First palynological record for the Lower member of Cerro Morado Formation (Miocene), La Rioja Precordillera

The finding of palynological remains in the lower member of the Cerro Morado Formation is reported for the first time. The fossiliferous levels are located at the headwaters of the Guandacol river in southwestern La Rioja Province. In this area the Cerro Morado Formation has been divided into two me...

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Detalles Bibliográficos
Autores principales: Barreda, V., Limarino, C., Fauqué, L., Tripaldi, A., Net, L.
Formato: JOUR
Materias:
Cerro Morado Formation
La Rioja Province
Miocene
Palynology
Precordillera
Sedimentology
biostratigraphy
morphology
paleoecology
palynology
sedimentology
Argentina
Acer pensylvanicum
algae
Amaranthaceae
Botryococcus
Chlorophyta
Dinophyceae
Ephedraceae
Fagaceae
Magnoliophyta
Malvaceae
Nothofagidites
Pediastrum
Podocarpaceae
Restionaceae
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00027014_v40_n1_p81_Barreda
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:The finding of palynological remains in the lower member of the Cerro Morado Formation is reported for the first time. The fossiliferous levels are located at the headwaters of the Guandacol river in southwestern La Rioja Province. In this area the Cerro Morado Formation has been divided into two members. The lower member, composed of sandstones, mudstones and scarse conglomerates and limestones, contains the palynological remains described in this paper. The palynological assemblages are not diverse, they are poorly preserved and dominated by aquatic elements mainly related to colonial green algae (Pediastrum spp., Botryococcus sp.) and dinoflagellates. Sporepollen assemblages consist of aquatic herbs of Restionaceae (Milfordia sp.) and Malvaceae (Baumannipollis chubutensis Barreda, Baumannipollis sp., Malvacipolloides comodoroensis Barreda). Typical lake shore vegetation consisted of members of Ephedraceae [Equisetosporites claricristatus (Shakmundes) Barreda, E. notensis (Cookson) Romero, E. lusaticus (Krutzsch) Barreda] and scarse Chenopodiaceae (Chenopodipollis chenopodiaceoides (Martin) Truswell). Pollen grains related to Podocarpaceae (Podocarpidites marwickii Couper, P. elegans Romero) and Fagaceae (Nothofagidites acromegacanthus Menéndez and Caccavari, N. americanus Zamaloa, N. saraensis Menéndez and Caccavari) are also present, although in low percentages. The known stratigraphic ranges of the recognized species, and the similarities of these assemblages to others previously described from Argentina, point to an Early to Middle Miocene age for this unit. Finally, sedimentological and palynological evidences suggest the development of a large and perennial water body during the time of deposition of the lower member of Cerro Morado Formation.

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