Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil

Mateus Kroth; Leonardo Borghi; Fabia E.R. Bobco; Bruno Cesar Araújo; Luís Fernando Silveira; Guilherme Duarte; Laís de Oliveira Ferreira; Margot Guerra-Sommer; Joalice de Oliveira Mendonça

doi:10.1016/j.sedgeo.2021.106025

Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil

Mateus Kroth^*, Leonardo Borghi, Fabia E.R. Bobco, Bruno Cesar Araújo, Luís Fernando Silveira, Guilherme Duarte, Laís de Oliveira Ferreira, Margot Guerra-Sommer, Joalice de Oliveira Mendonça

^*Corresponding author for this work

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Abstract

The Aptian Romualdo Formation in the Araripe Basin represents the establishment of an epeiric sea in the Brazilian Northeast during the Early Cretaceous. This unit is composed by a succession of limestones, shales, sandstones, and coquinas, which constitute shell beds near the top. This last interval strongly suggests a marine influence in the whole basin based on the fossil assemblage. However, even though the establishment of marine waters during the deposition of the Romualdo Formation is a consensus, paleogeographical and paleoenvironmental aspects still need to be better understood. This study aims to perform a sedimentological analysis of the coquina interval, based on petrographic and taphonomic analysis of field data and in a new fully recovered well-core (2-AB-1-CE) drilled in the Serra do Mãozinha at Abaiara county in the Ceará State. The described rocks were subdivided into eight facies constituted by bivalves, gastropods, ostracods, peloids, micrite, siliciclastic grains, punctual foraminifers, and plant debris. Based on facies' vertical stacking at well 2-AB-1-CE, a main regressive pattern was observed. It was also possible to subdivide the coquina interval into high-frequency transgressive–regressive cycles. The regional distribution of the facies permitted the identification of a shallow epeiric sea throughout the basin, with variations in the paleoenvironment energy and siliciclastic input. These variations were mainly controlled by paleotopography, fluvial discharge, and sea-level oscillations. The data allowed the identification of two subsequent paleogeographical configurations controlled by sea-level change. The first one, related to a sea-level high, was characterized by a protected bay on the western border and a gulf in the rest of the basin. Then a sea-level fall led to the formation of closed and open lagoons associated with higher terrigenous supply. As such, this study adds new data for a better understanding of the Araripe Basin and the impacts of sea-level fluctuations in South America during the Aptian.

Original language	English
Article number	106025
Pages (from-to)	1-15
Number of pages	15
Journal	Sedimentary Geology
Volume	426
DOIs	https://doi.org/10.1016/j.sedgeo.2021.106025
Publication status	Published - Dec 2021

Bibliographical note

Funding Information:
The authors gratefully acknowledge the research and development project “Correlação estratigráfica, evolução paleoambiental e paleogeográfica e perspectivas exploratórias do Andar Alagoas”, sponsored by Shell Brasil Petróleo Ltda , with resources allocated to R&D institutions accredited by the Brazilian National Agency of Petroleum, Natural Gas and Biofuels - ANP (technical cooperation agreement # 20219 ). We express our special thanks to Julia Favoreto for the insightful discussions. We also acknowledge the valuable comments of two anonymous reviewers that helped us to improve the manuscript.

Publisher Copyright:
© 2021 Elsevier B.V.

Funding

The authors gratefully acknowledge the research and development project ?Correla??o estratigr?fica, evolu??o paleoambiental e paleogeogr?fica e perspectivas explorat?rias do Andar Alagoas?, sponsored by Shell Brasil Petr?leo Ltda, with resources allocated to R&D institutions accredited by the Brazilian National Agency of Petroleum, Natural Gas and Biofuels - ANP (technical cooperation agreement #20219). We express our special thanks to Julia Favoreto for the insightful discussions. We also acknowledge the valuable comments of two anonymous reviewers that helped us to improve the manuscript. The authors gratefully acknowledge the research and development project “Correlação estratigráfica, evolução paleoambiental e paleogeográfica e perspectivas exploratórias do Andar Alagoas”, sponsored by Shell Brasil Petróleo Ltda , with resources allocated to R&D institutions accredited by the Brazilian National Agency of Petroleum, Natural Gas and Biofuels - ANP (technical cooperation agreement # 20219 ). We express our special thanks to Julia Favoreto for the insightful discussions. We also acknowledge the valuable comments of two anonymous reviewers that helped us to improve the manuscript.

