Evidence of an abrupt environmental disruption during the mid-Paleocene biotic event (Zumaia section, western Pyrenees)
Evidence of an abrupt environmental disruption during the mid-Paleocene biotic event (Zumaia section, western Pyrenees)
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DOI：
10.1130/b26132.1
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发表时间：
2007-07-01
影响因子：
4.9
通讯作者：
Dinares-Turell, Jaume
中科院分区：
文献类型：
--
作者：
Bernaola, Gilen;Baceta, Juan Ignacio;Dinares-Turell, Jaume
在古新世中期生物事件（MPBE）期间，透光带和海底发生了突然的环境破坏。祖马亚剖面（西比利牛斯山脉）的钙质微浮游生物、浮游有孔虫和底栖有孔虫组合经历了快速而显着的转变。主要的钙质浮游生物组合变化表明从相对较冷的中营养条件转向更温暖、更贫营养的条件，表明海洋变暖导致环境受到干扰。底栖有孔虫组合也受到 MPBE 的显着影响；组合和bulliminids的多样性显示出净下降，而低食物和机会性类群的丰度则有所增加。浮游生态系统的重组可能涉及海底食物通量（类型和数量）的变化，从而引发底栖群落的变化。记录到与生物事件相关的 1%o 负 Delta C-13 偏移和 30% 碳酸盐含量下降。这表明，在MPBE期间，就像在古新世-始新世最热期（PETM）一样，大量同位素贫化碳输入海洋和大气可能会降低深海pH值，引发溶斜层快速浅滩并导致温室变暖。 MPBE 持续时间很短：根据石灰岩-泥灰岩对联的计数，整个 Zumaia 剖面岁差周期的地层表达，MPBE 持续时间与 52-53 key 类似，事件的核心代表与 10-11 key 类似。 Zumaia 路段是第一个承认并详细描述 MPBE 的陆上地区。由于其扩展的特征和出色的古生物学记录，该部分可能被证明是研究这一短暂事件的全球参考部分。
An abrupt environmental disruption occurred in the photic zone and at the seafloor during the mid-Paleocene biotic event (MPBE). Calcareous nannoplankton, planktic foraminifer, and benthic foraminifer assemblages at Zumaia section (western Pyrenees) underwent a rapid and remarkable transformation. The major calcareous plankton assemblage changes suggest a shift from relatively cooler mesotrophic to warmer, more oligotrophic conditions, indicating a disturbed environment due to the warming of the ocean. Benthic foraminifer assemblages were also significantly affected by the MPBE; diversity of the assemblages and buliminids show net decline and the low food and opportunistic taxa increase in abundance. The reorganization of the planktic ecosystem possibly involved changes in the food flux (type and quantity) to the seafloor, thus triggering changes in the benthic communities. A 1%o negative delta C-13 shift and a 30% carbonate content decrease are recorded in connection with the biotic event. This suggests that during the MPBE, as in the Paleocene-Eocene Thermal Maximum (PETM), an input of a large mass of isotopically depleted carbon into the ocean and atmosphere could have lowered the deep-sea pH, triggering a rapid shoaling of the lysocline and contributing to greenhouse warming. The MPBE was short lived: according to the counting of limestone-marl couplets, the stratigraphic expression of precession cycles throughout the Zumaia section, the MPBE lasted for similar to 52-53 key., with the core of the event representing similar to 10-11 key. The Zumaia section is the first land-based locality in which the MPBE is recognized and described in detail. Due to its expanded character and excellent paleontological record, this section may prove to be a global reference section for the study of this shortlived event.