2024 Volume 130 Issue 1 Pages 223-238
A drilling survey (GS-ND-2) was carried out at Yamazaki, Noda City, Chiba Prefecture, to investigate lateral changes in the sedimentary facies of the Kiyokawa Formation, and the different facies and physical properties of the Kiyokawa and lower Kioroshi formations in the central Kanto Plain. The sedimentary facies of the Kiyokawa Formation in core GS-ND-2 transition from terrestrial through marine and back to terrestrial facies, in ascending order. Similar facies changes were reported in core GS-KW-1 (Kashiwa City, south of Noda City); however, the facies and pollen zone boundaries of the two cores are offset, suggesting that marine retreat occurred later in the south of the study area. The N-values from standard penetration tests of the mud beds and the pollen assemblages in the Kiyokawa and lower Kioroshi formations are different, which allows them to be distinguished. It is important for sustainable groundwater use and the assessment of seismic hazard to better understand the changes in facies in the Kiyokawa Formation and the distribution of soft mud beds in the lower Kioroshi Formation.
