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Graphic correlation of the upper Eifelian to lower Frasnian (Middle-Upper Devonian) conodont sequences in the Spanish Central Pyrenees and comparison with composite standards from other areas

S. Gouwy, J.-C. Liao, and J.I. Valenzuela-Ríos

Plain Language Abstract

Three Eifelian-Givetian sections from the Spanish Central Pyrenees were correlated using graphic correlation based on conodont data. This correlation technique involves first and last occurrences of all taxa and is not solely based on zone-defining taxa. This allows a high resolution correlation, especially in areas where zone-defining taxa have delayed first occurrences. The technique uses an X-Y-graph to visualize the correlation by plotting the first and last occurrences as dots in the field of the graph and a line, separating the first and last occurrences, to correlate the two sections positioned along the axes of the graph. This way of correlating sections allows projection of data from one section onto another (reference section) thereby constructing a database for the studied area. In the Spanish Central Pyrenees, the conodont database was constructed with the Compte section, yielding the most detailed and complete conodont succession for the Givetian of the area, as reference. The combination of the three sections provides a more complete conodont range chart for the area and permits identification of all Givetian standard conodont zones and subzones by means of index taxa. For several intervals, the correlation shows important differences in thickness of the deposits between the sections. The correlation is a first step in the construction of a Pyrenean composite standard that, when integrated with data from the Ardenne, Anti-Atlas and the Montagne Noire composite standard, will contribute to the construction of a global Middle Devonian database. This global database will improve the accuracy of intercontinental correlations and correlations between shallow and deeper marine environments for the Eifelian and Givetian stages.

Resumen en Español

Correlación gráfica de las secuencias de conodontos del Eifeliense superior al Frasniense inferior (Devónico Medio-Superior) en el Pirineo Central español y comparación con los estándares compuestos de otras áreas

Mediante la correlación gráfica de las secciones del Eifeliense -Givetiense pertenecientes a diferentes facies en el Pirineo Central español, se establece un estándar compuesto (composite standard) local basado en conodontos con el que se pueden integrar los nuevos datos de los Pirineos. Esta base de datos de conodontos local se compara y correlaciona con el estándar compuesto del Devónico Medio que ya contiene datos del Anti-Atlas (Marruecos), Ardenne (Bélgica) y el estándar compuesto de la Montagne Noire. El proyecto de correlación comprende tres secciones pirenaicas (Compte, Villech y La Guàrdia d'Ares) pertenecientes al mismo escenario paleogeográfico situado tectónicamente en la parte sur de la Cadena Varisca Europea. La sección Compte, que ha proporcionado la sucesión de conodontos más completa y detallada para el Givetiense, es seleccionada como referencia para el proyecto de correlación. La combinación de datos de estas secciones permite identificar, por medio de los indicadores bioestratigráficos, todas las zonas y subzonas de conodontos estándar del Givetiense. Las correlaciones y comparaciones de alta resolución de estas secciones muestran diferencias de espesor en varios intervalos. Este estudio es un paso importante en la construcción de un estándar compuesto de alta resolución de los Pirineos, el cual, integrado en el estándar compuesto del Anti-Atlas, Montagne Noire y Ardenne, contribuirá a la construcción de una base de datos global de conodontos del Devónico Medio y a la mejora en la cronoestratigrafía y precisión en las correlaciones intercontinentales para los periodos Eifeliense y Givetiense.

Palabras clave: Correlación gráfica; Biostratigrafía de conodontos; Devónico Medio; Conjunto de litosferoclastos Armoricano; Peri-Gondwana; Pirineo Central español

Traducción: Enrique Peñalver (Sociedad Española de Paleontología)

Résumé en Français

Corrélation graphique des séquences de conodontes de l'Eifelien supérieur au Frasnien inférieur (Dévonien moyen-supérieur) des Pyrénées centrales espagnoles et comparaison avec des standards composites d'autres régions

En se basant sur une corrélation graphique des sections de l'Eifelien-Givétien provenant de différents faciès des Pyrénées centrales espagnoles, un standard composite local est établi à l'aide des conodontes, fournissant une base de référence pour comparer les nouvelles données provenant des Pyrénées. Cette base de données de conodontes locaux est comparée et corrélée au standard composite du Dévonien moyen contenant déjà les données de l'Anti-Atlas (Maroc), de l'Ardenne (Belgique), et le standard composite de la Montagne Noire. Ce projet de corrélation comprend trois sections des Pyrénées (Compte, Villech, et La Guàrdia d'Ares) appartenant au même contexte paléogéographique et situées dans la partie sud de la chaîne varisque européenne. La section du Compte, ayant livré la succession de conodontes la plus complète et détaillée pour le Givétien, est choisie comme référence pour le projet de corrélation. La combinaison des données de ces sections permet l'identification, au moyen de taxons indices, de toutes les zones et sous-zones standard à conodontes du Givétien. La corrélation à haute résolution et la comparaison de ces sections indiquent des différences de puissance dans plusieurs intervalles. Cette étude est un premier pas important pour la construction d'un standard composite à haute résolution des Pyrénées qui, intégré avec le standard composite de l'Anti-Atlas, de la Montagne Noire, et de l'Ardenne, contribuera à la construction d'une base de données globale des conodontes du Dévonien moyen et à l'amélioration de la chronostratigraphie et de la précision des corrélations intercontinentales pour les stades de l'Eifelien et du Givétien.

Mots-clés : corrélation graphique ; biostratigraphie des conodontes ; Dévonien moyen ; terrane armoricain ; péri-Gondwana ; Pyrénées centrales espagnoles

Translator: Antoine Souron

Deutsche Zusammenfassung

Grafische Korrelation der Conodonten-Sequenzen (oberes Eifelium bis unteres Frasnium/mittleres bis oberes Devon) aus den spanischen Zentral-Pyrenäen und Vergleich mit gemischten Normen aus anderen Gebieten.

Durch grafische Korrelation der Eifelium-Givetium Sektionen verschiedener Fazies der spanischen Zentral-Pyrenäen wurde eine lokale gemischte Norm, basierend auf Conodonten, eingeführt, auf die neue Daten Bezug nehmen können. Diese lokale Conodonten-Datenbank wird verglichen und korreliert mit der mitteldevonischen gemischten Norm, die schon Daten aus dem Anti-Atlas (Marokko), den Ardennen (Belgien) und der gemischten Norm der Montagne Noire enthält. Das Korrelations-Projekt beinhaltet drei Pyrenäen-Sektionen (Compte, Villech und La Guàrdia d'Ares), die demselben paläogeografischen Milieu angehören und tektonisch im südlichen Teil der europäischen Varisziden liegen. Die Compte-Sektion wurde als Referenz für das Korrelations-Projekt ausgewählt weil sie die kompletteste und detaillierteste Conodonten-Abfolge enthält. Daten-Kombination aus diesen Sektionen erlaubt die Identifizierung aller standardisierten Conodonten-Zonen und Subzonen aus dem Givetium mittels Index-Taxa. Die hochauflösende Korrelation und der Vergleich dieser Sektionen zeigen in mehrere Abschnitten Höhenunterschiede. Diese Untersuchung ist ein wichtiger Schritt zur Festlegung einer hochauflösenden gemischten Norm für die Pyrenäen, die, integriert in die gemischten Normen des Anti-Atlas, der Montagne Noire und der Ardennen zum Aufbau einer globalen mitteldevonischen Datenbank und zur Verbesserung der Chronostratigrafie und zur Exaktheit interkontinentaler Korrelation des Eifeliums und Givetiums beiträgt.

Schlüsselwörter: Grafische Korrelation; Conodonten-Biostratigraphie; Mittleres Devon; Armoricanische Terran-Assemblage; Peri-Gondwana; Spanische Zentralpyrenäen

Translator: Eva Gebauer

Arabic

669 arab

Translator: Ashraf M.T. Elewa

 

 

FIGURE 1. 1. Middle Devonian paleogeographic situation with indication of the study area (courtesy of R. Blakey, NAU Geology), 2. Map of Paleozoic rocks on the Iberian Peninsula and position of Figure 1.3, 3. Location of the studied Devonian outcrops.

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FIGURE 2. 1. Map of Paleozoic rocks on the Iberian Peninsula and position of Figure 2.2 (black square), 2. Structural geological map of the Spanish Pyrenees with indication of the studied area (white square) and 2. Structural geological map of the Spanish Pyrenees with indication of the studied area (red square) and the most important faults and thrust faults, FNP: North Pyrenean Fault, CPP: Petites Pyrénées thrust fault, CFN: Frontal North Pyrenean thrust fault, CFS: Frontal South Pyrenean thrust fault [modified from Barnolas and Pujalte (2004)], 3. Map of the Devonian facies areas and subdivision of the southern facies area in the southern Spanish Pyrenees [modified from Zwart (1979)], studied area in black square, location of the sections indicated by black stars.

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FIGURE 3. Graphic correlation between the Villech section and the composite standard for the Spanish Central Pyrenees (third round). The numbers represent the taxa listed in the range chart (Figure 5 and Figure 6), the error boxes indicate the sampling intervals. (sem./ lat.: semialternans/latifossatus).

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FIGURE 4. Graphic correlation between the La Guàrdia d’Ares section and the composite standard (third round). The numbers represent the taxa listed in the range chart (Figure 5 and Figure 6), error boxes indicate the sampling intervals.

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FIGURE 5. Conodont range chart based on the Spanish Central Pyrenean sections. Precise CSU values are given in the Appendix.

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FIGURE 6. Conodont range chart based on the Spanish Central Pyrenean sections (continued). Precise CSU values are given in the Appendix.

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FIGURE 7. Correlation of the three sections based on the results of the graphic correlation method.

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FIGURE 8. Graphic correlation of the three Compte subfacies area sections. The columns show the observed first occurrences of important taxa in the studied sections, indicated by their projected position on the Pyrenean CS. The numbers represent the taxa listed in the range chart (Figure 5 and Figure 6) and in the Appendix. (CSU: Composite Standard Unit).

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FIGURE 9. Correlation between the Pyrenean composite standard and the Middle Devonian composite standard. The numbers represent the taxa listed in the range chart (Figure 5 and Figure 6) and Appendix. See also legend in Figure 4.

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FIGURE 10. Graphic correlation of four composite standard (CS) databases, three from NW-Gondwana (Anti-Atlas, Pyrenees and Montagne Noire) and one from S-Laurussia (Ardenne) (Golonka, 2000). The standard reference section for the Middle Devonian CS and the Anti-Atlas CS is the Jebel Ou Driss section in the Eastern Anti-Atlas (Morocco) (Belka et al ., 1997). The standard reference sections for the Ardenne and Montagne Noire CSs are the Couvin-Givet section and the Pic de Vissou section, respectively. The columns show the observed first occurrences of important taxa in the regional CS’s, indicated by their projected position on the Middle Devonian CS. The numbers represent the taxa listed in the range chart (Figure 5-Figure 6) and in the Appendix.

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First and last occurrences of the species in the different sections and in the resulting Composite Standard (CSU values). Compte : Compte section, LGA : La Guàrdia d’Ares section, Villech: Villech section, CS: Composite Standard. *: first and last occurrence in the section that provided the first and last occurrence in the CS.

 

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author1S. Gouwy. (present address) Paleontology Section, Geological Survey of Canada (Calgary), 3303, 33rd Street, NW Calgary, Alberta, T2L 2A7 Canada. This email address is being protected from spambots. You need JavaScript enabled to view it. and Paleontology Department, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, 3000 Brussels

Sofie Gouwy graduated in Geology at the University of Leuven (Belgium) in 1995. She holds PhD's in Geology and Earth System Sciences from the University of Leuven and the University of Modena and Reggio Emilia (Italy) respectively on Middle and Upper Devonian conodont biostratigraphy and graphic correlation on outcrops in Belgium, Morocco, Italy and Spain. Gouwy was a Post-doc Fellow at the University of Missouri (Columbia, MO) where she worked on oxygen isotope analysis of conodont apatite on Devonian material from Illinois (US) and the Montagne Noire (France) and is currently a Post-doc Fellow at the GSC in Calgary. Gouwy's focus at the GSC is on Devonian conodont biostratigraphy of the Mackenzie Basin (NWT, Canada). Other research interests include paleogeography, paleoclimatology and event stratigraphy. She is a corresponding member of the International Subcommission on Devonian Stratigraphy.

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author2J.-C. Liao. Department of Geology, University of Valencia, E-46100, Burjasot, Spain. This email address is being protected from spambots. You need JavaScript enabled to view it.

Jau-Chyn Liao is a specialist on Palaeozoic conodont bio- and chronostratigraphy. Her current activities focus on Devonian high-resolution bio-chronostratigraphy based on conodonts and facies analysis. Her Ph.D. at the Universities of Madrid and Valencia (2014) provided a sound and a strong conodont database in the Spanish Central Pyrenees that supports global correlations. Furthermore, the integration of biofacies and microfacies studies allowed a sedimentological analysis of Palaeozoic carbonates. She was granted by LEONARDO DA VINCI fellow at SOWIWAS Gmbh and also by DAAD foundation at the Senckenberg Research Institute and Natural History Museum, Frankfurt (Germany). She was the Secretary of the Spanish Working Group of the IGCP-499 and is currently the Secretary of the IGCP-596. Also she is an active Board Member of IGCP Spanish National Committee since 2014. She is Corresponding Member of the International Subcommission on Devonian Stratigraphy.

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author3J.I. Valenzuela-Ríos. Department of Geology, University of Valencia, E-46100, Burjasot, Spain. This email address is being protected from spambots. You need JavaScript enabled to view it.

Nacho Valenzuela-Ríos is a Professor of Paleontology at University of Valencia (Spain). He also currently serves as Chair of the Spanish National Committee of IGCP-UNESCO and is the Director of the Applied Palaeontology Master Program jointly offered by the Universities of Valencia and Alicante. Nacho received his M.S. and Ph.D. (1989) from the University of Zaragoza, Spain. His Ph.D. was largely supported by the DAAD and by the Instituto de Estudios Altoaragoneses. He has been a Fulbright Fellow (University of California, Davis), and also was awarded with a Humboldt Research Fellowship (University of Braunschweig). Nacho is a Voting (Titular) Member of the International Subcommission on Devonian Stratigraphy. His more than 200 scientific contributions are devoted to establish very detailed local and global Devonian sequences that form the basis for the construction of a Devonian standard of reference using conodonts as the most effective tools. Conodont systematics and biostratigraphy are mandatory in his research. Recent works establish new biozonations of worldwide applicability. The combination of high-resolution biostratigraphy with geochemical and geophysical techniques has produced first results, as the climatic change demonstrated around the Lochkovian/Pragian boundary in the Pyrenees. Nacho has conducted fieldwork in Spain, Germany, the Czech Republic, Nevada, Uzbekistan, Mongolia and France.

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