Causation of barrier reefs of the Sekisei Lagoon and fringing reefs of the southern Okinawa Island in the southern Ryukyu Islands on island shelf on the basis of drilling and shallow reflection investigation

冲绳南部古石厂海岸全新世珊瑚礁在约15 ~ 20 m的平面上开始向上生长，约距今7600年。古石厂第一期珊瑚礁形成于距今6000年左右，是由于该区的隆起作用。第二个在距今4000年左右的近海形成，第三个在距今2500年左右的近海形成。在20 ~ 25 m深的平坦表面上，Sekisei泻湖的全新世珊瑚礁开始向上生长。在石垣岛南部，第一期珊瑚礁形成于距今约7000 ~ 6000年的隆升运动。距今5500 ~ 5000年，竹富岛发育边缘礁，石成泻湖内部形成斑礁。大约在距今3600年前，在关成泻湖的外部形成了堡礁。由于隆升运动和海平面的变化，在这些地区形成了三期全新世珊瑚礁。

Holocene coral reef in Gushichan coast in the southern Okinawa Island commenced to grow upward on the flat surface about 15〜20 m deep about 7600 yrs BP. The first phase of coral reef in Gushichan formed about 6000 yrs BP due to uplifted area. The second one was developed offshore about 4000 yrs BP, then after about 2500 yrs BP the third one was formed offshore. Holocene coral reef in the Sekisei Lagoon started to grow upward on the flat surface about 20〜25 m deep. In the southern Ishigaki Island, the first phase of coral reef was formed about 7000〜6000 yrs BP due to uplift movement. About 5500〜5000 yrs BP, a fringing reef developed in Taketomi Island and patch reef was formed in the inner part of the Sekisei Lagoon. Then about 3600 yrs BP, barrier reef was formed in the outer part of the Sekisei Lagoon. Three phases of Holocene coral reef have been formed in these areas due to uplift movement and sea-level change.