On the Pliensbachian/Toarcian boundary in the Lower Jurassic Toyora Group in southwest Japan
Journal Title: Volumina Jurassica - Year 2009, Vol 7, Issue 1
Abstract
The Toyora Group, consisting of continental shelf sediments, is exposed in southwest Japan. It is divided into three formations, the Higashinagano, the Nishinakayama, and the Utano formations in ascending order. The Nm Member, the lower part of the Nishinakayama Formation, has yielded abundant ammonites, indicating successive ages of Early Toarcian. The ammonite zonation was established on these materials, but the Pliensbachian/Toarcian (P/T) boundary was not defined clearly in previous studies. A total of 99 ammonite specimens including 11 genera and 16 species were collected along the Sakuraguchi-dani Valley. The first occurrence of [i]Dactylioceras helianthoides[/i] is the most suitable candidate for drawing the P/T boundary in the Toyora Group, the boundary being drawn at least 35.5 m lower than the previously indicated.
Authors and Affiliations
Kentaro NAKADA, Atsushi MATSUOKA
Keywords
Related Articles
- EP ID EP67924
- DOI -
- Views 61
- Downloads 0
Candidate sections for the GSSP of the base of the Bathonian Stage (Middle Jurassic)
In accordance with the recommendations of the International Commission on Stratigraphy (ICS), the leading candidate for the Global Boundary Stratotype Section and Point (GSSP) of the base of the Bathonian Stage is locate...
Próba korelacji wydzieleń litostratygraficznych górnej jury w podłożu Karpat zewnętrznych i zapadliska na podstawie mikroskamieniałości
Jurajskie korale w Polsce
Ammonites and ammonite stratigraphy of the uppermost Jurassic (Tithonian) of the Owadów–Brzezinki quarry (central Poland)
The Tithonian ammonite succession at the Owadów–Brzezinki quarry, central Poland shows the presence of Subboreal ammonites of both NE European (“Volgian”) and NW European (“Bolonian–Portlandian”) affinity, making possib...
Integrated stratigraphy of the Oxfordian global stratotype section and point (GSSP) candidate in the Subalpine Basin (SE France)
An integrated biostratigraphic approach, based on ammonites, calcareous nannofossils, dinoflagellates, combined with sedimentology, carbon-isotope and physical stratigraphy, is proposed for the Subalpine Basin (Thuoux an...