Tephrostratigraphy of Pleistocene-Holocene deposits from the Detroit Rise eastern slope (northwestern Pacific)

Abstract

The main goal of the study is to establish the spatial and temporal distribution of pyroclastic material from large explosive eruptions of the volcanoes of Kamchatka, the Kuril, and Aleutian Islands to create a generalized tephrochronological model and reveal patterns of explosive activity in this region. This paper presents new data on the composition of volcanic ash (tephra) found in the Pleistocene deposits of the northwestern Pacific from the eastern slope of the Detroit Rise (northwestern part of the Imperial Ridge), 450–550 km east of the Kamchatka Peninsula. Eleven layers and lenses of tephra aged from 28 to 245 ka, which were previously unknown, were studied in the core Lv63-4-2. Their stratigraphic position and age were determined based on age models developed in this study. Based on the geochemical composition of volcanic glass (determined using an electron microprobe), seven layers were correlated with tephra from several cores in the northwestern Pacific and the Bering Sea. The obtained results supplement the information on large explosive eruptions of volcanoes in the region and their periods of activity. They also allow the development of a generalized tephrochronological model of Quaternary deposits, which is necessary for stratigraphic correlation, and of paleooceanological and paleogeographic reconstructions.

A 6.2 Ma‐Long Record of Major Explosive Eruptions From the NW Pacific Volcanic Arcs Based on the Offshore Tephra Sequences on the Northern Tip of the Emperor Seamount Chain

“…The first one is DS2 from the Gorely eruptive center. DS2 tephra is similar to Gor28 from the onshore CKD sequence, to prevailing glass population in the WP4 tephra from the Meiji Seamount core (Derkachev et al, 2020), and to D2 ash from core Lv63-4-2 (Derkachev et al, 2023) (Figures 16a and 16b). In addition, compositionally identical tephra was also found in core ODP145-883D on the Detroit Seamount (Bigg et al, 2008) and in the Ledovy Bluff outcrop (Chukotka), ∼1,500 km north of the Detroit (Figure 17; Ponomareva et al, 2021).…”

“…(2021) and Derkachev et al. (2020, 2023), respectively. T2, T3, and T4 tephras according to van den Bogaard et al.…”

“…Core Lv63‐4‐2 (∼245 ka) is located ∼42 km northwest of Site 884B (Figure 1a; Derkachev et al., 2023). Besides Gorely DS2 (D2) and DS14 (D7) tephras, considered above, there are four more tephras linking Detroit sequence to Lv63‐4‐2 (Table 6).…”

“…For a 1-cm-thick layer, even a narrow isopach striking from the Kamchatka volcanic front to the Detroit Seamount yields a minimum tephra volume (V) of 7 km 3 and M = 5.8 (assumed density 800 kg/m 3 ) (Pyle, 1995). Taking Derkachev et al (2020Derkachev et al ( , 2023, respectively. T2, T3, and T4 tephras according to van den Bogaard et al (2014).…”

“…Cao et al (1995) geochemically characterized tephras from ODP Sites 881-884; however, the compositions obtained did not allow these authors to correlate any of the analyzed tephras between the cores or to specific source volcanoes. At the same time, recent studies of tephra from ∼215 ka-old core SO201-2-40 (Meiji Rise) and ∼245 ka-old core Lv63-4-2 (Detroit Seamount), ∼400 and 600 km east of Kamchatka, respectively (Figure 1a) have allowed Derkachev et al (2020Derkachev et al ( , 2023 to identify 36 tephra layers and lenses and geochemically link eight of them to their source volcanoes in Kamchatka. Seven of these tephras were identified at several sites and therefore can be used as markers in the NW Pacific region.…”