ric

Geo

Keywords:PaleoproterozoicSouth-American platformCrustal evolutionSiderianOrosirian

ks a

Brasiliano (Neoproterozoic) structural provinces (Tocantins, Bor-borema, Mantiqueira, Pampean), according to Almeida et al. (1981).Many basement inliers of these Brasiliano provinces e of variedgeotectonic/or structural origins e are also depicting records of thePaleoproterozoc rock asemblages and events.

Furhtermore, that importance of Paleoproterozoic rock units,blocks and terranes can also be inferred for the basement of the

preliminarily attested and identied: Siderian, Rhyacian, Orosirianand Statherian (thus following and respecting the Paleoproterozoicsubdivision proposed by IUGS/UNESCO 2004). In fact, this groups ofevents and super-events that led to the crustal growth of the South-American continent ts naturally and quite properly the division(periods) of the Paleoproterozoic Era. Additionally, the stages hereproposed to the South-American continent can be characterized asclose to or complying with Condies (2000) conception of episodiccontinental growth, encompassing groups of events and super-

Contents lists availab

e

els

Journal of South American Earth Sciences 32 (2011) 270e286E-mail address: bbleybn@usp.br.The geologic map of the South-American continent, whenanalyzed under the point of view of the composition and aggluti-nation of the Rodinia supercontinent (e.g. Fuck et al., 2008) (Fig. 1),is a very useful document to evaluate the importance of theparticipation of Paleoproterozoic rocks, terranes and differentblocks in the constitution of that supercontinent. Firstly, thatimportance should be emphasized for the basement framework ofthemain cratonic nuclei (Amazonian, So Luis, So Francisco, Rio dela Plata) of the South-American Platform. Additionally, importancecan also be pointed out for the basement framework of the main

block, As discussed below).In the last 25 years, the advance in the geologic knowledge of

the South-American continent has been notable, thanks to newsystematic geological and geophyxical mapping (carried out byuniversities, private and statal companies) and acquisition of newgeochronological data (mainly by UePb and SmeNd methods),obtained from laboratories of various parts of Brazil andworldwide.

Regarding the Paleoproterozoic, the collection of substantialdata has revealed a vast diversity of rock-forming processes, vari-able through the geologic time, so that its four major stages can beStatherianBrazilian cycle

1. Introduction0895-9811/$ e see front matter 2011 Elsevier Ltd.doi:10.1016/j.jsames.2011.02.004representing therefore examples of Wilson Cycles. In other cases, the records of extensional processesand those of convergent interaction of lithospheric plates (orogenies) are either concurrent in time (withdifcult discrimination between them) or concurrent in the geographic-geologic space (they occur indifferent and separated domains), privileging different regions. The four periods of rock-forming eventsdiscussed here (Siderian, Rhyacian, Orosirian, Statherian) are mainly recorded and recognizable for mostof the cratonic domains of the continent, but they are gradually being identied within the Paleo-proterozoic basement blocks (inliers) in the large Neoproterozoic (Brasiliano) provinces of the conti-nent. In the latter, such discrimination is much more difcult due to the overprint of the Brasilianothermo-dynamic processes. For many years (in the recent past), the word Transamazonian (event,orogeny, cycle) had been used to cover indiscriminately all these many different Paleoproterozoic events,of the four different periods. With the present discrimination of the four major stages (periods) on timeof rock-forming processes (igneous, metamorphic and sedimentary assemblages) the term Trans-amazonian has naturally become obsolete, and its usage is no longer advisable.

2011 Elsevier Ltd. All rights reserved.

major Phnerozoic syneclises (Amazonas, Paranaiba, Paran) andeven for some terranes docked in the Andean Chain (e.g. Arequipaby the International Stratigraphic Chart (IUGS/UNESCO 2004). There are some particular cases for whichrifting and drifting events precede the processes of convergent interaction between lithospheric plates,Received 20 July 2010Accepted 14 February 2011

register rock-forming events (orogeny and taphrogeny) clustered in the four different periods as denedThe Paleoproterozoic in the South-Amein the geologic time

Benjamim Bley de Brito NevesInstituto de Geocincias da Universidade de So Paulo, Departamento de Mineralogia e

a r t i c l e i n f o

Article history:

a b s t r a c t

The Paleoproterozoic bloc

Journal of South Am

journal homepage: www.All rights reserved.an continent: Diversity

tectnica, Rua do Lago 562, Cidade Universitria, 05508-080 So Paulo-SP, Brazil

nd terranes that constiture of the South-American continent basement

le at ScienceDirect

rican Earth Sciences

evier .com/locate/ jsames

meriB.B. de Brito Neves / Journal of South Aevents responsible for peaks of continental crust production withthe duration of some hundred million years.

In some of these proposed time intervals (periods), one maydistinguish taphrogenetic (distensional events) from orogeneticevents (convergent plate interactions), sometimes in a sequencesimilar to the complete or incomplete Wilson Cycles, sometimes asactivities concurrent in time (same time interval) but taking placein different regions.

Up to now, there has been a relatively complete representationof all the above-mentioned stages in the Amazonian, the largestand most complete Rodinias descendant (Fuck et al., 2008), SoFrancisco and Rio de la Plata cratons. Some of these stages/periodsvery represented, but some other still are demanding additionalresearchs and discussion. In other Paleoproterozoic terranes andblocks of the continent, either cratons or parts of the basement ofmobile belts, this representation is assigned to one, two or three ofthese events/super-events. In general, the four time intervalmentioned assembled tectonic processes that played an importantand well-orchestrated role in building the continent by (lateral and

Fig. 1. The Rodiniass descendants in South America (modied from Fuck et al., 2008). Thblocks. See other gure (Figs. 2, 3 and 4), as complement.can Earth Sciences 32 (2011) 270e286 271vertical) growth of its several continental tracts. These were lateroverprinted by Mesoproterozoic and Neoproterozoic thermal-tectonic events. The data available so far not sufcient to denewhich of these periods/super-events was the most conspicuous interms of the crustal growth. Up to now, apparently the Rhyacian(represented by orogenic cycles in all cratons, terranes and base-ment blocks) and the Statherian (territorial extension of the events,products and sub-products) are good candidates.

It is worth mentioning occurrences of high-grade ortho derivedrocks (and to a lesser extent, some volcanic sedimentary rockassemblages) in the time interval 2.5e2.3 Ga (Siderian), which isa new fact in the geology of South America to be distinguished. Inmost of the cases, these data present the support of very good litho-structural and isotopic data. This notable fact counteracts modelsanddataof continental crustal growthasproposedbyCondie (2000),which has already been reiterated by several researchers. Forexample, according to Windley (1995), the Siderian was a kind oflull in the continental crust growth process. Besides attesting tothis fact, there is a large perspective of other Siderian events to be

e main Paleoproterozoic domains are distinguished in different cratons, terranes and

meriidentied and/or better characterized. Mostly the Siderian rockassemblages are strongly reworked continental tracts, which wereincluded as inliers in Rhyacian belts and even within youngerProterozoic cycles.

In the geological literature concerning South-American conti-nent, there has been a tendency to include all these differentPaleoproterozoic super-events/events (ages and areas) in the so-called Transamazonian Cycle as proposed by Hurley et al. (1967)and Almeida et al. (1973), as a response to the rst geochronologicaldata, obtained by low resolution characteristics methods, such asKeAr and RbeSr. These studies were valid and important at theirtime, but this broad and non-discriminating name (Trans-amazonian event, cycle, orogeny) is totally out-of-date, in variousways, with the advent of new geologic, tectonic and geochrono-logical data. This generic name should be abandoned, because evena redenition (which could cover part of the Rhyacian events) couldbe hazardous for the progress of knowledge.

2. The Siderian period

The conrmation of rock-forming events during the Siderian ofSouth America is a relatively new discovery/fact and has beentreated with caution. These occurrences have been registered indifferent structural provinces of the continent, thanks to invest-ments in geologic cartography and precise and accurate isotopicstudies (run by the Brazilian Geological Survey and researchers ofdifferent universities).

Nonetheless, these occurrences have helped to overcome somepreconceived ideas. Therstwas the excessive coverage given to theso-called Transamazonian Cycle (throughout the whole Paleo-proterozoic). The second was the false dillema Transamazonian(designation misused throughout the whole Paleoproterozoic)versus Brasiliano (designation misused for most of the of post-Paleoproterozoic rock assemblages).

For descriptive purposes, the occurrences of Siderian rockassemblage are divide into two main groups: i) expressivegeographic-geologic occurrences (Bacajs, Granja, Luiz Alves) andii) punctual/local presence within older (Archean, Rhyacian)tectonic domains (see Figs. 1 and 2). These groups and other indi-cations suggest that many Siderian occurrences will be revealedwith the progress of the studies.

2.1. Amazonian Craton

2.1.1. Bacajs block and Central AmapAlthough extensional events were to be expected after the

Archean fusion (as is the case of the So Francisco Craton describedbelow), in the Amazonian Craton, the Siderian period was markedby orogenic formation of high- and low-grade metamorphic rocks.

The most notorious cases are the Bacajs domain, located in thesouth easternmost part of the Rhyacian Maroni-Itacaiunas Belt(Tassinari and Macambira, 2004), to the north of the Archean Car-ajs-Rio Maria blocks, south of the Amazonas River. In this domain,between reworked Arcehan rock units extensively crosscut by(Rhyacian and Orosirian) granitic intrusions, Vasquez et al. (2008)identied 2.36e2.34 Ga granite-greenstone-type terraness cros-scut by 2.31 Ga granitoid intrusions. In reality, these Siderian rockassemblages are true relicts present in the interior of a youngergranitic domain (of 2.21e1.86 Ga of age), situated along the Bacajsriver (Trs Palmeiras greenstone) and of supracrustal rocks in theXingu-Iriri mesopotamia. Banded porphyroclastic meta-tonalitesare recognized with boudins of mac igneous rocks (trendingNEeSW) juxtaposed to the supracrustal rocks yielding UePb agesof 2338 5 Ma, interpreted as representing igneous zircon

B.B. de Brito Neves / Journal of South A272crystallization. The supracrustal rocks are metamac, intermediatemetavolcanic (andesites, dacites), volcaniclastic, and some BIFs, allshowing geochemical afnities with island-arc settings. The meta-volcaniclastic and intermediatemetavolcanic rocks yield UePb agesof ca. 2.45 Ga and of 2.36e2.34 Ga respectively.

There is also unpublished information by CPRM (the BrazilianGeological Survey) of other similar occurrences east of the Bacajsdomain, which are true relicts inside a younger (Rhyacian) mobilebelt (Rosa-Costa et al., 2006).

North of the Amazonas River, within the context of the Maroni-Itacainas Belt and in its important Archean basement inlier, incentral Central Amap, Rosa-Costa et al. (2006, 2008) obtaineda large number of UePb and PbePb ages (specially by the evapo-ration method) in the 2.4e2.3 Ga interval. These age values weredetected at specic points within an Archean nuclei, but thepetrographic and isotopic data indicate true Siderian crustal growth.

