Estudio palinoestratigráfico del Oligoceno tardío-Mioceno en secciones de la costa patagónica y plataforma continental argentina

• Autores: Viviana Dora Barreda, Susana Palamarczuk
• Localización: Serie correlación geológica, ISSN-e 1666-9479, ISSN 1514-4186, Vol. 14, Nº. 1, 2000
• Idioma: español
• Títulos paralelos:
  • Palinostratigraphical study of the Late Oligocene-Miocene in sections of Patagonian shore and continental platform of Argentina
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• Resumen

  • The purpose of this study is to provide a preliminary palynostratigraphic correlation scheme based on integrated distributions of both, continental and marine palynomorphs from surface and subsurface sections (Upper Oligocene through Early-Middle Miocene) located along the Atlantic Patagonic Coast and in the Argentine Continental Shelf between latitudes 40º and 53º S. The age assignment is supported by concurrent information from known local and regional stratigraphic ranges of the species and by the presence of other diagnostic fossil groups. Four informal angiosperm pollen and dinocyst associations are proposed: M-M/R(Late Oligocene), C-T/L, G/C (Early Miocene) and T-B/H (late Early - Middle Miocene). The Lower association is characterized by the presence of Mutisiapollis viteauensis (Barreda) Barreda, Margocolporites tenuireticulatus Barreda and ?Reticulatosphaera actinocoronata (Benedek) Bujak and Matsuoka, and was recognized in Mazarredo and Punta Nava sections, southern San Jorge Gulf area, and in Aries x-1 well, Austral Basin, interval 530-350m. In Ra x-1 well, Colorado Basin, below depth 1790m (Elvira Formation), the association was not clearly recognized due to the scarcity of dinocysts, although the interval might represent the proposed M-M/R association.

    At level 1930m (the lowermost fertile sample) the presence of Tuberculodinium vancampoae (Rossignol) Wall indicates an age not older than Upper Oligocene. The C-T/L association , characterized by Cyperaceaepollis neogenicus Krutzsch, Tricolpites trioblatus Mildenhall and Pocknall, and Lingulodinium hemicystum Mc Minn, was identified in Ra x-1 well, interval 1790-1650m (top of Elvira Formation and basal Barranca Final Formation); Chenque Formation, lower Chenque section, San Jorge Gulf Basin; top of Punta Nava and El Faro sections in the southern San Jorge Gulf area, in the lower part of Monte Entrada and Monte Observación sections, Austral Basin, and in Aries x-1 well, interval 350-260m, Austral Basin. The G/C association, characterized by Glencopollis ornatus Pocknall and Mildenhall, and Cannosphaeropsis utinensis Wetzel, was recognized in Ra x-1 well between 1630 and 1610m, the uppermost level herein considered. Chenque Formation (upper Chenque section), San Jorge Gulf Basin; upper part of Monte Entrada and Monte Observacion sections, Austral Basin, Santa Cruz Province, are also included in this association. The T-B/H association, defined by the presence of Tubulifloridites antipodica Cookson, Baumannipollis chubutensis Barreda, and acmé of Hystrychosphaeropsis obscura Habib, was recognized in Antena and Cañadón Baumann sections, Chenque Formation, Chubut Province. This study indicates that integrated palynological data are of considerable promise for further, more detailed biostratigraphic correlation.