Chronology and processes of fluvial terrace formation in northeastern Kinki district, southwest Japan, based on cryptotephra analysis

Quaternary International 246 (2011) 190e202

Contents lists available at SciVerse ScienceDirect

Quaternary International journal homepage: www.elsevier.com/locate/quaint

Chronology and processes of fluvial terrace formation in northeastern Kinki district, southwest Japan, based on cryptotephra analysis Daisuke Ishimuraa, *, Yuya Kakiuchib a b

Department of Geophysics, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan Japan Management Association Research Institute Inc., Tokyo 105-0011, Japan

a r t i c l e i n f o

a b s t r a c t

Article history: Available online 1 September 2011

Kinki district is a tectonically active area in southwest Japan. This area is located far from active volcanoes, and eolian deposits covering fluvial terrace deposits are not as thick as those in Kanto district. Thus, terrace chronology and processes of terrace formation previously were poorly established in Kinki district. Cryptotephra analysis identified invisible tephra horizons in eolian deposits covering fluvial terrace deposits in Takashima, Sekigahara and Inabe regions, including the Kikai-Akahoya tephra (K-Ah: 7.3 ka), Aira-Tn tephra (AT: 26e29 ka) and Kikai-Tozurahara tephra (K-Tz: 95 ka) horizons. Taisanjino 1 terrace in Takashima and Md1 terrace in Inabe were formed during Marine Isotope Stage (MIS) 5e, and Nakano terrace in Takashima, L2 terrace in Sekigahara and L2 terrace in Inabe were formed during MIS 2, based on their ages and geomorphic features. Aggradational terraces formed during MIS 2 exhibit similar geomorphic features among the three regions, although these regions have different base-levels of erosion and active fault movements. This means that the terrace formation during MIS 2 was mainly affected by climate changes, not by base-level changes and active fault movements. The main factor of terrace formation during glacial periods was the decrease in precipitation and water discharge due to climate changes, because the study area was not affected by glacial and periglacial processes during MIS 2. This indicates that aggradational terraces formed during glacial periods not only in glacial and periglacial areas but also in non-glacial and non-periglacial areas. From processes of terrace formation during MIS 5e, the tectonic base-level descent was important for terrace formation during interglacial periods, because terraces were formed during MIS 5e by active fault movements in the Takashima region despite small lake-level changes. Uplift rates of the Kamidera and Kuwana faults were 1.08 mm/y and >0.5 mm/ y, respectively, based on the height of terrace surfaces formed during MIS 5e. Ó 2011 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction Crustal deformation rates within a plate convergence zone are fundamental information for understanding the kinematics of plate boundary processes and geologic and geomorphic development on land. At present, short-term (100e101 years) high-resolution deformation data are obtained from geodetic observations such as GPS. However the time period for which geodetic data are available is too short to discuss the long-term (103e106 years) deformation. Geologic and geomorphic data play an important role in evaluating long-term crustal deformation. In coastal areas, marine terrace surfaces are good indicators to estimate crustal deformation at plate convergent margins such as Japan (Ota and Omura, 1991), New

* Corresponding author. E-mail address: [email protected] (D. Ishimura). 1040-6182/$ e see front matter Ó 2011 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2011.08.039

Zealand (Berryman, 1993) and Papua New Guinea (Chappell, 1974). Because this information is limited to coastal areas, another indicator of long-term deformation on land is required. In recent years, fluvial terrace surfaces were used as an indicator of long-term crustal deformation in inland areas (Burbank et al., 1996; Berryman et al., 2000; Pazzaglia and Brandon, 2001). The major problem of using fluvial terrace surfaces is the complexity of fluvial processes. In order to derive crustal deformation rates from fluvial terrace surfaces, the responses of fluvial systems to many factors such as climate changes, base-level changes and tectonics must be considered. The first step to discuss and interpret fluvial processes is the determination of ages of fluvial terraces. Radiocarbon dating cannot be applied to geomorphic surfaces older than about 50 ka. Other methods (e.g. tephrochronology, OSL: optically stimulated luminescence, CRNs: cosmogenic radionuclides) are generally applied to construct the chronology of Pleistocene terrace sequences.

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

In Japan, tephrochronology is widely used to determine ages of marine and fluvial terraces because there are many tephras covering these terraces (Kaizuka et al., 1977; Machida, 1980; Ota and Omura, 1991). Tajikara and Ikeda (2005) and Matsu’ura et al. (2008) reported inland crustal deformation rates based on Pleistocene fluvial terraces, and these data were compared to shortterm crustal deformation data in northeast Japan. However, in Kinki district (southwest Japan), there were a few studies that identified tephra layers in terrace deposits (Ogura et al., 1992) and that detected volcanic glasses in eolian deposits covering terrace deposits (Kataoka and Yoshikawa, 1997). The Kinki district, however, have not been studied as extensively as those areas in northeast Japan, because this region is far from volcanoes (Fig. 1a) and eolian deposits overlying these terrace deposits are not thick. Therefore, information on the chronology of fluvial terrace sequences older than the limit of radiocarbon dating is lacking, and processes of terrace formation are poorly known in Kinki district. In this study, invisible tephra horizons were identified in eolian deposits covering fluvial terrace deposits based on cryptotephra analysis. Geomorphic and geologic surveys were conducted in Takashima, Sekigahara and Inabe regions (Figs. 2e5) to discuss processes of fluvial terrace formation in relation to climate changes, base-level changes and active fault movements. Previously, the

Fig. 1. (a) Distribution of three widespread tephras, K-Ah: Kikai-Akahoya tephra, AT: Aira-Tn tephra, K-Tz: Kikai-Tozurahara tephra, shown as isopachs (thickness in cm). Open triangles denote active volcanoes. PA: Pacific plate, PHS: Philippine Sea plate, EU: Eurasian plate, NA: North American plate. (b) Depth contour map of the upper surface of the Philippine Sea slab (Nakajima and Hasegawa, 2007). The contour interval is 10 km shallow than 60 km depth whereas it is 20 km deeper than 60 km depth. Gray lines show active fault traces (Nakata and Imaizumi, 2002). Arrow represents plate motion of the Philippine Sea plate relative to the Eurasian plate (Heki and Miyazaki, 2001). IKS: Isewan-Kohoku slab (Miyoshi and Ishibashi, 2008).

