The Impact of the Latest Danian Event on Planktic Foraminiferal Faunas at ODP Site 1210 (Shatsky Rise, Pacific Ocean).
The Impact of the Latest Danian Event on Planktic Foraminiferal Faunas at ODP Site 1210 (Shatsky Rise, Pacific Ocean).
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DOI：
10.1371/journal.pone.0141644
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Speijer RP
中科院分区：
文献类型：
--
作者：
Jehle S;Bornemann A;Deprez A;Speijer RP
在古近纪早期，海洋生态系统受到了几次短暂的古环境事件(<；200Kyr)的严重干扰，其中以古新世-始新世最热事件(PETM，~56 Ma)最为突出。在过去的十年中，发现了许多类似的古新世和始新世时期的事件。然而，对PETM之前的事件，如“最新大年事件”(“LDE”，~62.18 Ma)，特别是从开阔大洋的角度来看，相对较少受到关注。在这里，我们提供了新的有孔虫同位素(δ13C，δ18O)和沙茨基隆起(太平洋)大洋钻探计划第1210站的动物群数据，以重建当时的古海洋学条件。所研究的层序厚度约5米，覆盖约900 KYR，其中包括持续200 KYR的LDE。所有的表层栖息、地下栖息和底栖有孔虫都表现出负的δ13C漂移>；0.6‰，其幅度与之前从邻近的1209点报道的底栖有孔虫相似。δ18O-推断整个水柱升温1.6oC至2.8oC(在底栖生物和浮游有孔虫测试中测得的0.40.7‰δ18O)伴随着负δ13C漂移。基于表层和次表层生物之间稳定的同位素梯度，提出了在LDE之前和期间分层良好的上层海洋。坡度不太发达，但在事件发生后仍有所增强。全面的浮游有孔虫动物群分析补充了同位素数据，揭示了莫洛氏菌和副肉芽孢子虫的优势种。在LDE追踪期间，地下栖息的副藻类在同位素梯度强度的变化中表现出很高的丰度，因此，可能表明该分类群在分层良好的表层海洋中的最佳生存条件。此外，还报告了明显的区系变化，例如在大冰盖底部的Praemurica物种消失，以及整个大冰盖地区不断地用斑纹盘藻取代早斑盘藻。
The marine ecosystem has been severely disturbed by several transient paleoenvironmental events (<200 kyr duration) during the early Paleogene, of which the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most prominent. Over the last decade a number of similar events of Paleocene and Eocene age have been discovered. However, relatively little attention has been paid to pre-PETM events, such as the “Latest Danian Event” ("LDE", ~62.18 Ma), specifically from an open ocean perspective. Here we present new foraminiferal isotope (δ13C, δ18O) and faunal data from Ocean Drilling Program (ODP) Site 1210 at Shatsky Rise (Pacific Ocean) in order to reconstruct the prevailing paleoceanographic conditions. The studied five-meter-thick succession covers ~900 kyr and includes the 200-kyr-lasting LDE. All groups surface dwelling, subsurface dwelling and benthic foraminifera show a negative δ13C excursion of >0.6‰, similar in magnitude to the one previously reported from neighboring Site 1209 for benthic foraminifera. δ18O-inferred warming by 1.6 to 2.8°C (0.4–0.7‰ δ18O measured on benthic and planktic foraminiferal tests) of the entire water column accompanies the negative δ13C excursion. A well stratified upper ocean directly before and during the LDE is proposed based on the stable isotope gradients between surface and subsurface dwellers. The gradient is less well developed, but still enhanced after the event. Isotope data are supplemented by comprehensive planktic foraminiferal faunal analyses revealing a dominance of Morozovella species together with Parasubbotina species. Subsurface-dwelling Parasubbotina shows high abundances during the LDE tracing changes in the strength of the isotope gradients and, thus, may indicate optimal living conditions within a well stratified surface ocean for this taxon. In addition, distinct faunal changes are reported like the disappearance of Praemurica species right at the base of the LDE and the continuous replacement of M. praeangulata with M. angulata across the LDE.