Guillermo Albanesi | Universidad Nacional de Córdoba (original) (raw)

Papers by Guillermo Albanesi

Revista de la Facultad de Ciencias Exactas, Físicas y Naturales, Oct 3, 2016

El Doctorado en Ciencias Geologicas de la Facultad de Ciencias Exactas, Fisicas y Naturales, Univ... more El Doctorado en Ciencias Geologicas de la Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, se complace en presentar los primeros galardonados del Premio Dr. Carlos Gordillo. Este premio fue instituido por la Facultad mediante la Resolucion no 612 del Honorable Consejo Directivo, registrada el 23 de julio de 2010, a partir de una propuesta elevada por el Doctorado para poner en relieve y divulgar la tesis doctoral mas destacada de cada bienio. En virtud de que la realizacion de una tesis doctoral implica un esfuerzo mayusculo, de intensa dedicacion exclusiva durante un lapso de cinco anos para la persona que emprenda este importante desafio academico-cientifico, el Doctorado estima menester el reconocimiento de un trabajo de investigacion original, que se destaque por su aporte para el desarrollo del conocimiento en alguna de las diversas areas de las Ciencias de la Tierra. Una serie de condiciones referidas al contenido, a la forma, al estilo, al valor heuristico de las conclusiones y a la proyeccion conceptual de la tesis, se toma en cuenta para valorar su seleccion. Los lineamientos y los items necesarios para que el evaluador pueda reconocer el caracter de la tesis destacada se encuentran establecidos en el reglamento del premio. A traves del Premio Dr. Carlos Gordillo, el Doctorado en Ciencias Geologicas no solo tiene como proposito reconocer adecuadamente una tesis doctoral destacada, sino tambien presentarla como ejemplo para motivar y alentar la produccion de nuevas tesis de excelencia. Los aportes doctorales de alto valor innovador son considerados fuentes conceptuales indispensables para el desarrollo, la consolidacion y proyeccion de la nacion, y de la humanidad toda, dada la naturaleza universal del conocimiento cientifico. Entre los egresado de esta Facultad se encuentran doctores de notable trascendencia en el ambito de la docencia y de la investigacion cientifica; entre estas personas se distingue el Dr. Carlos Gordillo, cuya labor profesional estuvo vinculada durante extensos anos al estudio de las Sierras Pampeanas de la provincia de Cordoba. Su produccion cientifica, de sobresaliente alcance internacional, estuvo relacionada con la investigacion de las rocas del basamento, expuestas en gran parte del territorio provincial, asi como al inicio de metodologias novedosas para el estudio de minerales radioactivos y su eventual aprovechamiento, como fuentes de energia. El legado del Dr. Gordillo trasciende, asimismo, en su condicion de mentor de recursos humanos; entre los cuales, se encuentran destacados investigadores y profesores de esta Facultad. El Premio Dr. Carlos Gordillo consiste en la entrega de un diploma de honor, una medalla alusiva y la publicacion de una resena de la tesis por parte de la Facultad, para su divulgacion a toda la sociedad. Esta primera mencion, en referencia a los premios para los bienios 2011-2012 y 2012-2013, hace merecedor del premio al Dr. Juan Jose Rustan y al Dr. Mateo Martini para los periodos senalados, respectivamente. El jurado ad hoc que evaluo las tesis doctorales destacadas segun las pautas reglamentarias, partiendo del conjunto de tesis que recibieron la calificacion “Laureada”, fue elegido por el Consejo Asesor del Doctorado, y estuvo integrado por los siguientes academicos, profesores, investigadores de extensa trayectoria y reconocimiento: bienio 2011-2012, Dr. Miguel J. Haller, Dr. Miguel O. Mancenido, y Dr. Daniel E. Martinez; bienio 2013-2014, Dr. Federico Isla, Dr. Alberto Riccardi, y Dr. Jose Salfity, cuyo compromiso e importante labor son profundamente agradecidos por nuestro Doctorado.

Ameghiniana, Aug 1, 2013

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.

Micropaleontology, Apr 1, 2001

Chitinozoans from the Los Azules Formation, central Precordillera of Argentina are documented. Th... more Chitinozoans from the Los Azules Formation, central Precordillera of Argentina are documented. The formation is divided into three members. Two chitinozoan assemblages are recognized: the late Llanvirn Lower Los Azules Palynological Assemblage, in the middle member includes smooth forms, while the early Caradoc Upper Los Azules Palynological Assemblage, from the upper member, is mainly composed of ornamented specimens. Two new species are described: Eisenackitina yolei Ottone and Holfeltz and Hercochitina volkheimerii Ottone and Holfeltz. The Los Azules chitinozoan faunas have species in common with contemporaneous assemblages from Laurentia but also northern Gondwana and Baltica.