191

chronology of fluvial terraces based on cryptotephra analysis in the Takashima and Sekigahara regions was reported by Kakiuchi et al. (2010) and Ishimura (2010), respectively, whereas that of the Inabe region is described here for the first time. This paper summarizes the studies of Kakiuchi et al. (2010) and Ishimura (2010) and describes new data in Inabe. Integrating the results from the three regions allows discussion of the correlation of fluvial terraces, processes of their formation and crustal deformation associated with active fault movements. 2. Regional setting Southwest Japan is under a WNW-ESE to E-W compressional stress field (Tsukahara and Kobayashi, 1991) due to subduction of the Philippine Sea and Pacific plates (Fig. 1a). The upper surface of the Philippine Sea slab was depicted by seismological studies (Fig. 1b; Nakajima and Hasegawa, 2007), and the Isewan-Kohoku slab (IKS) extending northwest underneath Ise Bay was identified (Miyoshi and Ishibashi, 2008). Kinki district (Fig. 1) contains a tectonically active region known as the “Kinki Triangle” (Fig. 2a; Huzita, 1962). Within the Kinki Triangle, north-trending reverse faults and conjugate strike-slip faults are densely distributed (Fig. 2) (Huzita, 1962; Research Group for Active Faults of Japan, 1991). Tectonic evolution in this province in the past several millions of years was discussed by Huzita (1962), Yokoyama (1984), and Ishiyama et al. (2004) based on distribution of Plio-Pleistocene marine or fluvio-lacustrine sediments and subsurface geology. Vertical slip rates of two of the largest active faults in the Kinki Triangle, the Biwako-Seigan fault zone and Yoro-Kuwana-Yokkaichi fault zone (Fig. 2b), were estimated to be greater than 1 mm/y (Komatsubara, 2006; Ishiyama et al., 2007). Komatsubara (2006) calculated the vertical slip rate of the Aibano fault (Fig. 3), a west-dipping reverse fault located at the western margin of the Ohmi Basin, to be greater than 2.0 mm/y based on differences in altitudes of tephra horizons across the fault zone. Ishiyama et al. (2007) calculated the vertical slip rate of the Yoro fault (Fig. 5), a west-dipping reverse fault located at the western margin of the Nobi Plain, to be 1.2  0.1 mm/y for the past 106 years based on high-resolution seismic reflection profiles and cores. Kakiuchi et al. (2010) calculated uplift rates of the hanging wall block of the Kamidera fault (Fig. 3) to be 0.6e1.2 mm/y during the late Quaternary. Ishimura (2010) evaluated slip rates of most of the active faults in the Sekigahara region (Fig. 4) to be on the order of 0.1 mm/y, whereas some faults have slip rates greater than 1.0 mm/y. Plio-Pleistocene fluvio-lacustrine deposits, the Kobiwako Group and Tokai Group, are distributed in the northern part of the Kinki Triangle. A northward migration of sedimentary basins through time was identified based on detailed stratigraphy of lacustrine deposits established using tephrochronology, biostratigraphy and magnetostratigraphy (Yokoyama, 1984; Takemura, 1985; Kawabe, 1989). Modern sedimentary basins are the Ohmi Basin and Nobi Plain (Fig. 2b). Miyoshi and Ishibashi (2008) suggested the relationship between the basin migration since the Pliocene and the IKS based on the geometry of the IKS and distribution and ages of the Kobiwako Group and Tokai Group, and concluded that collision of east-moving southwest Japan lithosphere and IKS probably resulted in an increased E-W compressional stress field in the Kinki Triangle. Lake Biwa is the largest freshwater lake (670.3 km2) in the Japanese Islands, and has a long history since the early Pliocene (Yokoyama, 1984). This is a tectonic lake, bounded by the BiwakoSeigan fault zone on the west (Fig. 2b) (Research Group for Active Faults of Japan, 1991) and its deepest part (water depth 104 m) is located at the western margin of the northern lake. The Seta River is the only outlet of Lake Biwa, and thus the lake level (85 m a.s.l.) is as

192

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

Fig. 2. (a) Distribution of active faults in Kinki district from Nakata and Imaizumi (2002). (b) Index map of the study area. Locations of Figs. 3e5 are shown. The bathymetric contour interval in Lake Biwa is 10 m. Bw: Biwako-Seigan fault zone, Yr: Yoro-Kuwana-Yokkaichi fault zone, Sz: Suzuka-Toen fault zone.

Fig. 3. Geomorphic map of the Takashima region, with terrace classification and fault traces reinterpreted from Kakiuchi et al. (2010). Terrace classification in the Taisanjino Hill is almost the same as Kakiuchi et al. (2010). However, there are some differences from Kakiuchi et al. (2010) in the Aibano Hill. The contours of altitudes (100 m and 90 m) in Ado river delta and bathymetric contours in Lake Biwa were based on 1:25000-scale topographic maps. T1e11 are coring sites. Arrows show flow direction of rivers. The depths of AT tephra are from Komatsubara and Geo-Database Information Committee, Kansai Geotechnical Consultants Association (2010).

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

193

Fig. 4. Geomorphic map of the Sekigahara region adapted from Ishimura (2010). Ishimura (2010) estimated slip rates of each active fault as follows ((H): horizontal slip rate, (V): vertical slip rate), the Daigo fault: (V) 0.1e0.2 mm/y, the Ohshimizu fault: (V) 0.2e0.4 mm/y, the Sekigahara fault: (H) 1.0e2.1 mm/y, (V) 0.1 mm/y, the Monzen fault: (V) <0.1 mm/y, the Miyashiro fault: (V) 0.4e0.6 mm/y. S1-10 are coring sites. Arrows show flow direction of rivers.

high as the height of the Seta River bed at the lake mouth. The Seta River runs through a mountainous area uplifted by active faults (Fig. 2b) as an antecedent river, and has formed strath terraces (Ohashi, 1978). This indicates that the Seta River has incised the river bed to maintain its course and never dried for a long time. At present, the mean precipitation in the drainage of Lake Biwa is about 2000 mm/y and the outflow water discharge from the Seta River is about two-thirds of the input of the drainage of Lake Biwa (Ikeda et al., 1979). Therefore, the lake level has been controlled mainly by the height changes of the Seta River bed, not by sea-level changes. Deep drilling surveys in Lake Biwa have been conducted since the 1970s, and there are sufficient paleoclimatic data (Meyers et al., 1993; Xiao et al., 1997; Miyoshi et al., 1999; Kuwae et al., 2002; Toyoda, 2003; Hayashi et al., 2010). Tephras in the past 1 Ma were identified in the lake sediments (Takemura, 1990). Widespread Late Quaternary tephras such as Amagi-Kawagodaira tephra, KikaiAkahoya tephra, Ulreung-Oki tephra, Aira-Tn tephra, Sambe-Ikeda tephra, Aso-4 tephra, Kikai-Tozurahara tephra, and Aso-3 tephra also were identified in the lake sediments (Nagahashi et al., 2004). The study areas in northeastern Kinki district, Takashima, Sekigahara and Inabe regions (Figs. 3e5), have widely distributed fluvial terraces. Takashima (Fig. 3) is located at the western margin of Lake Biwa and lies at the geomorphic boundary between the Hira Mountains and Ohmi Basin. This geomorphic boundary almost coincides with the location of the Biwako-Seigan fault zone. Sekigahara (Fig. 4) is located between the Ibuki Mountains and Suzuka Range and contains the lowest water divide between the Ohmi Basin and Nobi Plain. Several short active faults are distributed in this region. Inabe (Fig. 5) is located between the Suzuka Range and Yoro Mountains and was uplifted by the movements of the YoroKuwana-Yokkaichi fault zone. These regions show close relationships between active faults and uplifted and deformed fluvial terrace surfaces. They are under different base-levels of erosion (sea

or lake) and tectonics (amount and sense of slip of active faults). The effect of climate changes is the same for the areas. During the last glacial period, there was no glaciation, and periglacial processes were probably limited to the summits of mountains because the altitude of the tree line during the last glacial period around Kinki district was estimated at about 1000 m a.s.l. (Fig. 2b) (Yonekura et al., 2001). 3. Methods 3.1. Terrace classification and mapping of profiles of fluvial terrace surfaces Initial mapping of fluvial terraces and active fault traces was based on interpretation of 1:10000- and 1:20000-scale aerial photographs. Fieldwork was conducted to investigate terrace and eolian deposits. Profiles of fluvial terrace surfaces and modern river beds were depicted using 1:2500- (contour interval: 2 m) and 1:25000-scale (contour interval: 10 m, partially 5 m) topographic maps. 3.2. Cryptotephra analysis No tephra layers in eolian deposits covering terrace deposits are visible in the study area, because tephra deposits may have been transported and dispersed vertically after deposition due to bioturbation, pedogenesis and fluvial and eolian processes on the surface. Cryptotephra analysis of eolian deposits in outcrops and drill cores identified glass and mineral concentration zones as tephra horizons (Fig. 6). Widespread tephras identified are as follows: Kikai-Akahoya (K-Ah) (age: 7.3 ka, refractive index of glass shards: 1.504e1.512), Aira-Tn (AT) (age: 26e29 ka, refractive index of glass shards: 1.498e1.501), and Kikai-Tozurahara (K-Tz) (age:

