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
Identifiers
UCM identifierORCIDScopus Author IDWeb of Science ResearcherIDDialnet IDGoogle Scholar ID

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Now showing 1 - 6 of 6
  • Publication
    Fossilization of ammonites and sedimentary events in deep environments of carbonate platform (highest Middle to lowest Upper Oxfordian, Iberian Range, Spain).
    (Università degli studi di Milano. Dipartimento di Scienze della Terra "A. Desio", 2004-03) Fernández López, Sixto Rafael; Meléndez Hevia, Guillermo
    In the Ricla area (Zaragoza, Aragonese Branch of the Iberian Range), at the top of the Yátova Formation, grey-reddish wackestone limestones grade into yellow-green siliciclastic limestones of the Aldealpozo Formation. These changes of facies between the two successive formations are associated with syndepositional palaeoreliefs developed during the Late Oxfordian. The uppermost deposits of the Yátova Formation represent an Oxfordian condensed section, from the upper Bifurcatus Zone (Middle Oxfordian) and Hypselum Zone (Upper Oxfordian). These deposits are interpreted as developed in an open marine, moderately deep carbonate platform, showing uniform lowenergy conditions with extremely reduced carbonate and terrigenous background sedimentation, and very low sedimentation rates. The low diversity of the benthic fauna, scarce development of sponge bioherms and ammonite populations inhabiting the platform are palaeobiological criteria which corroborate these palaeoenvironmental conditions. Ammonite assemblages are composed of Sub-Mediterranean taxa. Over 900 ammonite specimens have been collected from the upper Bifurcatus and Hypselum zones. Oppeliidae (45,2%) and Perisphinctidae (37,9 %) are dominant. Aspidoceratidae (14,3%) are common. Haploceratidae (2,2%) are scarce. Two phylloceratids and a lytoceratid have been found. Ammonoids are commonly preserved as concretionary calcareous internal moulds of reelaborated elements. Resedimented shells are scarce. The degree of packing of ammonite remains and the stratigraphical persistence display high values. Taphonomic features indicative of sedimentary starving in deep carbonate platform environments are: 1) high concentrations of reelaborated ammonites, 2) taphonic population of type two, 3) phragmocones completely filled with sediment, and 4) homogeneous concretionary internal moulds, bearing no signs of abrasion, bioerosion or dense encrusting by organisms (such as serpulids, bryozoans or oysters). In conclusion, the occurrence of these ammonite associations confirms the development of an advanced deepening phase, within a 3rd order deepening/shallowing cycle, in the Aragonese platform, during the late Bifurcatus to Hypselum zones.
  • Publication
    Taphonomy of an ammonite recorded association (Murchisonae Zone, Aalenian, Iberian Range, Spain). Palaeoenvironmental implications.
    (International Subcommission on Jurassic Stratigraphy, 2002) Fernández López, Sixto Rafael; Martínez Gutiérrez, Gemma; Martire, Luca
  • Publication
    Diagnóstico paleontológico de ciclos paleoambientales en plataformas epicontinentales carbonáticas. Ejemplos del Jurásico Medio de la Cordillera Ibérica
    (Alcalá de Henares (Madrid): Museo Arqueológico Regional, 2004) Fernández López, Sixto Rafael
    Aunque parece haber un acuerdo general entre los geólogos en cuanto a que el registro estratigráfico ha estado influenciado por ciclos paleoambientales, pocos estudios hacen referencia a la naturaleza del registro fósil y su carácter cíclico. Sin embargo, los ciclos estratigráficos representan fluctuaciones paleoambientales que también han influido en las entidades paleobiológicas y en la conservación de sus restos y señales. Por analogía con el modelo desarrollado en Estratigrafía Secuencial, la Paleontología puede proporcionar un modelo referente a procesos de distintas escalas representados por ciclos tafonómicos y ciclos paleobiológicos. Los conocimientos paleontológicos pueden ser aplicados en las investigaciones estratigráficas para identificar los ciclos y las discontinuidades del registro estratigráfico. De manera análoga, los conocimientos estratigráficos proporcionan un sistema conceptual en el que es posible contrastar los ciclos paleontológicos y las discontinuidades del registro fósil. La Estratigrafía Secuencial y la Paleontología Aplicada pueden desarrollar un sistema conceptual, integrado y predictivo, para interpretar y contrastar el carácter cíclico del registro geológico y los ciclos paleoambientales, analizando independientemente la ciclicidad del registro estratigráfico y la del registro fósil.
  • Publication
    Lower Bathonian ammonites of Serra de la Creu (Tivissa, Catalan Basin, Spain)
    (Muséum d'histoire naturelle de Genève, 2000) Fernández López, Sixto Rafael
    The study of ammonites of the Bajocian/Bathonian boundary from Serra de la Creu (Tivissa, province of Tarragona), a locality of the Catalan Basin, allows to recognize several bio- and chronostratigraphic units commonly missing in the Iberian Basin. The Parkinsoni Zone (Upper Bajocian) and the lowermost Zigzag Zone (Lower Bathonian) established for NW Europe areas can be identified in the Catalan and Iberian basins (Spain), although the ammonite fossil assemblages are composed by Submediterranean taxa.
  • Publication
    Taphonomy of Ammonite Condensed Associations – Jurassic Examples from Carbonate Platforms of Iberia
    (Geologische Bundesanstalt, 2002) Fernández López, Sixto Rafael; Henriques, María Helena Paiva; Duarte, Luís Vitor
    Condensed associations of ammonites developed in carbonate epicontinental platforms show different preservational features in expanded deposits of shallow environments in relation to condensed deposits of deep environments. Recognizing these types of condensed associations is important when analysing the relationship between condensed sections and stratigraphical cycles. Deep condensed associations are a very good indicator of relative sea-level rises and transgressive trends. In contrast, shallow condensed associations provide an indicator of relative sea-level falls and regressive trends. [ZUSAMMENFASSUNG] kondensierte Assoziationen von Ammoniten auf epikontinentalen Karbonatplattformen zeigen bei Ablagerung unter Seichtwasserbedingungen verglichen mit Ablagerungen unter Tiefwasserbedingungen ein unterschiedliches Erhaltungsbild. Die Erfassung der Typen kondensierter Assoziationen ist bei der Analyse der Beziehung zwischen kondensierten Profilen und stratigraphischen Zyklen von Bedeutung. Assoziationen, die in großer Tiefe kondensiert sind, sind gute Indikatoren für relativen Meeresspiegelanstieg und transgressive Trends. Dagegen sind Seichtwasserassoziationen Anzeiger relativer Meeresspiegelabsenkungen und regressiver Trends.
  • Publication
    Taphonomic features of ammonite associations developed in deep carbonate platform environments (Oxfordian, Iberian Range, Spain).
    (International Association of Sedimentologists, 2004) Fernández López, Sixto Rafael; Meléndez Hevia, Guillermo; Pena dos Reis, Rui; Callapez, Pedro; Dinis, Pedro