The Quaternary Research /+, p 3- +*,,*+,,a * * +, -5,** 0**,5*** **, - +* +* +, mmyr +* mmyr : I - +*, +* +33,**- ;,**0 +3/0,**- +31/ +311 +312 +32+ ; ; +32 Iseya and Ikeda, +33* +30, +33, ;,*** ;,**0 ;,**0 ;,**2,*++ 2 +0,*+,, ++ * + 0 20*+ D, + *, -*/ 2/01 + + + 1 * a Corresponding author : khori@litnagoya-u ac jp
94 /+, Fig + + Hori et al,*++ Landform classification map of the Nobi Plain Modified after Hori et al (,*++), - +* +*, - Hori et al,*++ - +/-* +/30 +0+/ II +31/ +202 +3+, + -** +302 + mm +332 -, +0/ +
,*+, 95 Fig,, Web Map showing borehole sites and cross sections across the former Ibi River channel The base map was based on the Digital Japan Web System provided by the Geospatial Information Authority of Japan +31/ - +0/* +322 +* cm AMS, +33- /* cm III CALIB/4*4, Hughen et al,,** ; Reimer et al,,** ; Stuiver et al,,**/ + AP+ / AP+ AP, X AP/ AP+ AP, AP- AP AP/, AP+ AP, AP- AP/
96 /+, -, +23,,/ / + Hori et al,*++ Fig - Old topographic map of the study area The former course of the Ibi River was displaced by civil engineering during the Meiji Era ( +202 +3+, ) Artificial ringed levees Wajyu-tei are found in the map The map is based on + : /*5*** scale topographic map of Tsushima and Ogaki published in +23, Modified after Hori et al (,*++) IV Hori et al,,*++ + *4- mscm m A +** m, B C - m,, m A AP+ -40 m B Hori et al,,*++ - 1 m / cm A, - B - m AP+ AP,, - m
,*+, 97 AP, AP / m +33, +** Bridge,,**- C AP, AP * m AP+ AP, AP + flood- -5,** cal BP basin Davis, +33, crevasse-splay deposits Aslan and Autin, +333 ; AP, AP Stouthamer,,**+ 0** cal BP C AP, AP AP/ AP+ +5/** B AP, AP AP/ AP, /4/ m 0** ** 0** AP, AP, AP AP/ AP, ** AP, V + Table + + Radiocarbon dates from borehole cores
98 /+,
,*+, 99 ** AP+ /o c +/30 +0+/ +31/ AP+ /od ** +32+ +, +- 3** 2** cal BP,**0 + AB /,5/** cal BP Fig / Schematic diagrams showing the evolution +5,** cal BP of landform and sedimentary sequences at the study site -5,** cal BP /oa AP+ AP, AP 5*** cal BP,**2,5/** cal BP,**0,**- ** AP+ AP, AP,**2 * m ST, + m AP, 0** +5,** cal BP, AP 0** cal BP 0** /ob AP, AP **,**0 + AP+ +5/** AP+ + +5/**
100 /+,, +,**2,**0 AP+, +, m + - +0/* +322, m AP/ +5** ** ** AP- +5** 0** + mm AP/ ** AP+ AP, - m ** * m Nakada et al, +33+ +322 +3// VI - - +* AP+ AP, AP,4, -4, mmyr + -5,** / km **,**2, + -mmyr - AP, +-4/ mmyr AP, 04, m 0* median probability + +** AP AP/ : +01**/3 : : +3-**-*2 +4,,4* mmyr :
,*+, 101 /1 /31 0+- +31/ 3/0 p +33, +31/ -* p : +2+ +22 +322 -,2 p Iseya, F and Ikeda, H ( +33* ) Sedimenation in coarsegrained sand-bedded meanders : Distinctive depo- Aslan, A and Autin, W ( +333) Evolution of the Holocene sition of suspended sediments Taira, A and Masuda, Mississippi River floodplain, Ferriday, Louisi- F (eds) Sedimentary facies in the active plate mar- ana : Insights on the origin of fine-grained flood- gin : 2+ ++,, Terra Pub plains Journal of Sedimentary Research, 03, 2** 2+/,*** Bridge, JS (,**-) Rivers and floodplains : Forms, pro-, + +/ cesses, and sedimentary record 3+ p, Blackwell +302 Publishing 1,-/,1 Davis Jr, RA ( +33, ) Depositional systems : An intro- +3// +*2 p duction to sedimentology and stratigraphy, second Nakada, M, Yonekura, N and Lambeck, K ( +33+ ) Late ed 0* p, Prentice-Hall Pleistocene and Holocene sea-level changes in Japan,**2 : Implications for tectonic histories and mantle