AN APPROACH TO RECOGNITION IN THE TRIASSIC SEA-LEVEL CHANGES ACCORDING TO THE MIXED CONODONT ELEMENTS.

1992 Fiscal Year Final Research Report Summary

• Project/Area Number: 03640652
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Stratigraphy/Paleontology
• Research Institution: TOKYO GAKUGEI UNIVERSITY
• Principal Investigator: IGO Hisaharu TOKYO GAKUGEI UNIVERSITY, FACULTY OF EDUCATION, ASSOCIATE PROFESSOR, 教育学部, 助教授 (70014818)
• Project Period (FY): 1991 – 1992
• Keywords: Mixed conodont elements / Eustatic movement / Guyot / Crack or fissure / Sea-level change / Turbidity current

Research Abstract

There are two types of the occurrence in the Triassic mixed conodont elements. The Taho limestone of Ehime Prefecture and the Kamura limestone of Miyazaki Prefecture yielded the Triassic mixed conodont elements in the sedimentary sequence.
The red calcarenite which yielded the middle Permian and the early to late Triassic mixed conodont elements filled with the cracks or fissures of the Permian limestone of the Akuda Formation. The laminated limestone which yielded almost a same mixed conodont elements of the Akuda Formation filled with the Permian limestone of the Karasawa Limestone Member of the Nabeyama Formation in the Kuzuu Town.
The Kamura and Taho limestone were influenced by eustatic movement between Anisian to Carnian.
The calcarenite and laminated limestone were deposited on the Permian limestone during the Triassic age. The Permian limestone deposited on the guyot of the oceanic floor. The calcarenite or laminated limestone had been influenced by sea-level change and formed mixed conodont elements as the Kamura and Taho limestone. When the guyot arrived at the trench, it fell into the trench. The Triassic sediments occurred the turbidity current. It filled into cracks or fissures of the broken Permian limestone.
In this investigation, we can recognized the Triassic sea-level changes according to mixed conodont elements.