New high resolution calcareous nannofossil analysis across the Danian/Selandian transition at the Zumaia section : comparison with South Tethys and Danish sections
Bernaola Bilbao, Gilen (Universidad del País Vasco. Departamento de Ingeniería Minera y Metalúrgica y Ciencia de los Materiales)
Martín-Rubio, M. (Universidad del País Vasco. Departamento de Estratigrafía y Paleontología)
Baceta Caballero, Juan Ignacio (Universidad del País Vasco. Departamento de Estratigrafía y Paleontología)

Fecha:	2009
Resumen:	A high resolution calcareous nannofossil biostratigraphic analysis was carried out across the Danian/Selandian transition at the Zumaia section (western Pyrenees). In the studied interval, spanning Varol's Subzone NTp7a to Zone NTp9, a sequence of 10 distinct calcareous nannofossil events is identified. The recognition of these bioevents confirms the continuous and expanded character of the Zumaia section and allows an accurate biostratigraphic correlation of the D/S transition between Zumaia, the Danish reference sections and the more southerly Tethys sections. According to this correlation, the abrupt transition from the upper Danian limestones (the calcisiltite unit) to the Lellinge Greensand that marks the D/S boundary in the type area correlates with the lithological change from the Aitzgorri Limestone Formation to the Itzurun Formation in Zumaia. The calcareous nannofossil bioevents recorded in connection with the organic-rich layer used to mark the base of the Selandian in the Tethys region were detected in Zumaia ~10 m below the top of the Aitzgorri Limestone Formation. This finding suggests that the organic-rich layer is considerably older than the Danian/Selandian (D/S) boundary at Zumaia and the type area, and thus using it to mark the D/S boundary in Tethys is not appropriate. According to a counting of limestone/marl couplets, which are demonstrated to be the stratigraphic expression of precession cycles throughout the Zumaia section, the organic-rich layer in the Tethys region is ~546 kyr older than the D/S boundary at the type area.
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Danian/Selandian ; Biostratigraphy ; Calcareous nannofossil ; Zumaia section
Publicado en:	Geologica acta, Vol. 7, Núm. 1-2 (Març-Juny 2009) , p. 79-92, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/124577
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000000272
DOI: 10.1344/105.000000272

14 p, 2.3 MB

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