Author:
MIZUSAKI ANA M. P.,MELO JOSÉ HENRIQUE G.,VIGNOL-LELARGE MARIA L.,STEEMANS PHILIPPE
Abstract
Fresh shale samples taken from a well-known outcrop section of the Silurian Vila Maria
Formation, located on the northeastern margin of the Paraná Basin (Três Barras Farm, Goiás State,
central-western Brazil), have been analysed for both palynological and radiometric age determinations.
The rocks yielded a fairly diverse, age-definitive cryptospore assemblage, and the same
samples proved suitable for Rb–Sr analysis, despite Silurian sedimentary rocks being rarely suited to
radiometric dating techniques. This study thus introduces an alternative, independent method for
estimating the minimum depositional age of the Vila Maria Formation. The Rb–Sr age value has been
calculated via an isochron diagram that yields 435.9±7.8 Ma. Accordingly, the latter value is interpreted
as the minimum depositional age of the analysed Vila Maria strata, implying their deposition
during Llandovery times. This concurs with the palynological results, which indicate an age no older
than Early Silurian and, more particularly, favour an Early to Middle Llandovery (Rhuddanian–Early
Aeronian) attribution.
Publisher
Cambridge University Press (CUP)
Cited by
23 articles.
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