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Sedimentary Geology 290 (2013) 4759

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Sedimentar

e ls1. Introduction

The study of rift basin evolution in a continental context, includingthat of the Espinhao Basin in eastern Brazil, has been receiving in-creasing attention because it enables a better understanding of depo-sitional processes and ll-sedimentation patterns and because of itsconsequent predictive value, especially for the oil industry. However,one of the greatest problems facedwhen dealingwith the stratigraphyof Precambrian basins is their lack of fossil content, which preventsmajor stratigraphic correlations, especially in sequences where onlya sedimentary record exists without intercalated volcanic rocks. Thislack of fossil content has led many authors to assemble models instratigraphic sections that are completely timeless (e.g., Martins-Neto, 2009). Despite the large number of published papers regarding

sequence of an intracontinental rift-sag basin system that developedapproximately 1700 Ma in the So Francisco paleoplate and itsmargins (Dussin and Dussin, 1995; Brito Neves, 1995; Uhlein et al.,1998; Martins-Neto, 1998, 2009) and is predominantly characterizedby siliciclastic sedimentation but also includes volcanism and tuffa-ceous contributions. Martins-Neto (2009 and references therein) pro-posed a single rst-order sequence with pre-rift, rift, transitional andmarine sag stages for this intracontinental basin. More recently,Chemale et al. (2012), based on UPb detrital and volcanic zircondata from the Espinhao Supergroup units, recognized three basinalcycles for the so-called Espinhao Basin units in the So FranciscoCraton with major sedimentation material sources from the Jequi(Neoarchean) and Transamazonian (Paleoproterozoic) orogeniccycles. Moreover, in the southern Espinhao, during the stable periodthe Espinhao Basin, many questions remainmapping and quantitative analysis; thus, detThe Espinhao Supergroup was described by

Corresponding author at: Instituto deGeocincias, Unido Sul, 9500 Bento Gonalves Avenue, Porto Alegre 91503308 6352; fax: +55 51 3308 7302.

E-mail address: marcelodega@hotmail.com (M.N. Sa

0037-0738/$ see front matter 2013 Elsevier B.V. Allhttp://dx.doi.org/10.1016/j.sedgeo.2013.03.002 2013 Elsevier B.V. All rights reserved.

Stratigraphya r t i c l e i n f o

Article history:Received 31 January 2012Received in revised form 26 February 2013Accepted 3 March 2013Available online 13 March 2013

Editor: J. Knight

Keywords:UPb zircon geochronologyStatherianStenianSedimentologyThe Espinhao Basin in eastern Brazil contains depositional sequences developed in the So Franciscopaleoplate and its margins. Detailed mapping was conducted and combined with UPb detrital zircon datingto determine the sedimentological-stratigraphic framework, provenance and minimum and maximum agesof the syn-rift-deposits. The two cycles have minimum ages of 1192 and 923 Ma and maximum ages of1785 and 1685 Ma. The rst depositional cycle, represented by the Bandeirinha and So Joo da Chapadaformations, is marked by contributions of Neoarchean and Paleoproterozoic detrital zircons. The secondcycle, the diamond-bearing Sopa-Brumadinho Formation, also contains Mesoproterozoic zircons formedbetween 1300 and 1190 Ma, which suggests an additional external source of Grenvillian age, that was notpreviously recorded in the So Francisco Craton. The investigation of such Mesoproterozoic intraplatesedimentary records, provides clues to understanding the history of the Rodinia active margins and, therefore,the kinematic reconstruction of its paleoplates.a b s t r a c tSedimentological and paleoenvironmentaEspinhao rift system, Brazil

M.N. Santos a,, F. Chemale Jr. b, I.A. Dussin c,d, M. MF. Guadagnin a,f, R. Armstrong g

a PPGGEO, Instituto de Geocincias, Universidade Federal do Rio Grande do Sul, Cx. Postal 1b Laboratrio de Geocronologia, Instituto de Geocincias, Universidade de Braslia, 70.904-c CPGEO, Instituto de Geocincias, Universidade de So Paulo, Brazild DEGEO-UFOP, Morro do Cruzeiro, CEP 35400-000, Ouro Preto MG, Brazile CGE/CPMTC/IGC-UFMG, Belo Horizonte MG, Brazilf Universidade Federal do Esprito Santo, Cx. Postal 030, 29500-000 Alegre, ES, Brazilg RSES, ANU, Canberra, Australia

j ourna l homepage: www.due to a lack of detailedailed studies are needed.many authors as the ll

versidade Federal doRioGrande9-900, RS, Brazil. Tel.: +55 51

ntos).

rights reserved.onstraints of the Statherian and Stenian

ins e, T.A.R. Assis e, A.R. Jelinek a,

1, 91501-970 Porto Alegre, RS, BrazilBraslia, DF, Brazil

y Geology

ev ie r .com/ locate /sedgeofrom 1800 Ma to 910 Ma in the So Francisco Craton, only two majorbasinal cycles are represented: the Lower (1680 to 1800 Ma) andUpper Espinhao (910 to 1190 Ma) basins. Chemale et al. (2012)distinguished two major basins in the Espinhao depositional locusthat allow models to be developed that include the temporal elementof its evolution.

The present work proposes a sedimentological-stratigraphic modelfor the paleogeographic evolution of these two basins in the southern

Serra do Espinhao based on detailed structural-stratigraphic mappingat a scale of 1:3000 and sedimentological and stratigraphic descriptionsof 26 sections. The model is supported by geochronological dataobtained from the southern Serra do Espinhao, Brazil. These datamade it possible to reconstitute the different depositional systems andtectonic stages beginning from the end of the Paleoproterozoic (ca.1700 Ma) to the beginning of the Neoproterozoic (~910 Ma) for thesectors studied in the region.

