Flood-dominated fluvio-deltaic system: a new depositional model for the Devonian Cabeças Formation, Parnaíba Basin, Piauí, Brazil

Anais da Academia Brasileira de Ciências

Luiza Corral M.o. Ponciano²  Jorge C. Della Fávera¹ 

[1] ,Universidade Federal do Rio de Janeiro Instituto de Geociências Departamento de GeologiaRio de Janeiro RJ ,Brasil

关键词: Parnaíba Basin;    Devonian;    Cabeças Formation;    flood-dominated fluvio-deltaic system;    delta-front sandstone lobes;    mouth-bar deposits;    hummocky cross-stratification;    Bacia do Parnaíba;    Devoniano;    Formação Cabeças;    sistema flúvio-deltaico dominado por inundações;    lobos de frente deltaica;    depósitos de barra de desembocadura;    estratificação cruzada hummocky;   

DOI  :  10.1590/S0001-37652009000400014

来源: SciELO

【 摘 要 】

The depositional model of the Cabeças Formation is re-evaluated in the context of the Devonian paleogeography of the Parnaíba Basin, and with particular reference to similarities between the formation's facies associations on the eastern border of the basin and the flood-dominated fluvio-deltaic system facies that have been discussed in recent literature. The widespread occurrence and nature of sigmoidal clinoforms (with asymptotic cross-stratification and climbing ripples) of the Cabeças Formation are here considered as strong evidence of flood-influenced depositional settings. Sandy strata of the Passagem Member, in the vicinity of Pimenteiras and Picos (Piauí State), are interpreted as the distal part of fine-grained mouth-bar deposits interbedded with delta-front sandstone lobes showing hummocky cross-stratification. Richly fossiliferous levels, with diverse megainvertebrates and plant cuticles, occur within the delta-front lobes and the distal mouth-bar deposits, reflecting continuation of shallow marine conditions.

【 授权许可】

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