Surface microtextures of quartz grains and minor sedimentary components across the Paleolithic Jeongok‐ri sediments, Yeoncheon, South Korea

Abstract

The Jeongok‐ri Paleolithic site in the central Korean peninsula is known as the first findspot of Acheulean‐type hand axes in East Asia. Although many previous studies have investigated the depositional environments of Jeongok‐ri sediments across the Paleolithic occupation, they remain controversial. In this study, we collected an 11‐m‐long core to obtain evidence from systematic surface microtextures of quartz grains (SMQs) concerning depositional environments in the Jeongok‐ri archeological site. SMQs in the Jeongok‐ri sediments are characterized by dominant angular to subangular outlines and small to large conchoidal fractures with arcuate steps, as well as sparse V‐shaped percussion cracks; these features suggest short distances and subaqueous transportation with grain‐to‐grain collisions and violent impacts of quartz grains. On the basis of simultaneous sedimentation of the hosting silt deposits, our SMQ results suggest that Jeongok‐ri sediments were originally fluvial, regardless of their intermediate sedimentary history. This evidence from quartz grain microtextures is consistent with minor sedimentary components found in the Jeongok‐ri core sediments, such as diatom grains as microfossil constituents, along with macroscopic charcoals and titanium‐bearing detrital magnetite grains. The geological and geomorphological conditions of the Jeongok‐ri site are also favorable for floodplain environments given the position adjacent to river terraces formed by the previous lateral erosion of a meandering channel in the nearby Hantan River. Our findings will help to understand environmental conditions during the development of Paleolithic cultures in East Asia.