Ecological disturbance in tropical peatlands prior to marine Permian-Triassic mass extinction

Daoliang Chu,Wenchao Shu,Paul B Wignall,Stephen E Grasby,Yuyang Wu,Huyue Song,Tamsin A Mather,Haijun Song,Yao Wang,Jinnan Tong,Jacopo Dal Corso

doi:10.1130/g46631.1

Abstract

AbstractThe Permian-Triassic mass extinction is widely attributed to the global environmental changes caused by the eruption of the Siberian Traps. However, the precise temporal link between marine and terrestrial crises and volcanism is unclear. Here, we report anomalously high mercury (Hg) concentrations in terrestrial strata from southwestern China, synchronous with Hg anomalies in the marine Permian-Triassic type section. The terrestrial sediments also record increased abundance of fossil charcoal coincident with the onset of a negative carbon isotope excursion and the loss of tropical rainforest vegetation, both of which occurred immediately before the peak of Hg concentrations. The organic carbon isotope data show an ∼5‰–6‰ negative excursion in terrestrial organic matter (bulk organic, cuticles, and charcoal), reflecting change in atmospheric CO2 carbon-isotope composition coincident with enhanced wildfire indicated by increased charcoal. Hg spikes provide a correlative tool between terrestrial and marine records along with carbon isotope trends. These data demonstrate that ecological deterioration occurred in tropical peatlands prior to the main marine mass extinction.

Highlights

The Permian-Triassic mass extinction (PTME)was the most severe extinction event of the Phanerozoic, both in marine and terrestrial settings (Wignall, 2015), but the relative timing of these crises is debated
The onset of the main phase of marine extinctions in South China, at the top of the Clarkina yini Zone, correlates with a peak in high mercury (Hg) concentrations and Hg/total organic carbon (TOC), while a second phase of extinctions at the top of the Isarcicella staeschi Zone corresponds to a rise in Hg concentrations and Hg/TOC that peaks in the following I. isarcica Zone (Wang et al, 2018, 2019)
Our results demonstrate that a synchronous onset of the negative carbon isotope excursion (CIE) is present in the bulk organic matter (OM), cuticle, and charcoal carbon isotope records from terrestrial settings (Fig. 2)

Summary

Introduction

Was the most severe extinction event of the Phanerozoic, both in marine and terrestrial settings (Wignall, 2015), but the relative timing of these crises is debated (e.g., S.Z. Shen et al, 2011; Gastaldo et al, 2015; Fielding et al, 2019). Most proposed kill mechanisms are linked to the effects of Siberian Traps eruptions (Wignall, 2001; Grasby et al 2011). Provides a chemostratigraphic marker in marine records A similar Hg enrichment event has been documented in contemporaneous terrestrial sediments

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Discussion

Conclusion