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11. Eocene palynoflora from the La Marcelina Formation, Patagonia, Argentina.

Author

Noetinger, Sol, Aramendía, Inés, Pujana, Roberto R, Massini, Juan L García, and Barreda, Viviana D

Subjects
EOCENE Epoch, POLLEN, TEMPERATE climate, BOTANY, PROTEACEAE
Abstract

Southern Patagonia contains several Eocene fossiliferous deposits that have only been superficially explored and studied. One of these corresponds to the La Marcelina Formation with outcrops in the south-western slope of the Deseado Massif, Santa Cruz Province, Argentina. No detailed palynological studies have been performed so far in this unit. Here we estimate the age, palaeoenvironment, and climatic conditions based on the analysis of terrestrially derived spores, algae cysts, and pollen grains. The recovered association supports an Eocene age and concurs with a mixed flora, including Gondwanan and Neotropical elements, dominated by Podocarpaceae, Nothofagaceae, and Proteaceae, and that probably developed under a temperate and humid climate. Overall, these results expand our understanding of the composition of Eocene floras from the highest latitudes of South America, as well as provide new evidence of past paleoclimates for the area. [ABSTRACT FROM AUTHOR]

Published
2023
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19. Reconstructing Cenozoic Patagonian biotas using multi-proxy fossil records

Author

Palazzesi, Luis, primary, Vizcaíno, Sergio F., additional, Barreda, Viviana D., additional, Cuitiño, José I., additional, del Río, Claudia J., additional, Goin, Francisco, additional, González Estebenet, M. Sol, additional, Guler, M. Verónica, additional, Gandolfo, María Alejandra, additional, Kay, Richard, additional, Parras, Ana, additional, Reguero, Marcelo A., additional, and Zamaloa, María del Carmen, additional

Published
2021
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25. The rise of grasslands is linked to atmospheric CO2 decline in the late Palaeogene.

Author

Palazzesi, Luis, Hidalgo, Oriane, Barreda, Viviana D., Forest, Félix, and Höhna, Sebastian

Subjects
PALEOGENE, GRASSLANDS, CLIMATE change, GRASSLAND soils, ATMOSPHERIC temperature, GRASSES
Abstract

Grasslands are predicted to experience a major biodiversity change by the year 2100. A better understanding of how grasslands have responded to past environmental changes will help predict the outcome of current and future environmental changes. Here, we explore the relationship between past atmospheric CO2 and temperature fluctuations and the shifts in diversification rate of Poaceae (grasses) and Asteraceae (daisies), two exceptionally species-rich grassland families (~11,000 and ~23,000 species, respectively). To this end, we develop a Bayesian approach that simultaneously estimates diversification rates through time from time-calibrated phylogenies and correlations between environmental variables and diversification rates. Additionally, we present a statistical approach that incorporates the information of the distribution of missing species in the phylogeny. We find strong evidence supporting a simultaneous increase in diversification rates for grasses and daisies after the most significant reduction of atmospheric CO2 in the Cenozoic (~34 Mya). The fluctuations of paleo-temperatures, however, appear not to have had a significant relationship with the diversification of these grassland families. Overall, our results shed new light on our understanding of the origin of grasslands in the context of past environmental changes. A better understanding of how grasslands have responded to past environmental changes will help predict the outcomes of future changes. This study explores past climatic fluctuations and shifts in the diversification rate of grasses and daisies, finding strong evidence for a simultaneous increase in their diversification rates following a reduction of atmospheric CO2 in the Cenozoic. [ABSTRACT FROM AUTHOR]

Published
2022
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28. Salvinialean megaspores in the Late Cretaceous of southern Patagonia, Argentina.

Author

SANTAMARINA, PATRICIO E., BARREDA, VIVIANA D., IGLESIAS, ARI, and VARELA, AUGUSTO N.

Subjects
*FERNS, *PALEONTOLOGY, *CRETACEOUS Period, *CRYPTOGAMS, *GEOLOGY
Abstract

We report here two megaspores species related to the aquatic ferns of the order Salviniales from the Late Cretaceous Mata Amarilla Formation (Austral Basin), southern Santa Cruz Province, Argentina. We identified the species Arcellites disciformis and Balmeisporites cf. B. holodictyus. The presence of A. disciformis, in particular, is significant not only because it represents the first record for the Southern Hemisphere, indicating a bi-hemispheric distribution for the species, but also because it increases the diversity of this genus in Patagonia. The new findings of salvinialean megaspores highlight the importance of water ferns in the Late Cretaceous aquiferous enviroments of southern South America. The common occurrences of Arcellites and Balmeisporites, whether in shallow, fresh or brackish water facies, indicates aquatic paleoenvironment of the Mata Amarilla Formation, as was inferred also from the sedimentological evidence. Their presence also indicates that the lower and middle levels of the Mata Amarilla Formation can be attributed to the megaspore Zone M3 (Albian-Cenomanian) defined for the Cretaceous of Patagonia. [ABSTRACT FROM AUTHOR]