Estonian Journal of Earth Sciences

The most extensive sea-level event of the Early Ordovician is known as the Evae transgression. Du... more The most extensive sea-level event of the Early Ordovician is known as the Evae transgression. During the highstand of this event, the conodont index species Oepikodus evae reached its acme and often coincided with the peak in conodont generic diversity. The main objective of this study is to statistically evaluate the degree of similarity in conodont species composition between the Argentine Precordillera, Laurentia, Baltica, Kazakhstania, South China, and Australia at that time. Cluster analysis shows two main faunal groups moderately to poorly differentiated, indicating that some paleogeographic barriers may not have decreased during the Evae transgression. On the other hand, a paleolatitudinal control over the distribution of species is suspected, considering the occurrence of a higher number of species dwelling in mid-low latitudes than in mid-latitudes. This suggests that this event could have been of a lesser magnitude or duration than previously claimed.

Journal of South American Earth Sciences, Dec 1, 2021

Journal of Vertebrate Paleontology, Apr 16, 2014

ABSTRACT A collection of over 550 elasmobranch teeth (Family Lonchidiidae) were obtained from fre... more ABSTRACT A collection of over 550 elasmobranch teeth (Family Lonchidiidae) were obtained from fresh water fluvial deposits of the Middle–Upper Triassic (Ladinian–Carnian) Paramillo Formation, in northwestern Mendoza Province, Argentina. The new hybodontid species, Lonchidion paramilloensis, sp. nov., solely based on teeth, is within a 20-m-thick interval containing black shale interbedded with andesitic sills and intercalated with lensoidal calcarenites. The teeth have a characteristic labial peg with an accessory cusplet and a low gracile crown that is narrower labiolingually and more elongate laterally. The teeth are similar to some North American Late Triassic and Late Cretaceous species of the genus Lonchidion (e.g., L. humblei, L. griffisi, L. selachos), but are distinct in having a low primary cusp, up to seven pairs of lateral cusplets, a rounded-triangular-shaped labial peg with one accessory cusplet, and an absence of other crown ornaments. Color analyses of upper tooth crowns indicate an ichthyolith alteration index (IAI)/conodont alteration index (CAI) value of 6.0–6.5 (360–610°C). Considerable pitting and alteration of specimens indicates thermal alteration to 610°C and (or) chemical alteration.

Geological Journal, Nov 8, 2017

Handling Editor: I. Somerville This study includes 3 localities from the Jáchal area in the Centr... more Handling Editor: I. Somerville This study includes 3 localities from the Jáchal area in the Central Precordillera of San Juan Province, from north to south: the Oculta creek, Las Aguaditas creek, and Cerro La Chilca sections. We deal with the graptolite faunas and conodont index species recorded from units that overlie the carbonate San Juan Formation, spanning the lower part of the Los Azules, Las Aguaditas, and Gualcamayo formations in their respective areas. The index graptolites and associated species are reported, which enable the recognition of the Levisograptus dentatus Zone in the Central Precordillera. The presence of graptolites in the limestones from the top of the San Juan Formation at the Cerro La Chilca section is documented for the first time. The record of representatives of the Lenodus variabilis, Yangtzeplacognathus crassus, Eoplacognathus pseudoplanus, Histiodella, and Periodon lineages recognized in these units, linked with respective graptolite zones, provide precise information for global correlation purposes. The use of conodont and graptolite zones from different areas of the Central Precordillera enables the verification of the diachronous contact between the San Juan Formation and overlying units, which spans the lower to middle Darriwilian, in our investigated sections and classical localities previously documented.

Geological Magazine, Jan 29, 2015

Two tuffs in the Lower Cretaceous Agrio Formation, Neuquén Basin, provided U-Pb zircon radioisoto... more Two tuffs in the Lower Cretaceous Agrio Formation, Neuquén Basin, provided U-Pb zircon radioisotopic ages of 129.09 ± 0.16 Ma and 127.42 ± 0.15 Ma. Both horizons are well constrained biostratigraphically by ammonites and nannofossils and can be correlated with the 'standard' sequence of the Mediterranean Province. The lower horizon is very close to the base of the Upper Hauterivian and the upper horizon to the Hauterivian/Barremian boundary, indicating that the former lies at c. 129.5 Ma and the latter at c. 127 Ma. These new radioisotopic ages fill a gap of over 8 million years in the numerical calibration of the current global Early Cretaceous geological time scale.