Even if all these cases demand additional geologic and isotopicinvestigation, they are a valuable discovery for several reasons. Asthe Maroni-Itacainas Belt as a whole characteristically containsmany pre-Rhyacian remains, the discovery of new Siderian crustalgrowth records are to be expected. Isolated citations exist in theliterature of the occurrence of zircons of Siderian age in the abovementioned areas and in many others (Almeida et al., 2007), thusconstituting a theme that deserves attention and systematic revi-sion for the future.

2.2. The So Francisco Craton (the Siderian Taphrogenesis)

2.2.1. Basement of the Itabuna-Salvador-Juazeiro (Bahia) andMineiro Belts (Minas Gerais)

Several relatively isolated tectono-magmatic events took placein the So Francisco Craton, resulting in the formation of mac(dike swarms), mac-ultramac complexes and various graniticrocks of immediately post-Neoarchean ages. Due to their impor-tance and nature, these rocks were referred to as representative ofa Siderian Taphrogenesis by Delgado et al. (2003).

Mac dike swarms are known in the southern (QuadrilteroFerrfero) and in the northern (Serrinha bock) parts the craton. It isalso worth mentioning the Contenda-Jacobina Fault Zone (strikingapproximately NeS), which hosts the important Jacar River mac-ultramac layered complex (ca. 2475 Ma age). Several sub-alkalinegranitic and syenitic bodies are also recognized in southern Bahia,considered to be an intraplate-type magmatic event intrusive intoArchean TTG complexes. These are clearly post-Archean rock units(ages between 2.56 and 2.4 Ga), some of which are relatively verylarge (up to 200 km long).

In the northeast of the craton (Serrinha Block, Fig. 3), Oliveiraet al. (2004) pointed out the intrusion of monzonitic and mon-zodioritic rocks of alkaline nature and of Siderian age, and they havea discussed the presence of tonalitic rocks of this age in the ItapicuruRiver Greenstone. These authors have also suggested the possibilitythat part of the greenstone volcanism (reaching back-arc conditionsin the Rhyacian) might started earlier, in the Siderian (Fig. 4).

Despite the need of more detailed studied, events and rockssimilar to those found in Bahia have briey been reported withinthe basement of the southern part of the craton in Minas Gerais.

Togetherwith intraplatemagmatism,which can be considered tobe isolated or taphrogeny-related process, it is necessary to stress outthe evolution process of the Atlantic-type continental margin thatpreceded the opening of an ocean and the development of the so-called Mineiro Belt (predating the Rhyacian orogenies). The litho-stratigraphic development of the Minas Supergroup sedimentsconstitutes a notable sedimentary record of the development of apassive continental margin (somehow comparable to that of theCretaceous Atlantic-type margins of South America). This taphroge-

can Earth Sciences 32 (2011) 270e286netic process (riftedrift transition) still has a poor geochronological

meriB.B. de Brito Neves / Journal of South Acontrol, based on a few PbePb data for carbonaceous sediments, aswell as some detrital zircons from clastic sediments, which are well-understood in the regional geologic context. These events took placebetween 2.25e2.40 Ga, preceding the orogenic evolution of theMineiro Belt, according to vila et al. (2010).

Basedon these andother similardata for the So FranciscoCraton(e.g. evolution of the Colomi Group, northern part of the craton) and

Fig. 2. The main paleoproterozoic domains for the central and northern part of south AmeriConceio; 4 e Luis Alves Craton.can Earth Sciences 32 (2011) 270e286 273other cratonic nuclei, the expectation is open for new records anddata related to this taphrogenesis that resulted and succeeded therst expressive agglutinations of continental masses by the end ofthe Neoarchean. Particularly for this craton, the dominant idea isthat the extensional events following the Neoarchean fusion wereimportant. The discrimination of such events (overprinted by theRhyacian orogenic events) should be urgently pursued.

ca, with emphasis for the Siderian domains: 1e Granja Massif; 2e Bacajs; 3 e Almas-

meriB.B. de Brito Neves / Journal of South A2742.3. The Rio de la Plata Craton

2.3.1. Taquaremb blockThe incontestable majority of geochronological information for

thedifferent terranes that constitute theRiode la Plata Cratonpointsto its consolidation in the Rhyacian, with localized later remobili-zations during Orosirian (late deformation?) and Statherian events(magmatism). The consolidation in the Rhyacian and the extremelyuniform character of the chrono-tectonic history of this craton isrmly based on the recent synthesis, by Rapela et al. (2007).

On the other hand, there are (up to now) some isolated obser-vations, such as those in Tickyj et al. (2004) and Hartmann et al.

Fig. 3. Sketch tectonic map of the main Archean blocks (paleoplates) and the mobile belts (So Francisco Craton and surroundings (modied of Barbosa and Sabat, 2004).can Earth Sciences 32 (2011) 270e286(2008) referring to the presence of pre-Rhyacian rocks, which areworth mentioning. In the northernmost of the craton, in the so-called Taquaremb block, west of the exposurewindow of the RioGrande do Sul basement, in the Santa Maria Chico Complex gran-ulitic rocks (polycyclic, with partial retrograde metamorphism tothe amphibolite facies) of granodioritic composition, presentedUePb (SHRIMP) ages of 2.35 Ga, obtained from zircon cores.

These rocks are admittedly relicts inside a Paleoproterozoicdomain, as already recorded in the literature. Additionally, someother zircon nuclei from granulitic rocks of trondhjemitic natureyielded Archean ages (Hartmann et al., 2008 and Tickyj et al., 2004),which indicates the possibility of pre-Rhyacian protoliths, whose

Rhyacian and Orosirian) that were developed among them, in the eastern domain of the

Rio N

meriFig. 4. The principal Statherian occurrences in South America: Orogenic development (sedimentary, volcano-sedimentary, volcanic and plutonic activities).

B.B. de Brito Neves / Journal of South Anature and extension are open research themes for the future.Possible metamorphic reworking of these rock in the Orisirian willbe discussed later in this paper.

2.4. The Luiz Alves Craton/terrane

The Luiz Alves cratonic segment (Figs. 1, 2, and 5) is a terranesituated in the southern coast of Brazil (from south of So Paulo toSanta Catarina), between two Brasiliano belts: the Ribeira belt (thePien magmatic arc) to the north and the Dom Feliciano (Brusque-Tijucas belt) to the south. This terrane has behaved as stablenucleous during the Brasiliano orogeny, and so it is an importanttectonic element responsible for the segmentation of the broadMantiqueira Province. In despite of the modest size of this stablenucleous (10,000 km2), it is the most concise and complete andwell-documented representation of the Siderian crustal growthamong all the cratons of the continent (Basei et al., 1998, 2008).Actually, this terrane has worked out as a microplate during theBrasiliano tectonic scheme of plate interactions.

The so-called Santa Catarina Granulite Complex is composedof; i) various high-grade, hyperstene-bearing tonalitic-granodio-ritic orthogneisses showing conspicuous gneissic foliation andcontaining enclaves, fragments and boudins of mac-ultramacrocks and ii) migmatitic gneisses. Components of metasedimentaryorigin are minority. There is also an intrusive mac-ultramaccomplex (Barra Velha) composed of gabbros, gabbro-norites andwebsterites, all affected by high-grade metamorphism. To thenorth, TTG-type felsic and leucocratic orthogneisses predominate,with several charnockite intercalations.

The Brasiliano deformation is limited to the vicinity of shearzones, being accompanied by granitic intrusions (to the north)and several internal (e.g. Campo Alegre) and foreland (e.g. Itajai)volcano-sedimentary basins.egro Juruena accretionary belt) and the anorogenic processes and records (diversied

can Earth Sciences 32 (2011) 270e286 275Two high-grade metamorphic episodes are clearly identied inthe basement complexes based on excellent control by geochro-nological data: the rst and more important at ca. 2.35 Ga (ageobtained from various rock types, in most domains); the secondevent at ca. 2.15 Ga is (superposed to the rst one) is represented bydeformed granitoids, some felsic granulites and paragneisses. Mostprobably, these events are separated by a signicant time intervalduring which erosion and deposition of sedimentary rocks musttook place. Sm/Nd model ages are of ca. 2.8e2.7 Ga.

2.5. Basement inliers of the (Brasiliano) Borborema province

2.5.1. The Granja massif (NW Cear/NE Piau)This massif is exposed only in the north-western most part of

the Borborema Province and also constitutes part of the basementParnaba Syneclise basement, which covers at least two thirds ofthe original original size of the massif, leaving exposed an area ofapproximately 6.000 km2. The basement of this relatively stablenucleus (within the mobile belt) is constituted by high-grade rocks,mainly TTG orthogneisses, amphibolitic gneisses and garnet-amphibolites inter-layered with kinzigitic rocks, some mac gran-ulites and locally migmatites, trending NEeSW and obeyinga striking fabric of Brasiliano shear, which additionally separatesthese nuclei from the Neoproterozoic supracrustal domains (MdioCorea Belt). Thermo-barometric data indicate granulite meta-morphism for these rocks around 750 C and pressures of 7e8 kbar(Santos et al., 2008). The rocks of this massif are intruded by Bra-siliano granites and it is deeply affected by Neoproterozoic shearzones.

Despite Neoproterozoic reworking events (granites, shearing),the geochronological data (summarized by Santos et al., 2008) arevery good, which discriminates this massif as one of the mostconcrete and expressive record of the Siderian events in the

meriB.B. de Brito Neves / Journal of South A276continent. UePb, with data for different rock types that showpredominant ages between 2,30 and 2,36 Ma. TDM model ages aremostly between 2.38 and 2.48 Ga (only two values above 2.54 Ga),and with weakly positive eNd, values between 0.4 and1.9,indicating the juvenile nature of this Siderian magmatic (andmetamorphic) event.

Similarly to the Luiz Alves Craton, the Granja Massif representsan interesting tectonic high within the Brasiliano domains, the

Fig. 5. An outline for the main tectonic elements of the southeast of South America (cent(Curitiba block or microplate) and the Siderian (Luis Alves craton) blocks, that have workecan Earth Sciences 32 (2011) 270e286latter one presenting very clear Siderian signature. Additionally, itis necessary to stress that the Granja Massif is a context verydifferent (composition, structure and age) from that of So LuisCraton situated further in Maranho state (composed of Rhyacianrock assemblages). Several authors correlated both areas or sug-gested a continuation of Granja (Cear State) in Maranho (SoLuis), which is not supported by the available geological andgeochronological data.

ral and southern part of the Mantiqueira province). Special remarks for the Rhyaciand out as foreland for the adjacent Brasiliano belts.

meri2.5.2. Rio Piranhas Massif (Rio Grande do Norte Terrane)In the eastern portion of the Rio Grande do Norte terrane (the

northern segment of the Borborema Province), in the Rio Piranhasmassif, which is an extensive Rhyacian basement inlier (naturallimit) for the Brasiliano Belt from Serid to the west). Dantas et al.(2008) have recently pointed out the presence of some supracrustalrocks (Santa Luzia sequence) that yielded Siderian ages (mainlybetween the cities of Lages and Angico). These are amphiboliticrocks (meta-andesites and metabasalts) and intercalated withbanded iron formations and calc-silicatic units, exposed withina domain of Rhyacian calc-alkaline orthogneisses (Caic complex).

