Login

Join for Free!
114045 members
table of contents table of contents

Lacustrine strata of the Los Rastros Formation (Middle to Upper Triassic) at …


Biology Articles » Paleobiology » Micropaleobiology » Miospores and chlorococcalean algae from the Los Rastros Formation, Middle to Upper Triassic of central-western Argentina

Abstract
- Miospores and chlorococcalean algae from the Los Rastros Formation, Middle to Upper Triassic of central-western Argentina

Miospores and chlorococcalean algae from the Los Rastros Formation, Middle to Upper Triassic of central-western Argentina

Eduardo G. Ottone, Adriana C. Mancuso and Magdalena Resano

Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón n° 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina. ottone@gl.fcen.uba.ar , amancu@gl.fcen.uba.ar, magdaresano@yahoo.com

Abstract. 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 subordinate 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.

Key words. Argentina. Triassic. Miospores and chlorococcalean algae. Systematics. Lacustrine environment.

Ameghiniana, Mar./June 2005, vol.42, no.2, p.347-362. An Open Access Article.


rating: 4.00 from 2 votes | updated on: 16 Sep 2007 | views: 7001 |

Rate article:







excellent!bad…