Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic\u2013Jurassic transition

Jun Shen,Runsheng Yin,David J Bottjer,Donald Penman,Shucheng Xie,Xiao Shi,Liqin Li,Jianxin Yu,Qinglai Feng,Yongdong Wang,Thomas J Algeo,Guozhen Xu,Shuang Zhang,Noah J Planavsky

doi:10.1038/s41467-022-27965-x

Abstract

Direct evidence of intense chemical weathering induced by volcanism is rare in sedimentary successions. Here, we undertake a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, chemical index of alteration (CIA), and clay minerals) of two well-dated Triassic–Jurassic (T–J) boundary sections representing high- and low/middle-paleolatitude sites. Both sections show increasing CIA in association with Hg peaks near the T–J boundary. We interpret these results as reflecting volcanism-induced intensification of continental chemical weathering, which is also supported by negative mass-independent fractionation (MIF) of odd Hg isotopes. The interval of enhanced chemical weathering persisted for ~2 million years, which is consistent with carbon-cycle model results of the time needed to drawdown excess atmospheric CO2 following a carbon release event. Lastly, these data also demonstrate that high-latitude continental settings are more sensitive than low/middle-latitude sites to shifts in weathering intensity during climatic warming events.

Highlights

Volcanic source Mixing trend Erosional HgIncreasing terrestrial sourcesPost-ME ME Pre-ME Qilixia section ME Pre-MEVolcanic Continental plants-0.1 Erosional Hg
The Central Atlantic Magmatic Province (CAMP) coincided with ~3–6‰ negative carbon isotope excursions (CIEs) in both carbonates and organic matter, which have been used to constrain its onset and duration[4,6,9,39,40]
The presence of negative CIEs in carbonate and organic carbon isotope profiles of both marine and terrestrial T–J boundary sections serves to demonstrate the global extent of the underlying carbon-cycle perturbations[4,6,7,8,9,39,40]

Summary

Introduction

~200 kyr (Fig. 2), suggesting a protracted shift in tropicalsubtropical conditions relative to high-latitude settings. This pattern is consistent with predictions of more rapid temperature increases at high-latitude sites during the initial stages of warming (similar to the modern[61]). CO2 by silicate weathering at a million-year timescale following a major emission event such as the CAMP eruptions[11,42]. LOSCAR is suitable for investigation of the effects of carbon-cycle perturbations on atmospheric CO2 concentrations and silicate weathering rates at timescales ranging from centuries to millions of years[62,63,64,65].

Methods

Results

Conclusion