The supracrustal rocks and associated gneisses present SiderianUePb ages (ca. 2.33 Ga), ca. 150 Ma older than those of the classicRhyacian Caic Complex basement, which underlies these Side-rian rock units.

2.6. The basement of the Tocantins Province

2.6.1. Almas-Conceio block (northeastern portion of the GoisCentral Massif)

In the Tocantins Province, in the ample portion of the basementwest of the northern segment of the Neoproterozoic Braslia Belt, aninteresting occurrence of Siderian rocks was identied withina Rhyacian orthogneissic domain (Fuck et al., 2001). These rocks arepart of the western basement of the Braslia Belt (Brasiliano) andprobably extend to the north-western portion of the So FranciscoCraton.

In the domain between Almas and Conceio (parallels 11 S and13 S), and part of the basement of the Arai and Natividade sedi-mentary groups, Statherian in ages, rocks of calc-alkaline nature of2346 16 Ma, interpreted as the crystallization age. Similarly,a granite-gneiss north of Conceio do Tocantins yielded the age of2375 6Ma, which is equally interpreted as of the formation age ofthe igneous protolith. SmeNd model ages falling in the 2.6e2.5 Gainterval and positive eNd values (between zero and 1.0) arereported for these rocks.

Although preliminary, these results (because of the place theyoccupying) (Fig. 2) trigger the discussion whether a (tectonic,paleogeographic) relationship exists with those rocks and the rockunits and values found in the Granja (north-western part of Bor-borema Province) and those of in the Bacajs massifs (south east-ernmost part of the Amazonian Craton). The distribution of theGranja and Almas-Conceio occurrences (present position asresult of the last Brasiliano events), in both sides of the Trans-brasiliano Lineament deserves special attention.

2.7. The Mantiqueira Province basement

2.7.1. The Quirino Complex/unitIn the structurally complex northern part of the Mantiqueira

Province (eastern Araua Central and Northern Ribeira), localexposures (structural and erosional windows) of Paleoproterozoicrocks are attributed to the Statherian and older periods (Heilbronet al., 2004, synthesis work). In general, high-grade rocks of theRhyacian cycles are more commonly found in the whole basementof this northern part of this province.

The Quirino Complex occurs as an intensely reworked base-ment at the central part of theNeoproterozoicmobile belt (along thebasement of the Paraba do Sul klippe), that is placed along an axialzone of structural divergence, composed of high-grade rocks, horn-blende meta-tonalites andmetagranodiorites with enclaves of calc-silicate, mac and ultramac rocks. Two groups of rock units wererecently identied and described in this Quirino Complex (Vianaet al., 2008), representing solid proof of the existence of two crus-

B.B. de Brito Neves / Journal of South Atal growthpulses. Therst consists of high-potassiumrocks, yieldingUePb zircon ages of ca. 2308Ma, and the second ofmedium- to low-potassium rocks with Rhyacian ages (2169e2137 Ma).

3. The Rhyacian period

The Rhyacian events and super-events (in the sense of Condie,2000) of continental crust formation and growth represent themost abundant records of the sialic basement in the continent(cratons, Proterozoic belts and so on), in terms of number andquality of geologic and isotopic data as well as of the diversity ofstyles of occurrences. These events are concretely recorded withinthe cratons and the reworked massifs of the basement, as well aswithin the smaller exposures (several types) of the basement of theMeso- and Neoproterozoic mobile belts. In all cases with plenty andincreasing literature. Additionally, as complementing this fact, theincidence of Rhyacian ages is quite overwhelming in the detritalzircon studies of supracrustal rocks of (Meso- and Neoproterozoic)mobile belts.

When stressing out that in the 250 Ma time interval (between2300 and 2050 Ma) crustal growth was conspicuous, it is worthmentioning that:

i) The exact gographical-geological location of these cratonicnuclei, massifs, terranes and blocks of Rhyacian age areunknown, and theymight have been apart from each other bythousands of kilometers

ii) Certainly several rock-forming cycles (Wilson-type or not)must have taken place at the same time or in series,competing mutually or not. Therefore, misleading simpli-cations (same cycle, undue continuities) should be ruled out.

As expressed above, the data on Rhyacian events and super-events are abundantly registered in the literature, a substantial partof which is referenced in this text. For each area/case, it must beimplicit here that there are very good published studies (whichreading is advisable).

This incontestable wealth of data on the Rhyacian crustalgrowth in different crustal and geotectonic types is a fact worth ofvarious developments. Considering the abundande of Rhyaciandata their pattern similar to those in other continents, all leads thatthese crustal growth peaks are indicators of a global phenomenon(e.g. Condie, 2000, among others). On the other hand, the existenceof large continental masses (supercontinents) in the Rhyacian issupported by many authors and studies (supercontinents Atlantica,NENA, Hudsonia, Columbia, NUNA, Capricornia etc.), on the basis ofdata relative to the Paleoproterozoic as a whole and to the Rhyacianperiod in particular.

Regarding South America, the main records relative to theRhyacian are illustrated in Figs.1 and 3 theywill be described as vemain types of records.

a) Relatively complete and linear mobile belts involving andpartially reworking preexisting, Archean nuclei. They usuallypresent some clearly juvenile (accretionary) portionse includingvolcano-sedimentary, granite-greenstone and similar contexts,TTG associations etc. e and others that clearly represent (bygeologic and isotopic means) the reworking of preexisting Pale-oproterozoic and Archean terranes, which now gure asauthentic basement inliers in these belts.

The best examples are in the Eastern Mobile Belt of Bahia or theItabuna-Salvador-Juazeiro belt (Fig. 3), according to Delgado et al.(2003), Barbosa and Sabat (2004); in the Mineiro Belt (vilaet al., 2010); and in the Maroni-Itacainas Belt, in the eastern

can Earth Sciences 32 (2011) 270e286 277portion of the Amazonian Craton (or the so-called Transamazonas

meriBelt of Santos, 2003), according to Rosa-Costa et al. (2006, 2008).One may also include in this context the western portion of BahiaState (Western Mobile Belt of Bahia, part of the So FranciscoCraton) and part of eastern Gois ( Dianpolis e Silvnia Belt),which present several discontinuous Rhyacian basement windows,underneath Proterozoic and Phanerozoic covers. An additionalexample of these Rhyacian events and mobile belts is recorded insome the large massifs, such as the Gois Central Massif (clus-tering granite-greenstone terrains), Pernambuco-Alagoas, and SoJos do Campestre, to be commented (See Delgado et al., 2003;Dantas et al., 2008; Della Giustina et al., 2008).

As a result of these cycles of continental mass agglutination inthe Rhyacian, important (epi-Rhyacian) cratonic nuclei wereformed and acted as forelands to Orosirian and subsequent mobilebelts and on which expressive sedimentary and volcano-sedi-mentary sequences developed.

In general, the Rhyacian mobile belts include large Meso- andNeo-Archean cratonic nuclei (and also some smaller nuclei andblocks) and rework others, through complex paleogeographicand tectonic histories, with succeeding accretionary and collisionalprocesses, which sometimes exceed the formal limit for the Oro-sirian (2.05 Ga).

In the cases of the So Luis and Rio de La Plata cratons (andprobably in the case of Paranapanema craton) as well as of theCuritiba terrane (microplate), the data of the basement are alsoindicating Rhyacian ages, but they do not present Archean nuclei,and they are dealt as separated cases below.

b) Segments of previous Rhyacian mobile belts which are not cir-cumscribing Archean nuclei. Regarding their tectonic rolesduring the evolution of the Brasiliano structural provinces,these segments use to present two kinds of behavior: i) Stable(cratonic) segments (e.g. So Luis, Rio de la Plata); ii) reworkedsegments (descratonised or regenerated) due the overprintof new thermal and tectonic conditions (so-called massifs).So, these latter have worked out as basement inliers (differenttypes) into the Brasiliano frame (e.g. Rio Piranhas, Gois Central,Curitiba etc.). Sometimes, in some erosional windows of theMeso and Neoproterozoic mobile belts, these massifs (struc-tural highs, hinterlands etc.) use to play an important role.

As already mentioned, the incontestable majority of UePb datafor the Rio de la Plata Craton granitic-migmatitic and granite-greenstone basement point to crustal growth events in the Rhya-cian (see Rapela et al., 2007), with the majority of the ages fallingbetween 2,2 and 2,05 Ga. There are only a few relic tracts thatpresent indication of local old Archean and Siderian rock units.

The So Lus Craton, is a small fraction of the Western AfricanCraton that remained in South America after the Pangea ssion andis exposed complying with Cretaceous tectonic injunctions. Kleinand Moura (2008) identied three distinct events of rock forma-tion, all showing characteristics of juvenile origin. The older event,ca. 2240 Ma, is characterized by the formation of supracrustal rocks(sedimentary and volcano-sedimentary). This was followed byevent of 2168e2147 Ma, marked by the deposition of supracrustalrocks and the emplacedment of granitoids of calc-alkaline char-acter (quartz-diorites, tonalites and granodiorites of island arcs).The nal event, ca. 2090e2086 Ma is represented by two mica-bearing, peraluminous (S-type) granitoids, interpreted as repre-sentatives of a collisional events.

