Benthic foraminifera and environmental turnover across the Cretaceous/Paleogene boundary at Blake Nose (ODP Hole 1049C, Northwestern Atlantic)
Benthic foraminifera and environmental turnover across the Cretaceous/Paleogene boundary at Blake Nose (ODP Hole 1049C, Northwestern Atlantic)
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DOI：
10.1016/j.palaeo.2004.02.028
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发表时间：
2004-05-31
影响因子：
3
通讯作者：
Thomas, E
中科院分区：
文献类型：
--
作者：
Alegret, L;Thomas, E
在布莱克鼻（西北大西洋）的下半深海ODP站点1049处发现的沉积物为研究白垩纪/古近纪（K/P）边界相对靠近墨西哥尤卡坦半岛的希克苏鲁布撞击构造的环境变化提供了机会。在1049 C孔中，边界位于一个9厘米厚的层的底部，有大量的小球，被认为是撞击喷出物。最高的马斯特里赫特软泥下面，最低的丹尼中上层软泥上面的球床含有保存完好的半深海底栖有孔虫。相比之下，球床本身包含浅（浅海）和深（半深海）物种的混合物，标本在保存方面差异很大。该组合可能是由K/P冲击触发的改造和下坡搬运形成的。穿过球床（即，K/P界线），只有约7%的底栖有孔虫物种灭绝，与全球底栖有孔虫的低灭绝率相似。底栖有孔虫组合和形态组的定量分析表明，在最后的马斯特里赫特相对富营养化，稳定的环境，中断的食物供应突然减少底栖生物在K/P边界和动物群的多样性减少，其次是在最早的丹尼阶逐步恢复。这种复苏可能与地表初级生产者的逐步复苏有关，（C）2004年爱思唯尔公司版权所有。
Sediments recovered at lower bathyal ODP Site 1049 on Blake Nose (Northwestern Atlantic) offer an opportunity to study environmental changes at the Cretaceous/Paleogene (K/P) boundary relatively close to the Chicxulub impact structure on the Yucatan peninsula, Mexico. In Hole 1049C, the boundary is located at the base of a 9-cm-thick layer with abundant spherules, considered to be impact ejecta. Uppermost Maastrichtian oozes below, and lowermost Danian pelagic oozes above the spherule-bed contain well-preserved bathyal benthic foraminifera. The spherule-bed itself, in contrast, contains a mixture of shallow (neritic) and deeper (bathyal) species, and specimens vary strongly in preservation. This assemblage was probably formed by reworking and down-slope transport triggered by the K/P impact. Across the spherule-bed (i.e., the K/P boundary) only similar to7% of benthic foraminiferal species became extinct, similar to the low extinction rates of benthic foraminifera worldwide. Quantitative analysis of benthic foraminiferal assemblages and morphogroups in the >63-mum size fraction indicates a relatively eutrophic, stable environment during the latest Maastrichtian, interrupted by a sudden decrease in the food supply to the benthos at the K/P boundary and a decrease in diversity of the faunas, followed by a stepped recovery during the earliest Danian. The recovery was probably linked to the gradual recovery of surface-dwelling primary producers, (C) 2004 Elsevier B.V. All rights reserved.