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Title: Palaeoenvironmental turnover across the Ypresian-Lutetian transition at the Agost section, Southastern Spain: In search of a marker event to define the Stratotype for the base of the Lutetian Stage
Authors: Ortiz, Silvia ×
Gonzalvo, Concepcion
Molina, Eustoquio
Rodriguez-Tovar, Francisco J.
Uchman, Alfred
Vandenberghe, Noël
Zeelmaekers, Edwin #
Issue Date: 2008
Publisher: Elsevier Scientific Pub. Co.
Series Title: Marine Micropaleontology vol:69 issue:3-4 pages:297-313
Abstract: Marker events to define the stratotype for the base of the Lutetian Stage are poorly defined. To
elucidate such markers and characterize palaeoenvironmental turnovers, we conducted an
integrated study of the Ypresian–Lutetian (Y–L; early-middle Eocene) transition at the
continuous Agost section (southeastern Spain). This 115-m-thick section, which consists of
hemipelagic marls intercalated with hemipelagic limestones and turbidity sandstones, spans
from planktic foraminiferal Zones P9 to P12 (E7 to E10) and calcareous nannofossil Zones CP11
to CP14a (NP13 to NP16). We report quantitative analyses of planktic and benthic foraminifera
and characterization of trace fossil assemblages that are integrated with mineralogical analyses.
Relative to benthic forms, planktic foraminifera constitute more than 80% of the foraminiferal
assemblage.We found that the most abundant planktic species belong to the genera Acarinina,
Morozovella, Subbotina, and Pseudohastigerina. Benthic foraminiferal assemblages are strongly
dominated by calcareous taxa, with bolivinids being the most abundant group. Trace fossils
showed the succession Nereites–Zoophycos–Cruziana ichnofacies throughout the Agost section.
In addition to changes in palaeobathymetry, we deduced that quantity and quality of organic
matter flux influenced by turbidity currents are the main factors controlling benthic
assemblages. We distinguished several mineralogical boundaries at the Agost section, each
associated with lithological facies changes suggesting a change in provenance rather than
changes in weathering conditions.We made three observations that indicate an increase in sea
water temperatures or a possible hyperthermal event related to the first occurrence (FO) of
hantkeninids (i.e., the P9/P10 boundary): 1) a distinct peak in abundance of the benthic
foraminifera Aragonia aragonensis; 2) the low-diversity of benthic foraminiferal assemblages;
and 3) the occurrence of the planktic foraminifera Clavigerinella eocenica and Clavigerinella
jarvisi. Benthic foraminiferal and trace fossil assemblages also suggest an associated relative fall
of sea level from upper-middle bathyal to sublittoral depths. These characteristic indicators
point to this boundary as a promising feature for defining the Global Stratotype Section and Point
(GSSP) for the base of the Lutetian Stage. However, complementary magnetobiostratigraphic
studies carried out at the Agost section point to the FO of calcareous nannofossil Blackites inflatus
(base of CP12b), which occurred 3–5 Myr before the P9/P10 boundary, as the most suitable.
ISSN: 0377-8398
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Geology
× corresponding author
# (joint) last author

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