Sediment provenance variations in the southern Okhotsk Sea over the last 180 ka: Evidence from light and heavy minerals

Abstract

In this study, we investigate light and heavy minerals in sediment core OS03-1 located at the Academy of Sciences Rise of the southern Okhotsk Sea to determine their distributions and sources over the last 180 ka (thousand years). The sediment mainly consists of terrigenous and volcanic detritus. Ubiquitous drop-stones and volcanic detritus throughout the core and high detrital input suggest that sea ice, driven by wind and Kamchatka Current, was the main transport agent of detrital materials to the southern Okhotsk Sea. The ternary diagram of heavy minerals (hornblende-hypersthene-epidote) shows an expansion of detritus provenance from the eastern in cold periods to the northeastern in warm intervals of the Okhotsk Sea. It mainly relates to the shift of Aleutian Low. Combined with previous records, accumulation rates of quartz indicated a maximum extent but not perennial sea ice coverage during the glacial periods.

Spatial Distribution and Provenance of Detrital Minerals of Surface Sediment in the Okhotsk Sea

“…Hypersthene and magnetite are abundant in the volcanic ash layers in the sediments of the Okhotsk Sea. Their contents are particularly high in the K2 volcanic layer (Wang et al, 2017). The sediment around the Kamchatka peninsula has high magnetite contents (Figure 3E).…”

“…These four provinces are the area around the Kamchatka Peninsula (Figure 4B), the southern Okhotsk Sea (Figure 4C), the northwestern Okhotsk Sea (Figure 4D), and the southwestern Okhotsk Sea (Figure 4E). For comparison purposes, garnets were also picked from the upper sediments of core OS03-1 (Figure 4F), which is located in the southern central Okhotsk The provenance of the sediments in the core has been well established through heavy mineral data (Wang et al, 2017). The garnet types of surface sediments are mainly types A, Bi, and Bii (Figure 4A).…”

“…The input of volcanic material is obviously dominant in the sediments in this region (Dessert et al, 2009), while in most areas of the Okhotsk Sea, the sediments are derived from terrigenous materials (Gorbarenko et al, 2002). In core OS03-1, which is located in the south-central Okhotsk Sea, the detrital grains are mainly silicate minerals, including hornblende, epidote, and hypersthene (Wang et al, 2017). The trace element geochemistry also shows that volcanic materials and terrigenous materials transported by the Amur River and sea ice in this area (Zou et al, 2015).…”

“…For example, the KO volcanic ash layer covers almost the entire Okhotsk Sea, and the K2 volcanic ash layer (Nemo Volcanic eruption, Nemo-III caldera, Onekotan Island) is distributed around the eastern coast of Sakhalin Island (Derkachev et al, 2016). The hypersthene contents of these ash layers are very high, especially that of the K2 layer (Wang et al, 2017). The volcanic rocks on the south Kamchatka Peninsula are mainly double-pyroxene dacites (Izbekov et al, 2004), which are rich in orthopyroxene (primarily hypersthene).…”

“…The study of detrital minerals and their assemblages in core samples from the south central Okhotsk Sea shows that the heavy mineral contents are very high in the fine sand grain size fraction, and the hornblende, hypersthene, and garnet contents vary significantly. In particular, the garnet content varied in accordance with the paleoclimate changes, which indicates that the provenances of the sediment were also transitional (Wang et al, 2017). Studies of the provenance of surface sediments in the Okhotsk Sea using detrital grains have mainly concentrated around Sakhalin Island, which is located in the western part of the Deryugin Basin (Gorbarenko et al, 2002;Nicholson et al, 2013).…”