NOAA/WDS Paleoclimatology - DSDP Site 219 Miocene -Recent Foraminifera Data

Knowledge of the biology of deep-sea benthic foraminifera was used to interpret the results of multivariate analyses (factor and cluster) on relative abundance data of benthic foraminifera at Deep Sea Drilling Project Site 219 (southeastern Arabian Sea; 1764 m depth) in combination with carbon and oxygen isotope data. Faunal data document major changes in deep-sea ventilation and productivity over the past 5.5 Ma, including the end of the Miocene-Pliocene Indo-Pacific "biogenic bloom" period at ~4.0 Ma. Interestingly, there is no simple correlation between high productivity and low oxygenation. Productivity fluctuated but became overall more pulsed, whereas overall oxygenation increased. We interpret the records as a combination of local to regional fluctuations in productivity probably caused by changes in monsoonal development, particularly its seasonality, and changes in oxygenation of intermediate depth waters in the Indian Ocean caused by global changes in climate and ocean circulation.

本研究借助深海底栖有孔虫（deep-sea benthic foraminifera）的生物学知识，结合碳氧同位素数据，对阿拉伯海东南部深海钻探计划（Deep Sea Drilling Project, DSDP）219站位（水深1764 m）的底栖有孔虫相对丰度数据开展多元统计分析（因子分析与聚类分析），并对分析结果进行解译。底栖有孔虫群落数据记录了过去5.5 Ma间深海通风与海洋生产力的重大变化，其中包括中新世-上新世印太"生物勃发期"（Indo-Pacific "biogenic bloom"）于距今约4.0 Ma的终结。值得注意的是，高生产力与低氧环境之间并未呈现简单的相关关系。生产力虽存在波动，但整体上愈发呈现脉冲式变化特征，而整体水体的含氧水平却有所提升。我们将上述记录解读为两类变化的共同作用：一是局地至区域尺度的生产力波动，其成因大概率与季风演化（尤其是其季节节律）的改变有关；二是印度洋中层水体含氧状况的变化，该变化由全球气候与海洋环流的改变所驱动。