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Agglutination of benthic foraminifera in relation to mesoscale bathymetric features in the abyssal NE Atlantic (Porcupine Abyssal Plain)

Agglutination of benthic foraminifera in relation to mesoscale bathymetric features in the abyssal NE Atlantic (Porcupine Abyssal Plain)
Agglutination of benthic foraminifera in relation to mesoscale bathymetric features in the abyssal NE Atlantic (Porcupine Abyssal Plain)
Abyssal hills, small topographic features rising above the abyssal seafloor (< 1000 m altitude), have distinct environmental characteristics compared to abyssal plains, notably the presence of coarser-grained sediments. As a result, they are a major source of habitat heterogeneity in the deep sea. The aim of this study was to investigate whether there is a link between abyssal hills and the test characteristics of selected agglutinated benthic foraminiferal species. We analysed 1) the overall morphometry, and 2) the granulometric and chemical (elemental) characteristics of the agglutinated tests of ten common foraminiferal species (Adercotryma glomerata, Ammobaculites agglutinans, Cribrostomoides subglobosus, Lagenammina sp.1, Nodulina dentaliniformis, Portatrochammina murrayi, three Reophax sp. and Recurvoides sp. 9) at four sites (two on top of abyssal hills and two on the adjacent plain) in the area of the Porcupine Abyssal Plain Sustained Observatory, northeast Atlantic. The foraminiferal test data were compared with the particle size distribution and elemental composition of sediments from the study sites in order to explore possible grain size and mineral selectivity. We found differences in the visual appearance of the tests (i.e. the degree of irregularity in their shape), which was confirmed by morphometric analyses, related to seafloor topography. The agglutinated foraminifera selected different sized particles on hills and plains, reflecting the distinct granulometric characteristics of these settings. These characteristics (incorporation of coarse particles, test morphometry) could provide evidence for the recognition of ancient abyssal hill environments, as well as other palaeoceanographic settings that were characterised by enhanced current flow. Furthermore, analyses of sediment samples from the hill and plain sites using wavelength dispersive X-ray fluorescence (WD-XRF) yielded different elemental profiles from the plains, probably a result of winnowing on the hills, although all samples were carbonate-rich. In contrast, the majority of the agglutinated tests were rich in silica, suggesting a preferential selection for quartz.
Abyssal hills, Benthic foraminifera, Elemental composition, Morphometry, Particle size
0377-8398
15-28
Stefanoudis, Paris V.
2cbf86e8-b292-4f14-8b03-c37469df1d96
Schiebel, Ralf
5c48accb-ee14-471a-801f-4267d8e4b2e1
Mallet, Romain
4d146704-d469-4642-bfc1-7821f017d36b
Durden, Jennifer M.
d7101246-b76b-44bc-8956-8ca4ae62ae1f
Bett, Brian J.
61342990-13be-45ae-9f5c-9540114335d9
Gooday, Andrew J.
d9331d67-d518-4cfb-baed-9df3333b05b9
Stefanoudis, Paris V.
2cbf86e8-b292-4f14-8b03-c37469df1d96
Schiebel, Ralf
5c48accb-ee14-471a-801f-4267d8e4b2e1
Mallet, Romain
4d146704-d469-4642-bfc1-7821f017d36b
Durden, Jennifer M.
d7101246-b76b-44bc-8956-8ca4ae62ae1f
Bett, Brian J.
61342990-13be-45ae-9f5c-9540114335d9
Gooday, Andrew J.
d9331d67-d518-4cfb-baed-9df3333b05b9

Stefanoudis, Paris V., Schiebel, Ralf, Mallet, Romain, Durden, Jennifer M., Bett, Brian J. and Gooday, Andrew J. (2016) Agglutination of benthic foraminifera in relation to mesoscale bathymetric features in the abyssal NE Atlantic (Porcupine Abyssal Plain). Marine Micropaleontology, 123, 15-28. (doi:10.1016/j.marmicro.2015.12.005).

Record type: Article

Abstract

Abyssal hills, small topographic features rising above the abyssal seafloor (< 1000 m altitude), have distinct environmental characteristics compared to abyssal plains, notably the presence of coarser-grained sediments. As a result, they are a major source of habitat heterogeneity in the deep sea. The aim of this study was to investigate whether there is a link between abyssal hills and the test characteristics of selected agglutinated benthic foraminiferal species. We analysed 1) the overall morphometry, and 2) the granulometric and chemical (elemental) characteristics of the agglutinated tests of ten common foraminiferal species (Adercotryma glomerata, Ammobaculites agglutinans, Cribrostomoides subglobosus, Lagenammina sp.1, Nodulina dentaliniformis, Portatrochammina murrayi, three Reophax sp. and Recurvoides sp. 9) at four sites (two on top of abyssal hills and two on the adjacent plain) in the area of the Porcupine Abyssal Plain Sustained Observatory, northeast Atlantic. The foraminiferal test data were compared with the particle size distribution and elemental composition of sediments from the study sites in order to explore possible grain size and mineral selectivity. We found differences in the visual appearance of the tests (i.e. the degree of irregularity in their shape), which was confirmed by morphometric analyses, related to seafloor topography. The agglutinated foraminifera selected different sized particles on hills and plains, reflecting the distinct granulometric characteristics of these settings. These characteristics (incorporation of coarse particles, test morphometry) could provide evidence for the recognition of ancient abyssal hill environments, as well as other palaeoceanographic settings that were characterised by enhanced current flow. Furthermore, analyses of sediment samples from the hill and plain sites using wavelength dispersive X-ray fluorescence (WD-XRF) yielded different elemental profiles from the plains, probably a result of winnowing on the hills, although all samples were carbonate-rich. In contrast, the majority of the agglutinated tests were rich in silica, suggesting a preferential selection for quartz.

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More information

Submitted date: October 2015
Accepted/In Press date: 29 December 2015
e-pub ahead of print date: 4 January 2016
Published date: March 2016
Keywords: Abyssal hills, Benthic foraminifera, Elemental composition, Morphometry, Particle size
Organisations: Ocean and Earth Science, Marine Biogeochemistry

Identifiers

Local EPrints ID: 382727
URI: http://eprints.soton.ac.uk/id/eprint/382727
ISSN: 0377-8398
PURE UUID: 80df1151-557e-4c2a-9017-0b78ae48aefa

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Date deposited: 13 Oct 2015 12:47
Last modified: 08 Jan 2022 15:26

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Contributors

Author: Paris V. Stefanoudis
Author: Ralf Schiebel
Author: Romain Mallet
Author: Jennifer M. Durden
Author: Brian J. Bett
Author: Andrew J. Gooday

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