Benthic foraminiferal abundances at the Cretaceous/Paleogene boundary of ODP Hole 117-1049C at Blake Nose, Northwest Atlantic (Appendix A)

• Main Authors: Alegret, Laia, Thomas, Ellen
• Format: Dataset
• Language: English
• Published: PANGAEA 2004
• Subjects: 171-1049C; Alabamina midwayensis; Alabamina spp.; Alabamina wilcoxensis; Allomorphina sp.; Allomorphina velascoensis; Ammodiscus sp.; Anomalinoides acuta; Anomalinoides affinis; Anomalinoides ammonoides; Anomalinoides rubiginosus; Anomalinoides spp.; Aragonia velascoensis; Arenobulimina truncata; Astacolus spp.; Bifarina spp.; Blake Nose; North Atlantic Ocean; Bolivinoides delicatulus; Bolivinoides draco; Bulimina kugleri; Bulimina midwayensis; Bulimina paleocenica; Bulimina spp.; Bulimina thanetensis; Bulimina trinitatensis; Bulimina velascoensis; Buliminella beaumonti; Buliminella grata; Buliminella sp.; Cibicidoides dayi; Cibicidoides ekblomi; Cibicidoides hyphalus; Cibicidoides proprius; Cibicidoides spp.; Cibicidoides velascoensis; Cibicidoides welleri; Clavulinoides amorpha; Clavulinoides spp.; Clavulinoides trilatera; Coryphostoma decurrens; Coryphostoma incrassata; Coryphostoma spp.; Coryphostomella sp.; Counting >63 µm fraction; DEPTH; sediment/rock; Dorothia bulletta; Dorothia spp.; DRILL; North Atlantic; Northwest Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.695112; https://doi.org/10.1594/PANGAEA.695112

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 spherulebed 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 ~7% 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-µm 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.