Maderas fósiles de la isla Seymour, Formación La Meseta, Antártica
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Date
1994
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Abstract
Se determinan maderas fósiles terciarias provenientes de la Formación La Meseta, en la isla Seymour (64°15' s., 56°40' W.). La megaflora se compone de cinco coniferas: Araucarioxylon novaezelandae Stopes, A. pseudoparenchyrnatosurn Gothan, A. seyrnourense sp. nov., Cupressinoxylon seyrnourense sp. nov., PhyIlocladoxylon antarcticurn Cothan y la dicotiledonea Nothofagoxylon scalariforme Cothan. Las seis especies identificadas, tres de las cuales son citadas por vez primera, tienen afinidades con especies arbóreas que crecen actualmente en zonas boscosas de climas lluviosos, temperados-fríos, con estaciones diferenciadas·. Sobre la base de este conjunto florístico, se injieren condiciones paleoclimáticas similares para los depósitos de la isla Seymour durante el Eoceno-Oligoceno. Se discute las condiciones de depositación y se concluye que las maderas se petrificaron en un medio rico en carbonatos. Las maderas habrían flotado en el mar, siendo depositadas en una zona protegida, probablemente una bahía. Estosfósiles, bien situados en los niveles eocénico-oligocénicos de la Formación La Meseta, pueden ser utilizados como indicadores en correlaciones estratigráficas entre el extremo sur de Sudamérica y otras localidades de la Antártica (isla Rey Jorge), en donde se han encontrado maderas fósiles similares.
Tertiary fossil woods found at La Meseta Formation, in Seymour lsland (64 0 17S; 56 50 W) are identified. The macroflora is composed by five coniferous species: Araucarioxylon novaezelandae Stopes. A. pseudoparenchyrnatosum Gothan; A. seymourense Torres. Cupressinoxylon seymourense Torres. PhyllocJadoxylon antarctícum Gothan ami one dicotyledoneus wood. Nothofagoxylon scalariforme Gothan. The six taxa identified, three of which are cited for the first time, have affinities with present trees that grow in forest areas of temperated cold rainy climates with differential seasons. A similar palaeoclimate is infered for the deposits from Seymour Island in the Eocene-Oligocene. The conditions of the deposit are discussed and it is concluded that petrification occurred in a carbonate rich medium. The woods would have floated in the sea, being deposited in protected zone, probably in a bay. These fossil woods come from well-defined levels of Eocene-Oligocene age from La Meseta Formation and can be used as guides in stratigraphic correlations with southern Southamerican areas (Chile) and other Antarctica localities (King George Island) in which similar tertiary woods have been found.
Tertiary fossil woods found at La Meseta Formation, in Seymour lsland (64 0 17S; 56 50 W) are identified. The macroflora is composed by five coniferous species: Araucarioxylon novaezelandae Stopes. A. pseudoparenchyrnatosum Gothan; A. seymourense Torres. Cupressinoxylon seymourense Torres. PhyllocJadoxylon antarctícum Gothan ami one dicotyledoneus wood. Nothofagoxylon scalariforme Gothan. The six taxa identified, three of which are cited for the first time, have affinities with present trees that grow in forest areas of temperated cold rainy climates with differential seasons. A similar palaeoclimate is infered for the deposits from Seymour Island in the Eocene-Oligocene. The conditions of the deposit are discussed and it is concluded that petrification occurred in a carbonate rich medium. The woods would have floated in the sea, being deposited in protected zone, probably in a bay. These fossil woods come from well-defined levels of Eocene-Oligocene age from La Meseta Formation and can be used as guides in stratigraphic correlations with southern Southamerican areas (Chile) and other Antarctica localities (King George Island) in which similar tertiary woods have been found.
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Serie Científica, nº 44, pp. 17-38, 1994