2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 140-28
Presentation Time: 3:45 PM

FACIES AND ARCHITECTURAL ELEMENTS OF THE MARIZAL FORMATION: POST RIFT DEPOSITS FROM A RIFT BASIN IN THE CRETACEOUS 


CARRERA, Simone C., Institute of Geosciences, University of São Paulo, Rua do Lago 562, Cidade Universitária, São Paulo, 05508-080, Brazil, FIGUEIREDO, Felipe T., Departamento de Geologia, Universidade Federal de Sergipe, Cidade Universitária Prof. José Aloísio de Campos Av. Marechal Rondon, s/n Jardim Rosa Elze, São Cristóvão, 49100-000, ALMEIDA, Renato, Institute of Energy and Environment, University of São Paulo, Av. Professor Luciano Gualberto, 1289, edifício materiais, Cidade Universitária, São Paulo, 05508-01, Brazil and FREITAS, B.T., Intitute of Geosciences, University of São Paulo, Rua do Lago 562, Cidade Universitária, São Paulo, 05508-080, Brazil

The Recôncavo Tucano Jatobá basin (Northeastern Brazil) is part of an aborted rift basin in the southern portion of the Gondwana during its Early Cretaceous breakup. The onset of the basin formation is recorded as lacustrine environments, which gave place to fluvial environments along the Neocomian and prevailed in the Aptian, with the deposition of the Marizal Formation. Previous works on this unit interpreted a fluvial system with evidences of transverse and axial rivers in the Central and northern Tucano segments of the basin, fed from the rift shoulders, suggesting short transport distances. In the present work the architectural elements analysis carried out in the central segment of the basin suggests a predominance of conglomerates and pebbly sandstones associated with scour fill elements with bar migration averaging towards the southwest, associated with aeolian dunes formed by northeastward palaeowinds. The southern segment, on its turn, record the superimposition of few 0.1-1.0 m thick dune sets of cross stratified and well sorted sandstones, organized in up to 4.5 m of aeolian dunes and fluvial deposits, both migrating to southwest. Dune heights and laterally persistent architecture resembles fluvial deposits, although textural and local pin stripe features show evidence of an aeolian origin. These results suggest an increase in the maturity of sediments southwards and the persistence of a fluvial system, with a lower contribution from proximal sources when compared to northernmost segments of the basin. The increased maturity can either be the result of reworked sedimentary sources adjacent to the site of deposition or alternatively indicate the distal part of the upstream larger river system. Paleocurrent data from fluvial and aeolian deposits reveal the continuity of flows towards southwest, which could be indicative of local reworking of aeolian dune fields by fluvial flows of the same trunk river interpreted for the northernmost portion.

Session No. 140

T238. Sedimentary Geology: The Now and the Next Generations of Scientists (Posters)
Monday, 20 October 2014: 9:00 AM-6:30 PM
Exhibition Hall C (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.354
© Copyright 2014 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: T238. Sedimentary Geology: The Now and the Next Generations of Scientists (Posters)
<< Previous Abstract | Next Abstract >>