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.
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