2. Geological setting

2.1. The Espinhao Rift System

Geomorphologically the Serra do Espinhao is divided into twosectors: southern and northern, each characterized by high topo-graphic relief and separated by a SENW low-relief zone (Saadi,1995). The present paper describes the southern sector, particularlythe region around the city of Diamantina, Minas Gerais (Fig. 1).

The Espinhao Rift is located in the So Francisco Craton (sensuAlmeida et al., 2000) in the Serra do Cabral region and is on theAraua Fold Belt in the Serra do Espinhao (Uhlein et al., 1995). Thetectonic evolution of the rift is still controversial in the literature.One commonly held description is that this is an ensialic intracratonicbasin (Dussin and Dussin, 1995; Martins-Neto, 1998). However,Almeida-Abreu (1993) proposed a rift basin model that evolved intoa passive margin with the generation of oceanic crust.

The depositional systems identied in the rift includeuvial, alluvial,lacustrine, deltaic, marine and eolian systems (Dossin et al., 1987;Garcia and Uhlein, 1987; Martins-Neto, 1998; Silva, 1998). During theBrasiliano Orogeny, there would have been a collision with the So

Francisco Craton and the partial deformation and metamorphism oflow-grade deposits in the Espinhao Basin (I.A. Dussin, 1994; Dussinand Dussin, 1995). Some of the deformed structures in the basin, suchas thrust faults and folds with vergence to the west, are attributed tothis collision (Dossin et al., 1992; Uhlein et al., 1995; Alkmim et al.,2007; Pedrosa-Soares et al., 2007).

2.2. Dating background

Geochronological data suggest dates for the rift opening of 1729 14 Ma and 1770 Ma by Pb/Pb and U/Pb zircon dating methods, respec-tively, from a granitic emplacement in the basement (Dossin et al.,1993) and a rhyolitic emplacement in the Conceio do Mato Dentro(Brito Neves et al., 1979; Fig. 1a), at the base of the basin. The datingof Pb/Pb on zircons from a hematitic phyllite located near the city of Di-amantina provides an age of 1710 Ma (Dossin et al., 1993), indicatingthe approximate age for the beginning of sedimentation in the basin.Machado et al. (1989) obtained an age of 906 2 Ma using the U/Pbmethod on mac rocks (Sute Pedro Lessa) that intrude into theEspinhao Basin, indicating a minimum age for the deposition of itssediments.

Chemale et al. (2012) obtained an age of 1192 16 Ma in zirconsfrom a conglomerate with a volcanogenic matrix from the Sopa-Brumadinho Formation in the Extrao region and proposed dividingthe basin into two sequences (i.e., Lower and Upper Espinhao). Thus,the Espinhao Supergroup in southern Espinhao, Minas Gerais, con-tains two unconformable successions that can be interpreted as twobasin ll cycles: (i) a Statherian succession (1780 to 1710 Ma) in anintracontinental rift and (ii) a StenianTonian succession (1180 to910 Ma) in an intracontinental rift-sag successor basin.

ed

48 M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fig. 1. (a) Localization map of the Espinhao Basin in the southern Espinhao. (b) Simpli

the four studied areas (modied after Chaves, 1997).geological map of the central portion of the Espinhao Basin indicating the locations of

2.3. Stratigraphic background

Lithostratigraphy has been widely used in the Espinhao Basin andstill remains a tool in the development ofmany studies. Pug (1968) di-vided the Espinhao Basin into eight formations: So Joo da Chapada,Sopa-Brumadinho, Galho do Miguel, Santa Rita, Crrego dos Borges,Crrego da Bandeira, Crrego Pereira and Rio Pardo Grande, from baseto top. Dossin et al. (1984) grouped the eight formations into twohigher-ranking units based on depositional systems and in the contextof basin evolution: the Diamantina Group, which includes the rstthree formations, and the Conselheiro Mata Group, which includes thelast ve formations (Fig. 2).

The pink quartzites with metaconglomerates are part of theBandeirinha Formation and are the subject of much controversy re-garding their stratigraphic position (pre-Espinhao or Espinhao),which is considered by Almeida-Abreu (1993) and a considerablenumber of additional authors to be part of the basin (Silva, 1995;Alkmim et al., 1996; Martins-Neto, 1998).

The grouping of similar lithologies to dene the Espinhao Basinstratigraphic units was introduced by Schll (1980) and Schll andFogaa (1979), who subdivided the So Joo da Chapada Formationinto the informal levels A, B and C and the Sopa-Brumadinho Formationinto the levels D, E and F. The three levels of the Sopa-Brumadinho For-mationwere given the designation ofmembers and are known asDatas,Caldeires and Campo Sampaio (Almeida-Abreu, 1993; Fig. 2).

This lithostratigraphic classication is relatively effective locally, butregionally, the depositional dynamics must be considered. More recentstudies have approached the Espinhao Basin deposits with relativelynew concepts in the use of tectonostratigraphy (Martins-Neto, 1998)and sequence stratigraphy (Silva, 1998; Martins-Neto, 2009).

3. Methodology

The present work used detailed geological eld mapping and geo-chronological UPb zircon dating.

of th(198

49M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fig. 2. Simplied stratigraphic arrangement of the Espinhao Basin showing the locationpilation and modication from Pug (1968), Schll and Fogaa (1979) and Dossin et al.

to scale.e dated samples. The rift is divided into basins, groups, formations and members. Com-4). *As proposed by Chemale et al. (2010). **Unit added by Almeida-Abreu (1993). Not

3.1. Stratigraphic-sedimentological mapping

To acquire data in the eld, the present work utilized detailed geo-logical mapping, at a scale of 1:3000, of the three sectors adjacent tothe city of Diamantina (the Guinda district, the Altitude Mximaand the Serra da Mida, from north to south; Fig. 3) and two in theExtrao region (Serrinha and Cavalo Morto). Although the Espinhaounits were affected by the Brasiliano Orogeny, these sectors werechosen because their stratigraphic sections are well preserved with-out major internal structural deformation. The mapping, at a scaleof 1:100, is based on a systematic survey of twenty-six sections, thatwas conducted at six sections in the Guinda sector, with ten sectionsin the Altitude Mxima, ve in the Serra da Mida, three in Serrinhaand two in the Cavalo Morto.