194

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

Fig. 5. Geomorphic map of the Inabe region. The vertical slip rates of active faults were estimated as follows, the Ichinohara fault: 0.1 mm/y (Yoshida, 1991), the Fumotomura fault: 0.1e0.4 mm/y (Ota et al., 2004), the Yoro fault: 1.2  0.1 mm/y (Ishiyama et al., 2007), the Kuwana fault: 1.0  0.2 mm/y (Ishiyama et al., 2004). I1e8 are coring sites. Arrows show flow direction of rivers.

95 ka, refractive index of glass shards: 1.496e1.500) (Machida and Arai, 2003). Drilling sites on terraces were chosen where original surfaces remained and artificial modifications were minimal based on aerial photograph interpretation and fieldwork. Drilling was conducted at more than two locations for each terrace surface using a percussion boring machine with a hydraulically-operated gasoline engine. Eolian and fluvial deposits were sampled at 5-cm intervals. Samples were then washed through 60-mm nylon mesh and dry sieved at 124 mm. Thin sections were made with 60e124 mm fractions. Volcanic glass, heavy minerals (amphibole,

orthopyroxene and clinopyroxene), high quartz and others (e.g., rock fragment, light minerals, plant opal and opaque) were counted. High quartz was counted separately because the K-Tz tephra characteristically contains high quartz (Machida and Arai, 2003) and it has been used as an indicator of the K-Tz horizon (Nakamura et al., 2008). More than four hundred grains were counted to estimate volcanic glass and heavy mineral contents, whereas more than two thousand grains were counted to estimate the highquartz content, as high quartz was much less abundant than volcanic glass and heavy minerals. The refractive index of glass

Fig. 6. Schematic soil profile in the study area.

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

shards was measured with a refractive index measuring system (RIMS 87: Kyoto Fission Track Co., Ltd.). The ratio of K-Ah and AT volcanic glasses was calculated based on refractive indices (Fig. 7) from counting more than sixty grains. Bubble-wall type glass with a refractive index higher than 1.503 was identified as K-Ah, whereas bubble-wall type glass with a refractive index lower than 1.503 is AT. Pumice or block type glasses with refractive indices around 1.503 were identified as “others”. 3.3. Tephra identification criteria Tephra horizons were identified based on volcanic glass content, high-quartz content and refractive index of glass shards. Fig. 7 shows typical results of cryptotephra analysis in each region. In this study, some samples used by Kakiuchi et al. (2010) were reanalyzed to check the consistency of tephra identification criterion. The K-Tz horizon could not be identified based on variation of volcanic glass and heavy mineral contents. Instead, the K-Tz horizon was identified based on peaks in high-quartz content (Locs. T3 and S1, Fig. 7). In Inabe, as high-quartz content is very low (less than 1&), determination whether terrace surfaces were formed before K-Tz tephra deposition was based only on the existence of high quartz in several layers below the AT horizon within eolian deposits (Loc. I5, Fig. 7). High quartz in the eolian deposits on the terraces formed after the K-Tz tephra deposition was hardly detected in Takashima and Sekigahara, and thus the existence of high quartz was a reliable indicator of K-Tz tephra. Although glasses derived from several tephras were mixed in the same horizon due to disturbances such as bioturbation and pedogenesis, the K-Ah and AT horizons can be identified based on refractive indices. When volcanic glass content shows one peak consisting mostly of K-Ah glass, the peak was identified as the K-Ah horizon (Locs. S9, I1, Fig. 7). When both AT and K-Ah glasses were observed, the layer in which AT glass content was larger than that of K-Ah was designated as the AT horizon and the layer in which K-Ah glass content was larger than that of AT was designated as the K-Ah horizon above the AT horizon (Locs. T9, S5, I2, Fig. 7). Other tephra horizons could not be recognized, as volcanic glasses of other tephras were very uncommon. 4. Results 4.1. Fluvial terrace sequences Figs. 3e5 shows geomorphic maps in the study areas. This study reinterpreted terrace classification and fault traces in Takashima from Kakiuchi et al. (2010). The geomorphic map of Sekigahara is from Ishimura (2010) and that of Inabe is from this study. Fig. 8 shows profiles of fluvial terraces and modern river beds in each study area. In Takashima (Fig. 3), Aibano and Taisanjino Hills are uplifted and deformed by the movements of the west-dipping Aibano and Kamidera faults, part of the Biwako-Seigan fault zone. Terrace steps are referred to as Aibano 1, Taisanjino 1-4, Okuyama, Nakano, and Kitoge terraces, in descending order of elevation (Togo, 1971; Komatsubara et al., 1998; Kakiuchi et al., 2010). Terrace surfaces older than Taisanjino 4 terrace are tilted opposite to the flow direction of the modern river due to active fault movements (Fig. 8a). In Sekigahara (Fig. 4), terraces are widely distributed in Sekigahara lowland bounded on the north by the left lateral Sekigahara fault. Ishimura (2010) classified fluvial terraces into H, M1-2 and L1-4 terraces in descending order of elevation. L2 terraces are widely distributed, and the amount of incision by the Fujiko River is about 20 m (Fig. 8b).

