Middle-Late Jurassic megaflora of Laguna Flecha Negra locality in Santa Cruz Province, Patagonia, and floristic assemblages of the Bahía Laura Complex. (June 2020)

• Record Type: Journal Article
• Authors: Sagasti, Ana J.; García Massini, Juan L.; Escapa, Ignacio H.; Guido, Diego M.; Morel, Eduardo M.
• Is Part Of: Journal of South American earth sciences. Volume 100(2020)
• Publication Date: 2020-06
• Subjects: Impressions -- Argentina -- Microphyllous conifers -- Volcaniclastic settings -- Cycadophytes -- Jurassic plant communities -- dry weather; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2020.102564
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: A Middle-Late Jurassic fossil plant assemblage is described from the Bahía Laura Complex at the Laguna Flecha Negra locality, Santa Cruz Province. The fossil assemblage is autochthonous, preserved in volcaniclastic sediments in the fringes of a geothermal landscape. Taxonomic study of the palaeoflora revealed 17 taxa. The recognized species have been previously described in Jurassic localities of Gondwana and illustrate the diversity of plant communities that lived in a volcanic setting. The dominant elements of this flora are microphyllous conifers of the families Araucariaceae and Cheirolepidiaceae. Fossil leaves of Cycadeoidales co-dominate the community. There is a low diversity and abundance of ferns. Composition of the plant community is compared to coetaneous floras of the Bahía Laura Complex to analyse geographical variations in the diversity of Middle-Late Jurassic assemblages of Santa Cruz Province, and a relative uniformity is recognized. Forest landscapes were dominated by conifer trees, with cycadeoids as small trees or shrubs. The herbaceous understory was dominated by fern communities with low species diversity; Equisetales and Isoetales appeared as subordinated elements. Microphyllous conifers and cycadophytes, as well as a low diversity of ferns, are indicative of relatively dry weather. Highlights: New Middle-Late Jurassic megaflora is described for Patagonia Argentina. Forest landscapes appear to be dominated by conifer trees and small cycads. Megafloras of the Bahía Laura Complex are analysed and compared. Climatic signature of megafloras indicate dryer weather than the Late Triassic.