The mapping work was conducted with the aid of satellite imagery(QuickBird sensor) with a resolution of 0.6 m, which provided a highdegree of detail for the units and greatly improved themapping accura-cy, as most previous studies were based on aerial photographs at a1:25,000 scale.

For the correlation of the sections, two datum horizons were used.One datum was the sedimentary breccia of the So Joo da ChapadaFormation occurring in the Altitude Mxima and Serra da Mida sec-tors. The other datum was the transgressive surface of the base of theGalho do Miguel Formation that occurs in the Guinda sector and inthe northern part of the Altitude Mxima sector.

Several thin sections were made from rocks collected along themeasured sections to provide a more detailed description of thefacies. To simplify the present work, the metasedimentary facies aredescribed with sedimentary nomenclature, because of the low-grade

metamorphism from the Brasiliano Orogeny (Caby and Arthaud,1987; Trompette et al., 1992; Dussin and Dussin, 1995; Uhlein et al.,1998; Uhlein and Chaves, 2001).

3.2. UPb zircon dating

The present geochronological studies are based on the dating ofEspinhao Supergroup continental sedimentary units exposed in thecentral segment of the southern Espinhao range near the town ofDiamantina, Minas Gerais, in the localities of Guinda, Sopa, AltitudeMxima and Extrao (Fig. 1b). Our studies complement those carriedout by Chemale et al. (2012) by focusing on the metasedimentaryrocks of the Bandeirinha, So Joo da Chapada and Sopa-Brumadinhoformations.

All samples were crushed and milled using a jaw crusher. Thezircon populations were separated by conventional proceduresusing heavy liquids and a magnetic separator after concentration byhand-panning. The zircons were photographed in transmitted andreected light, imaged using BSE (backscattered electron) and CL(cathodoluminescence), and dated using a laser-ablation microprobe(New Wave UP213) coupled to an MC-ICP-MS (Neptune) at the iso-tope laboratories of the universities of Braslia and Rio Grande doSul (Brazil) and with a SHRIMP RG at the Research School of EarthSciences, Canberra, Australia (ANU). Detailed analytical procedureswere provided by Chemale et al. (2012), and the data are shown inthe Supplementary Data Files. The histograms were prepared withIsoplot/Ex (Ludwig, 2003). For the detrital zircon histogram, weused the zircon data with discordance equal to or lesser than 10%.

ns o

50 M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fig. 3. Geological maps of the studied area in the Diamantina region showing the locatio

Mxima sector, and (c) Serra da Mida sector. AMF Altitude Mxima Farm; U unconfof stratigraphic sections, formations and unconformities. (a) Guinda sector, (b) Altitude

rmities; TS transgressive surface.

4. Results

The full results can be found at the library of the Instituto deGeocincias da Universidade Federal do Rio Grande do Sul (Santos,2011).

Twenty-six stratigraphically measured sections were correlated(Figs. 3, 4), and the results obtained are described below.

In the areas studied, relatively few faults are present. In theGuinda sector, there is a northsouth thrust fault that places theBandeirinha Formation on the So Joo da Chapada Formation. Inthe Serra da Mida sector, part of the basement is positioned on theSo Joo da Chapada Formation by a northsouth thrust fault(Fig. 1b). However, the measured sections do not include major inter-nal structural deformation.

4.1. Unconformities identied

Most of the unconformities that were identied are alreadyknown in the Espinhao Basin (Silva, 1995; Martins-Neto, 1998;Silva, 1998; Martins-Neto, 2009). With some changes, they includethe following, from base to top:

(a) Unconformity 1 (U.1) a subtle disconformity that occurs on thebasement composed ofmylonitized sandstone. Above theuncon-formity are pink sandstones and conglomerates (Fig. 4). Uncon-formity 1 occurs in the Altitude Mxima sector as a thrust fault.

(b) Unconformity 2 (U.2) an angular unconformity (markedlyerosive) that separates pink sandstones from the overlyingwhite sandstones and sedimentary breccia with excellent expo-sure in the Altitude Mxima sector (Figs. 4, 5a, 6a).

(c) Unconformity 3 (U.3) an angular unconformity separatingsandstones and phyllite from sandstone with good exposure inthe Serra da Mida sector (Figs. 4, 5b, c, 6a).

(d) Transgressive Surface 1 (TS 1)with good exposure to the westof Morro da Gota in the Guinda sector, TS 1 is marked by a sur-face on which there is evidence of an abrupt increase in waterdepth and that separates the sandstones of uvial origin frommarine sandstones (Fig. 4).

(e) Transgressive Surface 2 (TS 2) the surface of TS 2marks a largetransgression of the basin, separating eolian quartzite from theoverlying phyllite. This surface occurs along the road fromDiamantina to Conselheiro Mata.

(f) Unconformity 4 (U.4) an angular unconformity separating therotated deposits of the Espinhao Basin from those of the SoFrancisco Basin. Unconformity 4 is practically horizontalized(Alkmim et al., 1996), with good exposure in the Serra do Cabralregion (Fig. 1a).

