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[SGL37-P13] The structure found in Anamizu formation,formed by the Miocene andesitic volcanism in the west coast of the Noto Peninsula
Keywords:andesite, pyroclastic rock, Noto Peninsula
Anamizu formation, formed by the Miocene andesitic volcanism, is widely distributed in the west coast of the Noto Peninsula. We found a lot of rock structures like dike with NNE-SSW and NW-SE trending linear shape and high dip angle in the Anamizu formation. It consists of a few parallel rock facieses similar to pyroclastic rocks for example tuff breccia, lapilli tuff, and fine grain tuff. From its distribution form, we temporarily name it pyroclastic dike.
The pyroclastic dike has irregular shape and transitional boundary with the rocks of surrounding Anamizu formation. No brittle fracturing could be found, but plastic flow structure sometimes well develops especially in the fine grain tuff facies or fine matrix. It is hard as much as surrounding rocks.
Thin clay layer or crack develops along the fine grain tuff facieses. Based on X-ray diffraction analysis, this thin clay layer is mainly composed of smectite formed by the hydrothermal alteration or weathering. According to the observation of this thin clay layer by microscope, original structure of the rock and smectite(including iron saponite) is not broken.
In this paper, we report occurrences and properties of the pyroclastic dike.
The pyroclastic dike has irregular shape and transitional boundary with the rocks of surrounding Anamizu formation. No brittle fracturing could be found, but plastic flow structure sometimes well develops especially in the fine grain tuff facies or fine matrix. It is hard as much as surrounding rocks.
Thin clay layer or crack develops along the fine grain tuff facieses. Based on X-ray diffraction analysis, this thin clay layer is mainly composed of smectite formed by the hydrothermal alteration or weathering. According to the observation of this thin clay layer by microscope, original structure of the rock and smectite(including iron saponite) is not broken.
In this paper, we report occurrences and properties of the pyroclastic dike.