Early Eocene Thermal Maximum 3: Biotic Response at Walvis Ridge (SE Atlantic Ocean)
Early Eocene Thermal Maximum 3: Biotic Response at Walvis Ridge (SE Atlantic Ocean)
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DOI：
10.1029/2018pa003375
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发表时间：
2018-08
影响因子：
3.5
通讯作者：
E. Thomas;F. Boscolo-Galazzo;B. Balestra;S. Monechi;B. Donner;U. Röhl
中科院分区：
文献类型：
--
作者：
E. Thomas;F. Boscolo-Galazzo;B. Balestra;S. Monechi;B. Donner;U. Röhl
我们结合海洋钻探计划地点1262（古深度~ 3500 m）和1263（古深度~ 1500 m）的稳定同位素、钙质纳米浮游生物和底栖有孔虫记录，记录了早始新世气候最适期早期、古新世/始新世热极大期后~3.1 Myr的始新世第3热极大期的海洋生物响应。底水变暖可能降低了两个站点的垂直温度梯度，但1263站点的下降幅度大于1262站点。1262样地的植物和动物变化比1263样地更弱，表明碳酸盐溶解不是生物效应的最重要原因。底栖生物的组合变化比浮游生物更明显。钙质纳米化石经历了轻微的生态变化，这可能与温暖水域的存在有关，特别是在1263遗址，耐溶解分类群的数量增加。两个样地底栖有孔虫多样性均有所下降，但1263样地底栖有孔虫积累速率显著下降，1262样地底栖有孔虫积累速率保持稳定。在ETM3期间，海洋环流可能发生了变化，导致1263站点出现了较暖的（中间）水团。更明显的变暖可能导致有机物质的再矿化增强，因此到达底栖动物的食物减少。生物对X‐事件的响应不如对更早和更严重的高温事件，古新世/始新世热极大值和始新世热极大值2的响应明显。生物反应的程度反映了环境扰动的严重程度，但因地点（如沃尔维斯岭的古深度）而异。
We combine stable isotope, calcareous nannoplankton, and benthic foraminiferal records for Ocean Drilling Program Sites 1262 (paleodepth ~3,500 m) and 1263 (paleodepth ~1,500 m) on Walvis Ridge (SE Atlantic), to document the marine biotic response to Eocene Thermal Maximum 3, in the early part of the Early Eocene Climate Optimum, ~3.1 Myr after the Paleocene/Eocene Thermal Maximum. Bottom water warming may have decreased the vertical thermal gradient at both sites, but more at Site 1263 than at Site 1262. Floral and faunal changes were more muted at Site 1262 than at shallower Site 1263, indicating that carbonate dissolution was not the most important cause of biotic effects. Assemblage changes were more pronounced in benthos than in plankton. Calcareous nannofossils underwent minor ecological changes, possibly related to the presence of warmer waters, especially at Site 1263, and dissolution‐resistant taxa increased in abundance. Benthic foraminiferal diversity decreased at both sites, but benthic foraminiferal accumulation rates declined dramatically at Site 1263, remaining stable at Site 1262. Ocean circulation may have changed during ETM3, resulting in the presence of a warmer (intermediate) water mass at Site 1263. More pronounced warming may have caused enhanced remineralization of organic matter, so less food reached the benthos. The biotic response to the X‐event was less pronounced than that to earlier and more severe hyperthermal events, the Paleocene/Eocene Thermal Maximum and Eocene Thermal Maximum 2. The extent of the biotic response reflects the severity of the environmental disturbance but varies by location (e.g., paleodepth on Walvis Ridge).