4.2. Units identied

(a) Unit between U.1 and U.2 characterized by pink sandstoneswith ne to medium grain size, sparse granules and rare pebbles

Gcm

51M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fig. 4. Correlation of stratigraphic sections. Gmm matrix-supported massive gravel;

horizontal bedding; Sm massive sandstone; Fl nely laminated siltstones and mudston clast-supported gravel; St trough cross-bedded sandstone; Sh sandstone with

es (Miall, 1977); U unconformities; TS transgressive surface; and S sections.

52 M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759and, in some places, contains kyanite and exhibits a dominanceof plane-parallel and trough cross-bedding stratication. Locally,in the southern Altitude Mxima sector, there are massive con-glomerates that are both clast-supported and matrix-supported(Fig. 5e). The total thickness may reach 200 m, as in section 9.The unit corresponds to the Bandeirinha Formation and isboundedby a disconformity at the base and an angular unconfor-mity/erosive at the top (U.1 and U.2, Fig. 4). The angular charac-ter can be easily observed in the eld, where the BandeirinhaFormation dips to the eastnortheast and plunges at an angle

Fig. 5. (a) Angular unconformity between the Bandeirinha and So Joo da Chapada formatioChapada and Sopa-Brumadinho formations, Serra da Mida sector; the square in (c) represeda Chapada Formation aligned in the eastwest direction; (e) clast-supported and matrix-boulders, So Joo da Chapada Formation; and (g) uvial channels with geometry preserveof approximately 35, which is quite distinct from the overlyingunit that has a dip direction to the east and a plunge angle of ap-proximately 30 (Fig. 6a). The erosive character is clearlymarkedby the sedimentary breccia of the overlying unit (Fig. 5f), whichcontains clasts of pink sandstones of the Bandeirinha Formation.The sedimentary facies are located west of highway BR-367 nearthe Altitude Mxima farm (Fig. 3).

(b) Unit between U.2 and U.3 corresponds, in part, to the So Jooda Chapada Formation described by Pug (1968). This formationreaches thicknesses of up to 300 m in the Altitude Mxima

ns, Altitude Mxima sector; (b) and (c) angular unconformity between the So Joo dants (b); note the person for scale circled in yellow; (d) sedimentary breccia of So Joosupported conglomerates of the Bandeirinha Formation; (f) sedimentary breccia withd, Sopa-Brumadinho Formation.

ata

53M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759sector, with a decrease in grain size at the top of the formation.This unit is mainly located along highway BR-259, which con-nects the city of Gouveia to Datas (Fig. 1a), and consists of fourfacies. The rst is a massive sedimentary breccia with angularclasts of sandstones of varied sizes ranging from cobble to boul-der and grading laterally into sandstones. This facies has an

Fig. 6. Field measurements taken in the Diamantina region. (a) bedding inclination daverage thickness of 10 m with outcrops aligned in the northsouth direction in the Altitude Mxima sector, west of highwayBR-367. However, there are a few outcrops of sedimentary brec-cia aligned in the eastwest direction (Fig. 5d).Over the sedimentary breccia is a common occurrence of a he-matitic phyllite (composed mainly of sericite and hematite),which is the second facies. This facies reaches thicknesses of ap-proximately 10 to 20 m in the Serra da Mida sector west ofhighway BR-367. In the third facies, white sandstones occurthat are composed essentially of quartz and are micaceous insome places, with medium sand grain size, horizons of coarsesand with granules and pebbles and exhibiting primarily troughcross-bedding and plane-parallel stratication. The fourth faciesconsists of pelites previously assigned to the base of theSopa-Brumadinho Formation by Pug (1968). This facies hasgood exposure in the regions of Guinda and Serra da Midabut is often hidden by vegetation or by a soil prole. The thick-ness in the measured sections does not exceed 20 m.

(c) Unit between U.3 and TS 1 corresponds partially to theSopa-Brumadinho Formation. Exposures occur in the Guindaand Extraction regions in the district of Diamantina, where theunit can be easily observed in the mines of Diamante Vermelho,Lavrinha and Brumadinho, and consists primarily of sandstoneswith plane-parallel stratications that pass vertically and later-ally into pelites and conglomerates with diamonds. In Guinda,the total thickness of the unit reaches approximately 150 m.The sandstones are of medium to coarse grain size with pebblesand, in some areas, exhibit oxidation and trough cross-beddingstratication that represents the record of a uvial channel(Fig. 5g). Conglomeratic lenses typically reach a 5 m thickness(locally reaching 8 m) and have clasts of varied composition,including various sandstones, conglomerates and mudstones.The conglomerate matrix is predominantly sandy toward thenorth in the Brumadinho Mine, however, and is also pelitic.

(d) Unit between TS 1 and TS 2 corresponds to the Galho doMiguel Formation and consists of two sedimentary facies. The

plotted on stereonet diagrams, and (b) paleocurrent data plotted on rose diagrams.rst consists of ne sandstones with wave ripples. This faciesis well represented in thewesternMorro da Gota, Guinda sector.The second facies is located on the road from Campo Sampaio tothe Santa Rita region, comprising sandstones with large troughcross-bedding stratication withmedium grain size and restrict-ed occurrences of pebbles. This unit has a thickness of between2000 and 3000 m (Pug, 1968).

(e) Unit between TS 2 and U.4 corresponds to the ConselheiroMata Group and comprises ve sedimentary facies, which aredescribed below according to Pug (1968). The rst facies con-sists of mudstones with outcrops south of the Santa Rita villagethat are approximately 250 m thick. The second facies is com-posed of quartz sandstones that occur in the southwest andnortheast of Santa Rita and are 250 m thick. The third facies iscomposed of mudstones with sandy lenses and reaches a thick-ness of 200 m in southern Santa Rita. The fourth facies has athickness from 700 to 1000 m, as inferred from aerial photos,and marks the return of quartz sandstone. The fth facies out-crops south of Ribeiro do Batatal and is composed of mud-stones with a thickness of approximately 1000 m.