Stratigraphy & timescales, 2016

Abstract The state of the art on conodont and graptolite biostratigraphy of the Ordovician System... more Abstract The state of the art on conodont and graptolite biostratigraphy of the Ordovician System of Argentina is introduced. A composite biostratigraphic chart is assembled by precise ties of conodont and graptolite index species throughout the system. The conodont faunas of the Precordillera of western Argentina are dominated by components of the Tropical Domain during the Early Ordovician, but an increasing interplay of temperate to cold-water taxa is developed along the period. The conodont associations from northwestern Argentine basins (with major faunas in Cordillera Oriental and Sistema de Famatina) consist of mixed assemblages from both Domains characterizing transitional environments, always from the marine Shallow-Water Realm. Two series of biostratigraphic units, 29 conodont zones and 35 graptolite zones, are determined through the Ordovician System of Argentina, with several bizones divided into subzones. In the Argentine Precordillera, 17 conodont zones and 19 graptolite zones are determined. A number of these biozones are recognized in neighboring areas, such as San Jorge, Bloque de San Rafael, and Cordillera Frontal. In northwestern Argentine basins, the biozones are distributed in the Sistema de Famatina, Puna, Cordillera Oriental, and Sierras Subandinas, totalizing 12 conodont zones and 16 graptolite zones. Detailed graptolite zonations are achieved for the Lower Ordovician of northwestern Argentina and for the Middle and Upper Ordovician of the Precordillera. The conodont faunas from the Upper Ordovician are not well documented in Argentine basins instead. The graptolite assemblages of the Cordillera Oriental are characterized by faunas of high and medium paleolatitudes. Conversely, Middle and Upper Ordovician graptolite faunas of the Precordillera are referred to as low paleolatitudes.

Palaeogeography, Palaeoclimatology, Palaeoecology, Nov 1, 2013

Although documented from Estonia, Latvia, Sweden, eastern North America, and China, the Middle Or... more Although documented from Estonia, Latvia, Sweden, eastern North America, and China, the Middle Ordovician (Darriwilian) positive δ 13 C excursion known as the MDICE has previously not been recognized with certainty in South America. The most promising region in South America for detailed Middle Ordovician carbon isotope research is the Precordillera of western Argentina, where there are many excellent exposures of biostratigraphically well-dated carbonate successions spaning the Tremadocian through Sandbian stratigraphic interval. For this project, we collected numerous isotope and conodont samples from the middle Darriwilian Las Chacritas and Aguaditas formations at their type localities, which yielded important biostratigraphic data as well as informative δ 13 C carb values. In the E. pseudoplanus Zone in the upper half of the Las Chacritas Formation, there is a relatively modest but distinct δ 13 C carb excursion. Because its stratigraphic position and magnitude closely agree with the MDICE in other parts of the world, we recognize it as the first firm record of this excursion in South America. The fact that the δ 13 C carb curve from the Las Aguaditas Formation shows no such excursion is due to the existence of a stratigraphic gap between the Lower and Middle Members of this formation that cuts out the excursion interval. The Precordilleran MDICE is used for detailed long-range correlations with successions in Baltoscandia, Newfoundland, and China illustrating the usefulness of also this δ 13 C carb excursion as a global stratigraphic tool. A recent proposal of a greatly extended chronostratigraphic range of the Table Head Group on Newfoundland is rejected based on well-established biostratigraphic evidence.

Journal of South American Earth Sciences, Jun 1, 2023

Palaeogeography, Palaeoclimatology, Palaeoecology, Mar 1, 2007

High resolution graptolite–conodont biostratigraphy and biofacies analysis have been carried out ... more High resolution graptolite–conodont biostratigraphy and biofacies analysis have been carried out for the lower member of the Los Azules Formation exposed in the Cerro Viejo area, San Juan Precordillera, western Argentina. The rock succession is composed of alternating rich fossiliferous argillites and virtually barren volcanic ash beds (K-bentonites) of Darriwilian (Da2) age. Graptolite and conodont collections from the Los Azules

Micropaleontology, 1999

... The siliciclastic units bear rich graptolite and conodont faunas extensively described in the... more ... The siliciclastic units bear rich graptolite and conodont faunas extensively described in the paleontological literature (eg, Cuerda and Furque 1975; Cuerda 1986; Cuerda and Alfaro 1986; Peralta 1986; Hunicken and Ortega 1987; Ortega ...