Keywords

Facies Analysis
Lower Cretaceous
Mollusks
South America
Taphonomy

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.sedgeo.2021.106025

Cite this

Kroth, M., Borghi, L., Bobco, F. E. R., Araújo, B. C., Silveira, L. F., Duarte, G., Ferreira, L. D. O., Guerra-Sommer, M., & Mendonça, J. D. O. (2021). Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil. Sedimentary Geology, 426, 1-15. Article 106025. https://doi.org/10.1016/j.sedgeo.2021.106025

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title = "Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil",

abstract = "The Aptian Romualdo Formation in the Araripe Basin represents the establishment of an epeiric sea in the Brazilian Northeast during the Early Cretaceous. This unit is composed by a succession of limestones, shales, sandstones, and coquinas, which constitute shell beds near the top. This last interval strongly suggests a marine influence in the whole basin based on the fossil assemblage. However, even though the establishment of marine waters during the deposition of the Romualdo Formation is a consensus, paleogeographical and paleoenvironmental aspects still need to be better understood. This study aims to perform a sedimentological analysis of the coquina interval, based on petrographic and taphonomic analysis of field data and in a new fully recovered well-core (2-AB-1-CE) drilled in the Serra do M{\~a}ozinha at Abaiara county in the Cear{\'a} State. The described rocks were subdivided into eight facies constituted by bivalves, gastropods, ostracods, peloids, micrite, siliciclastic grains, punctual foraminifers, and plant debris. Based on facies' vertical stacking at well 2-AB-1-CE, a main regressive pattern was observed. It was also possible to subdivide the coquina interval into high-frequency transgressive–regressive cycles. The regional distribution of the facies permitted the identification of a shallow epeiric sea throughout the basin, with variations in the paleoenvironment energy and siliciclastic input. These variations were mainly controlled by paleotopography, fluvial discharge, and sea-level oscillations. The data allowed the identification of two subsequent paleogeographical configurations controlled by sea-level change. The first one, related to a sea-level high, was characterized by a protected bay on the western border and a gulf in the rest of the basin. Then a sea-level fall led to the formation of closed and open lagoons associated with higher terrigenous supply. As such, this study adds new data for a better understanding of the Araripe Basin and the impacts of sea-level fluctuations in South America during the Aptian.",

keywords = "Facies Analysis, Lower Cretaceous, Mollusks, South America, Taphonomy",

author = "Mateus Kroth and Leonardo Borghi and Bobco, {Fabia E.R.} and Ara{\'u}jo, {Bruno Cesar} and Silveira, {Lu{\'i}s Fernando} and Guilherme Duarte and Ferreira, {La{\'i}s de Oliveira} and Margot Guerra-Sommer and Mendon{\c c}a, {Joalice de Oliveira}",

note = "Funding Information: The authors gratefully acknowledge the research and development project “Correla{\c c}{\~a}o estratigr{\'a}fica, evolu{\c c}{\~a}o paleoambiental e paleogeogr{\'a}fica e perspectivas explorat{\'o}rias do Andar Alagoas”, sponsored by Shell Brasil Petr{\'o}leo Ltda , with resources allocated to R&D institutions accredited by the Brazilian National Agency of Petroleum, Natural Gas and Biofuels - ANP (technical cooperation agreement # 20219 ). We express our special thanks to Julia Favoreto for the insightful discussions. We also acknowledge the valuable comments of two anonymous reviewers that helped us to improve the manuscript. Publisher Copyright: {\textcopyright} 2021 Elsevier B.V.",

year = "2021",

month = dec,

doi = "10.1016/j.sedgeo.2021.106025",

language = "English",

volume = "426",

pages = "1--15",

journal = "Sedimentary Geology",

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publisher = "Elsevier BV",

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Kroth, M, Borghi, L, Bobco, FER, Araújo, BC, Silveira, LF, Duarte, G, Ferreira, LDO, Guerra-Sommer, M & Mendonça, JDO 2021, 'Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil', Sedimentary Geology, vol. 426, 106025, pp. 1-15. https://doi.org/10.1016/j.sedgeo.2021.106025

TY - JOUR

T1 - Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil

AU - Kroth, Mateus

AU - Borghi, Leonardo

AU - Bobco, Fabia E.R.

