Anisian foraminifers from allochthonous limestones of the Tanoura formation (Kurosegawa Terrane, West Kyushu, Japan)

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• 作者：Fumio Kobayashi ; Rossana Martini and Louisette Zaninetti
• 关键词：Foraminifers ; Anisian ; Allochthonous limestone ; Tanoura Formation ; Japan
  Mots clé ; s ; Foraminifè ; res ; Anisien ; Calcaires allochtones ; Formation Tanoura ; Japon
• 刊名：Geobios
• 出版年：2005
• 出版时间：November-December 2005
• 年：2005
• 卷：38
• 期：6
• 页码：751-763
• 全文大小：2868 K

文摘

Thirty-five species belonging to 21 genera of foraminifers are distinguished from allochthonous limestone blocks contained within the autochthonous mudstones and sandstones of the Carnian Tanoura Formation, Kurosegawa Terrane of West Kyushu (SW Japan). These blocks are considered to be Anisian in age, based on the occurrence of two foraminifers widely distributed in the Anisian of the Tethyan Realm, Pilammina densa and Meandrospira dinarica; they are associated with Involutinid-like forms, such as Triadodiscus and Aulotortus, and with other foraminifers. The allochthonous limestones are mostly composed of oolites, abundant bioclasts and detrital quartz grains. They are thought to have been redeposited during the Carnian on the shelf slope of the South Kitakami-Kurosegawa Old Land. Palaeogeographically, this terrane was part of the North Gondwana margin, then isolated eastwards before its Early Cretaceous amalgamation with South China. Three foraminiferal species, Triadodiscus eomesozoicus (Oberhauser), Triadodiscus? tanourensis, n. sp., and Triadodiscus? sp. are described from the Anisian allochthonous blocks.