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研究了南海南部ODP184航次1143站约1.2MaBP以来岩芯中的放射虫化石.通过分析其变化趋势得出以下沉积分布特征:1.2MaBP以来该海区放射虫动物群的丰度水平经历了由0.9MaBP以前的极低水平,到0.9～0.65MaBP的小幅度升高,以及0.65MaBP之后大幅显著回升的变化过程,丰度值在整个过程中呈阶段性逐步上升趋势,并存在规律性周期波动.分析认为,0.65 MaBP以后放射虫丰度的显著升高指示0.65 MaBP以后该海区属典型的上升流区,推测其原因为东亚季风的逐步强化.频谱分析发现,放射虫指标的变化在0.9MaBP之后存在约0.20 Ma的旋回周期,同本海区其他古海洋学指标的周期分析结果有良好对应,这一结果可能指示本海区特殊的古生态环境周期演变特征,同时,对0.1Ma和23 ka的轨道周期也有所响应.此外,放射虫的多项指标综合显示了大约0.47 MaBP存在的明显变化界线,在此年代之后放射虫动物群开始呈现显著的群落结构稳定,丰度值保持较高水平波动的状况,指示了0.47MaBP前后一次海洋生态环境突变事件.
We studied the radiolaria fossils in the core about 114 Ma of ODP 184 at the southern South China Sea for about 1.2MaBP.The following sedimentary distributions were obtained by analyzing the variation trend: The abundance level of the radiolarian fauna in the sea from 1.2MaBP experienced an increase from 0.9MaBP Previously, the level of abundance increased slightly from 0.9 to 0.65MaBP and significantly increased after 0.65MaBP. The abundance value gradually increased in a phased manner with periodic fluctuations. It is believed that the significant rise of radiolarian abundance after 0.65 MaBP indicates that the sea area is a typical upwelling area after 0.65 Ma BP, which is presumed to be due to the gradual strengthening of the East Asian monsoon.Foundation analysis showed that the change of radiolarian index existed after 0.9MaBP The cycle of about 0.20 Ma has a good correspondence with the periodic analysis results of other paleoceanographic indicators in the sea area. This result may indicate the peculiar characteristics of paleoclimate evolution in this area. Meanwhile, the orbital period of 0.1 Ma and 23 ka Also responded.In addition, a number of indicators of radioactive insects combined showed a clear change of about 0.47 MaBP boundaries, after which the era of radiolarian fauna open Showed a significant community structure and stability, abundance maintain a high level of volatility conditions, indicating a mutation in the marine environment around 0.47MaBP event.