Skip to Main Content
Book Chapter

The Bebedouro Formation, Una Group, Bahia (Brazil)

By
J. T. Guimarães
J. T. Guimarães
Geological Survey of Brazil (CPRM) Av. Ulysses Guimarães, 2862 – Sussuarana – Centro Administrativo da Bahia 41213-000 Salvador-Bahia, Brazil
Search for other works by this author on:
A. Misi
A. Misi
Universidade Federal da Bahia, Centro de Pesquisa em Geofísica e Geologia, Instituto de Geociências, Campus da Federação 40170-290 Salvador-Bahia, Brazil
Search for other works by this author on:
A. J. Pedreira
A. J. Pedreira
Geological Survey of Brazil (CPRM) Av. Ulysses Guimarães, 2862 – Sussuarana – Centro Administrativo da Bahia 41213-000 Salvador-Bahia, Brazil
Search for other works by this author on:
J. M. L. Dominguez
J. M. L. Dominguez
Universidade Federal da Bahia, Centro de Pesquisa em Geofísica e Geologia, Instituto de Geociências, Campus da Federação 40170-290 Salvador-Bahia, Brazil
Search for other works by this author on:
Published:
January 01, 2011

Abstract

The Bebedouro Formation (Fm.) is a Neoproterozoic glaciogenic succession at the base of the Una Group on the São Francisco Craton. The glaciogenic sequence is composed of diamictites, pelites and sandstones with a variety of lithofacies that are grouped into four associations: (i) ice-contact, (ii) pro-glacial, (iii) ice-rafted and (iv) aeolian (extraglacial). Thus, the Bebedouro Fm. is interpreted to have been deposited in a shelf marine environment where glacio-proximal sedimentation dominated. It variably overlies Palaeoproterozoic/Archaean basement and Mesoproterozoic metasedimentary rocks of the Chapada Diamantina Group.

The overlying carbonate succession (Salitre Fm.) is informally subdivided into five mappable units. Unit C, at the base, is composed of red argillaceous dolostone with typical negative δ13C signatures averaging –5.1‰ (VPDB). Unit B consists of grey laminated limestones that grade upward into grey dolostone with tepee structures of Unit B1; both have δ13C values around 0‰. The overlying Unit A consists of interbeds of greyish marl, shales and siltstones grading upward into massive black organic-rich limestone with oolitic and pisolitic beds of Unit A1. Positive δ13C signatures averaging +8.5‰ VPDB characterize the black limestones of Unit A1. 87Sr/86Sr ratios of well-preserved samples of these carbonate units show values of 0.70745 and 0.70765. These units can be correlated litho- and chemostratigraphically with formations of the Bambuí Group (São Francisco Basin) to the west.

You do not currently have access to this article.

Figures & Tables

Contents

Geological Society, London, Memoirs

The Geological Record of Neoproterozoic Glaciations

Emmanuelle Arnaud
Emmanuelle Arnaud
University of Guelph, Canada
Search for other works by this author on:
Galen P. Halverson
Galen P. Halverson
McGill University, Canada
Search for other works by this author on:
Graham Shields-Zhou
Graham Shields-Zhou
University College London, UK
Search for other works by this author on:
Geological Society of London
Volume
36
ISBN electronic:
9781862394117
Publication date:
January 01, 2011

GeoRef

References

Related

Citing Books via

A comprehensive resource of eBooks for researchers in the Earth Sciences

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal