Benthic foraminiferal response to the emergence of the Isthmus of Panama and coincident paleoceanographic changes@en

Late Cenozoic benthic foraminiferal faunas from the Caribbean Deep Sea Drilling Project (DSDP) Site 502 (3052 m) and East Pacific DSDP Site 503 (3572 m) were analyzed to interpret bottom-water masses and paleoceanographic changes occurring as the Isthmus of Panama emerged. Major changes during the past 7 Myr occur at 6.7-6.2, 3.4, 2.0, and 1.1 Ma in the Caribbean and 6.7-6.4, 4.0-3.2, 2.1, 1.4, and 0.7 Ma in the Pacific. Prior to 6.7 Ma, benthic foraminiferal faunas at both sites indicate the presence of Antarctic Bottom Water (AABW). After 6.7 Ma benthic foraminiferal faunas indicate a shift to warmer water masses: North Atlantic Deep Water (NADW) in the Caribbean and Pacific Deep Water (PDW) in the Pacific. Flow of NADW may have continued across the rising sill between the Caribbean and Pacific until 5.6 Ma when the Pacific benthic foraminiferal faunas suggest a decrease in bottom-water temperatures. After 5.6 Ma deep-water to intermediate-water flow across the sill appears to have stopped as the bottom-water masses on either side of the sill diverge. […]本研究对加勒比海深海钻探计划（Deep Sea Drilling Project, DSDP）502站位（水深3052米）与东太平洋深海钻探计划503站位（水深3572米）的晚新生代底栖有孔虫动物群（benthic foraminiferal faunas）开展分析，以解读巴拿马地峡隆起过程中底层水团演化与古海洋学变化。过去7百万年间的重大环境转变节点分别为：加勒比海区在6.7~6.2 Ma、3.4 Ma、2.0 Ma及1.1 Ma处出现显著演化，太平洋海区则在6.7~6.4 Ma、4.0~3.2 Ma、2.1 Ma、1.4 Ma及0.7 Ma处发生转变。6.7 Ma之前，两处站位的底栖有孔虫动物群均显示南极底层水（Antarctic Bottom Water, AABW）的存在；6.7 Ma之后，动物群特征指示暖水团取代了先前的冷水团：加勒比海区转为北大西洋深层水（North Atlantic Deep Water, NADW），太平洋海区则转为太平洋深层水（Pacific Deep Water, PDW）。北大西洋深层水的跨洋流动可能持续存在于加勒比海与太平洋间渐次抬升的海槛之上，直至5.6 Ma——此时太平洋底栖有孔虫动物群的特征显示底层水体温度出现下降。5.6 Ma之后，跨该海槛的深层-中层水体流动似乎宣告终止，海槛两侧的底层水团自此出现显著分化。[…]