Sedimentary and tectonic breccias at the base of the Ediacaran Tamengo Formation (Corumbá Group): a comparative study

Fernandes, Henrique Albuquerque; Boggiani, Paulo César; Afonso, Jhon Willy Lopes; Amorim, Kamilla Borges; Trindade, R. I.

doi:10.1590/2317-4889202220210062

Cited by 4 publications

(10 citation statements)

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“…The lower Tamengo Formation erosive surface is a regional limit recognized in the Bodoquena Range and Corumbá areas (Boggiani, 1998; Boggiani et al ., 2010; Campanha et al ., 2011; Fernandes et al ., 2022). This surface separates the upper Bocaina Formation from the Tamengo Formation, through an erosive contact which intercepts Bocaina Formation strata in distinct stratigraphic intervals (see Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Whereas this surface is not preserved in our working sections, this limit is recognized in the Fazenda Ressaca area (eastern Bodoquena) near the vicinity of the EDEM drill core and mine pit sections (Fernandes et al ., 2022). The same surface is observed around the Bodoquena city area, stratigraphically close to the Hori drill core and Sol Nascente outcrop sections (Fernandes et al ., 2022). Above this limit, the Tamengo Formation is composed of thick (>5 m) coarse polymictic breccias, interpreted as submarine, slope apron deposits (Fernandes et al ., 2022).…”

Section: Discussionmentioning

confidence: 99%

“…The same surface is observed around the Bodoquena city area, stratigraphically close to the Hori drill core and Sol Nascente outcrop sections (Fernandes et al ., 2022). Above this limit, the Tamengo Formation is composed of thick (>5 m) coarse polymictic breccias, interpreted as submarine, slope apron deposits (Fernandes et al ., 2022). Evidence of cannibalization, including the presence of silicified dolomite (Bocaina Formation), dolomitized sandstones (Cerradinho Formation) and basement clasts within lower Tamengo Formation breccias, indicates a drastic base level shift associated with regional uplifting and erosion of continental and basinal sediments, compatible with a first‐order tectonic event (Fernandes et al ., 2022).…”

Section: Discussionmentioning

confidence: 99%

“…Terminal Ediacaran depositional ages are confirmed by a 543 ± 2 Ma U–Pb SHRIMP dating age (Babinski et al ., 2008) and by 541.85 ± 0.75 Ma and 542.27 ± 0.38 Ma (Parry et al ., 2017), obtained in interbedded volcanic ash layers of upper Tamengo. The contact between these units is marked by a regional erosional surface, commonly associated with the occurrence of an overlying polymictic breccia level (Boggiani, 1998; Trompette et al ., 1998; Gaucher et al ., 2003; Boggiani et al ., 2010; Fernandes et al ., 2022), separating platform deposits of the Bocaina and Tamengo formations (Trompette et al ., 1998; D'el‐Rey et al ., 2016; Fernandes et al ., 2022 – Fig. 2).…”

Section: Geological Settingmentioning

confidence: 99%

“…The top of the Corumbá Group is represented by outer ramp shale and minor carbonate mudstones of the Guaicurus Formation, which overlays the Tamengo Formation limestones in an intermingled transitional contact (Boggiani, 1998; Gaucher et al ., 2003; D'el‐Rey et al ., 2016). The deposition of these units (Tamengo and Guaicurus formations) is possibly associated with the development of an active foreland system during the closure of the Clymene Ocean involved in the final stages of Western Gondwana amalgamation between 545 Ma and 510 Ma (Trompette et al ., 1998; Trindade et al ., 2006; Tohver et al ., 2010, 2012; Campanha et al ., 2011; D'el‐Rey et al ., 2016; McGee et al ., 2018; Warren et al ., 2019; Fernandes et al ., 2022).…”

Section: Geological Settingmentioning

confidence: 99%

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Sedimentary evolution and sequence stratigraphy of Ediacaran high‐grade phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group), Central Brazil: Implications for the Neoproterozoic phosphogenic event

et al. 2023

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Extensive phosphorite deposition is observed in the Neoproterozoic after a prolonged hiatus during most of the Mesoproterozoic era. This event is thought to represent an important record of major palaeoenvironmental, palaeoceanographic and biotic changes that shaped Neoproterozoic ecosystems, suggesting close relationships between phosphogenesis and the preservation of key Ediacaran biotas. However, high‐grade Ediacaran phosphorite deposits are relatively uncommon, diminishing the opportunity to test current phosphate mineralization–deposition models and their implications for Neoproterozoic research. In this scenario, widespread Ediacaran phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group – Central Brazil) are poorly explored in international literature. Nevertheless, recent advances in phosphate exploration gave access to continuous drill core sections and freshly opened mine pits, revealing an unprecedented record of complex phosphatic successions featuring the occurrence of Ediacaran microfossils assigned to the Doushantuo–Pertatataka assemblages. This work seeks to constrain main lithofacies, sequence stratigraphy and depositional settings from these phosphatic successions in order to analyse the sedimentary evolution of the unit under the current Neoproterozoic phosphorite research framework. These results indicate that the Bocaina Formation records secular sustained phosphate deposition. These deposits are related to unprecedented, microbialite reef rim phosphorites deposited during a lower accretionary rimmed platform stage, followed by the deposition of Doushantuo‐like, whole platform phosphorites associated with a later, drowned platform stage, therefore, reinforcing the evidence for the operation of strong allogeneic controls on phosphate mineralization–concentration. In addition, this study concludes that fossiliferous Ediacaran phosphatic deposits such as the Bocaina Formation are important to understanding Neoproterozoic phosphogenic events, because they may record the transition from a Precambrian to Phanerozoic‐like phosphogenesis associated with the instauration of the Ediacaran–Cambrian phosphatic taphonomic window. This evidence hints that the growing dataset from the Bocaina Formation may bring new, exciting perspectives for Neoproterozoic research as a whole.

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