LA-ICPMS U-Pb dating of zircon in paleotsunami deposits from Miyazaki plain, southwest Japan

Watanabe, Takahiro   ; Kagami, Saya   ; Yokoyama, Tatsunori   ; Niwa, Masakazu   

U-Pb dating of detrital zircons in paleotsunami deposits from the 1662 CE Kanbun-Hyuganada sea earthquake, Miyazaki plain on the Pacific coast of southwest Japan, was performed by a laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-ICPMS) system at Tono Geoscience Center, Japan Atomic Energy Agency. Twenty-five zircon grains were separated from the paleotsunami deposits by chemical abrasion and analyzed by the LA-ICPMS. U-Pb ages of the detrital zircons showed from ca. 14 Ma to 2405 Ma, and the age spectrum revealed high relative probability values around ca. 100 Ma and 2000 Ma. Detrital zircons with the age of ca. 100 Ma in the 1662 CE paleotsunami deposits could be partly originated from the Shimanto supergroup in southwest Japan. Moreover, the age spectrum of detrital zircons with Precambrian grains from the paleotsunami deposits was similar with those of fore-arc sandstones from central Kyushu Island.