Ji, H. S. ， Woo, K. S. ， Jo, K. N. ， Cheng, H. ， Edwards, R. L. ， Yi, S. H.
2011-04-01 JOURNAL OF THE GEOLOGICAL SOCIETY OF KOREA 2011 47(卷), 2(期), (139-153页)
Paleoclimatic changes over the past 300 years were inferred based on textural characteristics of the YC-2 stalagmite which grew in Yongcheon Cave, Jeju Island. Age dating was determined by counting annual growth laminae, and it is estimated that the stalagmite grew for longer than 241 years including the hiatus. Th-230/U-234 dating was also carried out to estimate the hiatus period, and both the parts just below and above the hiatus (15.29 similar to 15.42 mm above the bottom of the stalagmite) show the period of about 210 years, even though absolute ages cannot be obtained from both parts. Texturally, the stalagmite can be divided into two phases: Fluid inclusion-poor, columnar calcite (Phase A) and fluid inclusion-rich, columnar calcite (Phase B). Closed-spaced growth laminae with less fluid inclusions of the Phase A indicates that the growth rate was low due to the lower rate of water supply from outside. This also means that the stalagmite growth under more arid climate with lower rate of precipitation. This study implies that textural evidence of the stalagmite in Yongcheon Cave directly reflects the variations of East Asia summer monsoon intensity for the past 300 years.