Benthic Foraminifera and environmental turnover across the Cretaceous/Paleogene boundary at Blake Nose (ODP Hole 1049C, northwestern Atlantic)

Online Access: Get full text
doi: 10.1016/j.palaeo.2004.02.028
Author(s): Alegret, Laia; Thomas, Ellen
Author Affiliation(s): Primary:
University College London, Department of Earth Sciences, London, United Kingdom
Wesleyan University, United States
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, 208(1-2), p.59-83. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. Includes appendix. 95 refs.; illus., incl. sects., 1 table, sketch map
Summary: 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 ∼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. Abstract Copyright (2004) Elsevier, B.V.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Atlantic Ocean; Benthic taxa; Biostratigraphy; Biozones; Blake Nose; Blake Plateau; Cenozoic; Chicxulub Crater; Clastic sediments; Cretaceous; Depositional environment; Faunal list; Foraminifera; Impacts; Invertebrata; K-T boundary; Leg 171B; Lower Paleocene; Lower Paleogene; Marine environment; Marine sediments; Mesozoic; Microfossils; North Atlantic; Northwest Atlantic; ODP Site 1049; Ocean Drilling Program; Ooze; Paleobathymetry; Paleocene; Paleoecology; Paleogene; Productivity; Protista; Sediments; Spherules; Stratigraphic boundary; Tertiary; Trophic analysis; Upper Cretaceous
Coordinates: N300832 N300832 W0760644 W0760644
Record ID: 2004056661
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands