Enhanced flux of extraterrestrial 3He across the Permian–Triassic boundary

Abstract

The ca 252 Ma Permian-Triassic boundary (PTB) represents the most severe mass extinction event of the Phanerozoic, with the disappearance of~80% of marine invertebrate species. Large-scale eruption of the Siberian Traps is the commonly favored cause, although the link between volcanism and extinction remains debated. Here, we report evidence for an extraterrestrial 3 He influx in the PTB section of deep-sea bedded cherts from Japan. This unusual signal indicates a significant increase in the influx of interplanetary dust particles, likely related to an asteroid shower in the inner solar system. High-resolution stratigraphy indicates that the peak flux of dust particles occurred during the final 500 kyr of the Permian, concurrent with a pre-extinction decline in radiolarian diversity.

Development of Deep-Sea Anoxia in Panthalassa During the Lopingian (Late Permian): Insights From Redox-Sensitive Elements and Multivariate Analysis

“…The PTB sections of the Mino Belt, central Japan ( Figure 1) preserve high-resolution biostratigraphic records of the EPME in a mid-oceanic realm of the Panthalassa Ocean (Kuwahara et al, 1998;Yao et al, 2001;Sano et al, 2010;Nishikane et al, 2011;Sano et al, 2012a;Sano et al, 2012b;Nishikane et al, 2014;Kuwahara and Sano, 2017). The intensification of oxygendepleted conditions during the latest Lopingian has been reported from several PTB sections in the Mino Belt (Wignall et al, 2010;Algeo et al, 2011b;Sano et al, 2012b;Onoue et al, 2019). An improved understanding of the oceanic redox conditions during the Guadalupian and Lopingian (Kato et al, 2002;Kakuwa, 2008;Kato and Isozaki, 2009;Fujisaki et al, 2019) is central to understanding the link between global-ocean conditions and the EPME, as well as the subsequent delayed biotic recovery during the Early Triassic.…”

“…Oxygen-depleted conditions during the latest Changhsingian have been proposed from other pelagic deep-sea PTB sections in Japan, such as the Waidani, Gujo-Hachiman, Akkamori, Ubara, and Tenjinmaru sections ( Figure 1B; Kajiwara et al, 1994;Wignall et al, 2010;Algeo et al, 2011b;Sano et al, 2012b;Takahashi et al, 2014;Kaiho et al, 2016;Zhang et al, 2017;Onoue et al, 2019). Of these, the Waidani, Akkamori, Ubara, and Tenjinmaru sections have limited stratigraphic records from the late Changhsingian to Early Triassic, whereas the Gujo-Hachiman section preserves a longer record from the Capitanian to the latest Changhsingian Zhang et al, 2017;Fujisaki et al, 2019).…”

“…The Mo EF values and Mo EF /U EF ratios (Figure 7) demonstrate that H 2 S-rich (euxinic) conditions may have developed in the latest Changhsingian, concurrent with the EPME. Since the average sedimentation rate for the Changhsingian bedded chert of the Hashikadani Formation is ∼0.3 cm•kyr −1 (Onoue et al, 2019), the anomalous increases in Mo EF corresponding to the 60 cm stratigraphic interval at the end of the Permian indicate that the euxinic conditions in stage 3 began ∼200 kyr before the EPME (Figure 14). The increase in V EF and U EF does not coincide with the increase in Mo EF , and their values increase significantly at the EPME horizon ( Figure 7).…”

A Significantly High He Isotopic Signature from the End-Paleozoic (250 Ma) Extinction-related Interval: For Detecting Ancient Extraterrestrial Fluxes through the Earth's History since the Hadean

“…図 3 (a)バルク分析で得られた 3 He 濃度鉛直分布(青) ．地球外 3 He 濃度の鉛直分布(赤)もほぼ同じ傾向を示す． 0 m が P/T 境界を表し，下側ほど古い． 3 He 濃度は P/T 境界の下約 1.5 m(時間にすると約 50 万年)で高い値を 示 す． (b) 3 He/ 4 He 比の鉛直分布． 3 He 濃度の分布と同じ傾向を示すとともに P/T 境界下 2 m でもまだ高い． (c) イリジウム濃度の鉛直分布． 3 He 濃度の分布と同じ傾向を示す(Onoue et al, 2019 を改変) ． Fig. 3 (a) Vertical profiles of 3 He concentrations in bulk analysis (blue) and extraterrestrial 3 He concentrations (red) , (b) 3 He/ 4 He ratios and (c) iridium concentrations drawn after Onoue et al (2019) . They are higher below the P/T boundary.…”

“…There is a good correlation between 3 He and iridium concentrations. He flux (that is, product of flux and retention factor) drawn after Onoue et al (2019) . The product just before the P/T boundary was about five times higher than at quiet intervals.…”