Abstract
The end-Permian mass extinction was the largest biodiversity crisis in the Phanerozoic. Based on characteristic negative ∆33S signals of sedimentary pyrite, previous multiple sulfur isotope studies suggested shoaling of anoxic/sulfidic deep-waters onto a shelf, leading to the shallow-marine extinction. However, the validity of this shoaling model has been controversial. I compiled previously-reported multiple sulfur isotope records during the Permian-Triassic transition interval, and examined a stratigraphic relationship between the extinction horizon, redox oscillation in the depositional settings, and the multiple sulfur isotope record in each studied section. The compilation shows that the negative ∆33S signals do not correspond clearly to the extinction horizon or to the benthic anoxia/euxinia in the studied sections. The compilation also documents that the multiple sulfur isotope records during the Permian-Triassic transition are substantially variable, and that the negative ∆33S signals were observed in various types of sediments including shallow-marine carbonates, carbonates/siltstones of relatively deep-water facies, and abyssal deep-sea cherts. Those observations allow me to infer that the negative ∆33S signal is not a robust indicator of shoaling. Rather, this isotopic signal may reflect substantial sulfur isotope heterogeneity in the sediments controlled by local factors.
Highlights
The end-Permian mass extinction was the largest biodiversity decline in the Phanerozoic (e.g., [1])
Triassic (Figure 1a), which were presumably driven by sustained environmental stresses in this interval, such as recurrent Siberian Traps Large Igneous Province (STLIP) volcanism (e.g., [27]), elevated pCO2 (e.g., [28,29,30]) and pCH4 (e.g., [31,32]), global warming [33], and ocean acidification [34]
In many cases, the ∆33 S values of the younger sediments deviate slightly but significantly from zero. These nonzero ∆33 S records in the Proterozoic and Phanerozoic, which are detectable by high-precision multiple sulfur isotope measurements using a fluorination technique, most likely reflected mass-dependent fractionation (MDF) processes in the oceanic biogeochemical cycles (e.g., [53])
Summary
The end-Permian mass extinction was the largest biodiversity decline in the Phanerozoic (e.g., [1]). Several previous studies analyzed multiple sulfur topes in sedimentary records in the Permian-Triassic transition interval (Figure 1b), and isotopes in sedimentary records in the Permian-Triassic transition interval (Figure 1b), and tried to reconstruct the sedimentary sulfur cycle in association with bottom water redox tried to reconstruct the sedimentary sulfur cycle in association with bottom water redox conditions andconditions benthos activity duringactivity the three extinction events. I briefly review the multiple sulfur isotope system and its initial application to the Permianto sedimentary with the original shoaling models. I review later multiple sulfur isotope studies in the Permian-Triassic transition interval,.
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