Deep-sea environments across the Cretaceous/Paleogene boundary in the eastern South Atlantic Ocean (ODP Leg 208, Walvis Ridge)

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doi: 10.1016/j.marmicro.2006.12.003
Author(s): Alegret, Laia; Thomas, Ellen
Author Affiliation(s): Primary:
Universidad de Zaragoza, Departamento de Ciencias de la Tierra, Saragossa, Spain
Yale University, United States
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, 64(1-2), p.1-17. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. Supplemental information/data is available in the online version of this article. 71 refs.; illus., incl. 2 plates, charts
Summary: Sediments recovered at ODP Site 1262 on Walvis Ridge (eastern South Atlantic Ocean, paleodepth ∼2500-3000 m) offer an opportunity to look into the nature and cause(s) of the benthic foraminiferal turnover across the Cretaceous/Paleogene (K/Pg) boundary at abyssal depths at a location relatively remote from the location of the asteroid impact on the Yucatan peninsula. Late Maastrichtian assemblages were diverse and heterogeneous, reflecting oligo- to mesotrophic conditions at the sea floor. As at other locations, there was no significant extinction of benthic foraminiferal species at the K/Pg boundary, but the diversity and heterogeneity of the assemblages decreased precipitously. The percentage of infaunal buliminid taxa decreased rapidly, but the total percentage of infaunal taxa remained essentially unchanged. Benthic foraminiferal accumulation rates (BFAR) dropped at the boundary itself, and fluctuated strongly later in the Danian. After the K/Pg boundary, opportunistic taxa increased in relative abundance, and diversity and heterogeneity strongly fluctuated. There thus is no clear agreement between three proxies which have been used to indicate a high food supply to the sea floor: percentage buliminids, percentage infaunal taxa, and BFAR. This discrepancy might indicate that the food supply changed in character (e.g., type of food, temporal variability in flux), but did not show a long-term, large net change in total amount. The strong fluctuations in BFAR, heterogeneity and diversity indicate that environmental instability started at the K/Pg boundary, and persisted through planktic foraminiferal zones Pα and P1a. In lower planktic foraminiferal zone P1b, agglutinated species of the genera Spiroplectammina and Clavulinoides, thought to be infaunal and indicative of increasing levels of food supply, increased in relative abundance while the relative abundance of buliminids remained low. Possibly, agglutinated taxa took over at least part of the infaunal niche in the Paleocene, as a result of the rise in the calcium carbonate compensation depth. Towards the upper part of the studied interval (lower planktic foraminiferal Subzone 1c), benthic foraminiferal assemblages stabilized, with heterogeneity almost back to Maastrichtian values, although diversity and BFAR did not fully recover. Abstract Copyright (2007) Elsevier, B.V.
Year of Publication: 2007
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Angola Basin; Assemblages; Atlantic Ocean; Benthic taxa; Biostratigraphy; Buliminacea; Cenozoic; Cretaceous; Cretaceous-Paleogene boundary; Deep-sea environment; Foraminifera; Invertebrata; K-T boundary; Leg 208; Lower Paleocene; Marine environment; Mesozoic; Microfossils; ODP Site 1262; Ocean Drilling Program; Paleocene; Paleoenvironment; Paleogene; Productivity; Protista; Rotaliina; South Atlantic; Southeast Atlantic; Stratigraphic boundary; Tertiary; Upper Cretaceous; Walvis Ridge
Coordinates: S271100 S271100 E0013500 E0013400
Record ID: 2007116779
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands