Juan Carlos Gutiérrez-Marco

Bio: Juan Carlos Gutiérrez-Marco is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Ordovician & Paleozoic. The author has an hindex of 21, co-authored 138 publications receiving 1848 citations. Previous affiliations of Juan Carlos Gutiérrez-Marco include Complutense University of Madrid.

The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ13C chemostratigraphy

Abstract: The extensive work carried out during more than a decade by the International Subcommission on Ordovician Stratigraphy has resulted in a new global classification of the Ordovician System into three series and seven stages. Formal Global Boundary Stratotype Section and Points (GSSPs) for all stages have been selected and these and the new stage names have been ratified by the International Commission on Stratigraphy. Based on a variety of biostratigraphic data, these new units are correlated with chronostratigraphic series and stages in the standard regional classifications used in the UK, North America, Baltoscandia, Australia, China, Siberia and the Mediterranean-North Gondwana region. Furthermore, based mainly on graptolite and conodont zones, the Ordovician is subdivided into 20 stage slices (SS) that have potential for precise correlations in both carbonate and shale facies. The new chronostratigraphic scheme is also tied to a new composite δ13C curve through the entire Ordovician.

U-Pb depositional age for the upper Barrios Formation (Armorican Quartzite facies) in the Cantabrian zone of Iberia: Implications for stratigraphic correlation and paleogeography

Abstract: Zircons from a >45-cm-thick K-bentonite (altered ash-fall tuff) bed within the upper Barrios Formation (Ordovician Armorican Quartzite facies), in the Cantabrian zone of the Iberian Variscan belt were dated by isotope dilution–thermal ionization mass spectrometry. U-Pb analyses of six highly abraded single grains yielded concordant and overlapping error ellipses with a pooled concordia age of 477.47 ± 0.93 Ma. This age provides the depositional age of the Armorican Quartzite facies in the studied sector and establishes an absolute minimum age for the rifting that led to the opening of the Rheic Ocean in this section of northern Gondwana. This age is within error of the currently accepted interpolated age for the Tremadocian–Lower Ordovician Stage 2 (Floian) limit at 478.6 ± 1.7 Ma (Gradstein et al., 2004).

Proximal and Distal Hummocky Cross-Stratified Facies on a Wide Ordovician Shelf in Iberia

Abstract: The sandstone of the Monte da Sombadeira Formation (25 m to 200 m thick) crops out repeatedly on the flanks of open folds in an area 550 km long and 140 km wide (approximately 75 000 km2). At all localities there is a vertical change from mudstone to fissile siltstone into the sandstone of the formation itself and a return to fissile siltstone, then mudstone above the formation. Within the sandstone formation there are lateral facies differences, which are related to the paleogeography of the Ordovician shelf. Proximal localities have an interbedded mudstone/laminated siltstone facies with wave ripples and small hummocks. The associated sandstone facies has hummocky cross-stratification, which is characterized by: 1. deep scours at the bases of the beds; 2. high angles of dip to the hummocky cross-stratification; 3. deep scours at the tops of the beds; 4. wave ripples at the tops of the beds; and 5. beds that are variable in thickness and are often discontinuous. In contrast, distal localities have: 1. shallow erosion at the bases of beds; 2. low angle hummocky cross-stratification; 3. shallow erosion at the tops of beds; 4. rare or no wave ripples; and 5. beds that may be variable in thickness, but arc rarely discontinuous. Amalgamation of sandstone beds is found in the most proximal and distal localities but is less common in between. From the study we conclude: 1. the sandstone beds were emplaced during a regressive phase; 2. sandstone beds (up to 50 cm thick) with hummocky cross-stratification were deposited more than 100 km from the shore; 3. turbidite-like sandstones were not formed; 4. parallel lamination is the only current-formed structure preserved and wave-formed structures predominate generally throughout the sequence; and 5. it is possible in this case to distinguish between proximal and distal facies with hummocky cross-stratification. We estimate the average seaward dip of the Ordovician Iberian shelf was less than 0.1°, and we believe the low gradient had an important influence in determining the facies, by inhibiting the strength of offshore directed currents.

Giant trilobites and trilobite clusters from the Ordovician of Portugal

Abstract: Large quarrying surfaces of roofi ng slate in the Arouca Geopark (northern Portugal), formed under oxygen-depleted conditions, have yielded a unique Ordovician fossil lagerstatte that reveals new information on the social behavior of trilobites. It provides several of the world’s largest trilobite specimens (some reaching 70 cm), showing evidence of possible polar gigantism in six different species, as well as numerous examples of monotaxic and polytaxic size-segregated autochthonous trilobite clusters, some of which contain as many as 1000 specimens. These reveal a very diverse social behavior, which includes temporary refuge from predation and synchronous molting and reproduction, demonstrated for the fi rst time in fi contemporary families of three different trilobite orders from a single formation.

