3:30 PM - 5:00 PM
[O08-P79] The consideration of Geological Structure in caldera volcanoes at west of Sendai city
Keywords:Geological map, caldera, Geological structure
In Japan, geological maps are used for construction, disaster prevention.However, detailed geological maps have not been completed in large areas.
For this reason, we decided to research around west Sendai to make a detailed geological map.According to previous research, there are some kinds of sedimentary stones and volcanic stones. Some of them result from “Old Sendai lake” or “Jogi caldera”,“Fukano caldera”.
We selected Mt.Togami as the survey site because it is included in the area where Old Sendai Lake was presented, and it is near to Jogi and Fukano calderas.
We visited there four times to record the distribution of stones and their strike and dip.
We found mainly three types of stones around Mt.Togami.On the top of the mountain, there are andesite stones.From the top to the midst of the mountain, there are tufacious stones.From the midst of the mountain to the foothill, there are sedimentary stones such as siltstones and sandstones.
We found the distribution of siltstone layers near Mt.Togami is different from former geological maps and classified the layers as a Fukano layer, but we thought the layer could be reclassified as a Shirasawa layer. Eventually, we made a geological map based on this idea.
Also, through these field research, we found a clastic rock dike. The dike penetrates in a straight line, and it looks like chemically metamorphosed rock. For these reasons, we think this dike is made by some thermal action like a hot spring.
For this reason, we decided to research around west Sendai to make a detailed geological map.According to previous research, there are some kinds of sedimentary stones and volcanic stones. Some of them result from “Old Sendai lake” or “Jogi caldera”,“Fukano caldera”.
We selected Mt.Togami as the survey site because it is included in the area where Old Sendai Lake was presented, and it is near to Jogi and Fukano calderas.
We visited there four times to record the distribution of stones and their strike and dip.
We found mainly three types of stones around Mt.Togami.On the top of the mountain, there are andesite stones.From the top to the midst of the mountain, there are tufacious stones.From the midst of the mountain to the foothill, there are sedimentary stones such as siltstones and sandstones.
We found the distribution of siltstone layers near Mt.Togami is different from former geological maps and classified the layers as a Fukano layer, but we thought the layer could be reclassified as a Shirasawa layer. Eventually, we made a geological map based on this idea.
Also, through these field research, we found a clastic rock dike. The dike penetrates in a straight line, and it looks like chemically metamorphosed rock. For these reasons, we think this dike is made by some thermal action like a hot spring.