Geological reports of Shimane University

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Geological reports of Shimane University 9
1990-07-30 発行


Geologic examination of the borehole data from the eastem part of the Himeji Prefecture, Southwest Japan
Choi, Jung,Yill
Sato, Mitsuo
Geologic structure and stratigraphy of the Permo-Triassic strata of the Kozuki-Tatsuno Belt in the eastem part of the Himeji area, Southwest Japan were examined on the basis of the borehole data which has1440m depth from the ground. The rock unit in this area consists of the Pemian Tatsuno Group and the unnamed Triassic strata, and they are repeated by thrust fault Mudstones of the Tatsuno Group from the horizon 735m of the borehole yield Pseudoalbaillella aidensis, P. yanaharensis, P. globosa and P. spp. Sandstones of the Tatsuno Group are characterised by wacke including plagioclase, rock fragments and less amount of quartz grains, while sandsotnes of the Triassic formation is arenite. characterised by large amound of quartz, K-feldspar and less amount of rock fragments.
Although the Triassic formation is not distributed on the ground surface, the borehole data reveals that the strata correlative to the Hiraki Formation is widely distributed in the Kozuki-Tatsuno Belt.
The granitic rocks appears just beside to the east of the examined area, and this granites occurs in the1200m depth. Thus, the fault with NE-SW direction cut the strata and the block of the ground greatly upheaved about 900m judging from the difference of the horizons of contact between granitic intrusion and the sediments in each block.