rheology Palaeogeography, Palaeoclimatology, Pa- 1 /+ /0 laeoecology, 2/, +*1 +,, Hori, K, Usami, S and Ueda, H (,*++) Sediment facies +311 and Holocene deposition rate of near-coastal flu- /* 1+ 21 vial systems : An example from the Nobi Plain, +312 Japan Journal of Asian Earth Sciences, +, +3/,*- /+ 0* 1+ Hughen, KA, Baillie, MGL, Bard, E, Beck, JW, +33, Bertrand, C JH, Blackwell, PG, Buck, CE, Burr, GS, Cutler, KB, Damon, PE, Edwards, RL, Fair- +0 133+ banks, RG, Friedrich, M, Guilderson, TP, Kromer, B, McCormac, G, Manning, S, Bronk Ramsey, C, Reimer, P J, Reimer, RW, Remmele, S, Southon, JR, Stuiver, M, Talamo, S, Taylor, FW, van der,**0 / ++ Plicht, J and Weyhenmeyer, CE (,**) Marine* +3/0 marine radiocarbon age calibration, *,0 cal kyr 0 BP Radiocarbon, 0, +*/3 +*20 + +30, Reimer, P J, Baillie, MGL, Bard, E, Bayliss, A, Beck, XXIV /+ 1 JW, Bertrand, C JH, Blackwell, PG, Buck, CE, +32+ + Burr, GS, Cutler, KB, Damon, PE, Edwards, RL, - : +01 Fairbanks, RG, Friedrich, M, Guilderson, TP, Hogg, AG, Hughen, KA, Kromer, B, McCormac, G, +32 Manning, S, Ramsey, CB, Reimer, RW, Remmele, S, Southon, JR, Stuiver, M, Talamo, S, Taylor, FW, no / +-,3 van der Plicht, J and Weyhenmeyer, CE (,**) +32+ IntCal* terrestrial radiocarbon age calibration, *
102 /+,,0 cal kyr BP Radiocarbon, 0, +*,3 +*/2 // 0/ Stouthamer, E (,**+) Sedimentary products of avul-,**- -+ p sions in the Holocene Rhineo Meuse Delta, The +33,1* p Netherlands Sedimentary Geology, +/, 1-3, Stuiver, M, Reimer, P J and Reimer, RW (,**/) CALIB,**0 Radiocarbon Calibration http : calibqubacuk / /+ 0, calib +33- +332, : +*3 ++2 no EQ32 + Floodplain evolution and ringed artificial levee formation in the northern Nobi Plain, central Japan Kazuaki Hori* and Susumu Tanabe* +,a, Evolution and aggradation rates of floodplains river course and a rapid aggradation of natural on a centennial to millennial-scale were investi- levee deposits along the channel Additionally, gated by analyzing landform features and borehole core sediments This study was performed it was suggested that a part of the artificial ringed levee ( Wajyu in Japanese) distributed at the floodplain along the former course of the along the channel originated from the natural Ibi River flowing through the Nobi Plain, cen- levee which was formed in relation to the avultral Japan, because the microtopography in the sion Although the millennial-scale floodplain floodplain can be easily identified The sedi- aggradation rate was about -mmyr, the agmentary environment changed from a delta to gradation rate shows a large variation dependa floodplain after -5,** cal BP, and a floodbasin ing on the sedimentary environment The rate environment continued for nearly,5*** years is estimated to be more than +* mmyr on the However, an avulsion of the Ibi River that natural levee and + to, mmyr in the floodhappened approximately ** years ago caused basin channel erosion at the point that became a Keywords : fluvial system, floodplain, avulsion, overbank deposition, aggradation rate, Holocene * + Department of Geography, Graduate School of Environmental Studies, Nagoya University Furocho, Chikusa-ku, Nagoya, 0 20*+, Japan *, Institute of Geology and Geoinformation, AIST Central 1, + + + Higashi, Tsukuba, -*/ 2/01, Japan * a Corresponding author : khori@litnagoya-u ac jp