The Curitiba terrane/massif (microplate during the Brasilianoorogenic processes) in central-eastern Paran (exposure area ca.8000 km2) is a segment of a Rhyacian mobile belt separating twoBrasiliano contexts (the Apia Belt to the north and the Pien

B.B. de Brito Neves / Journal of South A278Magmatic Arc to the south), according to Siga et al. (1995). Thissmall high-grade massif presents complex and special historicand isotopic characteristics, being essentially composed by bandedgneisses, migmatites (tonalitic leucosome), amphibolites andcharno-enderbites etc. This is known as the Atuba Complex,exposed in a marked NE structural trend of the Brasiliano ductileshearing. According to geologic and isotopic data (Siga et al., 1995;Sato et al., 2003) protoliths of these rocks are Archean in age (TDMagesw 3.1e2.7 Ga) and underwent important metamorphism andmigmatization processes around 2100 Ma (2086e2130 Ma). It isinteresting to add that differently from So Luis Craton, almost alleNd data for this segment (of a Rhyacian mobile belt) presentnegative to strongly negative values. Besides, this segment wasreworked in various ways in the late Paleoproterozoic (StatherianTaphrogenesis, granitic plutonism), in the Mesoproterozoic (Caly-minian volcanism) and mainly in the Neoproterozoic (during theBrasiliano events).

c) Segments, various mobile belts fractions as those above des-cribed, occur as regenerated basement highs (massifs,inliers) to several ofMeso- andNeoproterozoicmobile belts. Sotheyare responsible for thebranchingof these belts aswell as forcontributing to their structural and geometric complexity. Thesebasement exposures in Borborema Province (Central Cear, RioPiranhas, So Jos do Campestre, Pernambuco-Alagoas etc),Mantiqueira Province (Quirino, Guanhes etc.) and TocantinsProvince (Gois Central massif) as well as Paleoproterozoicbelts further to the east (Cavalcante-Almas area) present ingeneral characteristics which are similar to those described inthe previous items. However, their integrity and continuity wasbroken by younger geological events during the Meso- andNeoproterozoic cycles, especially due to the Brasiliano cycle. Inpractically all Meso- and Neoproterozoic mobile belts there arereal records (local windows) and other indications of Paleo-proterozoic tracts, mainly Rhyacian in age.

d) Sedimentary and volcano-sedimentary sequences belonging togranite-greenstone terranes, occupyingmore or less sparse andrestrict domains. There are several references in the literatureof Rhyacian sedimentation (outside the classic domains ofcrustal growth during this period). The best documentedexample is that of the cover sequences of the Archean green-stone belts from Gois, described by Jost et al. (2008), whichleads to several other possibilities of new discoveries in thefuture.

In Central Brazil there is an Archean block of ca. 25,000 km2,forming a major part of the so-called Gois Central Massif , whichhave acted as backland for the Braslia Belt in the Brasilianodevelopment. In this block, several greenstone belts are welldocumented. The upper portions of these sequences are formedmetasedimentary piles, including carbonaceous phyllites, gray-wackes and dolomites (in Crixs), iron formations of differentfacies, phyllites, volcanic ashes and graywackes (in Guarinos), calc-silicate rocks, metacherts (in Pilar de Gois) etc. UePb dataobtained from the detrital zircons of Crixs graywackes indicateArchean (3.35 Ga, 2.8 Ga) and Rhyacian (2222 Ma, 2229 Ma) ages.Guarinos banded iron formations yielded Archean (2.6 Ga), Side-rian (ca. 2453 Ma) and also Rhyacian (2232 Ma) ages (detritalzircons). A SmeNd isochron indicates the age of T 2189 36 Ma,and negative eNd (6.89) for the Pilar de Gois calc-silicate rocksand metacherts. Based on these data and on other stratigraphicevidences, the authors (Jost et al. 2008) concluded that the threeupper sequences of the sedimentary unit/group of the greenstonesare coeval, probably lateral facies variations, and they must havebeen constrained to the same Rhyacian tectonic-sedimentary

can Earth Sciences 32 (2011) 270e286processes.

the domain of the Serrinha and Uau blocks (Fig. 3), the ages forthese supracrustal rocks (felsic andmac metavolcanic rocks) fall in

(north of Manaus) a magmatic arc suite followed by collisionalgranitoids of ages between 1975 and 1968 Ma. Further south,

merithe 2.2e2.15 Ga time interval, according to Oliveira et al. (2004).This is a similar situation as that of Gois, above described. ThisRhyacian age records can be further identied in other similarcrustal types in this craton and in others, even in cases where theinfrastructure yielded Archean ages.

e) Within the GoisCentralMassif, to thewestof theNiquelndiacomplex, a small exposure of the Serra daMesaGroupbasement(between Uruau and Mara Rosa) occurs. There is the record ofmeta-volcano-sedimentary sequence, crosscut by granites,which is worth mentioning. The Campinorte Sequence (ex-posed due to the erosion of the Serra da Mesa) is composed ofmetapsammites and metapelites (being quartz-micaschists themost common rocks), with gondite andmetachert lenses (DellaGiustina et al., 2008) and subordinate meta-rhyolites andpyroclastic rocks. Ortho derived metamorphic rocks (tonalitesand granodiorites) are intrusive into this sequence, and theyyieldUePb ages of 2.18e2.16Ga. SmeNddeterminations lead topositive or slightly negative eNd values, indicating the juvenilenature of these rocks, thatwere strongly reworked by Brasilianoevents. Most probably, similar rocks/contexts of larger surcialexpression can occur in this massif, west of the large bodiesmac-ultramac bodies underlying Statherian and youngermetasediments.

f) The recognition of Paleoproterozoic (mostly Rhyacian) gneissicand migmatitic rock types within the basement (erosional orstructural windows) of all Brasiliano structural provinces haswidely been described in the literature. Most of these indica-tion were based on RbeSr and KeAr methods. This hascontributed to the spreading of the generic term Trans-amazonian basement. This mean Transamazonian as syno-nimous of Paleoproterozoic (geological time), what deserves tobe rened. For the basement of the major Paleozoic syneclises(Parnaba, Amazonas and Paran), such generalization has alsobeen common, from scarce data (RbeSr and KeAr) obtainedfrom deep well cores. In all cases, proper revision of suchinformation is necessary by means of methods of more robustgeochronological methods. These indications should not bepromptly ruled out, but they have to be subject of isotopicstudies for the future.

g) Detrital zircons of Rhyacian age are very common in Meso-proterozoic and Neoproterozoic rocks of the mobile belts. It isnecessary to stress out beforehand that in the study of detritalzircons of these mobile belts variable quantities of grains ofOrosirian and Statherian (and even of younger periods) agesare found, showing that the expositions/source areas for thesebelts were very much varied.

4. Orosirian period

In the Orosirian, the forms of crustal evolution of the South-American platform were very diversied, with important, accret-ionary and collisional orogenic events, with their own characteristicmarks, distinct from the preceding and succeeding periods. Besidesthat, there is also a diversied range of records of anorogenic tectonicIn the So Francisco Craton, eastern Bahia, there is a series ofgreenstone belts with supracrustal rocks related to oceanic envi-ronments, so including many back-arc basins (Delgado et al., 2003).The geochronological control of all these occurrences is stillpreliminary. At least for the Rio Itapicuru and Rio Capim green-stones northern segment of the Itabuna-Salvador-Cura Belt, in

B.B. de Brito Neves / Journal of South Aprocesses, plutonism above all.Valrio et al. (2009) identied magmatic arc associations (I-typegranites) and volcanic and granitic associations of collisional naturewith ages between 1.9 Ga and 1.88 Ga. In turn, Fraga et al. (2009)described to the northeast (Brazil-Guianas border) a suite of sub-alkaline charnockitic rocks, monzogranitic to leucogranodioriticcomposition, named Serra da Prata suite, with ages between 1943and 1933 Ma, to which the authors attributed a post-collisionalnature. All these data show the importance of the Orosirian mag-matism in the Amazonian region, despite their integration is stilllacking.

This important accretionary belt (in which collisional eventsAdditionally to the events and super-events discriminatedbelow, there are many reconnaissance geochronological determi-nations throughout the basement of the Brasiliano provinces thatyielded ages between 2.0 and 1.8 Ga and that were almostcompulsively alluded to the Transamazonian Cycle. These deter-minations possibly have their own geologic meaning, such as tec-tono-magmatic reworking, metamorphism, uplift and cooling(which is the case of many KeAr values of ca. 1.8 Ga) etc., whichshould be properly checked in the future and then, correctly inte-grated to the Orosirian context.

4.1. Accretionary orogenies/terranes

4.1.1. The Ventuari-Tapajs (or Tapajs-Parima) BeltAs an accretionary province, the Ventuari-Tapajs (Tassinari and

Macambira, 2004; Cordani and Teixeira, 2007) or Tapajs-Parima(Santos, 2003) is particularly outstanding in the Amazonian craton.It is localized the central-western part of the Craton, presentingNNW-SSW structural trends, about 3000 km long (from Venezuelato the basement of the Alto Xing basin, in Mato Grosso, Brazil) andup to 450 kmwide. This orogenic belt was accreted to the west sideof the so-called Central Amazonian Craton (composed of Archaennuclei and Rhyacian belts). The present degree of knowledge of thisaccretionary belt is still pretty low due to various regional condi-tions (lack of detailed geological maps, rain forest, indian territoriesetc.). There is a strong demand for the completion of the studiesbecause of different mineral resources there present (e. g. Goldoccurrences).

In this province, a notable succession of magmatic arcs isrecognized by the authors cited above (Jacareacanga, Cur, Cre-porizo, Tropas, Parauari etc., in chronological order) developedbetween 2.03 and 1.87 Ga. Some secondary sedimentation events(arc-related basins) and other minor collisional events have beenidentied locally. Isotopic data indicate a juvenile nature of theoriginal rocks, with eNd values ranging from positives (up to 2.1)and weakly negatives (1.6). This seems to be consensual amongresearchers. The presence of supracrustal rocks of sedimentaryorigin (from the greenschist to the amphibolite facies) is subordi-nate in the Province.

There are some minor divergences regarding the limits andevolution mode of this accretionary belt (the same is valid for theprovinces that delimit it). This is fully understandable and expec-ted, having in mind the Amazonian region is still poorly known. Aparticular focus of divergences is the delimitation of this provincefrom the younger accretionary Statherian Rio Negro-Juruenaprovince, to the west and from the Rhyacian Maroni-Itacainasprovince, to the east (see Fig. 2).

Regarding the transition zone between the areas mapped asMaroni-Itacainas and Ventuari Tapajs, there is a series of newcontributions to be considered. Almeida et al. (2007) identied

can Earth Sciences 32 (2011) 270e286 279have been identied, so far) has no similar in the South-American

assigned from the Paleoproterozoic to the beginning of the Paleo-

mericontinentet, and it is characterized for being for many years animportant source of primary and secondary (alluvial) gold.

4.1.2. The Cabo Frio TerraneThe easternmost part of the Ribeira Belt (northern Mantiqueira

Province, northern sector) was recognized as a tectono-strati-graphic terrane (in the sense of Howell, 1995) by Heilbron et al.(2004), due to its litho-structural characteristics and geologicevolution. This Orosirian terrane (Schmitt et al., 2008) of unknownprovenance (Africa?) played the role of a backland that dockedalong the easternmost part of the Ribeira orogen, at the end of theCambrian (ca. 520 Ma).

The so-called Regio dos Lagos Complex encompasses tonaliticto granitic orthogneisses with dioritic enclaves and amphiboliticlenses (representing old dismembered mac dikes). The UePb ageof the order of 1.9 Ga (admitted as of accretionary origin), what isan unusual fact in this continent (out of the Amazonian Craton)and unknown in the African counterpart. Some rare, high-grademetasedimentary aluminous bands (Bzios-Palmital metasedi-mentary association) with calc-silicate intercalations are associ-ated with the development of the Brasiliano orogeny (during itslatest phases in this continent).

