Holocene sea‐level change and Antarctic melting history derived from geological observations and geophysical modeling along the Shimokita Peninsula, northern Japan

Abstract

A Mid to Late Holocene sea‐level record based on combined geomorphological, geological and micropaleontological observations was obtained from well‐developed wave cut benches subaerially exposed along the Shimokita Peninsula, northern Japan. Results indicate that the benches were formed during mid to late Holocene sea‐level transgressions, reaching a maximum highstand level of 2 m above present at about 4,000 years ago. This timing corresponds to an abrupt, order of magnitude decrease in sedimentation rate as recorded in a core recovered from proximal Mutsu Bay. In addition, glacio‐hydro‐isostatic adjustment due to crustal deformation in response to postglacial sea‐level rise was modeled, and results are consistent with the reconstructed local 2 m highstand. Given that meltwater contributions from the major North American and European ice sheets had largely ceased by 7,000 years ago, these independent lines of evidence, taken together, indicate that melting of the Antarctic ice sheet ended by 4,000 years ago.

Widespread collapse of the Ross Ice Shelf during the late Holocene

“…Thus, ice-shelf retreat in the Ross Sea is consistent with ice-core records of atmospheric warming in the region. Timing of ice-shelf retreat observed here is also well correlated with far-field Holocene sea level records (36)(37)(38). Further CS radiocarbon age constraints of grounding-line retreat and ice-shelf collapse around Antarctica will help identify the relationship and phasing of regional and global climate, oceanographic, and sea-level variations in the late Pleistocene and Holocene.…”

Holocene Antarctic melting and lithospheric uplift history of the southern Okinawa trough inferred from mid- to late-Holocene sea level in Iriomote Island, Ryukyu, Japan

“…Subsequent studies confirmed such melting which ceased at about 4 to 2 ka (Lambeck, 2002;Peltier, 2002;Yokoyama et al, 2012), though detailed behavior of Antarctic ice sheet is still under debate (Gehrels, 2010). Accurate determination of HHS timing is important to deconstruct the GIA induced lithospheric deformation .…”

“…Magnitude and timing of HHS at far-field sites is not sensitive to changes in ice distributions at individual locations. Rather, they are sensitive to changes in sea water loading component due to local coastline migrations as well as relatively smaller (<3e4 m ESL) sea level changes during the Holocene (e.g., Yokoyama et al, 2012). Thus we employed ANU model (Lambeck et al, 2014) for the last deglaciation up to 6000 years ago.…”

“…The relative rise in sea level, for example from 7000 years ago, can be monitored from such locations and can be used to understand the geophysical structure of the lithosphere and the mantle as well as to quantify the melting history of ice sheets, in particular, the response of the Antarctic ice sheet to deglacial climate change (Yokoyama and Esat, 2011;Yokoyama et al, 2012). At many coastal sites, peak Holocene RSL is often above the present day sea level due to GIA and is called the Holocene High Stand (HHS).…”

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.…”