Science Links Japan | For elucidating the mechanism of arsenic contamination of groundwater in Asia with special reference of research in Bangladesh. Depositional processes of plant material assemblages in fluvial sediments: examples from plant megafossils in Miocene Tokiguchi Porcelain Clay Formation at Onada mine in Tajimi, central Japan.

For elucidating the mechanism of arsenic contamination of groundwater in Asia with special reference of research in Bangladesh. Depositional processes of plant material assemblages in fluvial sediments: examples from plant megafossils in Miocene Tokiguchi Porcelain Clay Formation at Onada mine in Tajimi, central Japan.

Accession number;00A0386824

Title;For elucidating the mechanism of arsenic contamination of groundwater in Asia with special reference of research in Bangladesh. Depositional processes of plant material assemblages in fluvial sediments: examples from plant megafossils in Miocene Tokiguchi Porcelain Clay Formation at Onada mine in Tajimi, central Japan.

Author; SANEYOSHI MOTOTAKA (Shimane Univ.) NAKAYAMA KATSUHIRO (Shimane Univ.) TSUKAGOSHI MINORU (Osaka Museum of Natural History, JPN)

Journal Title;Earth Science

Journal Code:F0193A

ISSN:0366-6611

VOL.54;NO.2;PAGE.127-143(2000)

Figure&Table&Reference;FIG.10, TBL.4, REF.37

Pub. Country;Japan

Language;Japanese

Abstract;Depositional processes of plant material assemblages are clarified with the context of depositional environment. Focused sediment is the Miocene Tokiguchi Porcelain Clay Formation in central Japan. Seven facies of Gcm, St, Sm, Fl, Fr, Fm, and C are recognized in this formation. They are interpreted as the deposits of sediment gravity flow such as debris flow, bedload of perennial flow such as channel flow, deposits of flood flow, and suspended fallout deposits such as some swamp deposits. Combination of these facies, paleocurrent, and architectures indicates that the immature sandy braided fluvial system with huge swamp and standing water (pond) area were developed near from mountain slope. Numerous plant megafossils are identified in the flood flow deposits of facies Fl, some of them are deposited as bedload, and others are suspended fallout deposits. However, cupules of Fagus occur only in the suspended fallout part in flood flow deposits. Some plant megafossils are also obtained in debris flow deposits of facies Gcm, swamp deposits of facies Fm, and swampy pond deposits of facies Fr. Typical plant megafossil in facies Gcm is the cone of Pinus fujiii, which must be transported and deposited under grain dispersive pressure. Type of transport behavior of plant debris are mainly suspension, associating with traction and grain dispersion. Spatial maldistribution of plant megafossils may reflect the short distance of transportation. (author abst.)

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