GEOLOGICAL EVIDENCES OF EJECTED BLOCKS OF AKIYOSHI LIMESTONES IN THE SEA AT THE P/T BOUNDARY IMPACT EVENT

Introduction: The Akiyoshi limestone blocks in Yamaguchi, Japan is recently considered to be ejected blocks in the sea at the Permian-Triassic (P/T) boundary event [1]. &The main purpose of the paper is that geological evidences of Akiyoshi limestones relating with impact event in the sea at the P/ boundary. Geological evidences of the P/T boundary event: The followings are evidences to show geological evidences of the Akiyoshi limestone at the P/T boundary events. (1) Japanese islands are located at old north blocks of China sub-continents at the P/T boundary event near Equator. (2) As there is no sedimentation of limestone after the P/T event, the Akiyoshi limestone blocks are broken to move. (3) Strongest stress is observed at limestone of 243m in depth with brown clay layer of Fe-Ni- bearing grains. (4) Overturned structure with fossil evidences is observed at Permian limestone blocks. (5) Separated and brecciated blocks of limestones are observed mainly at rims of the Akiyoshi limestones. (6) The Akiyoshi limestones are mixed with Permian deep sea-sediments of the same or younger ages which are disappeared at West-East directions along Japan islands, though previous model of sea-mount should be located by all sediments after collision to old Japan islands. (7) Several Permian limestones of Hirao-dai, Akiyoshi-dai, Zomeki, Taishaku-dai, Atetsu-dai and Oume are distributed in Japanese islands separately through ca.1,000km apart. Structure of Akiyoshi limestone: Although Akiyoshi-dai limestone blocks of 16km EW by 8km NS are located as central location with higher height of as larger carter basin structure of 25kmNS x 28km WE in size, basin sediments are completely flowed out mainlky due to the recent weathering to show similar basin structure of the crater finally with ca.700m in depth (difference between the highest mountain and the lowest valley). Summary: The Akiyoshi limestone blocks are considered to be geological relicts of impact event into the sea-bottom near the Equator at the P/T event. References: [1] Y.Miura et al. (2004):LPSC 35