Biotic and environmental changes in the Panthalassa Ocean across the Norian (Late Triassic) impact event

Honami Sato, Yutaro Takaya, Kazutaka Yasukawa, Koichiro Fujinaga, Tetsuji Onoue, Yasuhiro Kato

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Stratigraphic records of impact ejecta preserved in a pelagic deep-sea setting occur within Upper Triassic successions of the subduction-generated accretionary complexes of central Japan. A significant biotic turnover in radiolarians occurred during the ~ 300 kyr time interval after the impact event, which is characterized by a remarkable reduction in the burial flux of radiolarian silica. However, the nature of the environmental conditions at this time remains unclear. To investigate the environmental changes that triggered a decline in radiolarian burial flux after the impact event, geochemical proxies (major, trace, and rare earth elements) were applied to the middle–upper Norian (Upper Triassic) bedded chert succession of the Mino Belt, central Japan. A progressive environmental deterioration is evident from (1) a post-impact shutdown of burial flux of primary and silica- and apatite-secreting organisms; and (2) a subsequent abrupt increase in chemical weathering associated with a sustained reduction in the burial flux of radiolarian silica. No significant redox changes were observed across the impact event. The continental weathering proxies suggest a transient increase in weathering intensity occurred during the decline of radiolarian burial flux, likely in response to a short-term warm and humid period. Our results delineate a remarkable record of progressive environmental changes in the Panthalassa Ocean after this large impact event. [Figure not available: see fulltext.].

Original languageEnglish
Article number61
JournalProgress in Earth and Planetary Science
Volume7
Issue number1
DOIs
Publication statusPublished - 2020 Dec 1

Keywords

  • Bedded chert
  • Environmental changes
  • Impact event
  • Late Triassic
  • Norian
  • Radiolaria

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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