4.3. Geochronological results

The UPb results are from three main detailed sedimentary unitscollected from the section where the Brasiliano (Neoproterozoic toEopaleozoic) deformation did not affect the stratigraphic order.

The basal unit, represented by the Bandeirinha Formation, con-tains detrital zircons of Archean and Paleoproterozoic ages, whereonly 98 out of 182 dated zircons meet the necessary concordance(between 90 and 110%; Fig. 7). The zircons formed in the Neoarchean

54 M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759are dominant (peak at 2664 Ma) and are related to the basementrocks formed during the Jequi Cycle. A subordinate contribution ofzircon formed at peaks of 2838, 3076 and 3272 Ma (Archean) and2468, 2155 and 1785 Ma (Paleoproterozoic). The youngest zirconpopulation dates to 1785 Ma, which is interpreted here as the maxi-mum depositional age for the Banderinha Formation.

The So Joo da Chapada Formation in the Serra da Mida sector,which overlies the Bandeirinha Formation in an angular unconformity,contains dominant Paleoproterozoic zircons formed at 2138 Ma (Fig. 7).

Fig. 7. Relative probability histograms for the studied samples from southern Espinhaoand corresponding to Bandeirinha, So Joo da Chapada and Sopa-Brumadinho forma-tions. Detrital zircons data with discordance equal or lesser then 10%.The zircon populations formed at 2702, 2835 and 3338 Ma occur subor-dinately. A small population of zircon that crystallized at 1713 Ma isrecognized; this age is very close to the age of the K-alkaline intrusionsin the basal units of the So Joo da Chapada Formation, which wasdated at 1703 12 Ma by Chemale et al. (2012).

Out of the 574 detrital zircons dated from the Sopa-BrumadinhoFormation in the Guinda-Sopa and Extrao sectors, 468 grains areconcordant. The cumulative probability histogram (Fig. 7) shows sim-ilar distributions of Paleoproterozoic and Archean detrital zircon ages.However, as discussed by Chemale et al. (2012), a population is alsorecognized at 11801190 Ma, which is the maximum depositionalage for this formation.

5. Discussion

5.1. Stratigraphic position of the Datas Member

The most signicant change in the stratigraphic sedimentaryfacies unit position is at the pelitic horizon of the Datas Member(Almeida-Abreu, 1993), which was previously assigned to the Sopa-Brumadinho Formation by Pug (1968). The pelitic horizon wasdisplaced in the present work to the top of the So Joo da ChapadaFormation because there is a gradation and intercalation of the sand-stones of this unit with the pelites. Moreover, it becomes possible toobserve the angular nature of the unconformity 3 (U.3) above thepelites/quartzites of the Datas Member.

5.2. Northsouth and eastwest faults and their sedimentological control

The volume available for sediment deposition (i.e., accommoda-tion) depends on the relationship between subsidence and relativesea-level changes (Emery and Myers, 1996). Given the importanceof fault-controlled subsidence for the generation of accommodationin rift basins, Morley (1999) proposed that regions close to the cen-ters of faults exhibit the greatest displacement, with the displacementdecreasing toward the edges (Fig. 8). These assumptions directly in-uence sedimentary deposit thickness estimates, which tend to behigher in the middle and lower in the edges of these faults.

The propagation of northsouth-oriented normal faults during thedeposition of the So Joo da Chapada Formation explains why thebreccias in the Altitude Mxima sector have thicknesses that increasetowards their northern and southern edges and decrease in the cen-tral portions. The deposition of the breccia would have started fromindividual faults, each with its own depocenter, and, with the propa-gation of the faults, the breccia would have been deposited in smallamounts in the center of a new fault generated by the union of twoolder faults. The shift of the depocenter in the So Joo da ChapadaFormation also explains why the greatest thickness of the sandstonepackages deposited after the breccia is now located in the central por-tion of the Altitude Mxima sector.

The Sopa-Brumadinho Formation reaches its greatest thickness inthe Guinda, Serrinha and Cavalo Morto sectors and has most likely un-dergone major subsidence in this region. This subsidence may explainthe probable formation of a lacustrine system (Sopa-Brumadinho For-mation) in these sectors, which experienced a more pronounced subsi-dence than the surrounding sectors, and the subsequent marinetransgression of the Galho do Miguel Formation in the Guinda sector.

The eastwest faults were denoted as F.1 to F.4 (Fig. 4) and werecharacterized as transfer faults with greater or lesser degrees of mag-nitude. These faults exerted a substantial inuence on the sedimenta-tion, as few sedimentary breccias formed along them (Fig. 5d), andlimited the compartments of different subsidence intensity.

Because the fault-controlled subsidence had a greater inuence onthe generating accommodation and more effectively controlled thesedimentation than relative sea-level changes in the Lower Espinhao

Basin and the early stages of Upper Espinhao Basin, this subsidence

55M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759pattern is an important consideration in stratigraphically characteriz-ing tectonic system tracts with respect to the spatial and temporaldistribution of depositional systems. The importance of this charac-terization is that studies of similar basins may use the informationregarding the evolutionary behavior of the depositional system de-scribed here to determine tectonic system tracts and, hence, thestage of evolution reached by the basin. The nomenclature of the sys-tem tracts used was from Prosser (1993), whose method of describ-ing rift basin stratigraphies is based on identifying distinct rift

Fig. 8. Variation of the thickness of the So Joo da Chapada Formation that was the re-sult of fault propagation. Modied from Morley (1999).evolution stages, each with linked characteristic depositional sys-tems. Unlike models of sequence stratigraphy applied to passive con-tinental margin settings (Catuneanu et al., 2009), the model proposedby Prosser (1993) allows for the observation of a consistent pattern inthe evolution of depositional systems in active-fault-bounded basins,where sedimentation is not essentially controlled by the change inrelative sea level but is tectonic.

