Ishidohara (Aokiyama Fm): Early Miocene, Japan
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
|
Bivalvia
- Protobranchia
- Solemyidae
|
|||||||
|
Solemya (Acharax) tokunagai
Yokoyama 1925
|
|||||||
|
Bivalvia
- Venerida
- Vesicomyidae
|
|||||||
|
Calyptogena (Electenagena) sp.
Dall 1891
|
|||||||
| see common names | |||||||
Geography
| Country: | Japan |
| Coordinates: | 35.1° North, 139.9° East (view map) |
| Paleocoordinates: | 35.3° North, 137.0° East (Wright 2013) |
| Basis of coordinate: | estimated from map |
| Geographic resolution: | outcrop |
Time
| Period: | Neogene | Epoch: | Miocene |
| 10 m.y. bin: | Cenozoic 5 | ||
| Key time interval: | Early Miocene | ||
| Age range of interval: | 23.04 - 15.98 m.y. ago |
Stratigraphy
| Geological group: | Hota | Formation: | Aokiyama | ||
| Local section: | Ishidohara | ||||
| Stratigraphic resolution: | bed | ||||
| Stratigraphy comments: The Hota Gp has a thickness of nearly 2000 m and is divided into the Maejima, Takazuru, and Aokiyama Fms in ascending order. The Aokiyama Fm is largely composed of tuff, tuffaceous sandstone, and mudstone. The collection is derived from siltstone in the upper part of the Aokiyama Fm. The age of the unit is considered to be of early Miocene age (18 Ma) on the basis of radiolarian bioostratigraphy (Stichocorys wolffii-Cralocycletta costata zones). | |||||
Lithology and environment
| Primary lithology: | gray lithified siltstone | ||
| Includes fossils? | Y | ||
| Lithology description: Gray-dark gray massive siltstone, and with some very fine grained sandstone | |||
| Environment: | deep-water indet. | Tectonic setting: | forearc basin |
| Geology comments: Deep-sea siliciclastic environment | |||
Taphonomy
| Modes of preservation: | body |
| Size of fossils: | macrofossils |
| Articulated whole bodies: | all |
Collection methods and comments
| Collection methods: | selective quarrying,field collection |
| Reason for describing collection: | taxonomic analysis |
| Collection method comments: Collections housed in IGUT (Institute of Geoscience, University of Tsukuba). Collecting locality no longer exists. | |
| Taxonomic list comments:Authoritatve and modern nomenclature. Both taxa desibribed in paper. | |
Metadata
| Database number: | 57692 | ||
| Authorizer: | A. Hendy | Enterer: | A. Hendy | Research group: | marine invertebrate |
| Created: | 2005-12-18 12:26:13 | Last modified: | 2025-02-22 15:12:02 |
| Access level: | the public | Released: | 2005-12-18 12:26:13 |
| Creative Commons license: | CC0 |
Reference information
Primary reference:
| 15516. | K. Ogasawara, K. Hisada, and N. Kitada. 1994. Early Miocene Calyptogena from the Aokiyama Formation, Hota Group, Boso Peninsula, Japan. Annual Report of the Institute of Geoscience, the University of Tsukuba 20:33-37 [A. Miller/A. Hendy] |