A new record of late Ediacaran acritarchs from La providencia group (Tandilia System, Argentina) and its biostratigraphical significance

Autor(es)

Julia Arrouy, Maria ^[1] ; Gaucher, Claudio ^[2] ; Poire, Daniel G. ^[1] ; Xiao, Shuhai ^[3] ; Gomez Peral, Lucia E. ^[1] ; Warren, Lucas V. ^[4] ; Bykova, Natalia ^[5] ; Quaglio, Fernanda ^[6]

Afiliação do(s) autor(es)

^[1] UNLP, CONICET, FCNyM, Ctr Invest Geol, Diagonal 113 275, La Plata, Buenos Aires - Argentina

^[2] Univ Republica, Fac Ciencias, Dept Paleontol, Montevideo - Uruguay

^[3] Virginia Tech, Dept Geosci, Blacksburg, VA - USA

^[4] Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, Dept Geol Aplicada, Rio Claro - Brazil

^[5] Russian Acad Sci, Siberian Branch, Trofimuk Inst Petr Geol & Geophys, Prospekt Akad Koptyuga 3, Moscow - Russia

^[6] Univ Fed Sao Paulo, Dept Ecol & Biol Evolut, Sao Pablo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of South American Earth Sciences; v. 93, p. 283-293, AUG 2019.
• Citações Web of Science: 1

Resumo

A well preserved assemblage of organic-walled microfossils is described from the Alicia and Cerro Negro formations of the La Providencia Group. The microbiota is dominated by Leiosphaeridia species (L. minutissima, L. tenuissima, L. crassa and L. jacutica) and comprises colonial sphaeroids (Synsphaeridium sp.) and filamentous microfossils of the genus Siphonophycus. The assemblage is assigned to the Late Ediacaran Leiosphere Palynoflora (LELP), which is consistent with the occurrence of the discoidal fossil Aspidella (< 565 Ma) in the overlying unit. The distribution of microfossils within the Alicia Formation is mainly controlled by the shallowing upward trend and thus, environmental factors. This is indicated by the abundance and size of filaments, which tend to occur near to the paleoshore in shallow water settings. Furthermore, large leiospheres also occur in shallower facies together with filaments, in accordance with existing models for acritarch ecology and distribution in the Proterozoic marine successions. The absence of acanthomorphic acritarchs is thus interpreted as a real evolutionary trend, and not as a result of preservational or environmental biases. Regarding the preservation of microfossils, a higher Thermal Alteration Index for the Alicia Formation, compared with older and younger units, is interpreted as a result of hydrothermal overprint and/or contact metamorphism by basic dikes. (AU)

• Processo FAPESP: 15/24608-3 - Análise multi-proxy da formação Cerro Negro, Argentina: bioestratigrafia e paleoambiente do primeiro fossillagerstätte Ediacarano da América do Sul
• Beneficiário: Lucas Verissimo Warren
• Modalidade de apoio: Auxílio à Pesquisa - Regular