Revista de la Facultad de Ciencias Exactas, Físicas y Naturales, Oct 3, 2016

El Doctorado en Ciencias Geologicas de la Facultad de Ciencias Exactas, Fisicas y Naturales, Univ... more El Doctorado en Ciencias Geologicas de la Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, se complace en presentar los primeros galardonados del Premio Dr. Carlos Gordillo. Este premio fue instituido por la Facultad mediante la Resolucion no 612 del Honorable Consejo Directivo, registrada el 23 de julio de 2010, a partir de una propuesta elevada por el Doctorado para poner en relieve y divulgar la tesis doctoral mas destacada de cada bienio. En virtud de que la realizacion de una tesis doctoral implica un esfuerzo mayusculo, de intensa dedicacion exclusiva durante un lapso de cinco anos para la persona que emprenda este importante desafio academico-cientifico, el Doctorado estima menester el reconocimiento de un trabajo de investigacion original, que se destaque por su aporte para el desarrollo del conocimiento en alguna de las diversas areas de las Ciencias de la Tierra. Una serie de condiciones referidas al contenido, a la forma, al estilo, al valor heuristico de las conclusiones y a la proyeccion conceptual de la tesis, se toma en cuenta para valorar su seleccion. Los lineamientos y los items necesarios para que el evaluador pueda reconocer el caracter de la tesis destacada se encuentran establecidos en el reglamento del premio. A traves del Premio Dr. Carlos Gordillo, el Doctorado en Ciencias Geologicas no solo tiene como proposito reconocer adecuadamente una tesis doctoral destacada, sino tambien presentarla como ejemplo para motivar y alentar la produccion de nuevas tesis de excelencia. Los aportes doctorales de alto valor innovador son considerados fuentes conceptuales indispensables para el desarrollo, la consolidacion y proyeccion de la nacion, y de la humanidad toda, dada la naturaleza universal del conocimiento cientifico. Entre los egresado de esta Facultad se encuentran doctores de notable trascendencia en el ambito de la docencia y de la investigacion cientifica; entre estas personas se distingue el Dr. Carlos Gordillo, cuya labor profesional estuvo vinculada durante extensos anos al estudio de las Sierras Pampeanas de la provincia de Cordoba. Su produccion cientifica, de sobresaliente alcance internacional, estuvo relacionada con la investigacion de las rocas del basamento, expuestas en gran parte del territorio provincial, asi como al inicio de metodologias novedosas para el estudio de minerales radioactivos y su eventual aprovechamiento, como fuentes de energia. El legado del Dr. Gordillo trasciende, asimismo, en su condicion de mentor de recursos humanos; entre los cuales, se encuentran destacados investigadores y profesores de esta Facultad. El Premio Dr. Carlos Gordillo consiste en la entrega de un diploma de honor, una medalla alusiva y la publicacion de una resena de la tesis por parte de la Facultad, para su divulgacion a toda la sociedad. Esta primera mencion, en referencia a los premios para los bienios 2011-2012 y 2012-2013, hace merecedor del premio al Dr. Juan Jose Rustan y al Dr. Mateo Martini para los periodos senalados, respectivamente. El jurado ad hoc que evaluo las tesis doctorales destacadas segun las pautas reglamentarias, partiendo del conjunto de tesis que recibieron la calificacion “Laureada”, fue elegido por el Consejo Asesor del Doctorado, y estuvo integrado por los siguientes academicos, profesores, investigadores de extensa trayectoria y reconocimiento: bienio 2011-2012, Dr. Miguel J. Haller, Dr. Miguel O. Mancenido, y Dr. Daniel E. Martinez; bienio 2013-2014, Dr. Federico Isla, Dr. Alberto Riccardi, y Dr. Jose Salfity, cuyo compromiso e importante labor son profundamente agradecidos por nuestro Doctorado.

Ameghiniana, Aug 1, 2013

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.

Micropaleontology, Apr 1, 2001

Chitinozoans from the Los Azules Formation, central Precordillera of Argentina are documented. Th... more Chitinozoans from the Los Azules Formation, central Precordillera of Argentina are documented. The formation is divided into three members. Two chitinozoan assemblages are recognized: the late Llanvirn Lower Los Azules Palynological Assemblage, in the middle member includes smooth forms, while the early Caradoc Upper Los Azules Palynological Assemblage, from the upper member, is mainly composed of ornamented specimens. Two new species are described: Eisenackitina yolei Ottone and Holfeltz and Hercochitina volkheimerii Ottone and Holfeltz. The Los Azules chitinozoan faunas have species in common with contemporaneous assemblages from Laurentia but also northern Gondwana and Baltica.

