Partial collapse of the marine carbon pump after the Cretaceous-Paleogene boundary
Partial collapse of the marine carbon pump after the Cretaceous-Paleogene boundary
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DOI：
10.1130/g37581.1
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发表时间：
2016-04-01
期刊：
影响因子：
5.8
通讯作者：
Schmidt, Daniela N.
中科院分区：
文献类型：
--
作者：
Birch, Heather S.;Coxall, Helen K.;Schmidt, Daniela N.
白垩纪末期一颗小行星的撞击导致了海洋生物的大规模灭绝。表层到深海碳同位素梯度的迅速下降表明有机物通过生物泵向深海的转移受到了严重干扰。然而，这一观点受到了深海底栖生物依赖地表食物的生存以及用作示踪剂的浮游有孔虫中同位素分异的不确定性的挑战。在这里，我们提供了新的稳定碳（δ C-13）和氧（δ O-18）同位素数据，这些数据是在大西洋东南部一个轨道定年的深海序列中精心选择的浮游生物和底栖有孔虫中测量的。我们的方法独特地将三角洲O-18有孔虫示踪物种栖息地深度的证据与物种特异性三角洲C-13生态调整相结合，并将同位素模式与相应的底栖生物组合数据进行比较。我们的研究结果表明，海洋环流和有孔虫生命效应的变化有助于但不能解释所有观测到的表层到深海有孔虫三角洲C-13梯度的崩塌。我们得出的结论是，由于海洋物种的灭绝，生物泵被削弱了，但没有以前认为的那么严重，持续时间也较短（最大1.77毫秒）。
The impact of an asteroid at the end of the Cretaceous caused mass extinctions in the oceans. A rapid collapse in surface to deep-ocean carbon isotope gradients suggests that transfer of organic matter to the deep sea via the biological pump was severely perturbed. However, this view has been challenged by the survival of deep-sea benthic organisms dependent on surface-derived food and uncertainties regarding isotopic fractionation in planktic foraminifera used as tracers. Here we present new stable carbon (delta C-13) and oxygen (delta O-18) isotope data measured on carefully selected planktic and benthic foraminifera from an orbitally dated deep-sea sequence in the southeast Atlantic. Our approach uniquely combines delta O-18 evidence for habitat depth of foraminiferal tracer species with species-specific delta C-13 eco-adjustments, and compares isotopic patterns with corresponding benthic assemblage data. Our results show that changes in ocean circulation and foraminiferal vital effects contribute to but cannot explain all of the observed collapse in surface to deep-ocean foraminiferal delta C-13 gradient. We conclude that the biological pump was weakened as a consequence of marine extinctions, but less severely and for a shorter duration (maximum of 1.77 m.y.) than has previously been suggested.