The on shore sized of the Cabo Frio Terrane is modest, estimatedto be a little less than 3000 km2, but its presence, characteristicsand age are extremely important. In fact, it must have acted as anexotic terrane, such as a microplate or a fraction of an Orosirian arc(coming from African?) docked/incorporated to the MantiqueiraProvince, at the end of the Ribeira Belt development (east of theBzios back-arc), in the northernmost portion of the Province (inthe Rio de Janeiro State).

4.2. Orogens and other collisional events

4.2.1. The Jacobina-Areio (Jacobina e Contendas) BeltThe Contendas (Areio)-Jacobina Fold System in the central part

of the So Francisco Craton (Fig. 3) stretches out from north tosouth for ca. 500 km, being less than 30 km in width and altitudesabove 1000 m last century. The literature is extensive.

The sedimentation environment of the Jacobina Group wasa relatively stable platform (foreland basin?; post-Rhyacian trans-tractional rift?), due to the maturity of most of its metasediments.These rocks were folded andmetamorphosed between 2.0 and 1.96Ga, according regional inferences, since there are no direct deter-minations. Characteristically, this narrow and linear belt delineatedthe eastern border of the Archean Gavio-Lenois cratonic nucleus,and the collision of this nucleus with other segments (Archeanmicrocontinents and Rhyacian belt) to the east. South of this belt,this hilly structure overlies the volcano-sedimentary deposits of theContendas Mirante Complex, and is affected by this latest defor-mation phase registered there, most probably the collisional eventthat marked the end of the Itabuna-Salvador-Juazeiro Belt accre-tionary history.

In general, the litho-stratigraphic context of the Jacobina Ridgeconsists composed of siliciclastic rocks (monomictic conglomer-ates, quartzites, schists) intercalated with metabasic rocks, meta-tuffs and iron- and manganese-rich jaspilites. The Campo Formosomac-ultramac complex and several internal ultramac bodiesrepresent Orosirian mantle manifestations (Delgado et al., 2003).Folding is intense, close to isoclinal folds present, with rupture ofanks, and clear vergence toward the Archean block in the west.The geochronological data point to Rhyacian sources (the youngestdetrital zircons yield ages ca. 2.08 Ga) and the nal deformationphase, based on data obtained from intrusive granites, occurredbetween 1.94 and 1.91Ga (RbeSr data). The constraint of this

B.B. de Brito Neves / Journal of South A280collisional belt to the Orosirian is practically consensual, probablyzoic. This block, derived from Laurentia, has a controversial tectonichistory, but Grenvillian ages (end of the Mesoroterozoic) undoubt-edly predominate.

There is a region in the Arequipa Massif where high-grademetamorphic rocks are exposed (Mollendo, San Juan, Beln). Oro-sirian ages from 1910 Ma to 1811 Ma, obtained by reconnaissancemethods (Tosdal, 1996), were attributed to these rocks and theirsignicance with respect to the general context of the massif is stilldebatable. There are some preliminary indications that other coevalprotoliths were rejuvenated during the Grenvillian, under high-grade metamorphic conditions.

Anyway, the record of Orosirian events (probably of collisionalnature) in the Arequipa Massif must be considered and furtherinvestigated.

4.2.3. The Orosirian reworking4.2.3.1. The Taquaremb block (basement of the Dom FelicianoBelt). There is a considerable amount of geochronological data, notyet properly synthesized, on tectonic processes already occurring inthe Orosirian, which are interpreted as the nal processes of theRhyacian belts. The formal time limit (2.05 Ga) between the end ofthe Rhyacian and the beginning of the Orosirian is not always welldened well constrained in the Amazonian and So Franciscocratons.

In the Rio de la Plata Craton a similar example is found in theTaquaremb block (alreadymentioned above, when referring to theSiderian), which is a marginal exposure of the craton, lateral tothe Brasiliano domain, at the westernmost of Rio Grande do SulState. The basement of the Rio de La Plata craton and adjacent areashas already been described in detail as part of the history of theRhyacian crustal evolution (Rapela et al., 2007, among others). Inthe Santa Maria Chico Granulitic Complex e garnet-rich granuliticrocks (pyroxenites and lherzolites) e isolated metamorphicevents of 2.35 Ga (considered as the rst regional metamorphicevent) have already been identied and described as Siderianremnants within a real Rhyacian domain.

Recently, Tickyj et al. (2004), dating monazites of this complexusing UePb methods, identied important Orosirian reworking inthese high-grade rocks. From a total of half a hundred determina-tions, 30% of the data (obtained at garnet rims) are indicating agesbetween 1844 and 2014 Ma. The context of these isotopic deter-minations (SHRIMP UePb) is substantial and valuable and must beconsidered and properly discriminated, although the real signi-cance in regional tectonic terms is still an open problem.

4.3. Orosirian anorogenic volcanism and plutonism

One of the most striking characteristics of the Orosirian periodin the continent was the intraplatemagmatism that affectedmainlyall the central and eastern portions of the Amazonian regionbetween 2000Ma and 1860Ma. These processes are also importantas a mark of the stable regime that succeeded the Rhyacian orog-enies and as an eastward intracratonic equivlent of coeval accre-tionary processes (Ventuari-Tapajs, to the west). But, this belt wascomposing a group of collisional events occurring to the east,following the long accretionary history of the Itabuna-Salvador-Cura belt. It is worth adding that the geochronological knowledgeis still indirect and other types of investigation are required.

4.2.2. The Arequipa MassifThe Arequipa Massif is a basement inlier of the Andean

cordillera stretchingout fromthe Peruvian coast tonorthernChile. Itunderwent a notorious plycyclic evolution, with isotopic ages

can Earth Sciences 32 (2011) 270e286also affected by part of this magmatism.

part explosive (ignimbrites and common breccias), which privi-

merileged the areas consolidated in the Rhyacian (small extension overthe recently-consolidated Ventuari-Tapajs). The original extensionexceeded 700,000 km2, which makes it comparable to several LIPsof the world, always intercalated with the anorogenic plutonismand more locally and restrictedly with some sedimentary contexts.The ages come from various sources and methods and spreadbetween 1900 Ma and 1870 Ma (maximum values up to 2000 Ma).Good recent reviews and syntheses are in Santos (2003) andTassinari and Macambira (2004).

The associated anorogenic plutonism is notable, closely relatedin time and space to the volcanism, privileging the Archean blocksfrom Carajs (Serra dos Carajs, Cigano, Seringa, Estrela, Para-upebas, Pojuca granites) and Rio Maria (Jamon, Musa, Redeno,Bannach, Gradas granites etc., felsic dikes). Generally these areA-type granitoids, with ample compositional variation. Syenitesand monzogranites the dominant rock types (see DallAgnol et al.(2006) for an updated synthesis). The ages for these graniticrocks are very close to one other, ranging in the interval between1.9e1.8 Ga (1.88 Ga is considered the most frequent value).

The conjunction of these magmatic events between 2.0 and 1.86Ga, their vast extension, the context of the succeeding ample cra-tonization (epi-Rhyacian) justied the proposal of a LIP in thisregion. These magmatic events preceded (in time and in terms ofcratonic tectonics) the establishment of the Roraima ortho-platformal basin (to be discussed).

Out of the Amazonian region, a few anorogenic magmatismevents of this period are pointed out in the So Francisco Craton. Inthe Paramirim block, a fraction of the Archean-Paleoproterozoicbasement between the Espinhao and ChapadaDiamantina, there isan important occurrence of syenitic magmatism hosting the mostexpressive uraniferousmineralization of Brazil. The syenites (rich inalbite and titanite) of Lagoa Real present (crystallization) ages of ca.1904 44 Ma (Chaves et al., 2007, zircon ages by LA-ICPMS),following an intense metamorphic recrystallization around1860 69Ma (with uraninite precipitation). This is not a completelysolved problem and other obstacles exist due to later tectonicreworking (Espinhao?, Brasiliano?); nonetheless, the Orosirianages must be taken into account.

In northwest of Bahia, south-southeastern margin of the Par-naba Basin, the Angico Dias carbonatitic complex yielded an age of2.01 Ga (UePb in zircon and baddeleyite), and therefore must beconsidered as the rst occurrence of this type of rock in all thePaleoproterozoic of South America. Pyroxenites, alkaline dunites,syenites, carbonatites and lamprophyres are found in the complex,which is inserted in a context of alkaline basaltic magmatism in anintraplate environment (Delgado et al., 2003).

Several other occurrences of mac and ultramac bodies inBahia, showing discordant relationship with the structures of thedomains of Rhyacian mobile belts and they have been pointed outas candidates of Orosirian intraplate magmatism, lacking geologicand geochronological support.

4.4. The Roraima plateau e Roraima Supergroup

The Roraima Supergroup (Reis et al., 1990) covers a large regionof northern Brazil and neighboring countries (more than160,000 km2) and is characterized by plateaus supported by sub-This large plutonic and volcanic province has generally beenreferred to as Uatum (group, complex, magmatism) and includesa diversied suite of multiple designations Iriri-Iricoum-Surumu-Cuchivero-Iwokrama in northern Brazil and neighboring countries.Special emphasis is given to the intermediate and acid volcanism, in

B.B. de Brito Neves / Journal of South Ahorizontal (weakly and locally deformed) siliciclastic units. Itoverlies and characterizes the large orthoplatformal domain con-structed after the end of the Uatum volcanism-plutonism.

The supergroup is composed essentially of various siliciclasticrocks (conglomerates, sandstones, arkosean sandstones, shales)intercalated with tuffs and volcanic ashes (Santos et al., 2003a, b).There are several peculiar characteristics in the Roraima plateau: itselevated altitudes, its notable geographic scenarios of a thick sedi-mentary plateau submitted to dissecation, the limit of countries(Venezuela, Brazil, Guianas), the locus of the rst, oldest (pre-1873Ma), great stable area in the evolution of the Amazonian Craton(Amazonian-Laurentian block), and the source of detrital diamonds.The original Roraima extension can be estimated as a much biggerarea, such is the amount of its remnants widespread around it.

This unit overlies the (LIP) Uatum and it has been recentlydated by means of UePb analyses of zircons from tuffaceousintercalations, which indicated an age of 1873 3 Ma (Santos et al.,2003a, b). This determination is very well constrained by the age ofthe underlying basement and also by the ages obtained for macdikes (Statherian Avanavero or Pedras Pretas magmatism, ca. 1782Ma) that crosscut the supergroup. It is worth adding that in the SoFrancisco Craton (and adjacent zones) similar stability conditionswould only took place ca. 100 million years later (ca. 1.76e1.78 Ga),with the development of vast and thick siliciclastic covers (ChapadaDiamantina and similar areas, to be discussed).