5.3. Tectonic evolution, stratigraphy and paleogeography

The subsidence duration can vary greatly in basins formed in an ex-tensional context. According to Allen and Allen (2005), the subsidencein continental rifts with normal crust thickness occurs over long periodsof time which may even exceed 30 My. The So Francisco Craton has acrustal thickness of approximately 37 to 40 km (Assumpo et al.,2002), which is consistent with the normal thickness of the continentalcrust (35 kmon average, Allen and Allen, 2005). Given the assumptionsdescribed above and the fact that the two depositional sequences of theEspinhao Rift Systemare separated by anunconformity that represents500 Ma (Chemale et al., 2010; Fig. 9), it is reasonable to consider thatthese depositional sequences constitute two distinct basins that occupythe same deposition locus because the large gap in question indicatestwo distinct tectonothermal events.

The Altitude Maxima sector is an important area for stratigraphicstudy because the superposition of all units that represent the differ-ent stages of fault-controlled subsidence are found within it.

The nomenclature used in this study for both basins (i.e., Lowerand Upper Espinhao) is that proposed by Chemale et al. (2010).5.4. Lower Espinhao Basin

The Lower Espinhao Basin sedimentation evolved through twodistinct stages of rifting. The rst stage conditioned the depositionof the Bandeirinha Formation, whereas the So Joo da Chapada For-mation represents the second stage (Almeida-Abreu, 1993, 1995).

During the rst phase of mechanical extension responsible for theopening of the basin, small, normal faults resulted in the deploymentof relatively poorly developed depositional systems occupying smalland disconnected areas. During the second phase of rift evolution(i.e., with the increase in the extension and subsidence rates), mag-matic activity would have been generated by asthenospheric decom-pression (Dussin and Dussin, 1995), as would the propagation offaults, which is very important in increasing the area of sedimenta-tion and the full development of depositional systems.

5.4.1. Bandeirinha FormationAccording to Silva (1998), the surveying and integration of strati-

graphic sections in the Altitude Mxima sector enable the recognitionof three depositional systems for the unit: dominant braided uvialfans, alluvial fans and subordinate eolian sediments. The two horizonsof alluvial conglomerates identied are of local character, with their de-positions associated with normal faults in a northsouth orientationand, eventually, with eastwest transfer faults that border the southern

Fig. 9. Variations of the temporal positioning of the Espinhao Basin.part of the unit (F.2, Fig. 4). The subdivision of the Bandeirinha Forma-tion into depositional sequences (i.e., Olaria and Natureza) accordingto Martins-Neto (1998) and Silva (1998) was not adopted in thiswork because the local character of conglomeratic levels was identied;these levels represent erosional diastems representing minor breaks inthe geologic record (Barrel, 1917) and reect dynamic depositional en-vironments rather than unconformities.

The following are all consistent with the rift initiation system tractdescribed by Prosser (1993): the disconnection of the BandeirinhaFormation outcrop regions, the small area of deposition, the subaerialcharacter of the basin with sufcient water to supply the uvial sys-tems during their development, the dominantly longitudinal drainagesystems (or parallel axes, Fig. 6b) and paleorelief marked by smallfault scarps and local areas with axial topographic highs. The reddishcolor of the sandstone is not diagnostic for the climatic conditions atthe time of deposition (Sheldon, 2005).

5.4.2. So Joo da Chapada FormationThis unit represents the initial development of alluvial deposits in

the Altitude Mxima region and is characterized by the presence of abreccia followed by the formation of an extensive braided uvial

system (Garcia and Uhlein, 1987) and the subsequent formation ofoodplains, most likely during a major ood event. Braided riveroodplains are usually associated with large, wide rivers (Nansonand Croke, 1992) in a manner analogous to the modern upstreamsegment of the Tagliamento River in northeastern Italy (van derNat et al., 2002). Occurring contemporaneously with sedimentation,hematite phyllite of volcanic origin with chemical alteration bymetamorphism (T.M. Dussin, 1994) or weathering (Knauer andSchrank, 1994) is an indicator of igneous activity resulting fromthe distentional process active in the basin (Dussin and Dussin,1995).

The paleocurrent pattern of the So Joo da Chapada Formationuvial systems (mean vector of 103) is clearly distinct from that ofthe Bandeirinha Formation (mean vector of 081) and seems to indi-cate a readjustment of the uvial channel direction as a direct conse-quence of the rotation of the hanging wall because both bedding andpaleocurrent have a difference of 20 for the two units (Fig. 6a, b). Therotation of the hanging wall changed the predominantly NNE longi-tudinal drainage pattern to an exclusively ESE transverse drainagepattern (axis perpendicular), which predominated during the laterstages of rift sedimentation.

Fordham et al. (2010)mapped and calculated the proportion of thesurcial facies distribution in the Great Basin region (i.e., a series of riftbasins in arid and semi-arid settings in the USA that are referred to asdrylands) and showed that the basin ll is largely dominated by thedeposits of transverse catchments at different stages of rift evolution.

Axial uvial systems were restricted to a narrow corridor by theprogradation of lateral systems occupying a small to negligible pro-portion of surcial lithofacies. The sedimentation in the lower andmiddle parts of the So Joo da Chapada Formation seems to haveevolved in a context similar to that of the drylands because, in additionto the limited presence of any lake or axial uvial systems, transverseuvial systems predominated over time. The mudstones and nesandstones present in the top of the So Joo da Chapada Formationmark a gradual ooding of the uvial channels with the consequentformation of a broad oodplain or the eventual generation of a lakesystem. Although they have a signicant areal distribution, the verticaldeposits of this ooding are not notable in comparison to thoseexhibited by other rifts (e.g., Tanganyika and Malawi; Scholz et al.,1998; Chorowicz, 2005).

