Holocene relative sea-level change and rate of sea-level rise from coastal deposits in the Toyooka Basin, western Japan

Abstract

This study presents relative sea-level (RSL) change from 11,200 to 500 cal. BP in the Toyooka Basin, western Japan. Diatom assemblage and sedimentary sulfur analyses were performed for 32 sediment cores obtained from thick Holocene fluvial and marine deposits. An age model was constructed based on tephrochronology and 31 radiocarbon ages from elevations of −46.85 to +1.51 m in 19 cores. The RSLs in the Toyooka Basin are −31.05 m in elevation at 10,000 cal BP, above −4.00 m at 7900 cal. BP, −0.47 m at 6700 cal. BP and +0.15 m at 3300 cal. BP. A rapid sea-level rise, at a rate of about 23 mm/yr, is observed during the period from 10,600 to 10,300 cal. BP. Relative sea-level rose at a rate of about 12 mm/yr between 10,000 and 7900 cal. BP. The rate of sea-level rise decelerated at 7900 cal. BP, from about 12 mm/yr (10,000–7900 cal. BP) to 3 mm/yr (7900–6700 cal. BP). The mid-Holocene sea-level highstand probably occurred between 7000 and 6000 cal. BP, but it remains difficult to constrain its elevation. These RSL features described here may provide a typical example of Holocene sea-level changes resulting from both eustatic and hydro-isostatic components for the Japanese islands.

Luminescence dating of Holocene beach-ridge sands on the Yumigahama Peninsula, western Japan

“…Comparison of our results with the sea-level history of Tanigawa et al (2013) indicates that the corrected IRSL age of 8.1 ± 1.3 ka that we obtained for sample YG-1, the most landward and oldest of our samples, was slightly overestimated, even if the error range is consid- (Tanigawa et al, 2013) and an age inferred from Nishinada Ruin (Sasaki et al, 2011) (Fig. 1C).…”

“…The Japan Sea coast of western Japan in the region of the Yumigahama barrier has been tectonically stable during the last 100 kyr (Okuno et al, 2014). Therefore, the Holocene sea-level history of the Yumigahama Peninsula can reasonably be approximated by the reconstruction by Tanigawa et al (2013) of the history of the Toyooka Basin, 150 km east of our study area (Fig. 6).…”

“…6). Tanigawa et al (2013) showed that the post-glacial rise ceased there at 6700 cal BP and that sea level during the following stillstand was close to the present sea level. Thus, the maximum duration of the formation of the sequence of beach ridges of the Yumigahama barrier was from 6700 cal BP to the present (Fig.…”

Holocene Relative Sea-Level Changes from Near-, Intermediate-, and Far-Field Locations

“…Investigations of Holocene RSL in the far-field region of Asia are concentrated in southeast Asia [150][151][152][153], although studies have expanded in recent years to include South Korea [154], the Philippines [155], China [145 -148], the MalayThai peninsula [160 -164 ], and Japan [165 ]. These records are characterized by a mid-Holocene highstand attributed to hydro-isostatic processes [166,167 ], which varies in magnitude and timing of initiation.…”

Late Holocene uplift of the Izu Islands on the northern Zenisu Ridge off Central Japan

“…11). Since relative sea-level reconstructions show that sea level was likely stable at the study site during the past 2000 years (Sato 2008;Woodroffe et al 2012;Yokoyama et al 2012;Tanigawa et al 2013;Tanabe et al 2016), the occurrence of the emerged sessile assemblages cannot be explained by eustatic sea level changes; instead, it requires local crustal uplift.…”