POSICIONES ESTRATIGRAFICAS y EDADES DE LAS PRINCIPALES FLORAS JURASICAS ARGENTINAS

Pedro N Stipanicic, Maria R Bonetti

Abstract


he stratigraphic positions and relations of the main Argentine jurassic floras are discussed, tending to define their ages with the greatest possible accuracy. Por this purpose, those elements of reference, of chronological character, that offer smaller vertical dispersion are taken into account: a) levels with cephalopods; b) synorogenic and synepeirogenic diastrophic phases; e) absolute radimetric datings of igneous rocks related to sediments bearing fossil plants. Since several jurassic floras were dated for their relation with arnmonitiferous levels, some of the classic sections taken as standard are discused, making evident that ir is neccessary to introduce several biostratigraphical and chronological changes in those sequences, In the present paper the floras contained in liassic strata are analized.

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