【摘要】 浮游有孔虫深水种Globoquadrinadehiscens于10Ma左右从西太平洋和南海绝灭,要比其他地区早大约3Ma.伴随这一事件还见以表层暖水种增多而深水种大幅度减少为主要特征的生物群变化.古生物和氧同位素结果指示当时表层水变暖和温跃层变深,我们认为是与早期西太平洋暖池的发育有关.该种在西北和西南太平洋呈阶段性消失也说明暖水堆集比赤道区更强,尽管印尼海道在晚中新世已大为变窄,穿越印尼海道的径流可能尚保持较高的通量水平而使赤道区暖水堆集不特别明显.南海的浮游氧同位素值通常比开放西太平洋的低,也说明中新世时期的上层海水环境与现代相似,都是暖池边缘区比中心区变化大.暖池边缘区水体环境多变和温度梯度较高可能是受季风的影响,结果造成深水种的降低和G.dehiscens提早从南海地区绝灭.更多还原

【Abstract】 The disappearance at ~10Ma of the deep dwelling planktonic foraminifer Globoquadrina dehiscens from the western Pacific including the South China Sea was about 3Ma earlier than its final extinction elsewhere. Accompanying this event at ~10Ma was a series of faunal turnover characterized by increase in mixed layer, warm-water species and decrease to a minimum in deepwater species. Paleobiological and isotopic evidences indicate sea surface warming and a deepened local thermocline that we interpret as related to the development of an early western Pacific warm pool. The stepwise decline of G. dehiscens and other deep dwelling species from the NW and SW Pacific suggests more intensive warm water pileup than equatorial localities where surface bypass flow through the narrowing Indonesia seaway appears to remain efficient during the Late Miocene. Planktonic ~ 18 O values from the South China Sea consistently lighter than the tropical western Pacific during the Miocene also suggest, similar to today, more variable hydrologic conditions along the periphery than in the core of the warm pool. Stronger hydrologic variability affected mainly by monsoons and increased thermal gradient along the western margin of the Late Miocene warm pool may have contributed to the decline of deep dwelling planktonic species including the early extinction of G. dehiscens from the South China Sea region.更多还原