195

In Inabe (Fig. 5), terraces are distributed between the Yoro Mountains and Suzuka Range. Fluvial terraces were classified into Hu1-3, Hd1-2, Mu1-3, Md1-3 and L1-4 terraces in descending order of elevation. In this region, terraces in the upstream (e.g. Hu1) and downstream areas (e.g. Hd1) were classified separately, because the intersections of profiles of terrace surfaces were widely observed along the foot of the mountains. Profiles of terrace surfaces in the upstream area intersect with those in the downstream area because the gradient of terrace surfaces in upstream area is steeper than that in downstream area. Therefore, the difference in distribution of fluvial terraces was important to discuss the processes of terrace formation. For example, Mu2 terrace surfaces intersect with Md1 terrace surfaces at Ageki along the Inabe River (Fig. 8c). 4.2. Cryptotephra analysis Figs. 3e5 show drilling sites and outcrops in each area where cryptotephra analysis was conducted. Results of cryptotephra analysis and tephra correlation are shown in Figs. 7 and 9. The K-Tz horizon is clearly identified in the fluvial terrace sequence in the Takashima region, where the formation of Taisanjino 3 terrace coincides almost with the deposition of K-Tz tephra (Locs. T7-8, Figs. 3 and 9; Kakiuchi et al., 2010). For terraces younger than Taisanjino 3 terrace, high quartz is difficult to identify. Kakiuchi et al. (2010) also carried out chemical analysis of glass shards at the inferred K-Tz horizon (Locs. T1-3, T6, Figs. 3 and 9) and confirmed their identification. The K-Tz horizon in the Sekigahara region is identified based on high-quartz content (Locs. S1-2, Figs. 4 and 9; Ishimura, 2010). In Inabe, Md1 terrace surfaces were formed before K-Tz tephra deposition, based on the existence of high quartz in eolian deposits (Locs. I5, I7-8, Figs. 5 and 9). The age constraint by KTz tephra in Inabe is, however, weaker than that in the other regions. Both the AT and K-Ah horizons were identified in all regions (Figs. 7 and 9). Terraces covered by AT and K-Ah are Taisanjino 4 and Okuyama terraces in Takashima (Locs. T9-11, Figs. 3 and 9; Kakiuchi et al., 2010), M2 terrace in Sekigahara (Locs. S5, S7-8, S10, Figs. 4 and 9; Ishimura, 2010) and Mu2 and Md2 terraces in Inabe (Locs. I24, Figs. 5 and 9). Terraces overlain only by K-Ah include Nakano terrace in Takashima (Komatsubara et al., 1998), L2 terrace in Sekigahara (Locs. S4, S9, Figs. 4 and 9; Ishimura, 2010) and L2 terrace in Inabe (Locs. I1, I6, Figs. 5 and 9). In all areas, eolian deposits covering L2 terrace deposits consist only of black soil, and more than half of volcanic glasses are K-Ah glasses based on refractive indices (Locs. S9, I1, Fig. 7). The AT layer is also interbedded within L2 terrace deposits in Sekigahara (Locs. S3, S6, Figs. 4 and 9; Ishimura, 2010). 5. Discussion 5.1. Chronology of fluvial terraces and their correlations to MIS Fig. 10 shows the chronology of fluvial terraces in the three regions, summarizing the relationship between ages of fluvial terraces, tephras and sea-level change. In Takashima, Kakiuchi et al. (2010) reported ages of terraces as Aibano 1: 160e200 ka, Taisanjino 1: 105e140 ka, Taisanjino 2: 95e130 ka, Taisanjino 3: 90e100 ka, Taisanjino 4: 60e80 ka, and Okuyama: 25e30 ka. Ages of Nakano and Kitoge terraces were estimated at 8e29 ka and 3e4.5 ka based on AT and K-Ah tephras, radiocarbon ages and archaeological remains (Komatsubara et al., 1998). Terrace distribution indicates two kinds of fluvial terraces. One is distributed parallel to the modern rivers (Taisanjino 2e4; Fig. 3) and the other is distributed at 90 to the modern rivers (Aibano 1 and Taisanjino 1 terraces; Fig. 3). The latter terraces occupy the top of the Aibano and Taisanjino Hills (Fig. 3), and are interpreted to originate from deltaic

196

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

Fig. 7. Columnar sections and results of cryptotephra analysis. Data for the Takashima region are from Kakiuchi et al. (2010), whereas high-quartz contents and refractive indices were reanalyzed in this study. Data for the Sekigahara region are from Ishimura (2010). Data for the Inabe region are from this study.

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

197

Fig. 8. (a) Profiles of terrace surfaces in the Taisanjino Hill along the Ado River in Takashima based on 1:2500- (contour interval: 2 m) and 1:25000-scale (contour interval: 10 m, partially 5 m) topographic maps. (b) Profiles of terrace surfaces (M2 and L2 terraces only) along the Fujiko and Makita Rivers in Sekigahara based on 1:2500- and 1:25000-scale topographic maps. (c) Profiles of terrace surfaces (Md1, Md2, Mu2, and L2 terraces only) along the Inabe and Tagiri Rivers in Inabe based on 1:25000-scale topographic maps.

plains. The present Ado River delta is extensive, and its distribution is similar to that of Aibano 1 and Taisanjino 1 terraces (Fig. 3). In Lake Biwa, repetitive transgressions induced by interglacial climate and regression induced by delta development in interglacial periods were indicated by seismic surveys and boring data (Miyata et al., 1990; TuZino, 2010). Although the age of Taisanjino 1 terrace was estimated at 105e140 ka (Kakiuchi et al., 2010), it is correlated

to MIS 5e considering distributions of terraces and modern delta, and delta development in interglacial periods. From this perspective, the former type of terraces were formed by incision of the deltaic plain and thus their distribution is parallel to the modern rivers. Ages of fluvial terraces, based on age data of Komatsubara et al. (1998) and Kakiuchi et al. (2010), are considered as follows: Taisanjino 2 terrace, MIS 5d-5c; Taisanjino 3 terrace, MIS 5c-5b;

198

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

Fig. 9. Columnar sections of the Takashima, Sekigahara and Inabe regions. Results in the Takashima and Sekigahara regions are from Kakiuchi et al. (2010) and Ishimura (2010), respectively. Data in the Inabe region are from this study. Tephra correlation lines are drawn at the bottom of each tephra horizon. Dashed lines are tephra horizons with low reliability.

Taisanjino 4 terrace, MIS 4; Okuyama terrace, MIS 3-2; and Nakano terrace, MIS 2. Ages of M1, M2 and L2 terraces in the Sekigahara region were estimated and correlated based on tephras and geomorphic features as follows: M1 terrace, MIS 5; M2 terrace, MIS 4; L2 terrace, MIS 2 (Fig. 10; Ishimura, 2010). Satoguchi and Yamakawa (2006) estimated that correlatives of H terrace deposits deposited during several 10 ky after 248 ka based on plant fossils and tephras. In this region, L2 terrace was formed during 26e29 ka (AT) to 7.3 ka (K-Ah) and was interpreted as an aggradational terrace (Ishimura, 2010). The height of L2 terrace surface from alluvial plain decreases from Sekigahara to the Nobi Plain and L2 terrace deposits probably lie beneath the Nobi Plain (Fig. 8b). From these features, Ishimura (2010) correlated the L2 terrace surface to the Toriimatsu terrace surface in the eastern part of the Nobi Plain (Nobi Plain Quaternary

Research Group, 1977). Beneath the Nobi Plain, the Toriimatsu terrace deposits connect to the First Gravel bed. The First Gravel bed, a bottom layer of Holocene alluvial deposits, was formed during the Last Glacial Maximum (Nobi Plain Quaternary Research Group, 1977). Thus, Ishimura (2010) correlated the L2 terrace to MIS 2. Although the distribution of M2 terrace is less extensive than that of L2 terrace, M2 terrace has similar geomorphic features such as distribution and terrace surface gradient to the L2 terrace (Figs. 4 and 8b). Therefore, M2 terrace was interpreted as an aggradational terrace that was formed during MIS 4 because it was formed between 95 ka (K-Tz) and 26e29 ka (AT) (Ishimura, 2010). The time interval suggested by 10e40 cm thick eolian deposits below the AT horizon also supports this interpretation (Locs. S5, S7-8, S10, Figs. 7 and 9). Ishimura (2010) correlated M1 terrace to MIS 5 because the K-Tz (95 ka) horizon was identified directly above the fluvial