5. The Statherian period

In the crustal evolution of the South-American continent, theStatherian period is represented by two distinct and very wellcharacterized sets of tectonic events and super-events, withexceptional geologic and geochronological records. Exclusively inthe central-western portion of the Amazonian region, accretionaryprocesses were dominant, along the so-called Rio Negro-Juruenabelt. This belt was placed following a chelogenic scheme of crustalgrowth (typical for the Amazonian craton), from NNE to SSW, so itwas adjusted to the western side of the Ventuari-Tapajs (Orosirianin age). On the other hand, in the rest of the continent (even in theAmazonian Craton), taprhrogenic processes were by far predomi-nant, either sparsely or concentrated in area, constituting excep-tional basin-forming processes associated to magmatism, fromVenezuela to Uruguay.

For the Rio Negro-Juruena accretionary system there are rela-tively recent evolutionary syntheses by Santos et al. (2003a,b),Tassinari and Macambira (2004), Cordani and Teixeira (2007) thatgather much geologic and geochronological information. For thetaphrogenic processes, marked by several ssural intrusives,granitic and explosive volcanism, and extensional events, there isa previous synthesis by Brito Neves et al. (1995), presentlydemanding robust updating, in view of the substantial scienticadvances in last years.

These sets of Statherian crustal growth events must be viewedunder an optics that transcends the South-American continent. Inthe case of the accretionary belt, the Rio Negro-Juruena is only partof a much wider orogenic development (Rio Negro Juruena-Transcontinental-Labrador-Gothian-Kongsbergian) encompassing,to the north, the Laurentian and Baltic blocks, where it is beststudied and known (Brito Neves, 2004).

In the case of the taphrogenesis, it occurs in a similar way andpractically in all Paleoproterozoic blocks (which were certainlyseparated from each other) of this and other continents (speciallyNorth America and Africa). It is certainly represents a globalphenomenon.

In both cases (accretionary and taphrogenic processes) there areproblems with the heterogeneity of the data. In particularly, the

can Earth Sciences 32 (2011) 270e286 281recognition of accretionary processes in South America is far from

formation of basins during taphrogenesis, the coverage of the

meriTeixeira, 2007). From the reconnaissance methods used initially(RbeSr and KeAr), gradually passing to methods such as UePband SmeNd and some systematic mapping, the predominance ofStatherian orogenic activity has been conrmed. According toseveral researchers, the data fully attest the presence of a juvenile(or little affected by crustal contamination) accretionary crustalprovince for the Rio Negro Juruena Belt. The eNd(t) values arepredominantly positive (up to 4), side-by-side with slightlynegative values (down to 2.0).

5.2. Intraplate basic magmatism

As said above, the Statherian taphrogenic events affected all thePaleoproterozoic blocks of the South-American continent, practi-cally with no exceptions, and a vast literature is available. Amongtheme is vast, and an extensive (though heterogeneously detailed)literature exists (e.g. see Brito Neves et al., 1995; Delgado et al.,2003; Danderfer et al., 2009). The number and variety of casesare large and easily extrapolates any attempt of synthesis, oncethere are signicant occurrences (and corresponding literature) inthe Guyanas Shield (Brazil and neighboring countries) to the north,down to fractions in the Rio de la Plata Craton and the basement ofthe Dom Feliciano Belt (in Uruguay) to the south.

5.1. Accretionary events e Rio Negro Juruena Belt

The Rio Negro Juruena accretionary processes succeeded in timethe Orosirian Ventuari-Tapajs system, according to a long evolu-tion cycle, between 1780 and 1550 Ma (entering the Calymmianperiod) and sense of younging from NE to SE. The time interval isvery long even for a multiple accretionary process. The territorialdomain is also very large, as opposed to a non-satisfactory generalgeologic and isotopic knowledge. There are very few areas studiedin detail.

The orogenic belt roughly trends NW-SE in the central-westernportion of the Amazonian region, from Venezuela (Mit Complex)and Colombia (Casiquiare Domain) to the upper Juruena river, northof Mato Grosso (basement of the Parecis Basin), with a possibility ofan extension southwards into the Rio Apa massif, totaling morethan2600km. Thewidthusually proposed for theProvince is around400 km, but there are records of rocks of the same nature to thewestin the basement of the Rondonian Province, in Bolivia, within theso-called Paragua Craton (Bittencourt et al., 2010).

The Province is constituted by (granodioritic, tonalitic andgranitic) gneisses and migmatitic rocks, with a few metamacintercalations, forming a general scenario of calc-alkaline rockassemblagesof magmatic arc afnity, but as already said, ata reconnaissance level. The supracrustal units are more restrictedthroughout the Province, being recognized volcano-sedimentarycontexts (greenstone belt-type associations), some of them ofintermediate and felsic nature (rhyolites, rhyodacites, tuffs). Somesubvolcanic granites (1.65e1.55 Ga) are known, which record lateintraplate activities.

As mentioned before, the identication of this accretionarydomain (in Brazil) was mainly based on radar images andgeochronological data, resulting in several publications, inte-grated in the syntheses mentioned above (e.g. Cordani andideal, since it is located in a rain forest domain where detailedgeological maps are not available. The continuity of this beltnorthwards into Laurentia and Baltica is also an open questiondemanding further investigation.

When it comes to diversied intraplate magmatism and

B.B. de Brito Neves / Journal of South A282these intraplate extensional phenomena the basic magmatismdeserves attention, and it is here discussed separately only fordescriptive reasons:

a) In the Amazonian Craton, crosscutting the Roraima Supergroupand its basement (Brazil and neighboring countries), the so-called Avanavero or Pedras Pretas magmatism; this conistsof a series of thick sills, dikes and small plugs of gabbroid/basaltic composition. This magmatism is one of the mostimportant andexpressive events inSouth-America, and it canbeobserved in the1/5,000,000 geologicmap. Large sills, up to1 kmthick, basic igneous rocks of composition varying from tholeiiticto andesi-basalts were identied (Menezes Leal et al., 2006).

Recent determinations by the UePb method using zircon andbaddeleyite (Santos et al., 2003a, b) indicated an age of 1782 3Mafor this magmatism, which also constitutes a mark of age(maximum) for the Roraima Group.

From Serra do Carajs (north and south) to Rio Maria (throughXiguara) some volcanic records of this age interval are also known,consisting ofa basalt-and esite-rhyolite association studied by e.g.Rivalente et al. (1998). The basalts occur as NE- and NW-trendingdikes and are classied in two groups, of high- and low-TiO2. Thebasaltic rocks are concentrated to the north of the Serra dos Car-ajs. The geochronological data, resulting from the RbeSr method,varies from 1720 Ma (rhyolites) to 1874 Ma (basalts), with rela-tively low initial Sr87/Sr86 ratios, but relatively high errors (of theorder of 8%).

b) In the south-southeastern domain of the So Francisco Cratonat least three distinctgroups of mac dikes, according to theircomposition, nature and age (Statherian, Tonian and UpperCretaceous). There is a N-S-trending dike generation of somecentimeters to decimeters in width associated with sills andsmall basic stocks, partially deformed (superimposed Brasi-liano deformation along the margins of the craton) andpartially undeformed, marking the presence of the Statheriantaphrogenesis in that region. The deformed rocks were trans-formed in quartz-chlorite schists and chloritoid-sericite schists.The undeformed part show gabbroic features and composition.

KeAr data indicate ages from the Statherian to the Calymmian.The baddeleyte UePb dating of the Ibirit gabbro yielded the age of1714 5 Ma (with lower discordia intercept pointing to Brasilianovalues). The predominant trend of these rocks, ages, position in thecontext of the craton (of the So Francisco paleocontinent) areindications of a post-Orosirian extensional event to which theevolution of the Northern Espinhao rift system (basin).

c) The innermost portion of the Rio de la Plata Craton in Uruguay(Pedra Alta Terrane) is marked by an important dike swarm(called Florida) trending approximately EeW, which can berecognized at various scales and has been the object ofnumerous petrologic and isotopic works (e. g. Teixeira et al.,1999). To the east, this swarm is suddenly truncated by theSarandi Del Yi fault system (part of the Brasiliano events).

From the compositional point of view basic rocks of the ande-sitic-tholeiitic and basaltic-andesitic types are recognized. Theoriginal magmas display some degree of contamination with theolder continental crust. The dikes are up to 50 m thick (generally

meri5.3. Felsic magmatism

The following description and order follow expository reasonsmainly, because it is recognized that there are several concreteindications of causal relationships between the igneous events andthe basin tectonism.

5.3.1. The Amazonian regionIn the northern part of the Amazonian region (Guyanas Shield)

there are sparse records of Statherian granitic plutonism and felsicvolcanism.

It is worth stressing out that there are plutonic and volcano-sedimentary activities in the southern portion of the Craton, in thenorthern portion of Mato Grosso, between the Roosevelt and TelesPires rivers, covering an area of ca. 40,000 km2. This seems to bea kind of cratogenic tract, as an exotic terrane in the interior of theRio Negro-Juruena Province (with which the relationship has notyet been properly established). Various felsic volcanic (from daciteto rhyolite) and volcaniclastic rocks (ignimbrites, tuffs, ashes), andsubordinated basalts are associated with anorogenic (A-type)granites (Leite et al., 2001). The general characteristics of thismagmatism and of the associated volcano-sedimentary rocksindicate intracratonic or intraplate extensional environment.

5.3.2. Central BrazilIn the central-eastern part of the continent, between meridians

40Wand 48Wand parallels 11S and 20S several occurrences ofStatherian felsic activities are found. These occurrences precededthe installation of the Brasiliano Cycle (differentiation of cratons,terrains, massifs and mobile belts), acting as a part of the substrateof this development, and because of that they exhibit thereforedifferent grades of reworking. Only, in some local cases, the rockunits are undeformed and they preserved igneous texture andstructures.

Toward west, in Gois and the south of Tocantins, the Gois TinProvince stands out, where several granitic rocks (some 15 smallbodies), and volcanic and sedimentary associations, including sili-ciclastic and volcanic rocks (Arai and Natividade groups) wereidentied two groups of ages: ca. 1.77 Ga (called Rio Paran sub-province) and from 1.58 up to 1.77 Ga (Rio Tocantins subprovince).From the litho-stratigraphic, tectonic and metallogenetic points ofview (Dardenne and Schobbenhaus, 2001), all these occurrencesare together indicative of intraplate activity and display remarkableliterature.

In the eastern portion (and with attested subsupercial con-nection), from Bahia (north) to Minas Gerais (south), a complexsystem of Statherian sedimentary to volcano-sedimentary basins(rifts and syneclises) developed and was later deformed in the pre-Brasiliano and in theBrasiliano, constituting the so-called EspinhaoFold System. It is attested by a vast and increasing bibliography (seeDelgado et al., 2003 and Danderfer et al., 2009). In Minas Gerais,betweenSerroand Itabira, adozenof small tomedium-sizedgraniticbodies (Borrachudos Suite) described by Dussin and Dussin (1995),are intruded in the Archan-Paleoproterozoic basement (Guanhesblock) under an anorogenic regime. Similar granites have beendescribed in the Paramirim corridor, in central-western Bahia, alonga fraction of the Paleoproterozoic basement, between two majorbeltsof the volcano-sedimentary (Espinhao-Chapada Diamantina)groups.

