"Quimioestratigrafia das rochas ediacarianas do extremo norte da faixa Paraguai, Mato Grosso"

Figueiredo, Milene Freitas

doi:10.11606/d.44.2006.tde-19032007-083041

Cited by 11 publications

(18 citation statements)

References 62 publications

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“…More recently, Figueiredo (2006) and subsequently Alvarenga et al (2007) described a new unit, the Serra Azul Formation, in between carbonates of the Araras Group and the siliciclastics of the Alto Paraguay Group (Fig. 1B).…”

Section: Regional Settingmentioning

confidence: 96%

Age and provenance of the Cryogenian to Cambrian passive margin to foreland basin sequence of the northern Paraguay Belt, Brazil

McGee

Collins

Trindade

et al. 2014

Geological Society of America Bulletin

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The Paraguay Belt in central South America developed in response to the collision of the Amazonian craton, the São Francisco craton, and the Paranapanema block. The alleged "Brasiliano" age (ca. 620 Ma) of orogenesis has recently been questioned by paleo magnetic and radioisotopic ages that indicate the closing stages of orogenesis occurred well into the Cambrian. We investigated the timing of deposition and source areas for these sedimentary rocks overlying the Amazonian craton using integrated U-Pb and Hf isotope data of detrital zircons from within this sequence. In total, 742 detrital zircon U-Pb ages were analyzed from samples taken from the base to the top of this sedimentary succession. Maximum depositional ages from the uppermost part of this sequence of rocks, the Diamantino Formation, indicate that fi nal deposition began no earlier than 560 ± 13 Ma and possibly as young as the Cambrian. Given that zircon inheritance in these rocks continues up until this age and that known Amazonian craton ages are older than ca. 950 Ma, we considered other potential sources for these sediments. This was achieved by integrating the U-Pb detrital zircon data with Hf isotopic data from these zircons that have ε Hf values ranging from -18 to 12. The ε Hf signature is consistent, with a predominantly Amazonian source until the early Neoproterozoic, at which point the signal becomes signifi cantly more evolved. These data, when combined with other evidence discussed here, are consistent with an ocean to the east of the present-day Amazonian craton that did not close until the latest Ediacaran-Cambrian.

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Section: Regional Settingmentioning

confidence: 96%

Age and provenance of the Cryogenian to Cambrian passive margin to foreland basin sequence of the northern Paraguay Belt, Brazil

McGee

Collins

Trindade

et al. 2014

Geological Society of America Bulletin

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“…The lithogeochemical results are displayed in Table 1, with the chemical classification of the carbonate rocks based on their Mg/Ca ratios (values after Figueiredo 2006). According to this classification, dolostones occur in Units 3 and 10, and magnesium limestone contribution occurs in units 4, 6 and 7.…”

Section: Lithogeochemistrymentioning

confidence: 99%

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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“…The cap dolostone grades to the very thick carbonate platform of the Araras Group, which has 87 Sr/ 86 Sr ratios increasing upwards through the group from 0.7074 to 0.7080, interpreted as typical for the Ediacaran Period (Figueiredo 2006(Figueiredo , 2010.…”

Section: Amazon Craton-northern Paraguai Beltmentioning

confidence: 99%

The Cryogenian and Ediacaran Records From the Amazon Palaeocontinent

Figueiredo

Babinski

2014

Springer Geology

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The Amazon Craton was involved in the buildup of the Rodinia and Gondwana supercontinents during the Neoproterozoic. During this era, Earth's surface was marked by important transformations including global glaciations, atmospheric and ocean oxygenation pulses, and the turnover of life forms. Most of these events were recorded on the margins of the Amazon Palaeocontinent in the time interval between the breakup of Rodinia and the assembly of Gondwana, today located on its southeastern border as part of the Paraguai Fold-Thrust Belt. This paper reports the age constraints obtained for the respective sedimentary successions based on several tools, including geochronology using U-Pb, Pb-Pb, and Ar-Ar methods, isotope chemostratigraphy of C and Sr, and palaeobiology. According to the results, the sedimentary successions record surface conditions from the early Cryogenian to the early Cambrian.

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"Quimioestratigrafia das rochas ediacarianas do extremo norte da faixa Paraguai, Mato Grosso"

Cited by 11 publications

References 62 publications

Age and provenance of the Cryogenian to Cambrian passive margin to foreland basin sequence of the northern Paraguay Belt, Brazil

Age and provenance of the Cryogenian to Cambrian passive margin to foreland basin sequence of the northern Paraguay Belt, Brazil

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

The Cryogenian and Ediacaran Records From the Amazon Palaeocontinent

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