Identification and correlation of visible tephras in the Lake Suigetsu SG06 sedimentary archive, Japan: chronostratigraphic markers for synchronising of east Asian/west Pacific palaeoclimatic records across the last 150 ka
The Lake Suigetsu SG06 sedimentary archive from Honshu Island, central Japan, provides a high-resolution palaeoenvironmental record, including a detailed record of explosive volcanism from Japan and South Korea. Thirty visible tephra are recorded within the 73 m-long SG06 core, which spans the last ̃150 ka. Here we describe and characterise these tephras based on major element glass composition, which is useful for the identification and correlation of these tephras and the age models of the records in which they are found. Utilising the large number of radiocarbon measurements (n > 600) from terrestrial plant macrofossils in the Lake Suigetsu SG06 record, we are able to provide precise and accurate ages for the tephras from eruptions within the last 50 ka. Glass compositional data of some of the largest eruptions from Japan (K-Ah, AT, Aso-4, Aso-A, Aso-D, and Ata; sampled at proximal outcrops) are also presented. These data show that the major element glass chemistry is distinctive for many of the visible SG06 tephra units, and allows some of the layers to be correlated to known eruptions from volcanoes in Japan and South Korea, namely K-Ah (SG06-0967), U-Oki (SG06-1288), AT (SG06-2650), Aso-4 (SG06-4963/SG06-4979), K-Tz (SG06-5181), Aso-ABCD (SG06-5287) and Ata (SG06-5181). The following ages were obtained for the SG06 tephra units: 3.966-4.064 cal. ka BP (95.4% probability range) for the SG06-0588 tephra, 10.242-10.329 cal. ka BP (95.4% probability range) for SG06-1293, 19.487 ± 112 SG062012 ka BP (2 σ) for SG06-1965, 28.425 ± 194 SG062012 ka BP (2 σ) for SG06-2504, 28.848 ± 196 SG062012 ka BP (2 σ) for SG06-2534, 29.765 ± 190 SG062012 ka BP (2 σ) for SG06-2601, 29.775 ± 191 SG062012 ka BP (2 σ) for SG06-2602, 43.713 ± 156 SG062012 ka BP (2 σ) for SG06-3485, 46.364 ± 202 SG062012 ka BP (2 σ) for SG06-3668, 49.974 ± 337 SG062012 ka BP (2 σ) for SG06-3912, 50.929 ± 378 SG062012 ka BP (2 σ) for SG06-3974, and improved ages for two of the most important tephra markers across Japan, the K-Ah (7.165-7.303 cal. ka BP at 95.4% probability range; SG06-0967) and AT tephra (30.009 ± 189 SG062012 ka BP at 2 σ; SG06-2650).