Paper No. 217-5
Presentation Time: 2:45 PM
EXTRATERRESTRIAL HELIUM-3 FLUX ACROSS THE PERMIAN/TRIASSIC BOUNDARY
ONOUE, Tetsuji1, TAKAHATA, Naoto2, MIURA, Mitsutaka1, SATO, Honami3, ISHIKAWA, Akira4, SODA, Katsuhito1, SANO, Yuji5 and ISOZAKI, Yukio4, (1)Department of Earth and Environmental Sciences, Kumamoto University, 2-39-1 Kurokami, Kumamoto, 860-8555, Japan, (2)Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, 277-8564, Japan, (3)Ocean Resources Research Center for Next Generation, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, 275-0016, Japan, (4)Department of General System Studies, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8902, Japan, (5)Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa-noha, 277-8564, Japan
The Solar System contains abundant submillimetre interplanetary dust particles (IDPs) that are enriched in
3He.
3He concentrations in ancient deep-sea sediments have been used to constrain the flux of IDPs onto the Earth for at least the last 100 Myr. However, the use of
3He in detecting IDP flux is often compromised by the diffusional loss of
3He in sedimentary rocks, with the exception of some Ordovician samples that record a period of unusually high extraterrestrial
3He (
3He
ET) flux. In this study, we report for the first time the preservation of extra-terrestrial
3Hein deep-sea bedded chertfrom a continuous Permian-Triassic boundary (PTB) section at Waidani in Japan, which was deposited in the Panthalassa superocean.
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 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 calculated3HeETfluxacross the PTB.The data document the presence of an up to 6-fold increase in IDP flux for the last 100–200 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 flux of interplanetary dust particles occurred during the final 100–200 kyr of the Permian, concurrent with a carbon isotopic excursion event and the development of highly anoxic–euxinic bottom-water conditions.