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Distribution of deep-sea benthic Foraminifera in the Neogene of Blake Ridge, NW Atlantic Ocean

Kuppusamy Mohan, Anil K. Gupta and Ajoy K. Bhaumik
Distribution of deep-sea benthic Foraminifera in the Neogene of Blake Ridge, NW Atlantic Ocean
Journal of Micropalaeontology (May 2011) 30 (1): 33-74


This study describes and illustrates the evolution of deep-sea benthic foraminifera from the Blake Ridge during the late Neogene. In total, 305 species of benthic foraminifera belonging to 107 genera were identified. The Blake Ridge receives fine-grained nannofossil-bearing hemipelagic sediments, transported from the Canadian continental margin by the Deep Western Boundary Undercurrent (DWBUC). We thus presume that changes in benthic foraminifera at Ocean Drilling Program (ODP) sites 991A, 994C, 995A and B and 997A reflect mainly changes in the intensity of the DWBUC, which is closely related to North Atlantic Deep Water (NADW) production. However, the dominance of Uvigerina peregrina, U. proboscidea and Cassidulina carinata during the late Miocene in all the holes suggests an increased influence of Southern Component Waters in the Blake Ridge region. During the early Pliocene (4.8-2.8 Ma) in all the sites benthic faunal assemblages suggest that there was an increased transport of organic-rich sediments by the DWBUC from the Canadian margin to the Blake Ridge, driven by increased production of NADW. During this time the species diversity (Sanders' rarefied values) was low. In the younger interval (since 2.8 Ma), the faunal data suggest less transport of organic-rich sediments to the Blake Ridge, which appears to be related to weakening of the DWBUC during cold intervals. An increase in species diversity at 3 Ma probably resulted from decreased population of bacteria due to low organic matter and/or less competition. In the late Pleistocene (c. 0.6 Ma), Stilostomella lepidula became extinct in all the studied holes, suggesting that this species may have possessed a mode of feeding which no longer existed in the cold, well-oxygenated oceans of the present.

ISSN: 0262-821X
EISSN: 2041-4978
Serial Title: Journal of Micropalaeontology
Serial Volume: 30
Serial Issue: 1
Title: Distribution of deep-sea benthic Foraminifera in the Neogene of Blake Ridge, NW Atlantic Ocean
Affiliation: Indian Institute of Technology, Department of Geology and Geophysics, Kharagpur, India
Pages: 33-74
Published: 201105
Text Language: English
Publisher: British Micropalaeontological Society, London, United Kingdom
References: 190
Accession Number: 2011-053969
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. 13 plates, 1 table, sketch map
N31°47'08" - N32°59'01", W75°55'48" - W75°28'07"
Secondary Affiliation: Indian School of Mines, IND, India
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201130
Program Name: ODPOcean Drilling Program
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