Extinction of larger benthic foraminifera at the Eocene/Oligocene boundary
Extinction of larger benthic foraminifera at the Eocene/Oligocene boundary
复制标题
DOI：
10.1016/j.palaeo.2011.09.008
复制
发表时间：
2011-11
期刊：
影响因子：
--
通讯作者：
L. Cotton;P. Pearson
中科院分区：
文献类型：
--
作者：
L. Cotton;P. Pearson
已知一些分布广泛的大型底栖有孔虫类群在始新世-渐新世过渡期灭绝。然而，通过过渡的详细记录是罕见的，很少有完整的部分是已知的。在这里，我们研究了一个明显完整的部分从坦桑尼亚从三个钻芯横跨始新世/渐新世边界的半远洋粘土继承。其中，较大的底栖有孔虫分散在粘土中，集中在石灰岩中，石灰岩作为次级泥石流沉积物出现。这些岩心使较大的底栖有孔虫地层与浮游有孔虫和超微化石生物地层以及稳定同位素（δ 18 O、δ 13 C）地层联系起来。这些记录表明，所有较大的底栖有孔虫灭绝事件都发生在始新世/渐新世边界附近，这是由南极有孔虫科Hantkeninidae的灭绝所确认的，而不是在渐新世下部显著的氧同位素漂移，这意味着最大的冰增长和全球海平面下降。这种相关性提出了有关机制的问题，负责预防和全球大型底栖有孔虫地层的影响。
A number of long-ranging and widespread larger benthic foraminiferal taxa are known to have become extinct during the Eocene–Oligocene transition. However, detailed records through the transition are rare, and few complete sections are known. Here we study an apparently complete section from Tanzania from three drill cores across the Eocene/Oligocene boundary in a hemipelagic clay succession. Within these, larger benthic foraminifera occur dispersed in the clays and concentrated in limestones which occur as secondary debris flow deposits. These cores allow the larger benthic foraminiferal stratigraphy to be tied to planktonic foraminifera and nannofossil biostratigraphy and stable isotope (δ18O, δ13C) stratigraphy. These records show that all of the larger benthic foraminifera extinction events occur close to the Eocene/Oligocene boundary as recognised by the extinction of the planktonic foraminiferal Family Hantkeninidae, rather than at the prominent oxygen isotope excursion in the lower Oligocene that signifies maximum ice growth and global sea-level fall. This correlation raises questions about the mechanism responsible for the extinctions and has implications for global larger benthic foraminiferal stratigraphy.