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Alegret, Ortiz & Kaminski (eds.), 2012. Ninth International Workshop on Agglutinated Foraminifera, Abstract Volume
Environmental control on shell structure and composition of agglutinated
foraminifera in the Marmara Sea
Eric ARMYNOT DU CHATELET 1 , Viviane BOUT-ROUMAZEILLES 1 , Rodolfo
COCCIONI 2 , Fabrizio FRONTALINI 2 , François GUILLOT 1 , Michael A.
KAMINSKI 3 , Philippe RECOURT 1 , Armelle RIBOULLEAU 1 , Alain
TRENTESAUX 1 , Nicolas TRIBOVILLARD 1 and Sandra VENTALON 1
1 Université Lille 1, UMR 8217 CNRS Géosystèmes, UFR Sciences de la Terre, Bât SN5, Avenue Paul
Langevin, 59655 Villeneuve d'Ascq, France.
2 Dipartimento di Scienze della Terra, della Vita e dell'Ambiente (DiSTeVA), Università degli Studi di
Urbino "Carlo Bo", Campus Scientifico Enrico Mattei, Località' Crocicchia, 61029 Urbino (Italy)
3 Earth Sciences Department, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi
Arabia.
e-mail: eric.armynot@univ-lille1.fr
The study of benthic foraminifera in complex marine system, like the Marmara Sea, represents
a key for understanding environmental factors behind foraminiferal species, density,
assemblage composition, and shell construction. Based on cross shore water depth transect,
this study aims at defining the geochemical conditions at the seafloor and identifying the
sediment constraints that act upon agglutinated test construction for selected species. Grain
size, mineralogical, and chemical analyses of the shells of species have been performed and
compared to the main geochemical conditions within the sediments. Although grains used to
construct their foraminiferal tests are agglutinated from among the available grains, both grain
size selection and sorting have been revealed. This suggests that the mineralogical
composition is related to the species and the sample localization within the basin. Our
observations further suggest that bottom water conditions of the Marmara Sea do not have
significant influence on agglutinated foraminiferal shell development, which is primarily
driven by sediment characteristics.
Grain shape characterization.
a) Global SEM backscattered
electrons (BSE)
image of a specimen of
Eggerelloides scaber; b)
SEM BSE image of the
selected surface for grain
analysis, c) Separation of
grains that are entirely
observed within the selected
area and calculation of the
shape parameters; d).
Distribution of surface of
grains (log). Log-normal
curve is superimposed. e)
Example of quartz analysis
on a specimen of Textularia agglutinans; SEM BSE image f) BSE Image after grey level threshold
adjustment; g) EDX Silica mapping.
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