Miospores and chlorococcalean algae from the Los Rastros Formation, Middle to Upper Triassic of central-western Argentina
Lacustrine strata of the Los Rastros Formation (Middle to Upper Triassic) at Río Gualo section (La Rioja province), yield a distinctive palynological assemblage of miospores and chlorococcalean algae. The miospore association is characterized by a relative abundance of corystosperm pollen grains wit...
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| Autores principales: | , |
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2005
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00027014_v42_n2_p347_Ottone http://hdl.handle.net/20.500.12110/paper_00027014_v42_n2_p347_Ottone |
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| Sumario: | Lacustrine strata of the Los Rastros Formation (Middle to Upper Triassic) at Río Gualo section (La Rioja province), yield a distinctive palynological assemblage of miospores and chlorococcalean algae. The miospore association is characterized by a relative abundance of corystosperm pollen grains with sub-ordinate inaperturates, diploxylonoid disaccates, spores, monocolpates, monosaccates and striate pollen grains. The phytoplankton are mostly represented by Botryococcus but also by Plaesiodictyon, a form probably related to the Hydrodictyaceae. Geological data and variations in phytoplankton content indicate that the lacustrine system probably evolved from a stretcht of freshwater with eutrophic conditions, into a body with oligotrophic conditions through the middle and upper part of the Río Gualo section. The genus Variapollenites is emended in order to amplify its original diagnosis. © Asociación Paleontológica Argentina. |
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