Cretaceous/Paleogene boundary bathyal paleo-environments in the central North Pacific (DSDP Site 465), the Northwestern Atlantic (ODP Site 1049), the Gulf of Mexico and the Tethys: The benthic foraminiferal record
Cretaceous/Paleogene boundary bathyal paleo-environments in the central North Pacific (DSDP Site 465), the Northwestern Atlantic (ODP Site 1049), the Gulf of Mexico and the Tethys: The benthic foraminiferal record
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DOI：
10.1016/j.palaeo.2005.03.031
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发表时间：
2005-08-15
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
上马strichtian底栖有孔虫组合（> - 63pm）多样化，表明下深海DSDP孔465A（北太平洋中部Hess Rise），墨西哥中东部和东北部的4个下深海陆地段，以及上至中深海Agost段（西班牙东南部Tethys地区）的中营养化条件。它们表明深海ODP孔1049C更富营养化（西北大西洋布莱克鼻）。底栖有孔虫在K/Pg分界处没有明显灭绝，但群落的多样性、异质性和非虫形类群比例均显著下降，除DSDP 465A孔虫形类群比例增加外。这些动物群的变化可能反映了由于K/Pg边界初级生产力的崩溃，海底食物供应的广泛减少对栖地动物群的影响。食物供应的减少对富营养化程度较高的西北大西洋ODP站点1049和太平洋DSDP站点465的底栖动物有明显影响，该站点距离尤卡坦半岛K/Pg撞击点较远。在这些地点，动物群在Parvulorugoglobigerina eugubina生物带（类似于100 ky）内恢复，尽管多样性和异质性在达曼早期仍然很低，可能表明环境压力。这种压力可能与初级生产者的大量或波动的食物供应有关，这些食物不容易被底栖动物利用，例如各种鞭毛藻的开花物种。底栖生物群落在墨西哥和西班牙的恢复速度较慢（类似于300公里）。K/Pg边界后的低氧条件只能从Agost（西班牙东南部）的底栖生物组合推断出来。然而，由于钻井扰动，太平洋DSDP 465A孔的短时间缺氧可能被掩盖，而墨西哥段和1049C孔则由于下坡运输而被不完全段掩盖。因此，底栖有孔虫组合似乎受到了崩溃的影响
Uppermost Maastrichtian benthic foraminiferal assemblages (> 63 pm) are diverse, indicating mesotrophic conditions in lower bathyal DSDP Hole 465A (Hess Rise, central North Pacific), in 4 lower bathyal land sections in central-East and Northeastern Mexico, and in the upper to middle bathyal Agost section (Tethys area, Southeastern Spain). They indicate more eutrophic conditions in lower bathyal ODP Hole 1049C (Blake Nose, Northwestern Atlantic). Benthic foraminifers did not suffer significant extinction at the K/Pg boundary, but diversity and heterogeneity of the assemblages and the percentage of infaimal morphogroups decreased drastically in all sections, with the exception of DSDP Hole 465A where the percentage of infaunal taxa increased. These faunal changes probably reflect the effect on the berithic faunas of a widespread decrease in the food supply to the sea floor, as a result of the collapse of primary productivity at the K/Pg boundary. The decrease in food supply apparently affected the benthic faunas least at more eutrophic NW Atlantic ODP Site 1049 and at Pacific DSDP Site 465, which is distal from the impact site of the K/Pg bolide on the Yucatan Peninsula. At these sites the faunas recovered within the Parvulorugoglobigerina eugubina Biozone (similar to 100 ky), although diversity and heterogeneity remained low through the early Daman, possibly indicating environmental stress. This stress might be related to a high or fluctuating food supply by primary producers that could not easily be used by the benthos, such as various bloom species of dinoflagellates. Benthic assemblages recovered more slowly (similar to 300 ky) in the Mexican and Spanish sections. Low oxygen conditions after the K/Pg boundary could be inferred from the benthic assemblages at Agost (Southeastern Spain) only. A short episode of hypoxia, however, may be obscured at Pacific DSDP Hole 465A by drilling disturbance, and in the Mexican sections and Hole 1049C by incomplete sections due to downslope transport. Benthic foraminiferal assemblages thus appear to have been affected by the collapse of