AU - Araújo, Bruno Cesar

AU - Silveira, Luís Fernando

AU - Duarte, Guilherme

AU - Ferreira, Laís de Oliveira

AU - Guerra-Sommer, Margot

AU - Mendonça, Joalice de Oliveira

N1 - Funding Information: The authors gratefully acknowledge the research and development project “Correlação estratigráfica, evolução paleoambiental e paleogeográfica e perspectivas exploratórias do Andar Alagoas”, sponsored by Shell Brasil Petróleo Ltda , with resources allocated to R&D institutions accredited by the Brazilian National Agency of Petroleum, Natural Gas and Biofuels - ANP (technical cooperation agreement # 20219 ). We express our special thanks to Julia Favoreto for the insightful discussions. We also acknowledge the valuable comments of two anonymous reviewers that helped us to improve the manuscript. Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/12

Y1 - 2021/12

N2 - The Aptian Romualdo Formation in the Araripe Basin represents the establishment of an epeiric sea in the Brazilian Northeast during the Early Cretaceous. This unit is composed by a succession of limestones, shales, sandstones, and coquinas, which constitute shell beds near the top. This last interval strongly suggests a marine influence in the whole basin based on the fossil assemblage. However, even though the establishment of marine waters during the deposition of the Romualdo Formation is a consensus, paleogeographical and paleoenvironmental aspects still need to be better understood. This study aims to perform a sedimentological analysis of the coquina interval, based on petrographic and taphonomic analysis of field data and in a new fully recovered well-core (2-AB-1-CE) drilled in the Serra do Mãozinha at Abaiara county in the Ceará State. The described rocks were subdivided into eight facies constituted by bivalves, gastropods, ostracods, peloids, micrite, siliciclastic grains, punctual foraminifers, and plant debris. Based on facies' vertical stacking at well 2-AB-1-CE, a main regressive pattern was observed. It was also possible to subdivide the coquina interval into high-frequency transgressive–regressive cycles. The regional distribution of the facies permitted the identification of a shallow epeiric sea throughout the basin, with variations in the paleoenvironment energy and siliciclastic input. These variations were mainly controlled by paleotopography, fluvial discharge, and sea-level oscillations. The data allowed the identification of two subsequent paleogeographical configurations controlled by sea-level change. The first one, related to a sea-level high, was characterized by a protected bay on the western border and a gulf in the rest of the basin. Then a sea-level fall led to the formation of closed and open lagoons associated with higher terrigenous supply. As such, this study adds new data for a better understanding of the Araripe Basin and the impacts of sea-level fluctuations in South America during the Aptian.

AB - The Aptian Romualdo Formation in the Araripe Basin represents the establishment of an epeiric sea in the Brazilian Northeast during the Early Cretaceous. This unit is composed by a succession of limestones, shales, sandstones, and coquinas, which constitute shell beds near the top. This last interval strongly suggests a marine influence in the whole basin based on the fossil assemblage. However, even though the establishment of marine waters during the deposition of the Romualdo Formation is a consensus, paleogeographical and paleoenvironmental aspects still need to be better understood. This study aims to perform a sedimentological analysis of the coquina interval, based on petrographic and taphonomic analysis of field data and in a new fully recovered well-core (2-AB-1-CE) drilled in the Serra do Mãozinha at Abaiara county in the Ceará State. The described rocks were subdivided into eight facies constituted by bivalves, gastropods, ostracods, peloids, micrite, siliciclastic grains, punctual foraminifers, and plant debris. Based on facies' vertical stacking at well 2-AB-1-CE, a main regressive pattern was observed. It was also possible to subdivide the coquina interval into high-frequency transgressive–regressive cycles. The regional distribution of the facies permitted the identification of a shallow epeiric sea throughout the basin, with variations in the paleoenvironment energy and siliciclastic input. These variations were mainly controlled by paleotopography, fluvial discharge, and sea-level oscillations. The data allowed the identification of two subsequent paleogeographical configurations controlled by sea-level change. The first one, related to a sea-level high, was characterized by a protected bay on the western border and a gulf in the rest of the basin. Then a sea-level fall led to the formation of closed and open lagoons associated with higher terrigenous supply. As such, this study adds new data for a better understanding of the Araripe Basin and the impacts of sea-level fluctuations in South America during the Aptian.

KW - Facies Analysis

KW - Lower Cretaceous

KW - Mollusks

KW - South America

KW - Taphonomy

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U2 - 10.1016/j.sedgeo.2021.106025

DO - 10.1016/j.sedgeo.2021.106025

M3 - Article

AN - SCOPUS:85118564953

SN - 0037-0738

VL - 426

SP - 1

EP - 15

JO - Sedimentary Geology

JF - Sedimentary Geology

M1 - 106025

ER -

Aptian shell beds from the Romualdo Formation (Araripe Basin): Implications for paleoenvironment and paleogeographical reconstruction of the Northeast of Brazil

Abstract

Bibliographical note

Funding

Keywords

UN SDGs

Access to Document

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