Estudio palinoestratigráfico integrado del entorno Oligoceno Tardío-Mioceno en secciones de la costa patagónica y plataforma continental argentina.

BARREDA, V. D.; PALAMARCZUK, S.

Serie Correlación Geológica

INSUGEO

Lugar: Tucumán; Año: 2000 vol. 14 p. 103 - 138

1514 4186

Abstract.- PALINOSTRATIGRAPHICAL STUDY OF THE LATE OLIGOCENE-MIOCENE IN SECTIONS OF PATAGONIAN SHORE AND CONTINENTAL PLATFORM OF ARGENTINA. The purpose of this study is to provide a preliminary palynostratigraphic correlationscheme based on integrated distributions of both, continental and marine palynomorphs from surface and subsurfacesections (Upper Oligocene through Early-Middle Miocene) located along the Atlantic Patagonic Coast and in the ArgentineContinental Shelf between latitudes 40º and 53º S. The age assignment is supported by concurrent information fromknown local and regional stratigraphic ranges of the species and by the presence of other diagnostic fossil groups. Fourinformal 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, AustralBasin, interval 530-350m. In Ra x-1 well, Colorado Basin, below depth 1790m (Elvira Formation), the association was notclearly 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 agenot older than Upper Oligocene. The C-T/L association , characterized by Cyperaceaepollis neogenicus Krutzsch, Tricolpitestrioblatus 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 GulfBasin; top of Punta Nava and El Faro sections in the southern San Jorge Gulf area, in the lower part of Monte Entrada andMonte 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-1well between 1630 and 1610m, the uppermost level herein considered. Chenque Formation (upper Chenque section), SanJorge Gulf Basin; upper part of Monte Entrada and Monte Observacion sections, Austral Basin, Santa Cruz Province, arealso 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 CañadónBaumann sections, Chenque Formation, Chubut Province. This study indicates that integrated palynological data are ofconsiderable promise for further, more detailed biostratigraphic correlation.