Person:
Fernández López, Sixto Rafael

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First Name
Sixto Rafael
Last Name
Fernández López
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Paleontología
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UCM identifierORCIDScopus Author IDWeb of Science ResearcherIDDialnet IDGoogle Scholar ID

Search Results

Now showing 1 - 8 of 8
  • Publication
    Formal proposal for the Global Boundary Stratotype Section and Point (GSSP) of the Bathonian Stage, at the base of the Zigzag Zone in the Ravin du Bès Section (Bas-Auran, Subalpine Basin, SE France).
    (2007) Fernández López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Henriques, María Helena Paiva; Lanza, Roberto; Mangold, Charles; Olivero, Davide; Tiraboschi, Daniele
    The Global Boundary Stratotype Section and Point (GSSP) for the base of the Bathonian Stage is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bès Section (43º57’38’’N, 6º18’55’’E), Bas-Auran area, in the Chaudon-Norante commune, around 25 km at the South-Southeast of Digne-les-Bains, in the “Alpes de Haute Provence” French department. The Ravin du Bès Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy (ICS): 1) The exposure extends over 13 m in thickness, comprising more than five metres of fossiliferous levels below and above the boundary. The Bathonian basal bed corresponds to the “Marno-calcaires à Cancellophycus”, is located 7.8 m below the “Terres Noires” Formation and forms part of a transgressive-facies cycle. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, stratigraphic gaps or hiatuses have been recorded. There is no evidence of taphonomic condensation (i.e. mixture of fossils of different age or different chronostratigraphic units). Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints in the Bas-Auran area. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation of the uppermost Bajocian and Lower Bathonian. The boundary can be characterized by both primary and secondary (auxiliary) biostratigraphic markers. The section appears to be suitable for biostratigraphic study of microfossils, such as foraminifera, but as yet there are no published studies. The base of Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the renewal of parkinsonids and the first occurrence level of Gonolkites convergens Buckman. This level coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds and allow characterizing the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate an Early Bathonian deepening half-cycle of second order. No data are currently available for strontium isotope (87Sr/86Sr ratio), oxygen isotope (δ18O) or carbon isotope (δ13C) chemostratigraphy. Bajocian and Bathonian deposits have been remagnetized with a steady normal polarity. Volcanogenic deposits suitable for direct radio-isotope dating are not known in the section. 4) The criteria of accessibility, conservation and protection are assured by the “Réserve Naturelle Géologique de Haute Provence”, protected under national law as recognised by UNESCO. The Cabo Mondego Section (Portugal), which provides complementary data of the ammonite succession at the Sub-Mediterranean Parvum Subzone and its chronocorrelation with the Northwest European Convergens Subzone, is suggested as the Bathonian auxiliary section and point (ASP) within this GSSP proposal.
  • Publication
    The base of the Zigzag Zone in the Ravin du Bès Section (Bas-Auran, Subalpine Basin, SE France) as the GSSP for the base of the Bathonian Stage
    (2008) Fernández López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Henriques, María Helena Paiva; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Tiraboschi, Daniele
    The Global Boundary Stratotype Section and Point (GSSP) for the base of the Bathonian Stage is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bès Section (43º57’38’’N, 6º18’55’’E), Bas-Auran area, in the Chaudon-Norante commune, around 25 km at the South-Southeast of Digne-les-Bains, in the “Alpes de Haute Provence” French department. The Ravin du Bès Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy (ICS): 1) The exposure extends over 13 m in thickness, comprising more than five metres of fossiliferous levels below and above the boundary. The Bathonian basal bed corresponds to the “Marno-calcaires à Cancellophycus”, is located 7.8 m below the “Terres Noires” Formation and forms part of a transgressive-facies cycle. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, stratigraphic gaps or hiatuses have been recorded. There is no evidence of taphonomic condensation (i.e. mixture of fossils of different age or different chronostratigraphic units). Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints in the Bas-Auran area. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation of the uppermost Bajocian and Lower Bathonian. The boundary can be characterized by both primary and secondary (auxiliary) biostratigraphic markers. The section appears to be suitable for biostratigraphic study of microfossils, such as foraminifera, but as yet there are no published studies. The base of Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the first occurrence level of Gonolkites convergens Buckman and the renewal of parkinsonids. This level coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds, enabling documentation of the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate interpretation of an Early Bathonian deepening half-cycle of second order. No data are currently available for strontium isotope (87Sr/86Sr ratio), oxygen isotope (δ18O) or carbon isotope (δ13C) chemostratigraphy. Bajocian and Bathonian deposits have been remagnetized with a steady normal polarity. Volcanogenic deposits suitable for direct radio-isotope dating are not known in the section. 4) The criteria of accessibility, conservation and protection are assured by the “Réserve Naturelle Géologique de Haute Provence”, protected under national law as recognised by UNESCO. The Cabo Mondego Section (Portugal), which provides complementary data on the ammonite succession in the Sub-Mediterranean Parvum Subzone and its chronocorrelation with the Northwest European Convergens Subzone, is suggested as the Bathonian auxiliary section and point (ASP) within this GSSP proposal.