Published
2018
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31. Edad y paleoambiente de la Formación del Buey (Mioceno), sierra de Famatina, La Rioja, Argentina: evidencias sedimentológicas y palinológicas

Author

Barreda, Viviana D., Ottone, Eduardo Guillermo, Davila, Federico Miguel, and Astini, Ricardo A.

Subjects
Sedimentología, Mioceno, Argentina, Palinología, Geología, Sierra de Famatina, CIENCIAS NATURALES Y EXACTAS, Ciencias de la Tierra y relacionadas con el Medio Ambiente
Abstract

Se analizan las facies y los paleoambientes sedimentarios de la Formación del Buey, sierra de Famatina, provincia de La Rioja. Se dan a conocer además, los primeros resultados palinológicos para esta unidad. La Formación del Buey está compuesta en forma mayoritaria por pelitas rosáceas a rojizas, con intercalaciones de conglomerados finos y conspicuos niveles carbonáticos, interpretados como depósitos fluviales entrelazados y lacustres. La asociación palinológica proviene de la facies lacustre, es poco abundante y diversa, y está integrada por polen, esporas y algas de agua dulce. El espectro polínico está compuesto por Podocarpaceae, probablemente alóctonas, Malvaceae, hierbas y arbustos mayormente xerofíticos y halofíticos de Chenopodiaceae, Ephedraceae, Convulvaceae y Asteraceae junto con formas de distribución tropical como Magnaperiporites (Convolvulaceae?) y Senipites (Symplocaceae). También se reconocen pteridofitas, briofitas y algas Chlorococcales (Pediastrum y Botryococcus). Especies de Malvaceae y Sparganiaceae/Thyphaceae constituirían la vegetación de un lago de agua dulce, un hábitat adecuado para el desarrollo de algas verdes planctónicas, en tanto que las formas restantes se habrían desarrollado en los márgenes del lago. El registro de especies xerofíticas y halofíticas, el desarrollo de calcretes y de yeso intrasedimentario, junto a la presencia de elementos tropicales sugieren condiciones semiáridas y temperaturas templado-cálidas a cálidas. Dataciones radimétricas recientes indican una edad miocena media para la Fm. del Buey; la evidencia palinológica es consistente con este rango temporal. Sedimentary facies and palaeoenvironments are described and interpreted from the del Buey Formation, Famatina Range, La Rioja Province. Miospores and algae are reported for the first time in this unit. The del Buey Formation is mainly composed by pinkish to reddish shales, some conglomerates, and conspicuous levels of mudstones, interpreted as braidplain and lacustrine deposits. The palynological assemblage, recovered from the lacustrine facies, is scarce and low-diversified. It is composed by probably allochtonous Podocarpaceae, together with Malvaceae and mostly halophytic-xerophytic herbs and shrubs of Chenopodiaceae, Ephedraceae, Convolvulaceae and Asteraceae, as well as tropical taxa such as Magnaperiporites (Convolvulaceae?) and Senipites (Symplocaceae). The assemblage also contains Pteridophyta, Bryophyta and Chlorococcales (Botryococcus and Pediastrum). Species of Malvaceae and Sparganiaceae/Thyphaceae would represent the vegetation of a freshwater lake, a habitat adequate to the development of planktonic green algae, whereas the remaining taxa could have developed in lacustrine marginal environments. The record of xerophytic and tropical taxa coupled with the development of calcretes and intrasedimentary gypsum suggest semiarid and warm to warm-temperate climate conditions. Recent isotopic data indicate a Middle Miocene age for the del Buey Formation, palynological evidence supports this temporal assignment. Fil: Barreda, Viviana D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Ottone, Eduardo Guillermo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Davila, Federico Miguel. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geología Básica y Aplicada. Cátedra de Estratigrafía y Geología Histórica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Astini, Ricardo A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geología Básica y Aplicada. Cátedra de Estratigrafía y Geología Histórica; Argentina

Published
2006

33. Juan Carlos Gamerro (1923–2013)

Author

Archangelsky, Sergio, primary, Archangelsky, Ana, additional, Palamarczuk, Susana, additional, Cárdenas, Orlando, additional, Morbelli, Marta A., additional, and Barreda, Viviana D., additional

Published
2013
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