Title: Permian palynofloral assemblages of the Chaco-Paraná Basin (Argentina): systematics and stratigraphic significance
Abstract:Core samples from an upper Palaeozoic, partly glaciogene borehole section (Ordonez: YPF Cd O es-1) in the southern Chaco-Parana Basin (Cordoba Province, northeastern Argentina) have produced variable ...Core samples from an upper Palaeozoic, partly glaciogene borehole section (Ordonez: YPF Cd O es-1) in the southern Chaco-Parana Basin (Cordoba Province, northeastern Argentina) have produced variable palynological results. Samples from the lower part of the section (i.e., from the diamictite-bearing upper Ordonez Formation) proved non-palyniferous. Those from the overlying, essentially post-glacial Victoriano Rodriguez Formation yielded spore-pollen assemblages in varying concentrations and in good to excellent states of preservation, thus providing the material basis for the present account. The palynomorph taxa represented in the assemblages comprise 20 species of spores (distributed among 14 genera) and 25 species of pollen grains (14 genera). The majority of the species are described in systematic detail. One trilete spore species -Convolutispora archangelskyi- is newly proposed. Several other, possibly new species (three of trilete spores, one of monosaccate pollen) are represented insufficiently for other than informal naming. The following new combinations, also of trilete spore species, are instituted: Converrucosisporites confluens (Archangelsky & Gamerro, 1979), C. micronodosus (Balme & Hennelly, 1956), and Anapiculatisporites tereteangulatus (Balme & Hennelly, 1956). Sculptural intergradation (granulate through verrucate) among three species -Granulatisporites austroamericanus Archangelsky & Gamerro, 1979, C. confluens, and C. micronodosus- prompts their informal grouping, proposed herein, as the Converrucosisporites confluens Morphon, which is also recognizable elsewhere in the Gondwanan Permian. The possibility, if not the likelihood, that G. austroamericanus is conspecific with Microbaculispora tentula Tiwari, 1965 is canvassed. The palynologically productive borehole section of the Victoriano Rodriguez Formation studied here is assignable to the middle to upper Cristatisporites Zone and to the succeeding Striatites Zone, thus signifying an Early Permian age for this section and facilitating correlation with strata of the Parana and Paganzo Basins. From this and prior work, the Ordonez well sequence embracing the Ordonez and Victoriano Rodriguez Formations includes, in addition to the latter two zones, the preceding (late Pennsylvanian) Potonieisporites-Lundbladispora Zone which is known from the lower to mid-upper part of the Ordonez Formation. Thus, the Carboniferous-Permian boundary can be inferred to lie within the upper part of the latter formationRead More
Publication Year: 2002
Publication Date: 2002-01-01
Language: en
Type: article
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Cited By Count: 50
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