10:45 AM - 11:00 AM
[MZZ48-01] A use of tuff beds in strata for natural resources at the Boso Peninsula – ‘Bosyu white clay’ or ‘Bosyu sand’
Keywords:Boso Peninsula, tuff, natural resources
From Neogene to Quaternary marine strata construct the Boso Peninsula. Their strata deposited on deep sea and rapidly uplifted, so their strata have enough degree of consolidation and are easy to dig. So, from ancient times, digging of the strata have done for various purpose on human life in the Boso Peninsula. They are majorly divided two formation. One is use of relief feature, and the other is use of components of the strata as natural resources. This time, an example of the latter case is introduced.
The strata are mainly constructed by hemi-pelagic mudstone and turbidite sandstone, and they include numerous tephra beds. Their tephra have wide variety, but especially fine glassy tephra are used as dental powder, rice polishing powder, material of roof tile and ceramics, admixture of cement from the latter part of the Edo Period, and then used on a small scale as polishing powder of glass, mold releasing agent even today (Oya, 1990; Saito, 1998). They are dug along mining gallery focus on the several 10cm to 2m thick single tuff bed, so the gallery tilt according to dip of strata, and suddenly change their height by fault. They are dug at several points and different horizons in the Boso Peninsula, so the characteristic of the strata is common in the Boso Peninsula, and show the geological history of the Peninsula. Their tuff beds are used and named as key beds for contrast of strata which distribute distant areas. For example, ‘Kd8’ tephra in the Kiwada Formation, Kazusa Grop, at Isumi City, and ‘TK-5’ and ‘Hn-8’ tephra in Higashinagata Formation, Chikura Group, at Tateyama City (Kawakami & Shishikura, 2006). These are all Pleistocene marine strata. Their origins are not specified, but ‘Kd8’ tephra is correlated to ‘Omig’ tephra in the Uonuma Group at the Niigata area (Kurokawa et al., 2002), so they are possibly from far away area. These tephra have both geological importance and usefulness as natural resources.
[References]
Kawakami, S. and Shishikura, M. ,2006, Geology of the Tateyama District. Quadrangle Series, 1:50,000, Geological Survey of Japan, AIST, 82p.
Katsuki, K., Sakai, H., Hiwatari, H., Ohashi, R. and Higuchi, Y. , 2002, Tephra beds in the Taira and Minagawa Formations in central Niitsu Hill to eastern Kamo area, Niigata Prefecture and their correlation, especially to the Kd18 and Kd8 beds in Boso Peninsula. Memoirs of the Faculty of Education and Human Sciences (Natural Sciences), Niigata University, 4(2): 65-125.
Oya, S., 1990, Consideration of ‘Boshu white clay’. Tateyama and cultural property, (24), 6-10.
Saito, N., 1998, Remained site of white clay quarry. Chiba Museum of Science and Industry (eds.), ‘Industrial and traffic heritages in the Chiba Prefecture’, 54-55, Chiba Prefectural Board of education.
The strata are mainly constructed by hemi-pelagic mudstone and turbidite sandstone, and they include numerous tephra beds. Their tephra have wide variety, but especially fine glassy tephra are used as dental powder, rice polishing powder, material of roof tile and ceramics, admixture of cement from the latter part of the Edo Period, and then used on a small scale as polishing powder of glass, mold releasing agent even today (Oya, 1990; Saito, 1998). They are dug along mining gallery focus on the several 10cm to 2m thick single tuff bed, so the gallery tilt according to dip of strata, and suddenly change their height by fault. They are dug at several points and different horizons in the Boso Peninsula, so the characteristic of the strata is common in the Boso Peninsula, and show the geological history of the Peninsula. Their tuff beds are used and named as key beds for contrast of strata which distribute distant areas. For example, ‘Kd8’ tephra in the Kiwada Formation, Kazusa Grop, at Isumi City, and ‘TK-5’ and ‘Hn-8’ tephra in Higashinagata Formation, Chikura Group, at Tateyama City (Kawakami & Shishikura, 2006). These are all Pleistocene marine strata. Their origins are not specified, but ‘Kd8’ tephra is correlated to ‘Omig’ tephra in the Uonuma Group at the Niigata area (Kurokawa et al., 2002), so they are possibly from far away area. These tephra have both geological importance and usefulness as natural resources.
[References]
Kawakami, S. and Shishikura, M. ,2006, Geology of the Tateyama District. Quadrangle Series, 1:50,000, Geological Survey of Japan, AIST, 82p.
Katsuki, K., Sakai, H., Hiwatari, H., Ohashi, R. and Higuchi, Y. , 2002, Tephra beds in the Taira and Minagawa Formations in central Niitsu Hill to eastern Kamo area, Niigata Prefecture and their correlation, especially to the Kd18 and Kd8 beds in Boso Peninsula. Memoirs of the Faculty of Education and Human Sciences (Natural Sciences), Niigata University, 4(2): 65-125.
Oya, S., 1990, Consideration of ‘Boshu white clay’. Tateyama and cultural property, (24), 6-10.
Saito, N., 1998, Remained site of white clay quarry. Chiba Museum of Science and Industry (eds.), ‘Industrial and traffic heritages in the Chiba Prefecture’, 54-55, Chiba Prefectural Board of education.