Aulotortus friedli from the Upper Triassic gravitational flow deposits of the Kumagawa River (Kyushu, Southwest Japan)

作者：Chablais Jerome^*; Martini Rossana; Onoue Tetsuji

来源：Paleontological Research, 2010, 14(2): 151-160.

DOI：10.2517/1342-8144-14.2.151

• Debris flow
• foraminifer
• limestone
• seamount
• shoal
• Upper Triassic

The benthic foraminifer Aulotortus friedli is reported from the Upper Triassic carbonates (capped seamount) of the Sambosan Accretionary Complex in Kyushu, Southwest Japan. Specimens were collected from shallow-water limestone clasts in a debris flow sequence near the Ose locality along the Kumagawa River. The limestone clasts mainly represent shoal facies where the benthic foraminifer is extremely abundant. Because of the remarkable preservation of the Japanese specimens, they allow further description of the involutinid A. friedli. In addition, a detailed sedimentary and environmental analysis of the gravitational deposits where A. friedli occurs is given. Using microfacies analysis together with the biostratigraphic range of A. friedli and associated foraminifers, a new interpretation is proposed of a seamount collapse process that occurred during the Norian-Rhaetian and preceded the major collapse event of the Sambosan seamount, which has been placed in the Middle to Late Jurassic.

• 出版日期2010-6