Decoupling of δ13Ccarb and δ13Corg during the Carnian Pluvial Episode in marine successions of South China

IF 3.6 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Chemical Geology Pub Date : 2025-09-13 DOI:10.1016/j.chemgeo.2025.123053

Enhao Jia , Jacopo Dal Corso , Kui Wu , Yong Du , Yuyang Wu , Fengyu Wang , Xu Dai , Huyue Song , Daoliang Chu , Lei Zhong , Zhiwei Yuan , Xiangmin Chen , Yuting Liu , Zhe Li , Haijun Song

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Abstract

The Carnian Pluvial Episode (CPE) was a major climate change in the early Late Triassic. Multiple ¹³C negative excursions are widely considered to be key indicators of CPE and may be associated with the activity of Wrangellia large igneous province (LIP). However, it is still not clear whether the increased terrestrial inputs due to enhanced hydrological cycle during the CPE disturbed the isotope signal in marine settings. This study analyzed the high-resolution carbon isotopes and element geochemistry of three typical marine section (Xiashulao, Erguan, and Duanqiao) in South China. Decoupling between δ¹³C_carb and δ¹³C_org (2–3 ‰ negative shift of δ¹³C_carb vs 3–4 ‰ positive shift in δ¹³C_org) during CPE is observed at two shallow marine sections, i.e., Xiashulao and Erguan. No decoupling of δ¹³C_carb and δ¹³C_org was found in Duanqiao, which may relate to its location in a deep slope or basin environment, receiving fewer terrestrial inputs. This study reveals the regulating effect of depositional environmental differentiation on the carbon isotope record during the CPE and proposes a model of organic‑carbonate carbon isotope decoupling driven by terrestrial input.

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华南海相层序卡尼期雨积期δ13Ccarb与δ13Corg的解耦

卡尼期雨积期（CPE）是晚三叠世早期的一次重要气候变化。多次13C负偏移被广泛认为是CPE的关键指标，可能与Wrangellia大火成岩省（LIP）的活动有关。然而，目前尚不清楚CPE期间由于水文循环增强而增加的陆地输入是否干扰了海洋环境中的同位素信号。本文对中国南方三个典型海相剖面（下树老、二关和端桥）的高分辨率碳同位素和元素地球化学进行了分析。下树老和二关两个浅海剖面观测到CPE期间δ13Ccarb与δ13Corg的解耦（δ13Ccarb负移2 ~ 3‰，δ13Corg正移3 ~ 4‰）。断桥地区δ13Ccarb与δ13Corg没有解耦，这可能与断桥地区处于深斜坡或盆地环境有关，受陆源输入较少。研究揭示了沉积环境分异对CPE时期碳同位素记录的调节作用，提出了陆源输入驱动的有机-碳酸盐岩碳同位素解耦模型。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Chemical Geology 地学-地球化学与地球物理

CiteScore

7.20

自引率

10.30%

发文量

374

审稿时长

3.6 months

期刊介绍： Chemical Geology is an international journal that publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry. The Journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry. Papers that are field, experimentally, or computationally based are appropriate if they are of broad international interest. The Journal generally does not publish papers that are primarily of regional or local interest, or which are primarily focused on remediation and applied geochemistry. The Journal also welcomes innovative papers dealing with significant analytical advances that are of wide interest in the community and extend significantly beyond the scope of what would be included in the methods section of a standard research paper.