Formal proposal for the Toarcian GSSP in the Peniche section

Reunion specialisee de la S.G.F. en hornmage it Serge Elmi
Peuplements et environnements jurassiques, Lyon (France), 22-23-24 av ril 20 I 0
Formal proposal for the Toarcian GSSP in the Peniche section
(Lusitanian Basin, Portugal)
Elmi Serge t (1), Rocha Rogerio B. (2), Duarte Luis Vitor (3), Mouterde Rene t,
Cabral Maria Cristina (4), Comas-Rengifo Maria Jose (5), Gomez Juan J. (5), Goy Antonio
Hesselbo Stephen P. (6), Jenkyns Hugh C. (6), Littler Kate (6), Mailliot Samuel (7),
Mattioli Emanuela (7), Oliveira Luiz C. V. (8), Osete Maria Luisa (9), Perilli Nicola (10),
Pinto Susana (4), Pittet Bernard (7), Ruget Christiane (11) & Suan Guillaume (7)
(5),
Former Toarcian Working Group Convenor (lUGS)
(2) Toarcian Task Group Convenor (lUGS), Departamento de Ciencias da Terra e CICEGe, Faculdade de Ciencias e
Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal ([email protected])
(3) Departamento de Ciencias da Terra, lMAR-CIC, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra,
3000-272 Coimbra, Portugal ([email protected])
(4) Departamento e Centro de Geologia, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, C6 _ 4°, 1749016 Lisboa, Portugal ([email protected] ; [email protected])
(5) Departamento-UEI de Paleontologia, UCM-CSIC . Jose Antonio Novais , 2 , 28040 Madrid, Spain
([email protected] ; [email protected] ; [email protected])
(6) Department of Earth Sciences, University of Oxford, Parks Road, Oxford OXI 3PR, United Kingdom
([email protected] ; [email protected]; [email protected])
(7) UMR 5125 PEPS, CNRS, Universite Lyon 1, Campus de laDOUA, Batiment Geode, 69622 Villeurbanne Cedex, France
([email protected] ; [email protected] ; [email protected] ;
[email protected] .ft)
(8) Petrobras/Cenpes, Cidade Universitaria, Ilha do Fundao, 21941-598, Rio de Janeiro, Brazil ([email protected])
(9) Departamento de Fisica de la Tierra I. Avenida Complutense sin, Universidad Complutense, 28040 Madrid, Spain
([email protected])
(10) Dipartimento Scienze della Terra, Uni versita degli Studi di Pisa, Via S. Maria 53, 56100 Pisa, Italy ([email protected])
(II)Chipier, 120 Route de Pimotin, 69420 Tupin_et S-emons, France ([email protected])
(I)
The Global Boundary Stratotype Section and Point (GSSP) for the base of the Toarcian Stage is proposed at
the base of micritic limestone bed 1"5e at Ponta do Trovao, in the Peniche section (39°22' IS" N, 9°23 '07"
W) (Lusitanian Basin, Portugal), located 80 kIn north of Lisbon. The Peniche section, as formal GSSP
candidate for the base of the Toarcian Stage, satisfies most of the requirements recommended by the
International Commission on Stratigraphy (ICS), in particular:
1) The Pliensbachian/Toarcian (PIT) boundary is included in a continuous section that comprises over 450m
of carbonate sediments; structural complexity, synsedimentary and tectonic disturbances, metamorphism
and strong diagenetic alteration are not relevant constraints in this area. At the PIT transition, observed in a
Fig. 1 - General view (from SW to NE) ofthe Ponta do Trovao section, Peniche Peninsula (Portugal); in the background,
the Pap6a Peninsula
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Reunion specialisee de la S.G.f. en hommage a Serge Elmi
Peuplements et environnements jurassi qu es . L\ on (F rance), 22-23-24 avril 2010
marl'limestone alternation unit, no vertical facies changes, stratigraphic gaps and hiatuses have been recorded.
In the succession, a marly increase is observed above the boundary.
2) The palaeontological record of Elisa and Mirabile Subzones shows abundant and diverse well preserved
macro and microfossil assemblages. The boundary has been characterized by both primary and secondary
(auxiliary) biostratigraphic markers (ammonites, brachiopods, calcareous nannofossils and ostracods). The
successive ammonite assemblages of the PIT boundary mainly contain taxa characteristic of the Mediterranean
and the Northwest European provinces that allow good global scale correlation.
3) High resolution stable isotopes (mainly carbon)and 87Sr/86Sr evolution show interesting changes just
above the PIT boundary, constituting powerful tools for global scale correlation. No data is currently available
for radioisotopic dating and magnetostratigraphy. The requirement of suitability for magnetostratigraphy is
available at the proposed ASP in Almonacid de la Cuba section (Iberian Range, Spain); here, the N2-R2
magnetozones boundary is recorded also just above the PIT boundary. Sequence stratigraphy analysis is
available for the Pliensbachian and Toarcian series of the Lusitanian Basin. Cyclostratigraphy analysis is
available for the Lower Toarcian of Ponta do Trovao.
The Almonacid de la Cuba section (Iberian Range, Spain), which provides complementary data of the
ammonite succession in the Northwest European Hawskerense and Paltum Subzones and its chronocorrelation
with the Peniche section, is suggested as the Toarcian auxiliary section and point (ASP).
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