Estonian Journal of Earth Sciences

The most extensive sea-level event of the Early Ordovician is known as the Evae transgression. Du... more The most extensive sea-level event of the Early Ordovician is known as the Evae transgression. During the highstand of this event, the conodont index species Oepikodus evae reached its acme and often coincided with the peak in conodont generic diversity. The main objective of this study is to statistically evaluate the degree of similarity in conodont species composition between the Argentine Precordillera, Laurentia, Baltica, Kazakhstania, South China, and Australia at that time. Cluster analysis shows two main faunal groups moderately to poorly differentiated, indicating that some paleogeographic barriers may not have decreased during the Evae transgression. On the other hand, a paleolatitudinal control over the distribution of species is suspected, considering the occurrence of a higher number of species dwelling in mid-low latitudes than in mid-latitudes. This suggests that this event could have been of a lesser magnitude or duration than previously claimed.

Journal of South American Earth Sciences, Dec 1, 2021

Journal of Vertebrate Paleontology, Apr 16, 2014

ABSTRACT A collection of over 550 elasmobranch teeth (Family Lonchidiidae) were obtained from fre... more ABSTRACT A collection of over 550 elasmobranch teeth (Family Lonchidiidae) were obtained from fresh water fluvial deposits of the Middle–Upper Triassic (Ladinian–Carnian) Paramillo Formation, in northwestern Mendoza Province, Argentina. The new hybodontid species, Lonchidion paramilloensis, sp. nov., solely based on teeth, is within a 20-m-thick interval containing black shale interbedded with andesitic sills and intercalated with lensoidal calcarenites. The teeth have a characteristic labial peg with an accessory cusplet and a low gracile crown that is narrower labiolingually and more elongate laterally. The teeth are similar to some North American Late Triassic and Late Cretaceous species of the genus Lonchidion (e.g., L. humblei, L. griffisi, L. selachos), but are distinct in having a low primary cusp, up to seven pairs of lateral cusplets, a rounded-triangular-shaped labial peg with one accessory cusplet, and an absence of other crown ornaments. Color analyses of upper tooth crowns indicate an ichthyolith alteration index (IAI)/conodont alteration index (CAI) value of 6.0–6.5 (360–610°C). Considerable pitting and alteration of specimens indicates thermal alteration to 610°C and (or) chemical alteration.

Geological Journal, Nov 8, 2017

Handling Editor: I. Somerville This study includes 3 localities from the Jáchal area in the Centr... more Handling Editor: I. Somerville This study includes 3 localities from the Jáchal area in the Central Precordillera of San Juan Province, from north to south: the Oculta creek, Las Aguaditas creek, and Cerro La Chilca sections. We deal with the graptolite faunas and conodont index species recorded from units that overlie the carbonate San Juan Formation, spanning the lower part of the Los Azules, Las Aguaditas, and Gualcamayo formations in their respective areas. The index graptolites and associated species are reported, which enable the recognition of the Levisograptus dentatus Zone in the Central Precordillera. The presence of graptolites in the limestones from the top of the San Juan Formation at the Cerro La Chilca section is documented for the first time. The record of representatives of the Lenodus variabilis, Yangtzeplacognathus crassus, Eoplacognathus pseudoplanus, Histiodella, and Periodon lineages recognized in these units, linked with respective graptolite zones, provide precise information for global correlation purposes. The use of conodont and graptolite zones from different areas of the Central Precordillera enables the verification of the diachronous contact between the San Juan Formation and overlying units, which spans the lower to middle Darriwilian, in our investigated sections and classical localities previously documented.

Geological Magazine, Jan 29, 2015

Two tuffs in the Lower Cretaceous Agrio Formation, Neuquén Basin, provided U-Pb zircon radioisoto... more Two tuffs in the Lower Cretaceous Agrio Formation, Neuquén Basin, provided U-Pb zircon radioisotopic ages of 129.09 ± 0.16 Ma and 127.42 ± 0.15 Ma. Both horizons are well constrained biostratigraphically by ammonites and nannofossils and can be correlated with the 'standard' sequence of the Mediterranean Province. The lower horizon is very close to the base of the Upper Hauterivian and the upper horizon to the Hauterivian/Barremian boundary, indicating that the former lies at c. 129.5 Ma and the latter at c. 127 Ma. These new radioisotopic ages fill a gap of over 8 million years in the numerical calibration of the current global Early Cretaceous geological time scale.

