11:30 AM - 11:50 AM
[BCG08-03] Enhanced flux of extraterrestrial 3He across the Permian–Triassic boundary
Keywords:Permian, Triassic, Bedded Chert, Helium, Interplanetary dust particle, Platinum group element
High 3He/4He ratios (up to 150 Ra; 1Ra = the atmospheric ratio) were detected from acid-insoluble residues fromthe uppermost Permian deposits, which suggeststhe existence of extraterrestrial He hosted mainly in IDPs. The estimated extraterrestrial fraction of 3He across the PTB revealsthat3HeETconcentrations are higher in the topmost ~1.5 m ofthe studied Permian deposits, which is 4–5 times greater than that measured in the overlying Triassic unit. Based on the 3HeET concentration and sedimentary mass accumulation rate of the PTB section at Waidani, we calculated 3HeET fluxacross the PTB.The data document the presence of an up to 4-fold increase in IDP flux for the last 500 kyr interval of the Permian.This unusual signal suggests a significant increase in the influx of interplanetary dust particles, likely related to an asteroid showerin the inner Solar System. High-resolution stratigraphy indicates that peak IDP flux occurred during the final 500 kyr of the Permian, concurrent with a pre-extinction decline in radiolarian diversity.