5.3.3. Northeastern Brazil (Borborema Province)The basement of the Borborema northern segment in Cear

(from the Mdio Corea to the Jaguaribeana belt) and in Rio Grandedo Norte (So Jos Belt, northwest of the Rio Piranhas Massif),

B.B. de Brito Neves / Journal of South Aseveral occurrences of anorogenic (acid to intermediate) volcanicrocks and associated granitic plutonism have been recognized. Allof them clearly cut the older dominantly Rhyacian basement, aswell as they are reworked by contractional and shearing events ofthe Brasiliano Cycle. This reworking can be local, but can transformgranitic rocks in augen-gneisses and volcano-sedimentary bandsinto true schist belts.

The exact areal extension of this volcanism-plutonism associa-tions is not yet known, because part of the volcano-sedimentary(Ors Group etc.) sequences and the granitic contexts (severalaugen-gneisses, Serra do Deserto Suite, suite G2 etc.) have beenstrongly involved together with the older basement rocks by theBrasiliano deformations. The complete discrimination still remainsto be done and evaluated.

In the Rio Grande do Norte Terrane, some granitic bodies oftabular shape and alkaline nature (intrusive in the Rhyaciangneissic-migmatitic substrate) have been identied and they yiel-ded UePb ages ca. 1740 Ma. Other coeval granites are present andeven some older ones, as intrusive (augen-gneisses) in this base-ment (Caic Complex, Rhyacian in age) were subsequentlydeformed and tansformed into gneisses by the Brasiliano events.These granitoids are very common and usually referred to as G2-type (G1 would be the granites of the Rhyacian basementthemselves).

In several parts of the Paleoproterozoic (Rhyacian) basement ofthe Transversal Zone (between Patos and Pernambuco EeW line-aments) gabbro-anorthositic bodies, always deformed by the Bra-siliano, have been identied Only in some of the many cases,Statherian ages have been conrmed (Delgado et al., 2003; Santoset al., 2010), and in many others are waiting age determinations.

5.3.4. MantiqueiraIn the northern part of the Mantiqueira Province, within the

domain of the Araua Belt basement, the presence of supracrustalrocks (Espinhao) and associated anorogenic granites (Borrachu-dos) has been debated. To the east, in the northern portion of theRibeira Belt basement in Minas Gerais and Rio de Janeiro, there aremany convergent ideas, which were reviewed by Heilbron et al.(2004). In Minas Gerais, there are successions of Statherian (andeven Mesoproterozoic) supracrustal rocks, as the So Joo Del ReiGroup, which were reworked in the Brasiliano. In Rio de Janeirothere are several references to granitic rocks (orthogneisses) ofalkaline nature and Statherian ages, so that the age value of 1.7 Gahas usually been used as the upper age limit for the basement rocksof the belt.

To the south, in Paran, along the southern border of the ApiaBelt and adjacent to the Lancinha Lineament (north-northeast ofCuritiba) some intensely deformed (mylonitic and ultra-mylonitic)granitoid bodies of alkaline afnity occur within younger volcano-sedimentary supracrustal rocks. In the Betara (close to thesouthern part of the fault) and Tigre (to the north) nuclei, alongthe same structural trend, Statherian intraplate granitoids(respectively 1748 and 1772 Ma old, Cury et al., 2002) weredescribed, demonstrating the presence of the Statherian taphro-genesis in the basement of the belt. Part of this Statherian graniticrocks were transformed into mylonites by the Brasiliano processesof extrusion.

Additionally inUruguay, in the central-westernportionof theNicoPerezTerraneea regenerated fractionof theRiode laPlata Cratoneimmediately east of the Sarandir Del Yi fault, there is an interestingoccurrence of a small subvolcanic granitic body (

B.B. de Brito Neves / Journal of South American Earth Sciences 32 (2011) 270e286284

B.B. de Brito Neves / Journal of South AmeriReferences

vila, C.A., Teixeira, W., Cordani, U.G., Moura, C.A.V., Pereira, R.M., 2010. Rhyacian(2,23e2,20Ga) juvenile accretion in the southern So Francisco craton, Brazil:geochemical and isotopic evidence from the Serrinha magmatic suite, Mineirobelt. Journal of South American Earth Science 29, 464e482.

Almeida, F.F.M., Amaral, G., Cordani, U.G., Kawahita, K., 1973. The Precambrianevolution of south America cratonic margin south of the Amazon river. In:Nairn, N.A., Stehli, F.G. (Eds.), The Oceans Basins and Margins. Plenum, NewYork, pp. 411e446.

Almeida, F.F.M., Hasui, Y., Brito Neves, B.B., Fuck, R.A., 1981. Brazilian structuralprovinces: an introduction. Earth-Science Reviews 17, 1e29.

Almeida, M.E., Macambira, M.J.B., Oliveira, E.C., 2007. Geochemistry and zircongeochronology of I-type higheK cal-alkaline and S-type granitoid rocks fromsoutheastern Roraima, Brazil: Orosirian collisionalmagmatism evidence (1.97e1.96Ga) in Central portion of the Guyana shield. Precambrian Research 155, 69e97.

Barbosa, J.S.F., Sabat, P., 2004. Archean and paleoproterozoic crust of the SoFrancisco craton, Bahia, Brazil: geodynamic features. Precambrian Research133, 1e27.

Basei, M.A.S., McReath, I., Siga Jr., , 1998. The Santa Catarina granulite complex ofsouthern Brazil: a review. Gondwana Research 1, 383e391.

Basei, M.A.S., Frimmel, H.E., Nutman, A.P., Precioszzi, F., 2008. West Gondwanaamalgamation based on detrital zircon ages from Neoproteroazoic Ribeira andDom Feliciano belts of South America and comparision with coeval sequencesfrom SW Africa. In: Pankhurst, R.J., Trouw, R.A.J., Brito Neves, B.B., De Witt, M.J.(Eds.), West Gondwana- Pre-Cenozoic Correlations across the South AtlanticRegion. Geological Society London, Special Publication, vol. 294, pp. 239e256.London.

Bittencourt, J.S., Leite Junior, W.B., Ruiz, A.S., Matos, R., Payolla, B.L., Tosdal, R.M.,2010. Rhe Rondonian eSan Ignacio province in the SW amazonian craton: anoverview. Journal of South American Earth Sciences 29, 28e46.

Brito Neves, B.B., 2004. A Histria dos Continentes Trajetrias e Tramas tectnicas.In: Mantesso-Neto, V., Bartoreli, A., Carneiro, C.D.R., Brito Neves, B.B. (Eds.),Geologia do Continente Sul-Americano - Evoluo da Obra de Fernando FlvioMarques de Almeida. Editora Beca, pp. 123e149. S. Paulo.

Brito Neves, B.B., S, J.M., Nilson, A.A., Botelho, N.B., 1995. A Tafrognese Estateriananos Blocos Paleoproterozicos da Amrica do Sul e processos subsequentes.Geonomos 3, 1e21.

Campal, N., Schipilov, A., 1995. The Illescas Bluish quartz Rapakivi granite (Uruguay-South Amrica): some geological features. In: Symposium on Rapakivi Granitesand Related Rocks.Belem, Brazil, 1995. Federal University Federal of Par, p. 18.Abstracts Volume.

Chaves, A.O., Tubrett, M, Rios, F.J., Oliveira, L.A., Alves, V.A., Fuzikawa, K.,Neves, J.M.C., Matos, E.C., Chaves, A.M.D.V., Prates, S., 2007. U-Pb ages related toUranium mineralizations of Lagoa Real, Bahia-Brazil: tectonics implications.Revista de Geologia 20, 141e156 (Fortaleza CE).

Condie, K.C., 2000. Episodic continental growth models: afterthoughts and exten-sions. Tectonophysics 322, 153e162.

Cordani, U.G., Teixeira, W., 2007. Proterozoic accretionary belts in the amazo-nian craton. In: Hatcher, R.D., Carlson, M.P., McBride, J.H., Cataln, J.R.M.(Eds.), 4-D Framework of Continental Crust. The Geological Society ofAmerica, pp. 297e320. Memoir 200, Boulder.

Cury, L.F., Kaulfuss, G.A., Siga Jr., O., Basei, M.A.S., Harara, O.M., Sato, K., 2002. IdadesU-Pb (zirces) de 1,75 Ga em Granitides Alcalinos Deformados dos NcleosBetara e Tigre: Evidncias de Regimes Extensionais do Estateriano na FaixaApia. Geologia USP: Srie Cientca 2, 95e108.

DallAgnol, R., Oliveira, M.A., Almeida, J.A.C., Althoff, F.J., Leite, A.A.S., Oliveira, D.C.,Barros, C.E.M., 2006. General Aspects of the granitogenesis of the CarajsMetallogenic province. In: Symposium on Magmatism, Crustal Evolution andMetallogenesis of the Amazonian Craton, 2006, pp. 99e114 (IGCP 510 Meeting).Belm-Par. Abstracts Volume and eld Trip Guide.

Danderfer, A., De Waele, B., Pedreira, A.J., Nalini, H., 2009. New geochronologicalconstraints on the geological evolution of Espinhao basin within the SoFrancisco craton-Brazil. Precambrian Research 170, 116e128.

Dantas, E.L., Negro, M.M., Buhn, B., 2008. 2,3 Ga continental crust generation in theRio Grande do norte terrane, NE-Brazil (VI SSAGI, San Carlos Bariloche, 2008).Book of Abstracts. In: VI South American Symposium on Isotope Geology, p. 40.also in CD-room.

Dardenne, M.A., Schobbenhaus, C., 2001. Metalognese do Brasil. Editora Uni-versidade de Braslia. CPRM Servio Geolgico do Brasil, Braslia, p. 392.

Delgado, I.M., Souza, J.D., Silva, L.C., Silveira Filho, N.C., Santos, R.A., Pedreirada Silva, A., Guimares, J.T., Angelim, L.A.A., Vasconcelos, A.M., Gomes, I.P.,Lacerda Filho, J.W., Valente, C.R., Perrotta, M.M., Heineck, C.A., 2003.Geotectnica do Escudo Atlntico. In: Bizzi, L.A., Schobbenhaus, C.,Vidotti, R.M., Gonalves, J.H. (Eds.), Geologia, Tectnica e Recursos Min-erais do Brasil, Texto, Mapas & GIS. CPRM- Servio Geolgico do Brasil,Braslia, pp. 227e334.

