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Bioclastic accumulation in a lake rift basin; the Early Cretaceous coquinas of the Sergipe-Alagoas Basin, Brazil

Ariely L. Rigueti, Patrick Fuhr Dal' Bo, Leonardo Borghi and Marcelo Mendes
Bioclastic accumulation in a lake rift basin; the Early Cretaceous coquinas of the Sergipe-Alagoas Basin, Brazil
Journal of Sedimentary Research (February 2020) 90 (2): 228-249


Coquinas constitute widespread deposits in lacustrine, estuarine, and shallow marine settings, where they are a valuable source of information on environmental conditions. Thick coquina successions were deposited in a series of lacustrine rift basins that formed along the Brazilian Continental Margin during the early stages of the opening of the South Atlantic Ocean, in the Early Cretaceous. In the Sergipe-Alagoas Basin, the coquina sequence, equivalent to the Morro do Chaves Formation, crops out in the Atol Quarry, and is considered a relevant analog for the economically important hydrocarbon reservoirs in the Pre-salt strata (Barremian to Aptian) of the Campos Basin (Pampo, Badejo, and Linguado oil fields), which occur only in the subsurface. The aim of this study is to generate a depositional and stratigraphic model through facies and stratigraphic analyses of a well core. These analyses allowed the geological characterization of the Morro do Chaves Formation and of its transition to the adjacent stratigraphic units, the Coqueiro Seco Formation above and the Penedo Formation below, contributing to the growing knowledge of sedimentation in rift basins and exploratory models in hydrocarbon-producing reservoirs. Facies analysis consists of sedimentological, taphonomic, and stratigraphic features of the rocks. Fourteen depositional facies were recognized, stacked into low-frequency and high-frequency, deepening-upward and shallowing-upward cycles driven by the interaction between climate and tectonism. A depositional model is presented, based on the correlation between well-core and outcrop data described in previous studies, providing insights into the spatial distribution of facies. The detailed analysis of facies and stacking patterns sheds light on depositional processes, paleoenvironmental conditions, and the evolution of the system through time, so we may better understand analogous deposits in the geological record.

ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 90
Serial Issue: 2
Title: Bioclastic accumulation in a lake rift basin; the Early Cretaceous coquinas of the Sergipe-Alagoas Basin, Brazil
Affiliation: Federal University of Rio de Janeiro, Institute of Geoscience, Department of Geology, Rio de Janeiro, Brazil
Pages: 228-249
Published: 202002
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 52
Accession Number: 2020-047108
Categories: Sedimentary petrologyEconomic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 4 tables, sketch map
S11°10'60" - S11°10'60", W38°01'00" - W38°01'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 202029
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