太平洋域周縁相礁性石灰岩の年代測定と地殻変動率生物源炭酸塩中の天然α放射性核種による過去15万年までの適用 (年代測定特集号)

概要

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Current works of the dating of shallow-water biogenic calcium carbonates and öolites by means of natural alpha-radioactive nuclides are reviewed in terms of Late Quaternary eustatic change of sea level and local tectonism. It is compared with the results of 230Th and 231Pa dates of the corals and Tridacna shells from the Ryukyu Islands. Based on the ecological evaluation of the fossils dated, altitude of the locality, and the radioactive age geochemically checked and, if necessary, corrected, the range of sea level change in a given time can be limited (Text-figure 1). Thus the rate of vertical displacement can be calculated as shown in Table 6. The conclusion is drawn that Kikai-jima of the Ryukyu Islands has been rather uniformly upheaved tectonically with the rate of 1.5-2.0mm·y-1 during the last 70, 000 years.
日本第四紀学会の論文