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

199

Fig. 10. Chronology of fluvial terraces in study areas and global sea-level change. Sea-level curve is modified from Chappell (1994). The ages of terraces in Takashima are from Komatsubara et al. (1998) and Kakiuchi et al. (2010). The ages of terraces in Sekigahara are from Satoguchi and Yamakawa (2006) and Ishimura (2010). The ages of terraces in Inabe are from this study. Dashed lines are terrace surfaces with low reliability of age determination.

deposits (Locs. S1-2, Fig. 9). Ages of the other terraces were then estimated based on their spatial relationships with M1, M2 and L2 terraces (Fig. 10; Ishimura, 2010). In the Inabe region, the Md1 terrace along coastal area has been correlated to MIS 5e because marine clay interbedded in this terrace deposit was correlated to the lower Atsuta Formation (Yoshida et al., 1991), which was deposited during 110e130 ka based on tephrochronology (Makinouchi et al., 2001). The K-Tz tephra covered Md1 terrace surfaces far from coastal areas. Mu2 and Md2 terraces were formed during MIS 5-3, as these terraces are covered by AT (26e29 ka) and K-Ah (7.3 ka) but not by K-Tz (95 ka). Along the Inabe River, L2 terrace deposits overlain by K-Ah tephra fill valleys in the mid-upstream area and probably lie beneath alluvial plain in the downstream area (Fig. 8c). The intersection of L2 terrace surfaces and alluvial plain is also identified along the Asake River and other tributaries (Fig. 5). These features are similar to L2 terrace in the Sekigahara region, and therefore L2 terrace is correlated to MIS 2. 5.2. Processes of terrace formation Correlation of some terraces to MIS 2 and MIS 5 was based on ages of fluvial terraces and their geomorphic expressions. Taisanjino 1-3 terraces in Takashima, M1 terrace in Sekigahara, and Md1 terrace in Inabe were correlated to MIS 5. Nakano terrace in Takashima, L2 terrace in Sekigahara, and L2 terrace in Inabe are correlated to MIS 2. This section discusses the processes and factors of terrace formation, focusing on the terraces formed during MIS 2 and MIS 5e. Aggradational terraces formed during MIS 2 are distributed in mid-upstream area in all regions. However, the study areas have different base-levels of erosion and active fault movements. This means that valley filling occurred during MIS 2 in the entire study area and was mainly affected by climate changes, not by base-level changes and active fault movements. In Japan, such river process during glacial periods were known and interpreted as due to the

increase in sediment supply caused by the expansion of the periglacial area (Hirakawa and Ono, 1974; Ito and Masaki, 1984) and/or the decrease in precipitation and discharge caused by the decrease in heavy rain produced by typhoons (Kaizuka, 1962; Sugai, 1993). However, the study area was not affected by periglacial processes during MIS 2 because the tree line during MIS 2 in Kinki district was estimated to be around 1000 m a.s.l. (Yonekura et al., 2001), and Takahara and Takeoka (1986) concluded that the subalpine coniferous forest developed during 15e25 ka at 810 m a.s.l. in the west of the Hira Mountains based on pollen analysis. Thus, the valley filling in the mid-upstream area during MIS 2 was caused by the decrease in precipitation and discharge. Pollen data suggested a dry and cold environment during MIS 2 around Lake Biwa (Miyoshi et al., 1999; Hayashi et al., 2010) and support this interpretation. From these data, the processes of formation of aggradational terraces during MIS 2 involved: 1) From MIS 3 to MIS 2, precipitation and discharge decreased and rivers were not able to transport much sediment to the downstream area; 2) Sediment supply surpassed sediment transportation and deposition occurred in the mid-upstream area during MIS 2; 3) From MIS 2 to MIS 1, precipitation and discharge increased and rivers were able to transport sediments from upstream to downstream. Consequently, incision occurred in the midupstream area and aggradational terraces were formed; 4) Deposition occurred in the downstream area during MIS 1 and the river gradient became gentle compared to that of MIS 2, as in the present rivers (Fig. 8). In Japan, processes of terrace formation during MIS 2 have been studied mainly in central and northeast Japan (Hirakawa and Ono, 1974; Ito and Masaki, 1984) based on tephrochronology. Although only a few studies indicated the effects of changes of precipitation and discharge on terrace formation (Kaizuka, 1962; Sugai, 1993), it

200

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

was generally interpreted that the increase of sediment supply due to glacial and periglacial processes affected the formation of aggradational terraces during MIS 2 in Japan. In New Zealand, aggradational fluvial terraces during the late Pleistocene were well studied based on radiocarbon dating, tephrochronology and OSL dating (Berryman et al., 2000; Eden et al., 2001; Litchfield and Berryman, 2005). Litchfield and Berryman (2005) concluded that the aggradation during MIS 2 was the result of climate effects, not of base-level controls, and suggested that the decrease in discharge was probably less important for aggradation than the increase in sediment supply due to periglacial processes. The interpretation that aggradational terraces during MIS 2 in the study area were affected mainly by climate changes is the same as in previous studies. However, because the fluvial terraces during MIS 2 have the same geomorphic features, such as aggradational terraces and steep terrace profiles, in both glacial and periglacial and in nonglacial and non-periglacial areas, the aggradational terraces were also formed by the decrease in precipitation and discharge, not by the increase in sediment supply due to periglacial processes. This indicates that aggradational terraces were formed during MIS 2 due to climate changes in southwest Japan because the climate zone during MIS 2 shifted southward (Ono, 1984) and thus decreases in precipitation and discharge occurred widely in southwest Japan due to the southward shifting of rain fronts and typhoon tracks. Pollen data suggested a dry and cold environment during MIS 2 in Shikoku (Miyake et al., 2003, 2005) and Kyushu district (Hatanaka, 1985). Several studies reported fluvial terraces formed during MIS 2 based on AT tephra in Kinki (Kataoka and Yoshikawa, 1997), Shikoku (Mizuno et al., 1993) and Kyushu districts (Nagaoka, 1986). Some show steep terrace profiles and lie beneath alluvial plains (Nagaoka, 1986; Kataoka and Yoshikawa, 1997). Thus, the aggradational terraces were formed during MIS 2 due to the climate changes not only in glacial and periglacial areas (e.g., central and northeast Japan, New Zealand) but also in non-glacial and nonperiglacial areas (southwest Japan). Terraces formed during MIS 5e are widely distributed in downstream areas in the Takashima and Inabe regions. Although the base levels of these regions are different, these regions are strongly affected by crustal uplift due to active fault movements. In interglacial periods, incision occurred in the mid-upstream areas and deposition occurred in downstream areas, and thus wide floodplains were formed in downstream areas, as in the present rivers (Figs. 3 and 5). The altitudes of terrace surfaces in downstream areas were controlled by base-levels of erosion, because a river profile in a coastal area is controlled by sea or lake level. Therefore, the relative base-level descent is significant for terrace formation in downstream areas during interglacial periods. The factors of the relative base-level descent are sea or lake-level changes and crustal uplift by active fault movements. The Inabe region is directly affected by sea-level changes and the amount of sea-level descent from MIS 5e to MIS 5d is about 40 m (Fig. 10; Chappell, 1994). Additionally, movements along the Yoro-KuwanaYokkaichi fault zone enhance the relative base-level descent. In the Inabe region, both factors affected the terrace formation in the downstream area during MIS 5e. On the other hand, lake-level changes are not well known around Takashima because tectonic uplift and subsidence are too large to estimate absolute lake-level changes. However, because the Seta River controlled the lake level and balanced the crustal uplift and incision of river bed, allowing it to maintain its course for a long time, it is possible to interpret that the amount of absolute lake-level changes from MIS 5e to MIS 5d was much less than that of sea-level changes. Another factor influencing relative lake-level descent is crustal uplift by active fault movements. In the Takashima region, the vertical slip rate of the Aibano fault (Fig. 3) was estimated to be >2.0 mm/y

