Geochronological evidence for pervasive miocene weathering, Minas Gerais, Brazil


Autoria(s): Carmo, ID; Vasconcelos, P
Contribuinte(s)

M. J. Kirkby

Data(s)

01/01/2004

Resumo

Ar-40/Ar-39 laser incremental-heating analyses of 22 individual grains of supergene cryptomelane from three weathering profiles, up to 400 km apart, in the Rio Doce valley and Barbacena regions at Minas Gerais, Brazil, show that the formation of weathering profiles in these regions is contemporaneous, suggesting a strong weathering event in the Middle to Late Miocene (10-8 Ma). The preservation of these Miocene samples at or near the present surface suggests that either erosion rates have been very low in the region since the Miocene or that a much thicker weathering mantle was present in the region originally. Assuming a constant thickness of weathering profiles in the region throughout the Tertiary, we may calculate weathering front propagation rates of 4-8 m Myr(-1) during the past 10 Ma. Copyright (C) 2004 John Wiley Sons, Ltd.

Identificador

http://espace.library.uq.edu.au/view/UQ:74050

Idioma(s)

eng

Publicador

John Wiley & Sons Ltd

Palavras-Chave #Geography, Physical #Geosciences, Multidisciplinary #(40ar/39ar) Geochronology #Weathering #Miocene #Paleoclimate #Southeastern Brazil #K-mn Oxides #Ar-40/ar-39 Analysis #Manganese Oxides #Evolution #Australia #Age #Ar #C1 #260109 Geochronology #780104 Earth sciences #040303 Geochronology
Tipo

Journal Article