  • Publication
    Ammonoid succession at the Bajocian-Bathonian transition in the Bas Auran area, Digne district, South-East France.
    (Università degli studi di Milano. Dipartimento di Scienze della Terra "A. Desio", 2008) Pavia, Giulio; Fernández López, Sixto Rafael; Mangold, Charles
    The uppermost Bajocian to lowermost Bathonian ammonoid succession has been studied in the Bas Auran area in view of choosing one of its sections as the Global Stratotype Section and Point (G.S.S.P.) of the Bathonian Stage. The Bas Auran ammonite assemblages display exceptional values of record quality. The stratigraphic distribution of 629 specimens referred to 63 species and 35 genera, collected during the last forty years from three sections (Ravin du Bès, Ravin d'Auran, Ravin des Robines), is plotted and analyzed, bed by bed. Over 85 stratigraphic levels, through 9 m in thickness, have been studied at the top of the "Marno-calcaires à Cancellophycus" formation, ranging from the latest Bajocian (Parkinsoni Zone, Bomfordi Subzone) to the earliest Bathonian (Zigzag Zone, Convergens Subzone) and the base of the Macrescens Subzone. Ammonoid assemblages are composed of Northwest European and Mediterranean elements, associated with Sub-Mediterranean ones, allowing chronocorrelation between the Northwest European Convergens Subzone and the Sub-Mediterranean Parvum Subzone. The basal boundary of the Zigzag Zone and of the Bathonian Stage is placed at the base of Sturani's bed 23 in the Ravin du Bes section and is identified by the first occurrence of Gonolkites convergens, and coincides with the loest occurrence of Morphoceras parvum. Features of the ammonoid succession indicate relatively homogeneous and good record quality, gradual biostratigraphic change and high degree of taxonomic similarity between the Bomfordi and Convergens subzones. Palaeontological criteria also indicate relatively high values of palaeontological and stratigraphic completeness at the base of levels RB070-RB071 (= level 23 in Sturani 1967) which corresponds to the Bajocian/Bathonian boundary. The Ravin du Bès Section, with forty-six successive ammonoid fossil-assemblages of the Convergens Subzone belonging to three biohorizons through five metres of thickness, shows maximum values of biostratigraphic and biochronostratigraphic completeness, being one of the most complete in the world. Therefore, the Ravin du Bès Section should be chosen as the Global Stratotype Section and Point for the base of the Bathonian Stage. Two biostratigraphic logs summarize the ammonite content from the uppermost Bomfordi to basal Macrescens subzones. Three plates illustrate the most characteristic ammonoid taxa at the Bajocian-Bathonian passage in the Bas Auran succession.
  • Publication
    Le stratotype de la base de l’Etage Bathonien à Bas-Auran (Réserve Géologique de Haute Provence)
    (2008) Olivero, Davide; Pavia, Giulio; Fernández López, Sixto Rafael; Mangold, Charles
  • Publication
    The Global Boundary Stratotype Section and Point (GSSP) for base of the Bathonian Stage (Middle Jurassic), Ravin du Bès Section, SE France
    (International Union of Geological Sciences, 2009-12) Fernández López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Henriques, María Helena Paiva; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Tiraboschi, Daniele
    The Bathonian GSSP is defined at the base of limestone bed RB071 in the Ravin du Bès Section, Bas-Auran area, southern Subalpine Chains (France). This section satisfies most of the erquirements recommended by the International Commission on Stratigraphy. The exposure extends over 13 m in thickness. No vertical biofacies, ichnofacies or taphofacies changes, stratigraphic gaps or hiatuses have been recorded at the Bajocian-Bathonian transition. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. There is a well-preserved, abundant and diverse fossil record, with key markers (ammonites and nannofossils). The base of Bathonian Stage and Zigzag Zone corresponds to the first occurrence level of Gonolkites convergens Buckman that coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils are present in all beds. The GSSP is below the Tethyan calcareous nannofossil NJT10b/11 zonal boundary (lowest Watznaueria barnesiae) and above the Bo real nannofossil NJ10/11 boundary (lowest Pseudoconus enigma). Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate interpretation of an Early Bathonian deepening half-cycle of second order. The criteria of accessibility, conservation and protection are assured by the “Réserve Naturelle Géologique de Haute Provence”. The Cabo Mondego Section (Portugal) is the Bathonian auxiliary section and point (ASSP) .T he proposal was voted by the Bathonian Working Group in December, 2007, and by the International Subcommission on Jurassic Stratigraphy in March, 2008, approved by the ICS in June 2008, and ratified by the IUGS in Ju,ly 2008.