(Komatsubara, 2006) and the uplift rate of the Kamidera fault (Fig. 3) was estimated to be 0.6e1.2 mm/y (Kakiuchi et al., 2010). These rates are larger than those of the Inabe region, and these active fault movements resulted in relative lake-level descent. Thus, active fault movements had an important role in terrace formation during MIS 5e in the Takashima region. From these data, the processes of terrace formation during MIS 5e involved: 1) Sediment supply to the downstream area increased due to climate changes, and wide floodplains including river deltas were formed in downstream areas during MIS 5e; 2) River incised floodplain and MIS 5e terraces were formed due to relative base-level descent by sea-level changes and active fault movements in Inabe, and mainly by active fault movements in Takashima. The main factor of terrace formation during glacial periods is the decrease in precipitation and discharge due to climate changes because terraces formed during MIS 2 are widely distributed in mid-upstream areas in all regions, and the study area was not affected by periglacial processes during MIS 2. In contrast, the terrace formation during interglacial periods is affected by climate changes, base-level changes and active fault movements and it is difficult to separate the contribution of each factor. However, the tectonic base-level descent is important for terrace formation during interglacial periods, because fluvial terraces were formed on the hanging wall side during MIS 5e in the Takashima region despite the small lake-level changes. 5.3. Estimation of uplift rate associated with active fault movements based on the height of terrace surface in the Takashima and Inabe regions Long-term uplift rates of active faults can be estimated based on the terrace surfaces formed at MIS 5e, and compared with previous work. In the Takashima region, Kakiuchi et al. (2010) calculated uplift rates of the hanging wall block of the Kamidera fault. However, they simply calculated the height of the terrace surfaces from alluvial plain as the amount of uplift and did not consider the original surface geometry of each terrace. Taisanjino 1 terrace was formed during MIS 5e and originated from a deltaic plain. The present deltaic plain is almost flat and its altitude is the same as the present lake level (85 m a.s.l.) (Fig. 8a). Thus, the uplift rates relative to lake level were estimated based on the height from Taisanjino 1 terrace surfaces to the present lake level. This height ranges from 101 m to 135 m (Fig. 8a) and the maximum uplift rate is estimated at 1.08 mm/y (terrace age is assumed to be 125 ka). Subsidence rates relative to lake level can be estimated at 1.07e1.53 mm/y based on the buried AT tephra depths in the Ado River delta (Fig. 3; Komatsubara and Geo-Database Information Committee, Kansai Geotechnical Consultants Association, 2010), assuming it was deposited at lake level. The vertical slip rate of the Kamidera fault is estimated at 2.15e2.61 mm/y. This rate is consistent with that of the Aibano fault (Komatsubara, 2006). In the Inabe region, the Md1 terrace is correlated to MIS 5e. If the geometry of river profile during MIS 5e is like that of the present, the amount of uplift from MIS 5e to MIS 1 can be estimated based on the height of Md1 terraces from the modern river bed. This height ranges from 30 m to 60 m (Fig. 8c) and the maximum uplift rate is 0.48 mm/y (terrace age is assumed to be 125 ka). Although the uplift rate in the anticlinal axis cannot be estimated due to lack of fluvial terraces, it may be greater than 0.5 mm/y, as indicated by the deformation pattern of Md1 terrace surfaces (Fig. 8c). In the footwall side, marine clay deposits during MIS 5e (lower Atsuta Formation) are buried at a depth of 78e101 m at the mouth of Inabe

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

River (Makinouchi et al., 2001). Subsidence rate relative to sea level based on the depth of the top of marine clay deposits was estimated at 0.62 mm/y (age is assumed to be 125 ka). The vertical slip rate of the Kuwana fault is estimated at >1.10 mm/y. Ishiyama et al. (2004) estimated vertical slip rates of Kuwana fault at 1.0  0.2 mm/y for the past 105 years based on the high-resolution seismic reflection profile. Thus, the present study’s estimation is consistent with previous research. 6. Conclusions Three tephra horizons, K-Ah (7.3 ka), AT (26e29 ka) and K-Tz (95 ka), were identified in eolian deposits covering fluvial terrace deposits based on cryptotephra analysis. The K-Tz tephra is an important time marker to correlate terraces formed during MIS 5. These cryptotephra analysis and the geomorphic features of fluvial terrace surfaces were used to establish the chronology of fluvial terraces and correlate ages of fluvial terraces to MIS. Processes and factors of terrace formation in northeastern Kinki district were examined by comparison of fluvial terraces formed during MIS 2 and MIS 5e in three regions. Fluvial terraces formed during MIS 2 exhibit similar geomorphic features among the three regions. The main factor of terrace formation during glacial periods was the decrease in precipitation and discharge due to climate changes. This indicated that the aggradational terraces formed in nonglacial and non-periglacial areas during MIS 2 similarly to glacial and periglacial areas. Fluvial terraces formed during MIS 5e are distributed on the hanging wall side in the Takashima and Inabe regions. The tectonic base-level descent was important for terrace formation during interglacial periods, because terraces were formed during MIS 5e by relative lake-level descent probably due to active fault movements in the Takashima region despite the small lake-level changes. In the Takashima and Inabe regions, crustal uplift rates of the Kamidera and Kuwana faults were estimated to be 1.08 mm/y and >0.5 mm/y, respectively, based on the height of terrace surfaces formed during MIS 5e. The subsidence rates on the footwall side were estimated based on the subsurface geology and vertical slip rates of active faults calculated for the Kamidera fault at 2.15e2.61 mm/y, and for the Kuwana fault at >1.10 mm/y. Acknowledgments We are grateful to Hiroyuki Tsutsumi for his helpful advice and encouragement during the course of this research. Comments by Keiji Takemura and Noelynna T. Ramos improved an early version of the manuscript. We thank Shigeru Sueoka, Jeffrey S. Perez, Taihei Nishikawa, Kunihiko Kobata, Masaharu Takiguchi, and Shin Saito for their assistance in drilling surveys. We also thank Atsumasa Okada for his advice and support. The landowners of the drilling sites are also thanked for allowing us to conduct our surveys on their properties. The two anonymous reviewers provided constructive comments that greatly improved the manuscript. This research was supported by Grant-in-Aid for Scientific Research by Japan Society for the Promotion of Science to Hiroyuki Tsutsumi (grant no. 20650155) and Atsumasa Okada (grant no. 18300315). References Berryman, K.R., 1993. Distribution, age, and deformation of late Pleistocene marine terraces at Mahia Peninsula, Hikurangi subduction margin, New Zealand. Tectonics 12, 1365e1379. Berryman, K., Mardan, M., Eden, D., Mazengarb, C., Ota, Y., Moriya, I., 2000. Tectonic and paleoclimatic significance of Quaternary river terraces of the Waipaoa river, east coast, North Island, New Zealand. New Zealand Journal of Geology and Geophysics 43, 229e245.

