SciELO - Scientific Electronic Library Online

 
vol.57 issue3Possibilities of crustal thinning in the Cuyo Basin from the analysis of gravity dataThe Miocene volcanic belt of the northern Precordillera, San Juan and La Rioja provinces, Argentina author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

  • Have no cited articlesCited by SciELO

Related links

  • Have no similar articlesSimilars in SciELO

Share


Revista de la Asociación Geológica Argentina

Print version ISSN 0004-4822

Abstract

LEANZA, H. A. et al. Lacustrine black shales near to the Paleogene - Neogene boundary in north-western Neuquén Province: palynological evidence. Rev. Asoc. Geol. Argent. [online]. 2002, vol.57, n.3, pp.280-288. ISSN 0004-4822.

Lacustrine sedimentary rocks referred to the Lileo Formation nov. cropping out near Los Miches locality, northwestern Neuquén Province, Argentine Republic, were sampled for palynological study. On the basis of the microfloristic analysis, the palynomorph-bearing beds can be ascribed a Late Oligocene to Early Miocene age. The sampled rocks are black, grey-green, dark grey and light brown shales alternating with thin,locally oolithic, light grey limestones, with yellowish white weathering. Among these rocks are interbedded andesites, tuffs, and volcanic agglomerates of mesosilicic composition. In the outcrops of the Guañacos river area, some irregular beds of fibrous carbonate have been observed as well as fibroradial nodular barite, together with some indeterminate fresh-water. The microfloristic assemblages have a relatively low diversity. In most of them the genus Nothofagidites dominates the association. The components present in the microflora are pollen grains corresponding to several angiosperm taxa, such as Baumannipollis sp. cf. B. variaperturatus, Corsinipollenites atlantica, Milfordia sp., Nothofagidites saraensis, Smilacipites sp. cf. S. echinatus and Tricolpites asperamarginis together with gymnosperm pollen grains of Araucariacites australis, Equisetosporites notensis and Podocarpidites spp. The Pteridophyta/Bryophyta elements are represented by Cyatheacidites annulatus, Cicatricosisporites sp., Deltoidospora sp., Lycopodiumsporites austroclavatidites, Ricciaesporites sp. and Laevigatosporites ovatus, whereas among the lacustrine taxa Azolla sp. and Botryococcus sp. (Chlorophyta) were recognized.

Keywords : Paleogene-Neogene boundary; Palynology; Lacustrine black shales; Lileo Formation; Neuquén; Argentina.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License