Marco Aurélio Piacentini Pinheiro

Geological Survey of Brazil | CPRM · Department of Geology

A systematic investigation of amphibolites and a metaultramafite granofels was carried out in the southernmost Brasília Orogen, part of the reworked margin of the São Francisco paleocontinent. These rocks occur interleaved within Neoproterozoic metasediments and the Archean-Paleoproterozoic basement. The amphibolites from the Andrelândia, Liberdade...

We present the first data on the geochemistry and isotopic age of zircons from rocks of the Roseta (lherzolite and olivine orthopyroxenite) and Córrego da Areia (olivine orthopyroxenite) ultramafic massifs localized among Archean–Proterozoic metamorphic strata in the southern folded framing of the São Francisco Craton. The examined zircons differ i...

The Campos Gerais Domain (CGD) in south-eastern Brazil is an approximately 180 km x 35 km area of Archean–Proterozoic rocks located southwest of the São Francisco Craton (SFC). The Archean–Paleoproterozoic evolution of the CGD — alongside its potential correlation with the SFC or other cratonic blocks in the region — is currently poorly-constrained...

A Certificação Kimberley (CPK) é um instrumento internacional que atesta a origem dos diamantes naturais, buscando coibir seu comércio quando proveniente de áreas de conflitos, e regulamentar seu mercado internacional. Instituído pela ONU em 2002, atualmente o CPK agrega 82 países signatários que respondem pela produção global de 99,8%. O Brasil ad...

Pure sediment derived melts are hallmarks of collision to post-collisional settings in modern-style plate tectonics (e.g. Himalayas mountain range). It remains unclear whether similar tectonics operated in the early Earth and if the archetypal magmas formed in collisional settings have evolved with time. Moreover, the production of high-K granitic...

Pure sediment derived melts are hallmarks of collision to post-collisional settings in modern-style plate tectonics (e.g. Himalayas mountain range). It remains unclear whether similar tectonics operated in the early Earth and if the archetypal magmas formed in collisional settings have evolved with time. Moreover, the production of high-K granitic...

The Quebra Osso Group encompasses one of the best preserved Archean komatiite flows in the Quadrilátero Ferrífero region, southern São Francisco craton (Brazil). It is commonly associated with the base of the Rio das Velhas greenstone belt within the Santa Bárbara tectonostratigraphic block. The Quebra Osso rocks are well exposed along the valley o...

The Morro do Onça suite is a package of ultramafic rocks in the southern São Francisco Craton, Brazil. Owing to the complete alteration of primary silicate minerals, the Morro do Onça suite has been the subject of diverging interpretations, including: part of a retrogressed eclogite-facies Paleoproterozoic ophiolite/accretionary wedge or an Archean...

O Granitoide Cupim, localizado na porção setentrional do Cinturão Mineiro, sul do Cráton São Francisco, constitui-se de granitos tipo-S, ou granitoides à duas micas, moderadamente foliados, com presença de granada. Feições petrográficas identificam monzogranitos leucocráticos a hololeucocráticos, de granulação média a grossa, com composição modal f...

Rocks of the Vazante Group in the Morro Agudo region (SE-Brazil) integrate a thick clay-carbonate sequence composed of twelve sedimentary facies and four facies associations (FAs), deposited in a mixed marine passive margin environment. This work carried out systematic isotope analyses of δ¹³C and δ¹⁸O on the two upper stratigraphic units of the Va...

The São Francisco paleocontinent comprises Archean nuclei and Paleoproterozoic magmatic arcs which were amalgamated during Siderian to Orosirian thermal-tectonic events (ca. 2.4-2.0 Ga). Located in the Porteirinha domain, one of these Archean segments, the Riacho dos Machados metavolcanosedimentary sequence encompasses metamafites and metaultramafi...

Sínteses tectônicas recentes como as de Kröner e Cordani (2003), Cordani et al. (2003a, 2003b, 2010a, 2010b, 2013) e de Brito Neves e Fuck (2014) segmentaram o embasamento da Plataforma Sul-Ameri- cana em dois amplos domínios geotectônicos: o domínio Amazonas ou pré-Brasiliano (de afinidades Laurencianas) e o domínio Brasiliano (de afinidades Gondw...

The Cristalândia do Piauí Block, located in the northwestern margin of the São Francisco Craton, represents the basement of the Rio Preto Fold Belt. It is composed of Archean orthogneisses of ca. 3.2 Ga reworked at 2.81 and 2.68 Ga with juvenile to moderately juvenile εHf values between -1.51 and -8.07, and high-K syenogranites dated at 2.65 Ga wit...

The Quebra Osso komatiite flow field is part of the 2.9–2.7 Ga Rio das Velhas greenstone belt, in the Quadrilátero Ferrífero province, located in the Southern São Francisco craton (Brazil). It is mostly composed of metamorphosed komatiites with a minor association of pyroclastic and metasedimentary rocks. Through a detailed and systematic study, th...

We present the first data on the geochemistry and isotopic age of zircons from rocks of the Roseta (lherzolite and olivine orthopyroxenite) and Corrégo da Area (olivine orthopyroxenite) ultramafic massifs localized among Archean–Proterozoic metamorphic strata in the southern folded framing of the São Francisco Craton. The examined zircons differ i...

The Espinhaço rift system encompasses taphrogenetic events from the Statherian to Tonian in the São Francisco-Congo (SFC) paleocontinent. The magmatism is represented mainly by metamorphosed anorogenic granites and rhyolites with subordinate amphibolites. Zircon U-Pb ­(LA-ICPMS and SHRIMP) ages from felsic (1748 ± 3 Ma and 1740 ± 8 Ma) and mafic (1...

The results of isotope U–Pb dating of zircons from lherzolite and vein olivine orthopyroxenite composing the Roseta ultramafic massif are presented. The zircons differ in their morphological, optical, and geochemical properties and in their age. Lherzolite samples that are almost deprived of cathodoluminescence are represented by two age clusters 7...

The investigation of ultrahigh temperature (UHT) metamorphic rocks, and their corresponding (pressure)-temperature-time (P-T-t) history is critical to distinguish between arc- or collision-related metamorphism. This is a very challenging task if mineral assemblages are highly retrogressed and isotopic systems are disturbed. Garnet-free granulites l...

The identification of markers of subduction zones in orogenic belts requires the estimation of paleo-geothermal gradients through pressure-temperature-time (P-T-t) estimates in mafic rocks that potentially derive from former oceanic units once. However, such markers are rare in supracrustal sequences specially in deeply eroded and weathered Pre...

The massif Roseta, located in the south-eastern part of Brazil, occurs among Neoproterozoic metamorphic strata of the southern margin of San Francisco craton. It is composed of the complex of lherzolites, clinopyroxene and clinopyroxene-free harzburgites, as well as having a limited spread of olivine websterites. There was detected in the massif a...

This geochronological and isotopic study focuses on one of the Archean-Paleoproterozoic basement domains of the São Francisco craton reworked in the Araçuaí orogen, the Porteirinha domain, Brazil. It also includes a thorough compilation of the U–Pb geochronological data related to the adjacent Archean and Rhyacian terranes from the São Francisco cr...

Ophiolites are fragments of the ancient oceanic lithosphere formed at constructive plate margins or transforming divergent plates. Through extensive thrust faults, these bodies or part of them are emplaced into the continental crust, inside rock piles of orogenic belts, in solid state, but these bodies can be relatively warm. The possible environme...