The increase in the depositional area of the So Joo da ChapadaFormation, the paleorelief marked by highs (as evidenced by brecciadeposition) and the tendency of individual faults to change to a singledominant fault resulted in the early rift climax system tract describedby Prosser (1993). This system tract can be clearly separated from therift initiation system tract by a possible onlap over a discontinuity,Unconformity 2 in this case, which is erosive and related to thebasin area expansion.

A ning upward pattern is present in So Joo da Chapada andmay indicate a decrease in fault-controlled subsidence and the conse-quent decrease in sediment supply, which was the result of the ero-sion of Lower Espinhao Basin source areas.

56 M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fig. 10. Geological map of the studied area in the Extrao region showing the location of stratigraphic sections, formations and transgressive surface 1 (TS 1).

5.5. Upper Espinhao Basin

The Sopa-Brumadinho Formation sedimentary deposits representa record of a new basin opening and occupy the same depositionallocus of the Lower Espinhao Basin. The boundary between the SoJoo da Chapada/Sopa-Brumadinho formations is marked by an angu-lar unconformity with a difference of approximately 10 in dip anglebut with the same dip direction (Fig. 6a). Considering the gap of ap-proximately 500 Ma between the two sedimentary units (Chemaleet al., 2010) and the coincidence in the dip direction, the newrifting (1180 Ma) most likely reactivated the faults of the rst rift(ca. 1.7 Ga).

5.5.1. Sopa-Brumadinho FormationThe deposition in a braided uvial system associated with alluvial

fans (Dossin et al., 1990), including lacustrine fan deltas (Martins-Neto, 1996, 1998), that occur in the northern Guinda sector is consistentwith the observed facies associations. There is evidence of thereworking of pelites in the Sopa-Brumadinho Formation oodplain orthe top of the So Joo da Chapada Formation.

The extensional process, acting more dramatically in the Sopa-Brumadinho Formation, favored the development of alluvial fans thathave progradedmainly to the east but are sometimes channeled towardthe northeast with high erosive power. The alluvial fans pass verticallyand laterally into uvial channels and into oodplain deposits. Unlikethe paucity of lacustrine systems in the Lower Espinhao Basin, at thetime of the Sopa-Brumadinho deposition, these lacustrine systems ap-pear to have exerted a great inuence on sedimentation. In the Extraoregion, lacustrine fan deltas overlap sediments ofuvial origin, and bothare directed to the east.

As shown in Figs. 10 and 11, the Cavalo Morto sector (sections 25and 26) has a more distal character because the layers of conglomerateare thinner, with a higher contribution of sand than is found in theSerrinha sector (sections 22, 23 and 24). The transition from one con-glomerate horizon to another (i.e., a conglomerate with a green claymatrix to a conglomerate with a sandy matrix) indicates an end to thetuffaceous contribution (Fig. 11). In the Serrinha sector, the absence ofthe second conglomerate horizon is the result of erosion caused by anuplift in antiform folds (Fig. 10). Given the presence of large bouldersand diamonds in this region, which demonstrates a possible proximityof sedimentation to the fault, it is likely that subsidence occurred

giond de

57M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fig. 11. Depositional evolution of the Extrao region. (a) Localization of the Extrao refan delta system, (c) end of the tuffaceous contribution, and (d) uvial sedimentation an

massive gravel; Gcm clast-supported gravel; St trough cross-bedded sandstone.(red box) in a rift system (b) tuffaceous contribution during deposition in a lacustrineposition of the eolian Galho do Miguel Formation. Gmm tuffaceous matrix-supported

58 M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759heterogeneously, with independent faults between Diamantina andExtrao. In the Guinda region, three conglomeratic lobes were identi-ed, and the third lobe, a pelitic matrix in its most northern portion inBrumadinho Mine, would also provide a fan delta on a lake system,although without a tuffaceous contribution. Regardless of the faults'geographical separation, which is expected in rift evolution models(Prosser, 1993; Gawthorpe and Leeder, 2000; Allen and Allen, 2005),both regions are considered to belong to the Sopa-Brumadinho Forma-tion because they have depositional systemswith similar characteristicsthat reect the stage of their tectonic evolution, they have diamondsassociated with them and they are beneath the Galho do MiguelFormation.

The concept of unconformities depends on the premise that theymust have a regional character because on the basin margins (i.e.,adjacent to border faults), unconformities can develop at many levelsin a section. This premise limits the internal subdivision of the Sopa-Brumadinho Formation into other units in which conglomerates havelenticular geometry and are of local scale.

The rift initiation system tract has not developed in the UpperEspinhao Basin because during its opening, it was inherently subjectto the reactivation of the Lower Espinhao Basin faults. The depositionof the uvial sediments, alluvial fan and deltaic lobes of the Sopa-Brumadinho Formation composes the early rift climax systems tractdescribed by Prosser (1993). This system tract records the large dis-placement of normal faults and gives the fault footwalls great impor-tance as sediment sources.

5.5.2. Galho do Miguel FormationPug et al. (1980) attributed the entire Galho do Miguel Formation

to deposition inmarine conditions; however, only the rst sedimentaryfacies unit seems to have been deposited under such conditions.

The high subsidence rates in the Guinda sector that favored thedevelopment of the lake system in the Sopa-Brumadinho Formationalso inuenced the marine transgression at the base of the Galho doMiguel Formation. The record of marine transgression is quite evidentin this region, which may be regarded as one of the rift depocenters atthe time of deposition of the Sopa-Brumadinho and Galho do Miguelformations (post-1180 Ma).

The facies association characterizes sedimentation in a coastalenvironment, with a change both laterally and vertically from marineto wind conditions (Dossin et al., 1987; Garcia and Uhlein, 1987),indicating the advancement of contemporary back-beach eoliandunes on the marine sediments.

