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Reef growth and the Late Holocene climatic change recorded in the Raised Coral Reef in Kikai-jima Islands, Ryukyu, Japan.

日本琉球喜界岛凸起珊瑚礁记录的珊瑚礁生长和全新世晚期气候变化。

基本信息

批准号：
08304031
负责人：
NAKAMORI Toru
金额：
$ 3.2万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

Field surveys on the Holocene Raised Coral Reef and present coral reefs around Shido-oke in the northern coast of Kikai-jima Island, Ryukyus, southwest Japan were carried out in 1996 and 1997. Six core samples (T-1-T-6) ranging from 2.44 to 3.99 min length and 5 cm in diameter were obtained by using hand corer which was equipped by this Grant. on the Terraces II to IV.Tabular and encrusting Acropora, such as A.hyacinthus, A.digitifera, A.gemmifera, and A.monticulosa predominate in the hermatypic coral assemblages. Species combination indicates that the all cores were deposited in the shallow marine environments from 0 to 10 min depth. Skeletons of the living Porites spp., Tridacna spp. and sea water samples were collected from every 5 m from 0 to 30 min depth on the reef slope off Shido-oke.SoftX-ray photos of the living and Holocene coral slabs were taken in the laboratory and the annual growth bands were studied to date the samples. The living (KS01-09) sample was taken from 9 min depth. Useries age of the fossil sample (1805) is 9.2 ka after Ota et al.(1998). Carbon and oxygen stable isotope ratios of the coral skeleton were measured by the mass spectrometry. Present sea surface temperature (SST) and monthly mean salinity around Kikai-jima Island are reconstructed from IGOSS SST data and 1ﾟ mesh salinity data of JODC,respectively.Paleo- and present SSTs around Kikai-jima were estimated according to the oxygen isotope anomaly model including the vital effects and the ice sheet size. It predicts that-the present mean SST is 21.9ﾟC,2.6ﾟC lower than the actually measured data. Early Holocene mean SST was also estimated to be 22.0ﾟC,which is discordant with the results calculated on the transfer function..

1996年和1997年，对日本西南部琉球群岛菊海岛北方海岸的四户屋周围的全新世隆起珊瑚礁和现代珊瑚礁进行了实地调查。利用本项目配备的手动取芯器，采集了6个岩心样品（T-1-T-6），长度为2.44 ~ 3.99min，直径为5cm。珊瑚组合以板状和包壳状鹿角珊瑚（A.hyacinthus）、指状鹿角珊瑚（A.digitifera）、芽状鹿角珊瑚（A.gemmifera）和山状鹿角珊瑚（A.monticulosa）为主。物种组合表明，所有的核心沉积在浅海环境从0到10分钟的深度。活的滨珊瑚属的珊瑚，三趾草属在Shidooke附近礁坡0 ~ 30 min深度每隔5 m采集一次海水样品，在实验室拍摄活珊瑚和全新世珊瑚片的软X射线照片，研究年生长带，测定样品的年代。活体（KS 01 -09）样本从9分钟深度处采集。该化石样品的铀系年龄（1805年）为9.2ka。（1998年）。用质谱法测定了珊瑚骨骼的碳、氧稳定同位素比值。利用IGOSS海表温度（SST）数据和日本海洋数据中心（JODC）1 × 10目盐度数据，分别重建了纪海岛附近的现今SST和月平均盐度，并根据考虑生命效应和冰盖大小的氧同位素异常模型估算了纪海岛附近的古SST和现今SST。预报结果表明，目前平均海表温度为21.9 ° C，比实测值低2.6 ° C。全新世早期的平均SST也被估计为22.0 ° C，这与传递函数计算的结果不一致。