Stratigraphy & timescales, 2016

Abstract The state of the art on conodont and graptolite biostratigraphy of the Ordovician System... more Abstract The state of the art on conodont and graptolite biostratigraphy of the Ordovician System of Argentina is introduced. A composite biostratigraphic chart is assembled by precise ties of conodont and graptolite index species throughout the system. The conodont faunas of the Precordillera of western Argentina are dominated by components of the Tropical Domain during the Early Ordovician, but an increasing interplay of temperate to cold-water taxa is developed along the period. The conodont associations from northwestern Argentine basins (with major faunas in Cordillera Oriental and Sistema de Famatina) consist of mixed assemblages from both Domains characterizing transitional environments, always from the marine Shallow-Water Realm. Two series of biostratigraphic units, 29 conodont zones and 35 graptolite zones, are determined through the Ordovician System of Argentina, with several bizones divided into subzones. In the Argentine Precordillera, 17 conodont zones and 19 graptolite zones are determined. A number of these biozones are recognized in neighboring areas, such as San Jorge, Bloque de San Rafael, and Cordillera Frontal. In northwestern Argentine basins, the biozones are distributed in the Sistema de Famatina, Puna, Cordillera Oriental, and Sierras Subandinas, totalizing 12 conodont zones and 16 graptolite zones. Detailed graptolite zonations are achieved for the Lower Ordovician of northwestern Argentina and for the Middle and Upper Ordovician of the Precordillera. The conodont faunas from the Upper Ordovician are not well documented in Argentine basins instead. The graptolite assemblages of the Cordillera Oriental are characterized by faunas of high and medium paleolatitudes. Conversely, Middle and Upper Ordovician graptolite faunas of the Precordillera are referred to as low paleolatitudes.

Palaeogeography, Palaeoclimatology, Palaeoecology, Nov 1, 2013

Although documented from Estonia, Latvia, Sweden, eastern North America, and China, the Middle Or... more Although documented from Estonia, Latvia, Sweden, eastern North America, and China, the Middle Ordovician (Darriwilian) positive δ 13 C excursion known as the MDICE has previously not been recognized with certainty in South America. The most promising region in South America for detailed Middle Ordovician carbon isotope research is the Precordillera of western Argentina, where there are many excellent exposures of biostratigraphically well-dated carbonate successions spaning the Tremadocian through Sandbian stratigraphic interval. For this project, we collected numerous isotope and conodont samples from the middle Darriwilian Las Chacritas and Aguaditas formations at their type localities, which yielded important biostratigraphic data as well as informative δ 13 C carb values. In the E. pseudoplanus Zone in the upper half of the Las Chacritas Formation, there is a relatively modest but distinct δ 13 C carb excursion. Because its stratigraphic position and magnitude closely agree with the MDICE in other parts of the world, we recognize it as the first firm record of this excursion in South America. The fact that the δ 13 C carb curve from the Las Aguaditas Formation shows no such excursion is due to the existence of a stratigraphic gap between the Lower and Middle Members of this formation that cuts out the excursion interval. The Precordilleran MDICE is used for detailed long-range correlations with successions in Baltoscandia, Newfoundland, and China illustrating the usefulness of also this δ 13 C carb excursion as a global stratigraphic tool. A recent proposal of a greatly extended chronostratigraphic range of the Table Head Group on Newfoundland is rejected based on well-established biostratigraphic evidence.

Journal of South American Earth Sciences, Jun 1, 2023

Palaeogeography, Palaeoclimatology, Palaeoecology, Mar 1, 2007

High resolution graptolite–conodont biostratigraphy and biofacies analysis have been carried out ... more High resolution graptolite–conodont biostratigraphy and biofacies analysis have been carried out for the lower member of the Los Azules Formation exposed in the Cerro Viejo area, San Juan Precordillera, western Argentina. The rock succession is composed of alternating rich fossiliferous argillites and virtually barren volcanic ash beds (K-bentonites) of Darriwilian (Da2) age. Graptolite and conodont collections from the Los Azules

Micropaleontology, 1999

... The siliciclastic units bear rich graptolite and conodont faunas extensively described in the... more ... The siliciclastic units bear rich graptolite and conodont faunas extensively described in the paleontological literature (eg, Cuerda and Furque 1975; Cuerda 1986; Cuerda and Alfaro 1986; Peralta 1986; Hunicken and Ortega 1987; Ortega ...