Detrital zircon U-Pb geochronology constrains the age of Brazilian Neogene deposits from Western Amazonia

Author(s)

Bissaro-Junior, Marcos C. ^[1] ; Kerber, Leonardo ^[2] ; Crowley, James L. ^[3] ; Ribeiro, Ana M. ^[4] ; Ghilardi, Renato P. ^[5] ; Guilherme, Edson ^[6] ; Negri, Francisco R. ^[7] ; Souza Filho, Jonas P. ^[6] ; Hsiou, Annie S. ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] UFSM, Ctr Apoio Pesquisa Paleontol Quarta Colonia, CAPPA, BR-97230000 Sao Joao De Polesine, RS - Brazil

^[3] Boise State Univ, Dept Geosci, Boise, ID 83725 - USA

^[4] Fundacao Zoobot Rio Grande Sul, Museu Ciencias Nat, BR-90690000 Porto Alegre, RS - Brazil

^[5] Univ Estadual Paulista, UNESP, Dept Ciencias Biol, Fac Ciencias, BR-17033360 Bauru, SP - Brazil

^[6] Univ Fed Acre, UFAC, Dept Ciencias Nat, BR-69915900 Rio Branco, Acre - Brazil

^[7] Univ Fed Acre, UFAC, Campus Floresta, BR-69980000 Cruzeiro Do Sul, Acre - Brazil

• Document type: Journal article
• Source: PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY; v. 516, p. 64-70, FEB 15 2019.
• Web of Science Citations: 6

Abstract

The fossiliferous beds of the Solimoes Formation, western Brazilian Amazon have yielded several vertebrate fossils that are key to understand the evolution of Neotropical biotas. Although this sedimentary unit has been studied for more than two centuries, no absolute dates are available so far, preventing more precise bio/chronostratigraphic interpretations and broader comprehension of the biotic/geological events that affected this northern portion of South America during the Neogene. Here, we present the first Neogene radioisotopic dates for the Brazilian Amazon, via U-Pb dating of detrital zircon from two classical sites. Both samples have small proportions of relatively young zircon grains, the dates from which are the maximum ages of deposition. LA-ICPMS analysis of two grains from the Niteroi locality yielded a weighted mean of 8.5 +/- 0.5 Ma and CA-TIMS analysis of two grains from the Talisma locality yielded a weighted mean of 10.89 +/- 0.13 Ma. These maximum deposition ages are in the Tortonian stage, late Miocene, confirming the age previously inferred based on biochronological data. (AU)

• FAPESP's process: 11/14080-0 - Cretaceous and Tertiary (Paleogene/Neogene) Squamates (Reptilia, Lepidosauria) from the Bauru, Aiuruoca and Acre basins: systematics, evolution and palaeoenvironments
• Grantee: Annie Schmaltz Hsiou
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 16/00476-3 - Geochemical taphonomy of macrovertebrates from fossil assemblages of Solimões Formation (Acre basin, upper Miocene)
• Grantee: Marcos César Bissaro Júnior
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate