EE1035, Aze, Okinoshima Island (Eocene of Japan)

Where: Japan (32.7° N, 129.8° E: paleocoordinates 38.0° N, 124.3° E)

• coordinate estimated from map

• small collection-level geographic resolution

When: Okinoshima Formation, Bartonian (41.3 - 38.0 Ma)

• Lower to middle part of the Okinoshima Formation. According to foraminiferal and molluscan biostratigraphy, the formation is assigned in age to the Auverisian to the Bartonian (Upper Eocene). The Okinoshima Formation falls within calcareous nannofossil Subzones CP14a–CP15b of Okada and Bukry (1980) and planktic foraminiferal Zones E10–E13 of Berggren and Pearson (2005), dating to the middle Eocene. The Okinoshima Formation including calcareous nannofossils such as Reticulofenestra umbilica and Discoaster barbadiensis, indicating Zones CP14–CP15 and planktic foraminifer, Acarinina primitiva, representing Zone P14 or older (Yamaguchi et al. 2004). These biozones of planktic microfossils assign the Okinoshima Formation to 43.5–39.0 Ma (Yamaguchi & Kamiya, 2007).

• bed-level stratigraphic resolution

Environment/lithology: offshore; lithified, fine-grained, glauconitic sandstone

• The biofacies consists of samples from muddy sandstones, sandy mudstones, and mudstones, which represent bioturbation and include few sedimentary structures that indicate wave and tidal influences. The planktic/total foraminifer ratios (P/T ratios) from the Okinoshima Formation is less than 0.03, suggesting water depths shallower than about 100–150 m. The lithofacies, P/T ratios, and molluscan assemblages indicate shallow-marine environments with little to no influence by wave and tidal action. Hence, the biofacies correlates with outer-shelf environments under warm-water conditions.
• Fine- to medium-grained glauconitic sandstone or sandy siltstone

Size class: macrofossils

Collected by K. Tanabe

• Repository: Department of Earth Sciences, Ehime University

Primary reference: K. Tanabe and N. Chiba. 1983. A new species of Deltoidonautilus (Cephalopoda) from the upper Eocene of western Kyushu. Venus (Japanese Journal of Malacology) 42:248-258 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 179880: authorized by Matthew Clapham, entered by Matthew Clapham on 03.07.2016

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Cephalopoda
 Nautilida - Hercoglossidae
Deltoidonautilus okinoshimensis n. sp.
Deltoidonautilus okinoshimensis n. sp. Tanabe and Chiba 1983 nautiloid