Late paleozoic climate revealed by coral fossil patterns

RESEARCH ARTICLE Late paleozoic climate revealed by coral fossil patterns Weijia Zhang1,2, Jiaju Li1☯, Xue Cheng1☯, Hangjie Yu3, Shaomin CaiID4* 1 Department of Mathematics, Physics and Information Sciences, Shaoxing University, Shaoxing, Zhejiang, China, 2 Department of AOP Physics, University of Oxford, Wellington Square, Oxford, United Kingdom, 3 Department of Physics, Sun Yat-sen University, Guangzhou, Canton, China, 4 Department of Medicine, Shaoxing University, Shaoxing, Zhejiang, China ☯ These authors contributed equally to this work. * shao_cai@163.com Abstract The study of coral fossils with clear growth lines inShiqiantan Formation (310 Ma) in China showed the growth line increments of a single coral growing in this area is related to the sun- light illumination time. Moreover, the daily increment of the growth line caused by calcium carbonate depositions has an unusual bimodal curve. The study of this bimodal curve indi- cated Shiqiantan had evident four-season changes in the Late Carboniferous period, and the climate at that time was similar to that of modern North China. The present paper updates the oldest existing record of climate analysis materials and provides important infor- mation for the study of Late Paleozoic climate, as well as the ancient obliquity of ecliptic. Introduction Ancient sediments, shells, ice sheets, and rocks have long been regarded as valuable materials for reconstructing past climatic, environmental conditions and are important parts of paleocli- matology. The two main methods include measuring incremental growth patterns on fossil

shells and analyzing oxygen isotope. Oxygen isotope research is often used to reconstruct Cenozoic paleoclimates. For example, the isotope information on shells is the most reliable source of knowledge about seawater tem- perature conditions and the growth rates of shells [1]. The basic premise for measuring the growth increment pattern is that the fossil shell usually contains growth zones or lines with regular periodic precipitation. For example, Cudennec and Yves–Marie Paulet’s study confirmed the validity of the growth hypothesis by using cal- cein labeling experiment on Patella vulgata in the intertidal environment, and the growth of an individual reflects all the features encountered in the intertidal zone during growth [2]. Another promising finding of Wells [3] indicated the small ridges and annulations on the epitheca of corals might represent the daily and annual changes in skeletal deposition, respec- tively. According to Zhang et al. [4] and Moya et al. [5], such growth ridges are the results of light-enhanced calcification, and calcification rate is directly proportional to light intensity, thereby providing a theoretical basis for the study. This paper studies paleoclimate by consid- ering light deposition calcification or growth line increments. PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0290127 August 15, 2023 1 / 13 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Zhang W, Li J, Cheng X, Yu H, Cai S (2023) Late paleozoic climate revealed by coral fossil patterns. PLoS ONE 18(8): e0290127.

https://doi.org/10.1371/journal.pone.0290127 Editor: Shamim Ahmad, Birbal Sahni Institute of Palaeosciences: Birbal Sahni Institute of Palaeobotany, INDIA Received: May 16, 2023 Accepted: August 2, 2023 Published: August 15, 2023 Copyright: © 2023 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: The authors received China’s Fourteenth Five-Year Plan Funding for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.