摘要
对南海北部 ODP 114 8站采自孔深 4 6 5 m以上的 170 0个沉积物样品 ,测定了 Ca CO3含量、Ca CO3堆积速率、非钙质堆积速率、浮游有孔虫丰度、粗组分百分含量 (>6 3μm)、浮游有孔虫破壳率和底栖有孔虫在有孔虫全群中的百分含量。碳酸盐百分含量和碳酸盐堆积速率自 2 4 Ma以来的变化呈现逐步下降的趋势 ,但在 2 4 .0～ 15 .8、14 .2～ 11.6、10 .6～ 4 .8和 3.4～ 0 Ma四个时期具有高碳酸盐生产力 ,其中 10 .6～ 4 .8Ma的高生产力与印度洋和太平洋中新世晚期和上新世早期的“生物勃发”相对应。非钙质和碳酸盐两者堆积速率变化趋势在总体上相似 ,反映了陆源物质输入对碳酸盐生产力的影响。 3.4 Ma后非钙质堆积速率的大幅度增长主要与青藏高原和台湾岛的隆起有关 ,它们也是上新世晚期和第四纪 Ca CO3百分含量显著下降的主要原因。 2 4 Ma以来南海北部碳酸盐的保存逐渐变弱 ,而碳酸盐溶解作用逐渐增强 ,在 15 .8～ 14 .2、11.6～ 10 .6和 4 .8～ 3.4 Ma存在 3个显著的碳酸盐溶解事件 ,其中 11.6～ 10 .6 Ma的溶解事件与赤道太平洋和加勒比海的中—晚中新世“碳酸盐崩溃”事件相当 。
The carbonate content (weight percentage), carbonate mass accumulation rate (MAR), non carbonate MAR, planktonic foraminiferal relative abundance, coarse fraction (>63 μm), planktonic foraminiferal fragmentation and benthic foraminiferal relative abundance have been determined from 1 702 samples in the upper 465 m Neogene sediments at ODP Site 1148 in the northern South China Sea. The carbonate content and carbonate MAR display a long term decreasing trend since 24 Ma, with 4 high peaks at 24.0~15.8, 14.2~11.6, 10.6~4.8 and 4~0 Ma, respectively. The high carbonate content and carbonate MAR at 10.6~4.8 Ma is thought to be an evidence for the occurrence of the late Miocene to early Pliocene biogenic bloom in the South China Sea. The general covariation between non carbonate and carbonate MARs probably indicates a significant impact of the terrestrial influx on the carbonate productivity. The rapid increase in non carbonate MAR after 3.4 Ma is associated with the coeval rapid lift of the Tibet Plateau and Taiwan Island, resulting in the marked decrease in carbonate content. The carbonate dissolution shows an increasing trend since 24 Ma in the South China Sea with 3 major carbonate dissolution events at 15.8~14.2, 11.6~10.6 and 4.8~3.4 Ma respectively. The dissolution event at 11.6～10.6 Ma appears to correspond to the middle to late Miocene carbonate crash in the eastern Equatorial Pacific and the Caribbean.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2002年第2期69-74,共6页
Marine Geology & Quaternary Geology
基金
国家自然科学基金资助项目 (4 99995 60 )
国家重点基础研究专项经费资助项目 (G2 0 0 0 0 785 0 2 )
关键词
古环境
碳酸盐含量
堆积速率
溶解作用
晚新生代
南海
古环境
carbonate content
mass accumulation rate
carbonate dissolution
Neogene
the South China Sea
