
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Status: open (until 02 May 2026)
- RC1: 'Comment on essd-2026-17', Anonymous Referee #1, 18 Mar 2026 reply
Data sets
Paleozoic-Mesozoic Terrestrial Total Organic Carbon and Organic Carbon Isotope Database Yaokai Tian, Daoliang Chu, Jiankang Lai, Xiang Shu, Cidong Zhang, Fangyu Cui, Liangyu Lou, Xiaokang Liu, Yuyang Wu, Qingzhong Liang, Xinchuan Li, Hong Yao, and Haijun Song https://doi.org/10.5281/zenodo.18163858
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I thoroughly enjoyed reading this paper. The dataset is extensive and precisely fills a long-standing gap in terrestrial records. This work will be highly impactful for researchers investigating deep-time terrestrial carbon cycles, hydrocarbon source rocks, and the interactions between life and climate on land. Its potential applications are broad, and I anticipate it will be widely utilized across diverse research fields. The manuscript is also clearly written and highly accessible, which is a significant strength. Only a few minor revisions are needed, all of which are straightforward to implement.
First, the figures feel a bit rough and basic right now. They do the job, but for a journal like ESSD that aims for high visibility, they could look a lot nicer. A round of polishing (cleaner colors, sharper layout, better fonts and legends) would make the whole paper feel more professional and attractive.
Second, age control is always the biggest challenge in terrestrial sediments. The authors explain their interpolation method clearly, but many readers will worry that it could create extra uncertainty or put samples in the wrong time bins. I’d strongly suggest adding a simple column (or at least a confidence level) for age uncertainty in the actual database file. It would also be good to add one short, honest paragraph in the Usage instructions section that directly tells people about this limitation and how to handle it. That small addition will make the dataset much safer and more useful.
Third, the data availability part feels a little incomplete. The Geobiology Database link is mentioned, but actually going online to browse or filter the data isn’t very convenient yet. The Excel file is easy to download, but keeping it updated over time could be tricky. I strongly recommend giving at least one additional, user-friendly and regularly updatable link (maybe a simple web dashboard or a clearly versioned live repository) so people can access and explore the data more smoothly and the authors can add new entries efficiently.
Minor points:
Overall, this is a rigorous and highly significant contribution that the field greatly needs. Following these modest revisions, the paper will be outstanding. I am pleased to recommend a minor revision and look forward to the revised manuscript.