南沙群岛永暑礁环礁潟湖的沉积速率与气候变化

永暑礁南永 3井岩心是我国首次完整地获得的环礁湖沉积高分辨率柱样 ,井深 5 90m ,全为松散的生物骨壳碎屑。通过高精度TIMS铀系测年计算了沉积速率。全井柱样全新世晚期 16 82aBP以来的平均沉积速率为 3 5mm/a,比同礁同期的礁坪沉积速率 1 2 1mm/a高 ,是高分辨率古环境研究的理想材料。以全湖沉积柱平均沉积速率为准 ,将全柱划分为 4个沉积速率高低交替阶段。这同祖国大陆近 170 0年来的气温波动、冷热分期的变化大体上一致 ,反映了南沙群岛地区对中国大陆乃至全球的气候变化的响应。

CLIMATE CHANGE AND THE DEPOSITIONAL VELOCITY IN THE LAGOON OF YONGSHU ATOLL, NANSHA ISLANDS

The core of Nanyong-3 well in the Yongshu Atoll is the highly distinguishable sediment pillar of atoll lagoon available undamagedly first time in China.The well is 5 90 m deep,in which there are all loose organic detritus. Depositional velocity is calculated according to the ages dated by the highly precise TIMS U system. The mean depositional velocity of the pillar in the last 1682 years of late Holocene was 3 5 mm/a, higher than that(1 21mm/a) of reef flat of Yongshu Atoll at the same time.These are good materials for highly distinguishable research of palaeo-environment. The whole pillar is divided into 4 alternative parts. The division is generally in accordance with the fluctuation of the air temperature and the change of the cold and warm period in the last 1700 years in mainland China, showing the responds of the Nansha Islands region to the historic climate change of China, even the world.