Abstract
The causes of the severest crisis in the history of life around the Permian-Triassic boundary (PTB) remain controversial. Here we report that the latest Permian alluvial plains in Shanxi, North China, went through a rapid transition from meandering rivers to braided rivers and aeolian systems. Soil carbonate carbon isotope (δ13C), oxygen isotope (δ18O), and geochemical signatures of weathering intensity reveal a consistent pattern of deteriorating environments (cool, arid, and anoxic conditions) and climate fluctuations across the PTB. The synchronous ecological collapse is confirmed by a dramatic reduction or disappearance of dominant plants, tetrapods and invertebrates and a bloom of microbially-induced sedimentary structures. A similar rapid switch in fluvial style is seen worldwide (e.g. Karoo Basin, Russia, Australia) in terrestrial boundary sequences, all of which may be considered against a background of global marine regression. The synchronous global expansion of alluvial fans and high-energy braided streams is a response to abrupt climate change associated with aridity, hypoxia, acid rain, and mass wasting. Where neighbouring uplands were not uplifting or basins subsiding, alluvial fans are absent, but in these areas the climate change is evidenced by the disruption of pedogenesis.
Highlights
The severest ecological crisis in Earth history, the Permian-Triassic mass extinction (PTME), occurred 252 Ma and killed over 90% of marine species and about 70% of continental vertebrate families[1,2]
Newell and colleagues[13] showed there was no independent evidence for tectonic activity in the Urals, and so explained the sudden influx of masses of sediment as a result of the reduction of vegetation that had long been recognized in the subsequent ‘coal gap’, the 10 Myr time span in the Early and Middle Triassic[14,15] when no coal, forests, or trees existed, presumably as a result of the devastating effects of the extinction
Terrestrial Permian-Triassic strata are widely distributed in North China, and show similar terrestrial fluvial-lacustrine sedimentary facies through the Permian-Triassic transition, against a background of regional regression (Fig. 2)
Summary
The severest ecological crisis in Earth history, the Permian-Triassic mass extinction (PTME), occurred 252 Ma and killed over 90% of marine species and about 70% of continental vertebrate families[1,2]. Combined with similar age populations of detrital zircons from the Late Permian-Early Triassic strata nearby[39,40], it is compelling to infer that the Sunjiagou and Liujiagou formations in northern Shanxi, North China share the same source area, originating from the Yinshan–Yanshan Orogenic Belt and Northern Qinling Orogen.
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