  • Publication
    Ammonite succession at the Bajocian/Bathonian boundary in the Cabo Mondego region (Portugal)
    (Taylor & Francis, 2006) Fernández López, Sixto Rafael; Henriques, María Helena Paiva; Mangold, Charles
    The Cabo Mondego outcrops exposed along the cliffs, on the western margin of the Iberian Plate, show an expanded stratigraphic section of Lower Bathonian deposits containing abundant ammonoids. Upper Bajocian deposits correspond to similar facies, of muddy limestones alternating with marlstones, although ammonoids are scarce. A detailed succession of ammonites across the Bajocian/Bathonian boundary has been recognized at Cabo Mondego, which can form a useful bio- and chronostratigraphic standard for the Lusitanian Basin. The revision of previous collections from the classical section and new field samplings of two other separate sections allow the recognition through up to twenty metres of thickness, the highest zone of Bajocian (Parkinsoni Zone) and the lowest zone of Bathonian (Zigzag Zone). The Parkinsoni and the Zigzag zones established for NW European areas and belonging to the Northwest European Province, can be identified in the Lusitanian Basin, although the ammonite fossil assemblages are composed of Submediterranean taxa. However, a subdivision of the Parkinsoni Zone is not possible, due to the scarcity of well preserved ammonoids. The Zigzag Zone can be recognized and characterized as composed of two subunits (Parvum and Macrescens subzones) as represented in diverse European basins of the Submediterranean Province. Ammonite fossil assemblages of the Parvum Subzone may be grouped into two successive horizons, which are biochronostratigraphically equivalent to the subdivisions of the Convergens Subzone distinguished in the Digne-Barreˆme area (SE France). New biochronostratigraphic data on the Bigotitinae, youngest members of Leptosphinctinae and oldest members of Zigzagiceratinae are relevant in understanding the evolution and faunal turnover of the West Tethyan Perisphinctidae during earliest Bathonian. The ammonite succession at the Bajocian/Bathonian boundary in the Cabo Mondego region (Portugal) represents one of the most complete biostratigraphic records so far recognized on the Iberian Plate.IAmmonoids, biostratigraphy, chronostratigraphy, Iberia, Lusitanian Basin, Middle Jurassic, palaeobiogeography.
  • Publication
    Ammonite horizons at the basal Bathonian zone (Parvum Subzone) in Cabo Mondego, Portugal
    (Institute of Geology Warsaw University, 2006) Fernández López, Sixto Rafael; Henriques, María Helena Paiva; Mangold, Charles
  • Publication
    Formal proposal for the Bathonian GSSP (Middle Jurassic) in the Ravin du Bès Section (Bas-Auran, SE France)
    (Springer Verlag, 2009) Fernández López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Henriques, María Helena Paiva; Lanza, Roberto; Mangold, Charles; Olivero, Davide; Tiraboschi, Daniele
    The Bathonian Global Stratotype Section and Point (GSSP) is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bès Section (43º 57' 38" N, 6º 18' 55" E), Bas-Auran area, “Alpes de Haute Provence” French department. The Ravin du Bès Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy: 1) The exposure extends over 13 m in thickness. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, condensation, stratigraphic gaps or hiatuses have been recorded. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation. The base of the Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the first occurrence level of Gonolkites convergens Buckman, which coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds and allow characterizing the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate an Early Bathonian deepening half-cycle of second order. 4) The criteria of accessibility, conservation and protection are assured by the “Réserve Naturelle Géologique de Haute Provence”. The Cabo Mondego Section (Portugal) is suggested as the Bathonian auxiliary section and point (ASSP) within this GSSP proposal.