201

Burbank, D.W., Leland, J., Fielding, E., Anderson, R.S., Brozovic, N., Reid, M.R., Duncan, C., 1996. Bedrock incision, rock uplift and threshold hillslopes in the northwestern Himalayas. Nature 379, 505e510. Chappell, J., 1974. Geology of coral terraces, Huon Peninsula, New Guinea: a study of Quaternary tectonic movements and sea-level changes. Bulletin of the Geological Society of America 85, 553e570. Chappell, J., 1994. Upper Quaternary sea levels, coral terraces, oxygen isotopes and deep-sea temperatures. Journal of Geography 103, 828e840. Eden, D.N., Palmer, A.S., Cronin, S.J., Marden, M., Berryman, K.R., 2001. Dating the culmination of river aggradation at the end of the last glaciation using distal tephra compositions, eastern North Island, New Zealand. Geomorphology 38, 133e151. Hatanaka, K., 1985. Palynological studies on the vegetational succession since the Wurm glacial age in Kyushu and adjacent areas. Journal of the Faculty of Literature 18, 29e71. Kitakyushu University (Series B). Hayashi, R., Takahara, H., Hayashida, A., Takemura, K., 2010. Millennial-scale vegetation changes during the last 40,000 y based on a pollen record from Lake Biwa, Japan. Quaternary Research 74, 91e99. Heki, K., Miyazaki, S., 2001. Plate convergence and long-term crustal deformation in central Japan. Geophysical Research Letters 28, 2313e2316. Hirakawa, K., Ono, Y., 1974. The landform evolution of the Tokachi Plain. Geographical Review of Japan 47, 607e632 (in Japanese with English abstract). Huzita, K., 1962. Tectonic development of the Median zone (Setouchi) of southwest Japan, since the Miocene. Journal of Geosciences 6, 103e144. Osaka City University. Ikeda, H., Ohashi, T., Uemura, Y., Yoshikoshi, A., 1979. Geomorphology of the Ohmi basin. In: Natural Environmental Research Laboratory of Shiga. Land and Life in Shiga. Foundation of Nature Conservation in Shiga Prefectuture, Shiga, pp. 1e112 (in Japanese). Ishimura, D., 2010. Chronology of fluvial terraces and fault activities in and around the Sekigahara region, central Japan. The Quaternary Research 49, 255e270 (in Japanese with English abstract). Ishiyama, T., Mueller, K., Togo, M., Okada, A., Takemura, K., 2004. Geomorphology, kinematic history, and earthquake behavior of the active Kuwana wedge thrust anticline, central Japan. Journal of Geophysical Research 109, B12408. doi:10.1029/2003JB002547. Ishiyama, T., Mueller, K., Sato, H., Togo, M., 2007. Coseismic fault-related fold model, growth structure, and the historic multisegment blind thrust earthquake on the basement-involved Yoro thrust, central Japan. Journal of Geophysical Research 112, B03S07. doi:10.1029/2006JB004377. Ito, M., Masaki, T., 1984. Ages of debris supply during late Pleistocene in the Chigawa valley, the eastern area of the northern Japanese Alps, central Japan. Geographical Review of Japan (Series A) 57, 282e292 (in Japanese with English abstract). Kaizuka, S., 1962. Vegetation of the Würm Glacial age and some climatic terraces in Japan. The Quaternary Research 2, 159e160 (in Japanese with English abstract). Kaizuka, S., Naruse, Y., Matsuda, I., 1977. Recent formations and their basal topography in and around Tokyo Bay, central Japan. Quaternary Research 8, 32e50. Kakiuchi, Y., Tsutsumi, H., Takemura, K., Suzuki, T., Murata, M., 2010. Uplift of fluvial terraces by the activity of the Kamidera fault in the northern part of the Biwako-seigan fault zone. The Quaternary Research 49, 219e231 (in Japanese with English abstract). Kataoka, K., Yoshikawa, S., 1997. Fluvial terrace deposits along the Suzuka River, Mie Prefecture, central Japan: chronology of terrace rarely intercalated with volcanic ash. The Quaternary Research 36, 263e276 (in Japanese with English abstract). Kawabe, T., 1989. Block movements of the Pliocene to Pleistocene sedimentary basins in Kinki district, Japan. Earth Science 43, 402e416 (in Japanese with English abstract). Komatsubara, T., 2006. Slip distribution of the Biwako-Seigan fault zone. Earth Monthly (Extra Edition) 54, 165e170 (in Japanese). Komatsubara, T., Geo-Database information Committee, Kansai Geotechnical Consultants Association, 2010. Shallow subsurface geology of the Ohmi basin. Journal of Geography 119, 683e708 (in Japanese with English abstract). Komatsubara, T., Mizuno, K., Sangawa, A., Nanayama, F., Kinoshita, H., Matsuki, H., Niimi, K., Yoshimura, T., Inoue, M., Ikawa, N., Kazuhara, H., Nakamura, Y., Zushi, T., Yokoigawa, H., 1998. Late Quaternary activity of the Aibano fault, western side of Lake Biwa, Kinki district, Japan. Bulletin of the Geological Survey of Japan 49, 447e460 (in Japanese with English abstract). Kuwae, M., Yoshikawa, S., Inouchi, Y., 2002. A diatom record for the past 400 ka from Lake Biwa in Japan correlates with global paleoclimatic trends. Palaeogeography, Palaeoclimatology, Palaeoecology 183, 261e274. Litchfield, N.J., Berryman, K.R., 2005. Correlation of fluvial terraces within the Hikurangi Margin, New Zealand: implications for climate and baselevel controls. Geomorphology 68, 291e313. Machida, H., 1980. Tephra and its implications with regard to the Japanese Quaternary period. In: The Association of Japanese Geographers. Geography of Japan. Teikoku-shoin, Tokyo, pp. 29e53. Machida, H., Arai, F., 2003. Atlas of Tephra in and around Japan [revised edition]. University of Tokyo Press, Tokyo (in Japanese). Makinouchi, T., Mori, S., Danhara, T., Takemura, K., Research Committee of the Ground of Nobi Plain, 2001. Ages of the basal gravel of alluvium (BG) and the lower marine clay member of late Pleistocene Atsuta Formation under the Nobi plain, central Japan. Journal of the Geological Society of Japan 107, 283e295 (in Japanese with English abstract).

