Chemostratigraphy of the Lower Arroyo del Soldado Group (Vendian, Uruguay) and Palaeoclimatic Implications

Gaucher, Claudio; Sial, Alcídes N.; Blanco, Gonzalo; Sprechmann, Peter

doi:10.1016/s1342-937x(05)71058-3

Cited by 77 publications

(63 citation statements)

References 26 publications

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“…The same discrepancy was noted by Paula- Santos et al (2015) in other studied sections of the Bambuí Basin, and also occurs in other Ediacaran basins around the world (e.g. Gaucher et al 2004, Gómez Peral et al 2007, Boggiani et al 2010, Frei et al 2011.…”

Section: Strontium Isotopessupporting

confidence: 70%

Chemostratigraphy of the lower Bambuí Group, southwestern São Francisco Craton, Brazil: insights on Gondwana paleoenvironments

et al. 2016

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ABSTRACT:The Bambuí Group, the most extensive carbonate-siliciclastic cover on the São Francisco craton, has been a matter of debate because of its potential correlations to global glacial events. Unfortunately, most available chemostratigraphic data came from samples collected on surface rock exposures, ever susceptible to the aggressive chemical weathering that characterizes the southeastern Brazil. On the other hand, we present here high-resolution chemostratigraphic studies based on C, O and Sr isotopic data from 53 samples collected along a weathering-free, continuous, 175 m thick sedimentary succession. This succession was recovered by borehole drilling in the southwestern São Francisco craton, where occur the Carrancas and Sete Lagoas formations, the lowermost units of the Bambuí Group. The drill cores reveal extremely irregular contacts between the basal diamictite and its basement, an Archaean foliated granodiorite. Geochronological and sedimentological data strongly suggest that the diamictite represents a lodgement till. This glaciogenic deposit is covered by a limestone succession which starts with impure carbonates showing aragonite pseudomorph fans and thin bands of black shale. The limestone pile grades to a marl-mudstone interval, which turns to a carbonate with biological components, succeeded by stromatolitic dolomite at the top. C and O isotopic signatures (referred to V-PDB) allow to the subdivision of the lower carbonate-pelite section into three intervals. The first isotopic interval corresponds to a cap carbonate, and displays negative values of δ 13 C (c. -4‰), and a large oscillation of the δ 18 O (-6 to -15‰

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Section: Strontium Isotopessupporting

confidence: 70%

Chemostratigraphy of the lower Bambuí Group, southwestern São Francisco Craton, Brazil: insights on Gondwana paleoenvironments

et al. 2016

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“…These ichnofossils are identical to the Tacuarí material (1), which is shown here in Fig. 2, A, D, and E. At site CCU 22, the succession is undeformed, flat-lying, and unconformably overlies folded late Ediacaran carbonates and shales of the Arroyo del Soldado Group (13,14). It is in turn overlain by Early Permian sandstones of the Tres Islas Formation (2).…”

mentioning

confidence: 54%

Comment on "Bilaterian Burrows and Grazing Behavior at >585 Million Years Ago"

Gaucher

Poiré

Bossi

et al. 2013

Science

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Pecoits et al . (Reports, 29 June 2012, p. 1693) describe bilaterian trace fossils and assign them an Ediacaran age based on the age of a granite interpreted as intrusive. We argue that the granite is not intrusive but in fact represents the basement of the sedimentary succession. Moreover, we show that identical trace fossils occur in nearby Carboniferous-Permian glacigenic rocks.

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“…Sedimentological evidence of such an event is so far lacking. Chemostratigraphic studies of the carbonates , Chiglino 2013 reported negative δ 13 C values (−3.5 ‰) at the base of the unit that may be related to periods of low plankton bioproductivity or sea level fluctuations (Gaucher et al 2004a, Frei et al 2011. The dark gray to black, laminated limestones of the Araticum section, start with a negative δ…”

Section: Discussionmentioning

confidence: 99%

Acritarchs of the Ediacaran Frecheirinha Formation, Ubajara Group, Northeastern Brazil

Chiglino

Gaucher

Sial

et al. 2015

An. Acad. Bras. Ciênc.

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We report for the first time the occurrence of organic-walled microfossils in Ediacaran limestones and marls of the Frecheirinha Formation, Ubajara Group, and the first Precambrian acritarchs so far reported for northeastern Brazil. The assemblage of the Frecheirinha Formation represents a low-diversity microflora comprising Leiosphaeridia, Lophosphaeridium and subordinated Bavlinella (=Sphaerocongregus). Sr values between 0.7075 and 0.7080 suggest an Ediacaran age. The acritarch assemblage is comparable to the Late Ediacaran Leiosphere Palynoflora (LELP) or Kotlin-Rovno assemblage, in broad agreement with chemostratigraphic data. Macrofossils belonging to the Ediacara fauna were reported from the overlying Jaibaras Group, which would constrain even further the depositional age of the Frecheirinha Formation to within ca. 575-555 Ma. A more comprehensive palynological study of the Frecheirinha Formation is necessary to confirm this age assignment.

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Chemostratigraphy of the Lower Arroyo del Soldado Group (Vendian, Uruguay) and Palaeoclimatic Implications

Cited by 77 publications

References 26 publications

Chemostratigraphy of the lower Bambuí Group, southwestern São Francisco Craton, Brazil: insights on Gondwana paleoenvironments

Chemostratigraphy of the lower Bambuí Group, southwestern São Francisco Craton, Brazil: insights on Gondwana paleoenvironments

Comment on "Bilaterian Burrows and Grazing Behavior at >585 Million Years Ago"

Acritarchs of the Ediacaran Frecheirinha Formation, Ubajara Group, Northeastern Brazil

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