The Eocene-Oligocene turnover of Deep-Water Agglutinated Foraminifera at ODP
Site 647, Southern Labrador Sea (North Atlantic)
By:Kaminski, MA (Kaminski, Michael A.)[ 1,2 ]; Ortiz, S (Ortiz, Silvia)[ 3,4 ]
MICROPALEONTOLOGY
Volume: 60
Issue: 1
Pages: 53-66
Published: 2014
View Journal Information
Abstract
We present a new record of deep-water agglutinated foraminifera ( DWAF) across the
Eocene-Oligocene Transition (EOT) in the southern Labrador Sea (ODP Site 647). We
studied 82 samples from Cores 647A-37R to -27R, and recovered over 100 species and
generic groups. The EOT represents an interval of rapid climatic change connected with
global cooling, Antarctic glaciation, a substantial decrease in atmospheric CO2, and
concurrent changes in the composition of deep waters in the world ocean. Our highresolution quantitative study of the DWAF faunal succession in abyssal Hole 647A confirms
earlier findings that the EOT was an interval of significant faunal turnover.
The faunal succession in Hole 647A is subdivided into two assemblages based on the
stratigraphic ranges of characteristic benthic foraminiferal species: late Eocene
Spiroplectammina trinitatensis-Reticulophragmium amplectens Zone and early Oligocene
Ammodiscus latus-Turrilina alsatica Zone. The boundary between these zones, i.e., the
Eocene/Oligocene (E/O) boundary, is characterized by the disappearance of 11 DWAF taxa,
most of them organically-cemented taxa. The boundary interval was also characterized by a
striking sharp decrease in DWAF abundance and diversity. Organically-cemented DWAF
taxa increased in abundance in the early Oligocene, but their diversity and abundance
never recovered to Eocene values. These data suggest a deepening of the calcite
compensation depth and associated changes, such as more vigorous ocean circulation in
coincidence with the E/O boundary interval.
The analysis of DWAF morphogroups reveals an acme in robust suspension-feeding tubular
forms previous to the extinction, suggesting increased bottom water activity. The E/O
boundary interval is characterized by an increase in DWAF infaunal taxa and
Spiroplectammina species, probably related to increased productivity, as already suggested
by the analysis of benthic elongate-cylindrical foraminifera at the same locality.
The faunal turnover across the EOT at Hole 647A suggests more vigorous deep-ocean
circulation in the latest Eocene and across the E/O boundary interval in the Labrador Sea. It
seems reasonable to link the disappearance of DWAF at the E/O boundary at Site 647 to
more than one mechanism, including inferred higher productivity, possible competition
from calcareous benthic foraminifera, changes in the CO2 content of the atmosphere and
ocean, the deepening of the calcite compensation depth, and concurrent changes in
taphonomic conditions caused by changes in the water masses in the North Atlantic.
Keywords
KeyWords Plus:EOCENE/OLIGOCENE BOUNDARY; BENTHIC FORAMINIFERA; ANTARCTIC
GLACIATION; OFFSHORE ANGOLA; LOMONOSOV RIDGE; FRAM STRAIT;
BIOSTRATIGRAPHY; PALEOCEANOGRAPHY; OCEAN; PALEOENVIRONMENTS
Author Information
Reprint Address: Kaminski, MA (reprint author)
King Fahd Univ Petr & Minerals, Dept Earth Sci, POB 301, Dhahran 31261, Saudi Arabia.
Organization-Enhanced Name(s)
King Fahd University of Petroleum & Minerals
Addresses:
[ 1 ] King Fahd Univ Petr & Minerals, Dept Earth Sci, Dhahran 31261, Saudi Arabia
Organization-Enhanced Name(s)
King Fahd University of Petroleum & Minerals
[ 2 ] UCL, Dept Earth Sci, London WC1E 6BT, England
Organization-Enhanced Name(s)
University College London
University of London
[ 3 ] Univ Pais Vasco UPV EHU, Fac Ciencia & Tecnol, Dept Estratig & Paleontol, Leioa
48940, Spain
Organization-Enhanced Name(s)
University of Basque Country
[ 4 ] PetrStrat Ltd, Parc Caer Seion LL32 8FA, Conwy, Wales
E-mail Addresses:kaminski@kfupm.edu.sa
Document Information
Document Type:Article
Language:English
Accession Number: WOS:000347173900006
ISSN: 0026-2803
eISSN: 1937-2795