Holocene sea level reconstruction using lagoon specific local marine reservoir effect and geophysical modeling in Tongatapu, Kingdom of Tonga

A review of MIS 5e sea-level proxies around Japan

“…The Toya tephra is widely distributed over much of Hokkaido and northern Honshu, sourced from eruptions that formed the Toya Caldera (Machida et al, 1987). Ages have been constrained to between 112-115 ka by stratigraphic correlations of tephras and terrace heights (Machida, 2002), though zircon U-Th-Pb dating and aliquot regeneration-red thermal luminescence dating have given ages of 108 ± 19 ka and 104 ± 30-118 ± 30 ka (Ito, 2014;Ganzawa and Ike, 2011). The ZP layer was deposited as thick airlaid tephra from an unknown volcano and is found below the Toya tephra and above MIS 5e surfaces in stratigraphic sequences, with ages estimated by Miyauchi (1985) between 110-120 ka (Matsuura et al, 2019;Miyauchi, 1985).…”

“…Though techniques defining tephra ages have become more precise over time, overreliance on tephra-based chronostratigraphy can be precarious, as certain tephra layers have been and still are described with large age uncertainties. Although the Toya tephra has since been more accurately constrained (Ito, 2014;Ganzawa and Ike, 2011), historical utilizations of ages from the original fission track age, along with ages from stratigraphic constraints of the ash layer in the northern part of Japan, resulted in a range of 90-130 ka (Okumura and Sagawa, 1984;Miyauchi, 1988;Ota and Omura, 1991). An applied example, updated ages of tephra-defined marine terraces from Tanegashima (Machida et al, 2001) compared with the original age interpretation (Ota and Machida, 1987) show a discrepancy of 20 kyr.…”

High spatial resolution magnetic mapping using ultra-high sensitivity scanning SQUID microscopy on a speleothem from the Kingdom of Tonga, southern Pacific

“…The speleothem sample was collected from Tongatapu Island, the Kingdom of Tonga, where is an archaeologically important region as a base for human migration to East Polynesia (e.g., Clark et al 2015). However, few quantitative paleoenvironmental studies using Earth-scientific methods have been reported (e.g., Roy 1997;Fukuyo et al 2020). The speleothem magnetism is expected to contribute to the studies of archaeology, such as the Polynesian expansion over the South Pacific islands during the Holocene, by providing information on magnetic minerals reflecting the change in depositional environment such as oxidation states, which might originate from human activity and/or environment.…”

High spatial resolution magnetic mapping using ultra-high sensitivity scanning SQUID microscopy on a speleothem from the Kingdom of Tonga, southern Pacific

“…Paleoenvironmental records such as the rock magnetic properties of this speleothem are important to understand SPCZ's variability since current climate models have di culties in projecting the SPCZ movement (Widlansky et al, 2012). The results will be able to contribute for the studies of paleoclimate and archeology, such as Polynesian expansion over the South Paci c islands during the Holocene (e.g., Clark et al, 2015;Fukuyo et al, 2020).…”