Yonabaru Clay, Shimajiri Formation, Okinawa: Late Miocene, Japan
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
|
Bivalvia
- Arcida
- Limopsidae
|
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| Listed as "species closely related to L. tajimae" | ||||||||||
| see common names | ||||||||||
Geography
| Country: | Japan | State/province: | Okinawa |
| Coordinates: | 26.5° North, 127.5° East (view map) | ||
| Paleocoordinates: | |||
| Basis of coordinate: | estimated from map | ||
| Geographic resolution: | basin |
Time
| Period: | Neogene | Epoch: | Miocene |
| 10 m.y. bin: | Cenozoic 6 | ||
| Key time interval: | Late Miocene | ||
| Age range of interval: | 11.63 - 5.333 m.y. ago |
Stratigraphy
| Formation: | Shimajiri | Member: | Yonabaru Clay | ||
| Stratigraphic resolution: | formation | ||||
| Stratigraphy comments: The Yonabaru Clay includes all Shimajiri Formation exposed below the upper tuffaceous pumiceous zone. The Yonabaru consists of bluish to gray silty to sandy clay, commonly with hackly to conchoidal fracture and fine dark-colored laminated to massive sand, weathering brown to gray, and in places contains large lime indurated concretions of sand. Most macrofossils are found in sandy beds intercalated with the clays. The Yonabaru passes under the cover of the basal gravels of the Naha limestone, and lap onto or are faukted against Paleozoic basement rocks. | |||||
Lithology and environment
| Primary lithology: | poorly lithified silty,sandy claystone |
| Secondary lithology: | planar lamination,concretionary,brown,gray sandstone |
| Includes fossils? | Y |
| Includes fossils? | Y |
| Lithology description: Bluish to gray silty to sandy clay, commonly with hackly to conchoidal fracture and fine dark-colored laminated to massive sand, weathering brown to gray, and in places contains large lime indurated concretions of sand. | |
| Environment: | deep-water indet. |
| Geology comments: Molluscs found in assemblages of the Yonabaru Clay indicate moderately shallow to moderately deep water. Probably a depth of less than 100 fathoms in shallow facies and probably not more than 300 fathoms in deeper facies. | |
Taphonomy
| Modes of preservation: | body,original aragonite |
| Size of fossils: | macrofossils |
Collection methods and comments
| Collection excludes: | some macrofossils |
| Collection methods: | selective quarrying,field collection |
| Reason for describing collection: | taxonomic analysis |
| Collection method comments: Collections held in USNM and UGSG repositories. | |
| Taxonomic list comments:Taxa described in text, but not listed for specific localities. Importantly this list contains bivalvia | |
Metadata
| Database number: | 42384 | ||
| Authorizer: | A. Hendy | Enterer: | A. Hendy |
| Modifier: | A. Hendy | Research group: | marine invertebrate |
| Created: | 2004-07-28 14:05:41 | Last modified: | 2025-02-22 15:12:02 |
| Access level: | group members | Released: | 2005-07-28 14:05:41 |
| Creative Commons license: | CC0 |
Reference information
Primary reference:
| 7337. | F. S. MacNeil. 1960. Tertiary and Quaternary Gastropoda of Okinawa: A comparison of the late Miocene, Pliocene, and Pleistocene Gastropoda of Okinawa with related faunas of East Asia together with a resume of the geological setting of the fossiliferous deposits. United States Geological Survey Professional Paper 339:1-148 [A. Miller/C. Ferguson/P. Wagner] |