Onset and termination of harsh environments during the latest Paleozoic to earliest Mesozoic Panthalassic Ocean

2015 Fiscal Year Final Research Report

• Project/Area Number: 24540499
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Stratigraphy/Paleontology
• Research Institution: Kyushu University
• Principal Investigator: Sano Hiroyoshi 九州大学, 理学(系)研究科(研究院), 教授 (80136423)
• Co-Investigator(Kenkyū-buntansha): SASHIDA Katsuo 筑波大学, 大学院生命科学研究科, 教授 (60134201) ; AGEMATSU Sachiko 筑波大学, 大学院生命科学研究科, 准教授 (50466661) ; KUWAHARA Kiyoko 芦屋大学, 教育学部, 講師 (20507131)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: ペルム紀末大量絶滅 / 環境回復 / 前期三畳紀 / パンサラッサ海

Outline of Final Research Achievements

We focused upon termination of harsh environments in the aftermath of end-Permian extinction event. Results are summarized as follows; (1) Marine harsh condition (O2-depleted) almost terminated no later than late Olenekian (Spathian) and radiolarian ecosystem fully recovered in a pelagic realm. Late Olenekian oxic condition was punctated by short-lived dysoxic events, which resulted in deposition of thin high-C claystone within grayish bedded chert. (2) Fully oxic condition returned in early Middle Triassic (early Anisin) after repetition of oxic/dysoxic condition. These two points mean unstable environments in late Early Triassic. (3) We found basaltic sandstone and conglomerate in the Lower Triassic siliceous claystone and postulate basaltic rocks as basement for Lower Triassic siliceous claystone. Displacement of basaltic debris by turbiditic and debris flows implies movement of water mass that has potential for mixing of seawater and oxygen supply into deep-marine environment.

Free Research Field

堆積岩石学