New findings on palynofacies characteristics of semi-enclosed deep-sea environments in the East Sea over 2 million years

Abstract

Phytoclasts in the form of plant debris in terrestrial sediments can be transported by water to distant areas because they are lighter than inorganic particles. The semi-enclosed East Sea, which is connected by narrow straits to other seas, is adjacent to continental shelves that are the source area of terrestrial sediment flowing into the East Sea. These shelves alternated repeatedly between terrestrial and marine environments as a result of eustatic sea-level changes during the Late Quaternary. Palynofacies analyses of the IODP Exp. 346 U1430 core, located in the Eastern South Korea Plateau (ESKP) of the East Sea, have revealed changes in the size and concentration of phytoclasts associated with glacial–interglacial cycles. These changes are generally negatively correlated with the global sea-level curve, and their anti-phase cycles with high amplitude are clearly evident during the last ca. 750 ka with the geotectonic stabilization period. In particular, several coarse-grained phytoclasts were observed during the glacial period, including the Last Glacial Maximum (LGM). These findings suggest that the concentration and size of phytoclasts flowing into the East Sea were influenced by changes in the distance of the source area, depending on the water depth of the strait and nearby shelves owing to sea-level changes in tandem with glacial–interglacial cycles and geotectonic events.

Seismic stratigraphy and structural evolution of the South Korea Plateau, East Sea (Sea of Japan)

“…We defined a total of four megasequence boundaries (MB1–MB4), which are correlated with the tectonostratigraphic framework of adjacent areas (i.e. the Ulleung Basin and its southwestern margin; KIGAM, 2006; Kim, Yi, et al, 2020; Kim, Yoo, et al, 2020). Approximate geological ages of the megasequence boundaries were obtained from the tectonostratigaphic correlations with known geological ages in the Ulleung Basin (Kim, Yi, et al, 2020; Kim, Yoo, et al, 2020).…”

“…the Ulleung Basin and its southwestern margin; KIGAM, 2006; Kim, Yi, et al, 2020; Kim, Yoo, et al, 2020). Approximate geological ages of the megasequence boundaries were obtained from the tectonostratigaphic correlations with known geological ages in the Ulleung Basin (Kim, Yi, et al, 2020; Kim, Yoo, et al, 2020). In addition, palynological analysis at IODP Site U1430, situated in the ESKP and part of IODP Expedition 346, were used to support our chronostratigraphic interpretation (Horozal et al, 2017; Tada et al, 2015).…”

“…Based on these geophysical data, numerous studies have been carried out in the fields of seismic stratigraphy (Cukur et al, 2015, 2018; Horozal et al, 2017; Kwon et al, 2009), structural evolution (Chough et al, 2018; Kim et al, 2007; Kim, Lee, Choi, et al, 2015; Kim, Lee, Park, et al, 2015), volcano‐tectonic evolution (Kim et al, 2011) and geo‐hazard assessment (Cukur et al, 2018; Kim et al, 2022). Moreover, the Integrated Ocean Drilling Program (IODP) Expedition 346, which collected data at Site U1430 in the Eastern South Korea Plateau (ESKP), played an important role in enhancing our understanding of palaeoclimatic and palaeoceanographic variability (Kim et al, 2019; Kim, Yi, et al, 2020; Kim, Yoo, et al, 2020). In addition to these previous studies, gas‐hydrate research has been actively conducted in the SKP.…”

A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)

“…They probably existed outside the cave, and were preserved in sediments after being transported into the cave by water. This assumption is supported by grass pollen in the coastal wetland (Yang et al, 2016;Song et al, 2017) and neritic to semi-pelagic ocean (Jun et al, 2020;Kim et al, 2020). The median (Φ) sand grain size and Ti/Al ratio (Fig.…”

Modern pollen–climate relationships and their application for pollen-based quantitative climate reconstruction of the mid-Holocene on the southern Korean Peninsula

“…Many studies have used various proxies to reconstruct the Holocene paleoclimate of the Korean Peninsula (KP) (Bae et al, 2020; Jo et al, 2011; Lim et al, 2017b, 2019; Song et al, 2018; Yum et al, 2003). In particular, many qualitative studies have been conducted based on pollen records (Chung et al, 2010; Jun et al, 2020; Kim et al, 2020; Lee et al, 2020a; Yi and Saito, 2003; Yoon et al, 2012). However, pollen-based quantitative paleoclimate reconstruction studies of the KP remain rare.…”