| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2012: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2011: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2010: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2009: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Research Abstract |
The purpose of this project is to know the recruitment and subsequent recovery processes of benthos at the azoic seafloor produced by drastic physicochemical events. This project made mainly by detailed field observations for the trace fossil assemblages associated with event deposits such as turbidite, tempestite, and tephra beds. The followings were obtained as the results: (1) The mono-specific pioneer animals characterized by small body-size were first recruited on the azoic conditions. In the case of shallow marine environments, the trace fossils such as Diplocraterion parallerum and Phycosiphon incertum produced by polychete and nematoda are preserved as a fossil record. In contrast, only the trace fossil Phycosiphon incertum is recorded in the sediments as the product of pioneer species. (2) In the case of the special bottom condition, which is characterized by the too much high sedimentation rate bottom condition, the azoic seafloor is continued. (3) It suggests that preservation potential for the trace fossils produced by shallow-burrowers is lower than that by deep-burrowers at the seafloor where stable bottom condition without any physical disturbances has continued. This is because trace fossils produced by shallow-burrowers were destroyed and obliterated by activity of the deep-burrowers. Therefore low diversified trace fossil assemblages have appeared under such the bottom conditions. These inferences strongly suggest that fossil records of ancient benthic animals seem to be controlled by the change in depositional conditions. In other words, the change in trace fossil diversity must be useful indicator for reconstruction of depositional environments.
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