| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
A cross-section of topography was drawn on the Holocene terraces along the coast of Shito-oke at the northeastern part of Kikai-jima, southwest Japan. Terraces I-IV were recognized on the basis of the section, as is the same case of the other part of the island. Fossil and living hermatypic coral communities were described along the section by a 1x1 m quadrat method. The fossil ones were found to be able to correlate to those inhabited on the shallowest reef slope and grooves. Well-preserved fossil corals were collected to measure AMS ^<14>C ages at the Institute of Geological and Nuclear Sciences, New Zealand. The results are suggested that ages of the Terraces II-IV are 5593-3859,2868-2633,2143-1212 yrs B.P,respectively.
Living hermatypic coral, Porites sp., and giant clam, Hippopus hippopus, were collected at the northern coast of Ishigaki-jima. Their growth lines and oxygen and carbon isotope ratios on the shell are closely related to climatic parameters, such as sea temperature, insolation and salinity, and are considered to be useful for reconstruction of the Holocene climate. Temperature and insolation were reorganized from the data published by the Japan Meteorological Agency. Sensors for sea water temperature and salinity were set on the reef flat on whick the samples were collected. It was concluded that the growth lines contain annual and daily bands and that width of the daily band is highly correlated to the insolation and sea temperature. The oxygen isotope ratio of the giant clam shell is in equilibrium with the sea water oxygen and is good indicator for seawater temperature.
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