Abstract
The stratigraphy of the Tetori Group (sensu lato) and other Early Cretaceous strata in the Hakusan Region in the Hida Belt, northern Central Japan, is reviewed based on recent advances in ammonoid biostratigraphy, U-Pb age determination of zircons using inductively coupled plasma-mass spectrometry with laser ablation sampling (LA-ICPMS), recognition of marine influence, and climatic change inferred from the occurrences of thermophilic plants and pedogenetic calcareous nodules. Four depositional stages (DS) are recognized: DS1 (Late Bathonian-Middle Oxfordian)—mainly marine strata characterized by the occurrences of ammonoids; DS2 (Berriasian-Late Hauterivian)—mainly brackish strata characterized by the occurrences of Myrene (Mesocorbicula) tetoriensis and Tetoria yokoyamai; DS3 (Barremian-Aptian)—fluvial strata characterized by the occurrence of abundant quartzose gravels and freshwater molluscs, such as Trigonioides, Plicatounio and Nippononaia; DS4 (Albian-Cenomanian)—volcanic/plutonic rocks which unconformably covered or intruded into the Tetori Group. I here propose new interpretation that 1) the Tetori Group (s.l.) in the Hakusan Region in the Hida Belt is divided into Middle-Late Jurassic Kuzuryu Group (corresponding to DS1) and unconformably overlying Early Cretaceous Tetori Group (sensu stricto) (corresponding to DS2-3); and 2) the Tetori Group (s.l.) in other areas is separated from the Tetori Group (s.s.), and divided into the Late Jurassic strata of the Kuzuryu Group (corresponding to the upper part of the same group in the Hakusan Region) and the Early Cretaceous Jinzu Group in the Jinzu Region in the Hida Belt, and the Late Jurassic-Early Cretaceous Managawa Group in the Hida Gaien Belt.
Original language | English |
---|---|
Pages (from-to) | 25-61 |
Number of pages | 37 |
Journal | Memoir of the Fukui Prefectural Dinosaur Museum |
Volume | 2015 |
Issue number | 14 |
State | Published - 2015/12 |
Keywords
- Central Japan
- Early Cretaceous
- Hakusan region
- Jurassic
- Kuzuryu Group
- Tetori Group
ASJC Scopus subject areas
- Paleontology