Abstract
The focus of this study was the Baekdusan-Kita 1 (B-KY1) eruption during the late Middle Pleistocene. We identified B-KY1 tephra between the Toya and Aso-1 tephras in the ODP 794A core from the Japan Basin of the East Sea/Japan Sea. The stratigraphic position of the B-KY1 tephra correlated exactly with the first B-KY1 to be identified, in the 20EEZ-1 core from the Kita–Yamato Trough. However, B-KY1 tephra in the ODP 794A core showed a wide range of geochemical compositions. The textural characteristics of B-KY1 tephra in the ODP 794A core was characterized by higher content of fine-grained bubble-wall shards than that of the B-KY1 tephra in the 20EEZ-1 core. The difference in B-KY1 tephra between the two coring sites may reflect shifts in wind direction during volcanic eruptions. We refined the eruption age of the B-KY1 tephra by examining distinct sedimentary facies related to the start of the penultimate deglaciation of this region at ca. 135 ka. The findings of this study suggest that the compositional diversity of B-KY1 tephra may have been influenced by subsequent mixing of comendite and comenditic trachyte magma with injected pantelleritic magma during the late Middle Pleistocene Baekdusan volcanic eruption.
Highlights
In the mid-10th century, Baekdusan experienced a VEI-7 explosive volcanic eruption, which produced large amounts of B-Tm tephra [1,2]
Distal tephras transported by explosive volcanic eruptions of Baekdusan have been identified in marine sediments of the East Sea/Japan Sea and Pacific Ocean, as well as in terrestrial sedimentary deposits on the islands of Japan (Figure 2)
The geochemical characters of B-KY1 tephra in the ODP 794A core distinguished it from Aso-4 (88 ka; Figure 5D), Toya, and Aso-1 tephras, which erupted from Japanese volcanoes (Figure 6)
Summary
In the mid-10th century, Baekdusan ( known as Changbaishan in Chinese) experienced a VEI-7 explosive volcanic eruption, which produced large amounts of B-Tm tephra [1,2]. A few terrestrial pyroclastic deposits found on Baekdusan have been dated to within 17,000 years [3]. No studies have reported terrestrial pyroclastic deposits intercalated with effusive Baitoushan I–III trachyte or comendite lava flows during the last Pleistocene and Pliocene. Distal tephras transported by explosive volcanic eruptions of Baekdusan have been identified in marine sediments of the East Sea/Japan Sea and Pacific Ocean, as well as in terrestrial sedimentary deposits on the islands of Japan (Figure 2). 448 ka) tephras [16,17] were first identified in sedimentary deposits from Tomakomai and the Oga Peninsula in Japan, respectively (Figure 1). Alkali Baekdusan tephras are distinguished from sub-alkali tephras derived from Japanese volcanoes (Figure 1)
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