Planktonic foraminiferal biostratigraphy and assemblage composition across the Cenomanian–Turonian boundary interval at Clot Chevalier (Vocontian Basin, SE France)
Articolo
Data di Pubblicazione:
2016
Citazione:
Planktonic foraminiferal biostratigraphy and assemblage composition across the Cenomanian–Turonian boundary interval at Clot Chevalier (Vocontian Basin, SE France) / F. Falzoni, M.R. Petrizzo, H.C. Jenkyns, A.S. Gale, H. Tsikos. - In: CRETACEOUS RESEARCH. - ISSN 0195-6671. - 59(2016 Apr), pp. 69-97. [10.1016/j.cretres.2015.10.028]
Abstract:
The CenomanianeTuronian boundary interval is generally considered a critical time for planktonic
foraminifera due to the environmental perturbations associated with Oceanic Anoxic Event 2. However,
only the rotaliporids became extinct at the onset of the event, whilst several lineages evolved and/or
diversified. This remarkable morphologic plasticity is often overlooked in the literature, partly because a
number of stratigraphic sections have only been studied in thin-section due to the degree of lithification
of the samples. Improved documentation of the morphological variability of planktonic foraminifera and
better defined species concepts are required in order to improve biostratigraphy, particularly as Helvetoglobotruncana
helvetica is an unreliable marker for the base of the Turonian. At the same time, detailed
study of the planktonic foraminiferal response to OAE 2 demands a more profound knowledge of the
assemblage composition.
We present new biostratigraphic, taxonomic, and quantitative data for planktonic foraminiferal species
from the Clot Chevalier section (Vocontian Basin, SE France), with the aim of (1) providing a detailed
biostratigraphic analysis of the section, (2) documenting the morphological plasticity of specimens in
this time interval and stabilizing species concepts, and (3) identifying promising markers to improve the
resolution of the present biozonation and allow regional correlation. Samples were processed with acetic
acid to extract isolated planktonic foraminifera. Assemblages were assigned to the upper Cenomanian
Rotalipora cushmani Zone and to the uppermost Cenomanianelowermost Turonian Whiteinella archaeocretacea
Zone. Planktonic foraminiferal bioevents and assemblage composition identified at Clot
Chevalier are compared with the well-studied Pont d'Issole section located ca. 15 km to the NE, highlighting
similarities and differences in the species occurrences that may complicate the stratigraphic
correlation between the two sections.
The results of our study support the validity and common occurrence of species that have been
misidentified and/or overlooked in the literature (i.e., Dicarinella roddai, Praeglobotruncana oraviensis,
Marginotruncana caronae) and indicate that primitive marginotruncanids evolved before the onset of
OAE 2, although species diversification occurred only after the event. Moreover, we believe that the first
appearance of P. oraviensis might represent a promising bioevent for approximating the Cenomanian/
Turonian boundary, after calibration with bio- and chemostratigraphically well-constrained sections.
Finally, we describe three new trochospiral species, named “Pseudoclavihedbergella” chevaliensis, Praeglobotruncana
pseudoalgeriana and Praeglobotruncana clotensis.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
late cretaceous; Cenomanian–Turonian boundary interval; planktonic foraminiferal taxonomy; biostratigraphy; quantitative analyses; oceanic anoxic event 2
Elenco autori:
F. Falzoni, M.R. Petrizzo, H.C. Jenkyns, A.S. Gale, H. Tsikos
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