202

D. Ishimura, Y. Kakiuchi / Quaternary International 246 (2011) 190e202

Matsu’ura, T., Furusawa, A., Saomoto, H., 2008. Late Quaternary uplift rate of the northeastern Japan arc inferred from fluvial terraces. Geomorphology 95, 384e397. Meyers, P.A., Takemura, K., Horie, S., 1993. Reinterpretation of Late Quaternary sediment chronology of Lake Biwa, Japan, from correlation with marine glacialeinterglacial cycles. Quaternary Research 39, 154e162. Miyake, N., Honda, M., Ishikawa, S., 2003. Fossil pollen assemblages during the last glacial period in the Uwa Basin, Ehime Prefecture, southwestern Japan. Japanese Journal of Palynology 49, 1e8 (in Japanese with English abstract). Miyake, N., Nakamura, J., Yamanaka, M., Miyake, M., Ishikawa, S., 2005. Vegetation changes since the last glacial period around the Itachino Mire in the Kochi Plain, southwestern Japan. The Quaternary Research 44, 275e287 (in Japanese with English abstract). Miyata, Y., Yamamura, T., Nabetani, A., Iwata, T., Obata, M., Yuuki, T., Tokuhashi, S., 1990. Formative processes of lacustrine deltas: an example from the Echi river delta, Lake Biwa 2. Geological setting and sedimentary facies. Journal of the Geological Society of Japan 96, 839e858 (in Japanese with English abstract). Miyoshi, N., Fujiki, T., Morita, Y., 1999. Palynology of a 250-m core from Lake Biwa: a 430,000 year record of glacial-interglacial vegetation change in Japan. Review of Palaeobotany and Palynology 104, 267e283. Miyoshi, T., Ishibashi, K., 2008. Neotectonics in and around the Kinki triangle in relation to the geometry of the subducted Philippine Sea plate. The Quaternary Research 47, 223e232 (in Japanese with English abstract). Mizuno, K., Okada, A., Sangawa, A., Shimizu, F., 1993. Explanatory text of strip map of the Median tectonic line active fault system in Shikoku, Japan. Scale 1:25000, tectonic map Series 8. Geological Survey of Japan (in Japanese with English abstract). Nagahashi, Y., Yoshikawa, S., Miyakawa, C., Uchiyama, T., Inouchi, Y., 2004. Stratigraphy and chronology of widespread tephra layers during the past 430 ky in the Kinki district and the Yatsugatake mountains: major element composition of the glass shards using EDS analysis. The Quaternary Research 43, 15e35 (in Japanese with English abstract). Nagaoka, S., 1986. The landform evolution of late Pleistocene in the Miyazaki plain, south Kyusyu, Japan. The Quaternary Research 25, 139e163 (in Japanese with English abstract). Nakajima, J., Hasegawa, A., 2007. Subduction of the Philippine Sea plate beneath southwestern Japan: slab geometry and its relationship to arc magmatism. Journal of Geophysical Research 112, B08306. doi:10.1029/2006JB004770. Nakamura, Y., Okada, A., Takemura, K., 2008. Late Quaternary activity of faults and recurrence interval of earthquakes in the eastern Hokuriku region, northern central Japan, on the basis of precise cryptotephra analysis of fluvial terrace sequences. Geomorphology 99, 59e75. Nakata, T., Imaizumi, T. (Eds.), 2002. Digital Active Fault Map of Japan. University of Tokyo Press, Tokyo (in Japanese). Nobi Plain Quaternary Research Group, 1977. Stratigraphy and microfossil analysis of Quaternary sediments in the Nobi plain, Central Japan. The Memoirs of the Geological Society of Japan 14, 161e183 (in Japanese with English abstract). Ogura, H., Yoshikawa, S., Konomatsu, M., Kitani, K., Mitamura, M., Ishii, H., 1992. Ages of the terrace deposits and their surfaces in the southern part of the Uemachi upland, the Osaka Plain, Japan. The Quaternary Research 31, 179e185 (in Japanese). Ohashi, T., 1978. Lake level history of Lake Biwa, deduced from terrace distribution. Earth Science Education 31, 75e81 (in Japanese). Ono, Y., 1984. Last glacial paleoclimate reconstructed from glacial and periglacial landforms in Japan. Geographical Review of Japan (Series B) 57, 87e100.

Ota, Y., Omura, A., 1991. Late Quaternary shorelines in the Japanese Islands. The Quaternary Research 30, 175e186. Ota, Y., Naruse, T., Tanaka, S., Okada, A., 2004. Regional Geomorphology of the Japanese Islands. In: Geomorphology of Kinki, Chugoku and Shikoku, vol. 6. University of Tokyo Press, Tokyo (in Japanese). Pazzaglia, F.J., Brandon, M.T., 2001. A fluvial record of long-term steady-state uplift and erosion across the Cascadia Forearc High, western Washington State. American Journal of Science 301, 385e431. Research Group for Active Faults of Japan, 1991. Active Faults in Japan: Sheet Maps and Inventories. University of Tokyo Press, Tokyo (in Japanese). Satoguchi, Y., Yamakawa, C., 2006. Depositional age of conglomeratic beds distributed around the Terabayashi area at the foot of Mt. Ibuki, Japan. The Quaternary Research 45, 29e39 (in Japanese with English abstract). Sugai, T., 1993. River terrace development by concurrent fluvial processes and climate changes. Geomorphology 6, 243e252. Tajikara, M., Ikeda, Y., 2005. Vertical crustal movement and development of basin and range topography in the middle part of the northeast Japan arc estimated from fluvial/marine terrace data. The Quaternary Research 44, 229e245 (in Japanese with English abstract). Takahara, H., Takeoka, M., 1986. Vegetational changes since the last glacial maximum around the Hatchodaira moor, Kyoto, Japan. Japanese Journal of Ecology 36, 105e116 (in Japanese with English abstract). Takemura, K., 1985. The Plio-Pleistocene Tokai Group and the tectonic development around Ise Bay of central Japan since Pliocene. In: Memoirs of the Faculty of Science, Kyoto University. Series of Geology and Mineralogy, vol. 51, pp. 21e96. Takemura, K., 1990. Tectonic and climate record of the Lake Biwa, Japan, region, provided by the sediments deposited since Pliocene times. Palaeogeography, Palaeoclimatology, Palaeoecology 78, 185e193. Togo, M., 1971. On the deformation of Aibano Hill, Shiga Prefecture. Geographical Review of Japan 44, 194e200 (in Japanese). Toyoda, K., 2003. Chemical composition of a drilled core of Lake Biwa in Japan and implications for source changes during the past 430,000 years. Quaternary International 105, 57e69. Tsukahara, H., Kobayashi, Y., 1991. Crustal stress in the central and western parts of Honshu, Japan. Journal of the Seismological Society of Japan (Ser. 2) 44, 221e231 (in Japanese with English abstract). TuZino, T., 2010. Re-examination of air-gun profiles from Lake Biwa (Japan), and depositional history of the lake in the Pliocene-Quaternary. Journal of Paleolimnology 43, 273e291. Xiao, J., Inouchi, Y., Kumai, H., Yoshikawa, S., Kondo, Y., Liu, T., An, Z., 1997. Aeolian quartz flux to Lake Biwa, central Japan, over the past 145,000 years. Quaternary Research 48, 48e57. Yokoyama, T., 1984. Stratigraphy of the Quaternary system around Lake Biwa and geohistory of the ancient Lake Biwa. In: Horie, S. (Ed.), Lake Biwa. Dr. W. Junk Publishers, Dordrecht, pp. 43e128. Yonekura, N., Kaizuka, S., Nogami, M., Chinzei, K., 2001. Regional Geomorphology of the Japanese Islands. In: Introduction to Japanese Geomorphology, vol. 1. University of Tokyo Press, Tokyo (in Japanese). Yoshida, F., 1991. Quaternary movement on the Ichinohara Fault near the southern foot of the Yoro Mountains, central Japan. Active Fault Research 9, 53e60 (in Japanese). Yoshida, F., Kurimoto, C., Miyamura, M., 1991. Geology of the Kuwana district, with geologic sheet map at 1:50,000. Geological Survey of Japan (in Japanese with English abstract).