Total for the last 12 months
number of access : ?
number of downloads : ?
ID 117697
Title Alternative
Lower Cretaceous litho-and bivalve-stratigraphy of the Sakawa-Ochi area, Kochi Prefecture, SW Japan
Author
Kozai, Takeshi Naruto University of Education
Keywords
下部白亜系
古生物地理
二枚貝
層序
四国
黒瀬川帯
Lower Cretaceous
Palaeobiogeography
Bivalves
Stratigraphy
Kurosegawa Belt
Shikoku
Content Type
Departmental Bulletin Paper
Description
The Ochi-Sakawa area is one of the classic fields of Paleozoic and Mesozoic stratigraphy in the tectonic Kurosegawa Belt in of Eastern Shikoku, Japan. The Mesozoic is characterized by shallow marine and brackish water deposits, in which Triassic and Jurassic shallow marine deposits are famous for their abundant megafossils, the Cretaceous deposits remaining until now largely unknown.
Located within the Chichibu Superbelt* the Cretaceous formations of the Ochi-Sakawa area consists of two tectonic blocks, being separated by a north-south trending fault, within the Yoshigahira and Sakashu belts. In both blocks, the Lower Cretaceous formations consist in ascending order of the Kaisekiyama Formation (Hauterivian), the Tosakamo Formation (Barremian-Aptian), the Kurohara Formation (Aptian), and the Yotsushiro Formation (Albian). Brackish water bivalves occur in the Kaisekiyama Formation and lower part of the Tosakamo Formation. Higher up, in the in the lower and middle parts of the Tosakamo Formation, Barremian shallow marine bivalves and in the upper part of the formation, Aptian marine bivalves occur. The Kurohara Formation yields Aptian shallow marine bivalves and the Yotsushiro Formation yields Albian marine bivalves and ammonites.
The Early Cretaceous faunas of the Sakawa block is characterized by the so-called Sakashu and Masaki faunal groups, while that of the Ochi block contains elements of the so-called Masaki faunal group. The differentiation of these faunas suggests a faunal transition between different environments within the Yoshigahira and Sakashu belts.

*Kumosoyama, Masaki, Yoshigahira, Sakashu and Nakagawa belts
Journal Title
Research bulletin of Naruto University of Education
ISSN
18807194
NCID
AA12124651
Publisher
鳴門教育大学
Volume
21
Start Page
283
End Page
293
Published Date
2006-03-03
EDB ID
DOI (Published Version)
URL ( Publisher's Version )
FullText File
language
jpn
TextVersion
Publisher
departments
Science and Technology