INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Paleobotany of the Upper Triassic Los Rastros Formation, Ischigualasto-Villa Unión Basin, La Rioja, Argentina
MANCUSO, ADRIANA CECILIA; OTTONE, EDUARDO GUILLERMO; PEDERNERA, TOMÁS; BENAVENTE, CECILIA ANDREA
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
PERGAMON-ELSEVIER SCIENCE LTD
Lugar: Amsterdam; Año: 2020
The Los Rastros Formation was deposited in adeltaic-lacustrine environment during the Late Triassic. Plant remains from theGualo area were systematically collected and compared with other localitiesfrom the Los Rastros Formation concerning the sedimentary evolution of thebasin. Subsequently, the Los Rastros paleoflora was contrasted with otherCarnian (Upper Triassic) units from Gondwana in a paleobiogeographic contextusing statistical methodologies: Raup-Crick similarity index and hierarchicalcluster analysis. The systematic study revealed 14 taxa for the Los RastrosFormation at the Gualo area. Plant vegetative remains of Equisetales (Neocalamitessp.), Osmundaceae (Cladophlebis sp. cf. C. mesozoica),Umkomasiales (Dicroidium odontopteroides, Johnstonia stelzeriana,Xylopteris argentina, X. elongata, and Zuberia feistmantelii),Ginkgoales (Baiera pontifolia, Sphenobaiera sp. cf. S.argentinae), Voltziales (Heidiphyllum elongatum), Coniferales (Rissikiamedia), and gymnospermous reproductive structures (Cordaicarpus sp.,Samaropsis sp. and strobilus sp. A). The stratigraphic distribution oftaxa throughout the Los Rastros Formation in the Gualo section is variable.Diminution of taxa recorded observed across the section could be explained bythe isolation of the paleolake product of the activity of a secondary fault.The plant taxa registered at the different localities of the Los RastrosFormation could be related to the location of each locality in the basin and thedifferent depositional conditions during the infill history of the basin ateach locality. Comparison among Los Rastros Formation plant records with otherpaleofloras from Gondwana by statistical analyses indicates differences with respectto a previous paleobiogeographic proposal.