Della Giustina, M.E.S.D., Oliveira, C.G., Pimentel, M.M., Melo, L.V., Fuck, R.A., 2008.U-Pb and Sm-Nd constraints on the nature and evolution of paleoproterozoicjuvenile crust in the Tocantins province, central Brazil (VI SSAGI, S. CarlosBariloche, 2001). Book of Abstracts. In: VI South American Symposium onIsotope Geology, p. 32 (also in CD-room).

Dussin, I.A., Dussin, T.M., 1995. Supergrupo Espinhao: Modelo de Evoluo Geo-

dinmica. Geonomos 1, 19e26.Fraga, L.M., Macambira, M.J.B., DallAgnol, Costa, J.B.S., 2009. 1,94e1,93 Ga char-nockitic magmatism from the central part of the Guyana Shield, Roraima, Brazil:single-zircon evaporation data and tectonic implication. Journal of SouthAmerican Earth Sciences 27, 247e257.

Fuck, R.A., Dantas, E.L., Pimentel, M.M., Junges, S.L., Moraes, R., 2001. Nd isotopes,U-Pb single grain and SHRIMP zircon ages from the basement rocks of theTocantins Province (III SAGI, Pucn-Chile, 2001). Abbreviated AbstractVolume. In: III South American Symposium on Isotope Geology, p. 40. also inCD-room.

Fuck, R.A., Brito Neves, B.B., Schobbenhaus, C., 2008. Rodinia descendants in southAmerica. Precambrian Research 169, 108e126.

Hartmann, L.A., Dunyi, L., Wang, L., Massone, H.J., Santos, J.O., 2008. Protolith age ofSanta Maria Chico granulites dated on zircons from an associated amphibolite -facies granodiorite in southernmost Brazil. Anais da Academia Brasileira deCincias 80, 543e551.

Heilbron, M., Pedrosa Soares, A.C., Campos Neto, M.C., Silva, L.C., Trouw, R.A.J.,Janasi, V.A., 2004. Provncia Mantiqueira. In: Mantesso Neto, V., Bartorelli, A.,Carneiro, C.D.R., Brito Neves, B.B. (Eds.), Geologia do Continente Sul-AmericanoEvoluo da Obra de Fernando Flvio Marques de Almeida. Editora Beca,S.Paulo, pp. 203e233.

Howell, D.J., 1995. In: Principles of terrane analysis: new applications for globaltectonics, 2nd ed. Chapman & Hall, London, p. 245.

Hurley, P.M., Almeida, F.F.M., Melcher, G.C., Cordani, U.G., Rand, J.R., Kawashita, K.,Vandoros, P., Pinson, W.H., Fairbairn, H.W., 1967. Test of continental drift bycomparision of Radiometric ages. Science 157, 495e500.

Jost, H., Dussin, I.A., Chemale Jr., F., Tassinari, C.C.G., Junges, S., 2008. U-Pb and Sm-Ndconstraints for the Paleoproterozoic age of the metassedimentary sequences ofthe gois Archean greenstone belts (VI SSAGI, S. Carlos Bariloche, 2001). Book ofAbstracts. In: VI South American Symposium on Isotope Geology, p. 45 (also inCD-room).

Klein, E.L., Moura, C.A.V., 2008. So Luis craton and Gurupi belt (Brazil): possiblelinks with the west Africa craton and surrounding Oan-African belts. In:Pankhurst, R.J., Trouw, R.A.J., Brito Neves, B.B., De Witt, M.J. (Eds.), WestGondwana- Pre-Cenozoic Correlations across the South Atlantic Region.Geological Society of London, Special Publication, vol. 294, pp. 137e151.London.

Leite, J.A.D., Saes, G.S., Macambira, M.J.B., 2001. The Teles Pires volcanic province:a paleoproterozoic silicic-dominated large igneous province in southwestAmazon Craton and tectonic implications. In: III South American Symposium onIsotope Geology (III SSAGI, Pucn-Chile, 2001), pp. 181e183. Extended Abstracts.

Menezes Leal, A.B., Girardi, V.A.V., Leal, L.R.B., 2006. Geologia, Petrograa e Geo-qumica dos Sills Cotingo e Pedra Preta, Estado de Roraima, Brasil. GeochimicaBrasiliense 20, 233e250.

Oliveira, E.P., Carvalho, M.J., McNaughton, N.J., 2004. Evoluo do SegmentoNorte do Orgeno Itabuna-Salvador-Cura: Cronologia de acreso de arcos,coliso continental e escape de terrenos. Geologia USP Srie Cientca 4,41e54.

Rapela, C.W., Pankhurst, R.J., Casquet, C., Fanning, C.M., Baldo, E.G., Gonzalez-Casado, J.M., Galindo, C., Dahlquiest, J., 2007. The Rio de la Plata craton and theassembly of SW Gondwana. Earth- Science Reviews 83, 49e82.

Reis, N.J., Pinheiro, S.S., Costi, H.T., Costa, J.B.S., 1990. A cobertura sedimentar pro-terozica do Supergrupo Roraima no norte do Estado de Roraima, Brasil. In:Anais XXXVI Congresso Brasileiro de Geologia, Natal-RN/SBG, pp. 66e81.

Rivalente, G., Mazzucchelli, M., Girardi, V.A.V., Cavazzini, G., Finatti, C., Barbieri, M.A.,Teixeira, W., 1998. Petrogenesis of the Paleoproterozoic basalt-andesite-rhyolitedyke association of the Carajs region, Amazonian craton. Lithos 43, 235e265.

Rosa-Costa, L.T., Lafon, J.M., Delor, C., 2006. Zircon geochronology and Sm-Ndisotopic study: further constraints for the Archean and paleoproterozoic geo-dynamical evolution of the southeastern Guiana shield, north of the amazoniancraton, Brasil. Gondwana Research 10, 277e300.

Rosa-Costa, L.T., Lafon, J.M., Delor, C., 2008. Electron microprobe U-Th-Pb monazitedating of the Transamazonian metamorphic overprint on Archean rocks fromthe Amap block, southeastern Guyanas shield, northern Brazil. Journal ofSouth American Earth Sciences 26, 445e462.

Santos, J.O.S., 2003. Geotectnica dos Escudos das Guianas e Brasil-Central. In:Bizzi, L.A., Schobbenhaus, C., Vidotti, R.M., Gonalves, J.H. (Eds.), Geologia,Tectnica e Recursos Minerais do Brasil, Texto, Mapas & GIS. CPRM- ServioGeolgico do Brasil, Braslia, pp. 169e226. 2003.

Santos, J.O.S., Hartmann, L.A., Bossi, J., Campal, N., Schipilov, A., Pinneyro, D.,McNaughton, N.J., 2003a. Duration of the Trans-amazonian cycle and itsCorrelation within south America based on U-Pb SHRIMP Geochroology of theLa Plata craton, Uruguay. International Geology Review 45, 27e48.

Santos, J.O.S., Potter, P.E., Reis, N.J., Hartmann, L.A., Fletcher, I.R., McNaughton, N.M.,2003b. Age, source, and regional stratigraphy of the Roraima supergroup andRoraima-like outliers in northern South America based on U-Pb geochronology.GSA Bulletin 115, 331e348.

Santos, T.J.S., Fetter, A.H., Nogueira Neto, J.A., 2008. Comparisions between thenorthwestern Borborema province, NE Brazil, and the southwestern PharusianDahomey belt, SW central frica. In: Pankhurst, R.J., Trouw, R.A.J., BritoNeves, B.B., De Witt, M.J. (Eds.), West Gondwana- Pre-Cenozoic Dorrelationsacross the South Atlantic Region. Geological Society London,Special Publication,vol. 294, pp. 101e120. London.

Santos, E.J., Van Schmus, W.R., Kozuch, M., Brito Neves, B.B., 2010. The Cariris Velhos

can Earth Sciences 32 (2011) 270e286 285tectonic event in northeast Brazil. Journal of South American Earth Sciences29, 61e76.

Sato, K., Siga Jr., O., Nutman, A.P., Basei, M.A.S., Mc Reath, I., Kaulfuss, G., 2003. TheAtuba complex, southern south American platform: archean components andpaleoproterozoic to Neoproterozoic Tectonothermal events. GondwanaResearch 6, 251e263.

Schmitt, R.S., Trouw, R.A.J., Van Schmus, W.R., Passchier, C.W., 2008. Cambrianorogeny in the Ribeira Belt (SE Brazil) and correlations within West Gondwana:ties that bind underwater. In: Pankhurst, R.J., Trouw, R.A.J., Brito Neves, B.B., DeWitt, M.J. (Eds.), West Gondwana e Pre-Cenozoic Correlations across the SouthAtlantic Region. Geological Society London, Special Publication, vol. 294, pp.279e296. London.

Siga Jr., O., Basei, M.A.S., Reis Neto, J.M., Machiavelli, A., Harara, O.M., 1995.O Complexo Atuba: um cinturo Paleoproterozico intensamente retrabalhadono Neoproterozico. Boletim IGc-USP e Srie Cientca 26, 69e98.

Tassinari, C.C.G., Macambira, M.J.B., 2004. A Evoluo Tectnica do Crton Ama-znico. In: Mantesso Neto, V., Bartorelli, A., Carneiro, C.D.R., Brito Neves, B.B.(Eds.), Geologia do Continente Sul-Americano Evoluo da Obra de FernandoFlvio Marques de Almeida. Editora Beca, S.Paulo, pp. 471e485.

Teixeira, W., Renne, P.R., Bossi, J., Campal, N., DAgrella Filho, 1999. 40Ar/39Ar and Rb-Sr geochronology of the Uruguayan dike swarm, Rio de La Plata Craton andimplications for Proterozoic intraplate activity in western Gondwana. Precam-brian Research 93, 153e180.

Tickyj, H., Hartmann, L.A., Vasconcellos, M.A.Z., Philip, R.P., Resmus, V.D., 2004.Electron micropobe dating of monazite substantiates ages of major geologicalevents in the southern Brazilian shield. Journal of South American EarthSciences 16, 699e713.

Tosdal, R.M., 1996. The amazonian-Laurentian connection as viewed from theMiddle Proterozoic rocks in the central Andes, western Bolivia and northernChile. Tectonics 15, 827e842.

Valrio, C.S., Souza, V.S., Macambira, M.J.B., 2009. The 1.90 e 1.88 Ga magmatism inthe southernmost Guyana Shield, Amazonas, Brazil: geology, geochemistry,zircon geochronology, and tectonic implications. Journal of South AmericanEarth Sciences 28, 304e320.

Vasquez, M.L., Macambira, M.J.B., Armastrong, R., 2008. Zircon geochronology ofgranitoids from western Bacaj domain, southeastern Amazonia Craton,Brazil: Neoarchean to Orosirian evolution. Precambrian Research 161,297e302.

Viana, S.M., Valadares, C.S., Tupinamb, M., Simonetti, A., 2008. Orthogneisses ofthe Quirino complex, central Ribeira belt: U-Pb LA-ICPM