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Abstract Detail

Paleobotanical Section

Gandolfo, Maria A. [1], Zamaloa, Maria C. [2], Hermsen, Elizabeth [3].

What are the Miocene floras from Tierra del Fuego, Patagonia, Argentina, telling us?

The early-middle Miocene Cullen and Carmen Silva Formations are exposed as coastal cliffs in the northeastern part of Isla Grande de Tierra del Fuego, Argentina. Fossils were first discovered in this region by Darwin during the journey of the HMS Beagle in the early 19th century. Otto Nordenskjöld and his crew later collected plant macrofossils from the Cullen and Carmen Silva Formations during the 1895-1897 Swedish scientific expedition to the Magellan Territories (Tierra del Fuego archipelago). These collections were shipped to Stockholm, Sweden, where they were studied by Per Dusén, who published them in the early 20th century. Since then, the macrofossil component of these floras has received little additional study, even though they represent the southernmost Miocene macrofossil floras known worldwide. New collections were made in the 1990s and in 2013 in order to better understand the ages and the taxonomic composition of the floras of the Cullen and Carmen Silva Formations. Based on 40K-40Ar dating, the age of the Cullen Fm. is Burdigalian (early Miocene, 19.3 + 0.7 Ma), while recently stratigraphic studies indicate a probable late early-middle Miocene age for the Carmen Silva Fm. Interestingly, although both formations are in close proximity to one another and of similar age, their paleofloras are quite distinct. The Cullen palynoflora is rich and diverse, and is composed of algae, spores of bryophytes and pteridophytes, and gymnosperm and angiosperm pollen grains; its macroflora is basically composed of Nothofagus, “Fagus”, and conifer remains. In contrast, the Carmen Silva palynoflora is poorly preserved and is dominated by Nothofagus pollen, whereas the macroflora comprises pteridophytes as well as diverse angiosperm remains. Comparison between these two floras and coeval paleofloras from New Zealand (Manuherikia, Double Hill, and Dunedin Volcanic Complex) indicate the need for further studies in order to understand the development of the flora of Tierra del Fuego, which is today more similar to the that of New Zealand than to that of the rest of Patagonia. High latitudes regions of the Southern Hemisphere were subject to the most dramatic changes caused by global cooling during the Neogene. Therefore, high-latitude Miocene floras from Isla Grande, Tierra del Fuego, are critical to understanding how the vegetation responded to climate shifts during that time.

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1 - Cornell University, L.H. Bailey Hortorium, Plant Biology Section, 410 Mann Library Building, SIPS, Ithaca, NY, 14853, United States
2 - Universidad de Buenos Aires, Departamento de Ecologa, Gentica y Evolucin, Facultad de Ciencias Exactas y Naturales, Intendente Giraldes 2620, Buenos Aires, C1428EHA, Argentina
3 - Ohio University, Department of Environmental and Plant Biology, Athens, OH, 45701, USA

Cullen Fm.
Carmen Silva Fm.
Tierra del Fuego

Presentation Type: Oral Paper:Papers for Sections
Session: 28
Location: Salon 13/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 8:30 AM
Number: 28003
Abstract ID:786
Candidate for Awards:None

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