Revisión bioestratigráfica de las pizarras del Ordovícico Medio en el noroeste de España (zonas Cantábrica, Asturoccidental-leonesa y Centroibérica septentrional)

Abstract: La revision completa de mas de un centenar de localidades fosiliferas del Ordovicico Medio situadas en el noroeste del Macizo Hesperico, muestra que el deposito de las pizarras y limolitas oscuras (Formacion Luarca y equivalentes), que siguen a las cuarcitas del Arenig, no fue tan uniforme como se consideraba hasta ahora. Las pizarras se sedimentaron esencialmente durante el Oretaniense en la Zona Asturoccidental-Leonesa y en la parte septentrional de la Zona Centroiberica (Dominio del Ollo de Sapo), donde el techo de la unidad se situa muy proximo al limite Oretaniense / Dobrotiviense, sin existir ningun yacimiento paleontologico de probada edad dobrotiviense (= "Llandeilo inferior" en sentido clasico). En la Zona Cantabrica, la sedimentacion arcillosa se inicia en el Oretaniense superior tardio y prosigue durante el Dobrotiviense. Para el conjunto del area estudiada se caracterizan, o proponen, diversas lagunas estratigraficas de alcance local o regional, y se discuten las circunstancias paleogeograficas generadas por las hipotesis mas recientes, que son contrastadas a la luz de los nuevos datos paleoecologicos y paleobiogeograficos. Estos indican que la sedimentacion tuvo lugar en areas externas y abiertas de la plataforma, relativamente mas profundas que en la region surcentroiberica, con areas de surco donde ingresan elementos mesopelagicos. Desde el punto de vista paleontologico, se reconocieron un total de 97 formas distintas (67 especies presentes en el Oretaniense y 45 en el Dobrotiviense), entre las que destaca la primera aparicion conocida de determinadas especies de trilobites y ostracodos, el registro mas moderno de otros, y algunos taxones en comun con Avalonia y Baltica, desconocidos hasta el presente en otras areas del suroeste de Europa

Revised Classification, Nomenclator and Typification of Gastropod and Monoplacophoran Families

Abstract: 2,604 names at the rank of subtribe, tribe, subfamily, family and superfamily have been proposed for Recent and fossil gastropods, and another 35 for monoplacophorans. All names are listed in a nomenclator giving full bibliographical reference, date of publication, typification, and their nomenclatural availability and validity under the International Code of Zoological Nomenclature. Another 790 names, established for categories above the familygroup (infraorder to subclass) are listed separately. A fully ranked, hierarchical classification summarizes recent advances in the phylogeny of the Gastropoda and Monoplacophora. In all, the classification recognizes as valid a total of 721 gastropod families, of which 245 are known exclusively as fossils and 476 occur in the Recent with or without a fossil record; and 20 monoplacophoran families, of which 1 only occurs as Recent.Nomenclatural acts in this work: Amberleya bathonica Cox & Arkell, 1950, fixed as type species of Amberleya J. Morris & Lycett, 1851, under Art. 70.3; Ampezzopleura tenuis Nutzel, 1998, fixed as type species of Ampezzopleura Bandel, 1991, under Art. 70.3; Proserpina nitida G. B. Sowerby II, 1839, designated type species of Despoena Newton, 1891; Buccinum glabratum Linnaeus, 1758, designated type species of Dipsaccus H. Adams & A. Adams, 1853; Murex ficus Linnaeus, 1758, designated type species of Ficula Swainson, 1835; Oncomelania hupensis Gredler, 1881, designated type species of Hemibia Heude, 1890; Murex metaxa Delle Chiaje, 1828, fixed as type species of Metaxia Monterosato, 1884 under Art. 70.3; Neridomus anglicus Cox & Arkell, 1950, fixed as type species of Neridomus J. Morris & Lycett, 1851, under Art. 70.3; Navicella clypeolum Recluz, 1843, designated type species of Orthopoma Gray, 1868; Trochus viadrinus M. Schmidt, 1905, fixed as type species of Parataphrus Chavan, 1954 under Art. 70.3; Helix pomatia Linnaeus, 1758, designated type species of Pentataenia A. Schmidt, 1855; Flammulina ponsonbyi Suter, 1897, fixed as type species of Phenacohelix Suter, 1892, under Art. 70.3; Cyrtolites corniculum Eichwald, 1860, fixed as type species of Pollicina Koken, 1895, under Art. 70.3; Purpurina elegantula d'Orbigny, 1850, designated as type species of Purpurina d'Orbigny, 1850, and lectotype of Turbo bellona d'Orbigny, 1850, designated as neotype of Purpurina elegantula; Pyramidella minuscula Monterosato, 1880, fixed as type species of Tiberia Jeffreys, 1884, under Art. 70.3; Cyclostoma delicatum Philippi, 1844, fixed as type species of Trachysma G. O. Sars, 1878, under Art. 70.3; Helix elegans Gmelin, 1791, fixed as type species of Trochoidea T. Brown, 1827, under Art. 70.3; Turritellopsis stimpsoni Dall, 1919, fixed as type species of Turritellopsis G. O. Sars, 1878, under Art. 70.3; Fusus averillii Gabb, 1864, fixed as type species of Volutoderma Gabb, 1876, under Art. 70.3; Voluta pepo Lightfoot, 1786, fixed as type species of Yetus Bowdich, 1822. Curnonidae d'Udekem d'Acoz, nom. nov., and Curnon d'Udekem d'Acoz, nom. nov., are established for Charcotiidae Odhner, 1926, and Charcotia Vayssiere, 1906, (between 27 March and 1 May), non Charcotia Chevreux, 1906 (January) [Amphipoda]; Yuopisthonematidae Nutzel, nom. nov., and Yuopisthonema Nutzel, nom. nov., are established for Opisthonematidae Yu, 1976, and Opisthonema Yu, 1974, non Gill, 1862 [Pisces]. The new family-group name Burnupiidae Albrecht is established in this work; and the names Scolodontina and Orthalicoidei are first used here to denote, respectively, a suborder containing the family Scolodontidae, and an infraorder containing the superfamily Orthalicoidea.