The deposit extrapolation of theGalho doMiguel Formation over thepossible limits of the rift represents the transition from fault-controlledto thermal subsidence, as proposed by Martins-Neto (1998), for theUpper Espinhao Basin. Therefore, this change in tectonic regime inthe Galho do Miguel Formation congures the immediate post-rift sys-tem tract of Prosser (1993).

5.5.3. Conselheiro Mata GroupThe deposition of this unit is marked by a period of tectonic stabil-

ity and a general trend of marine transgression, in which sedimenta-tion and accommodation was related to thermal subsidence bylithospheric cooling (Dussin and Dussin, 1995; Martins-Neto, 1998).

The depositional systems alternate between marine and coastalin response to three successive marine transgressions followed byprogradation (Dupont, 1995; Martins-Neto, 2009). The transgressivestage of the Conselheiro Mata Group may be correlated to the marinetransgression of the Caboclo Formation that overlies the alluvial, u-vial and eolian sediments of the Tombador Formation in ChapadaDiamantina. The transgressive surface in Chapada Diamantina repre-sents an expansion, erosion and deposition in marine conditionsover the units beneath and provides a regional surface for dening

the base of the Conselheiro Mata Group.The erosion of source areas most likely contributed to the decreasein the sediment grain size and the peneplanation of the topographydur-ing the Conselheiro Mata Group deposition, creating conditions for theinstallation of a marine/coastal system in which climatic and relativesea-level changes were the principal factors of deposition. The unit isconsistent with the late post-rift system tract of Prosser (1993).

6. Conclusions

Based on detailed eldwork at a scale of 1:3000, four unconfor-mities and two transgressive surfaces were identied in the strati-graphic interval of the Lower and Upper Espinhao Basins. Frombottom to top, the unconformities include the following: U.1, whichrepresents a disconformity, and U.2, U.3 and U.4, which represent an-gular unconformities. The available geochronological data up to U.3illustrate a gap of 500 Ma and separate the basin into two sequences,as described by Chemale et al. (2010).

The detrital zircon grains of the Lower Espinhao Basin (1780 to1680 Ma) indicate that the major contributions were Archean (peaksat 3300, 3000 and 2700 Ma) and Paleoproterozoic (peaks at 2400,21002200 and 1700 Ma), which are the main tectonic cycles of theSo Francisco Craton basement rocks. The Upper Espinhao (1200 to900 Ma) contains a dominant population of Paleoproterozoic and sub-ordinate populations at 2800, 2700, 1800 and 1200 Ma. The populationat 1200 Ma is interpreted as amaterial linked to the Grenvillian cycle inthe So Francisco Craton.

The Lower Espinhao Basin comprises the Bandeirinha Formation(limited by U.1 and U.2) and the So Joo da Chapada Formation (lim-ited by U.2 and U.3). The Datas Member, composed mainly of pelites,was incorporated into the So Joo da Chapada Formation. The UpperEspinhao Basin comprises the formations Sopa-Brumadinho, Galhodo Miguel and Conselheiro Mata.

The model of Morley (1999) was used to determine that the devel-opment of the So Joo da Chapada Formation was inuenced by thepropagation of northsouth faults. Thewesteast faultswere character-ized as transfer faults and had an important role in controlling the depo-sition and delimitation of the different rift compartments.

The lower rift (ca. 1700 Ma) underwent two fault-controlled sub-sidence events, each causing unconformities that limit the base of theBandeirinha Formation and the base of the So Joo da Chapada For-mation. The opening of the upper rift (ca. 1200 Ma) reactivated thefaults of the lower rift and set into motion a new fault-controlled sub-sidence event that created the unconformity at the base of theSopa-Brumadinho Formation. The creation of this syn-rift depositwas followed by a thermal subsidence (Martins-Neto, 1998) that gen-erated the transgressive surface at the base of the Galho do MiguelFormation, assigning the relative sea-level changes a greater impor-tance to the Conselheiro Mata Group.

Additionally, some units represent system tracts according to theProsser (1993) model, which reects the evolutionary stage of eachbasin. In the Lower Espinhao Basin, the rift initiation system tractand the early rift climax system tract were identied. In the UpperEspinhao Basin, the early rift climax system tract and immediatepost-rift system tract were identied.

Futureworks should carry out detailed sedimentologicstratigraphicstudies combined with dating methods (UPb detrital zircons,ArAr, etc.) in the sedimentary sequences in the Paleoproterozoic toMesoproterozoic paleoplates that formed the Rodinia Supercontinent(e.g., the Congo, Sahara, North China and Siberia paleoplates; Li et al.,2008) to track the agglutination of these crustal segments and theformation of Rodinia.

Acknowledgments

The authors would like to thank the ANP and PETROBRAS for

the nancial support of eld work and analysis. We gratefully thank

59M.N. Santos et al. / Sedimentary Geology 290 (2013) 4759Fernando F. de Alkmim for his comments and suggestions. We alsothank P. G. Eriksson, an anonymous reviewer and the Editor JasperKnight, for improving the quality of the manuscript.

Appendix A. Supplementary data

Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.sedgeo.2013.03.002.

References

Alkmim, F.F., Chemale Jr., F., Endo, I., 1996. A deformao das coberturas Proterozicasdo Crton do So Francisco e o seu signicado tectnico. Revista da Escola de Minas49, 2238.

Alkmim, F.F., Pedrosa-Soares, A.C., Noce, C.M., Cruz, S.C.P., 2007. Sobre a evoluotectnica do Orgeno Araua-Congo Ocidental. Geonomos 15, 2543.

Allen, P.A., Allen, J.R., 2005. Basin Analysis: Principles and Applications, Second edition.Blackwell Science 549.

Almeida, F.F.M., Brito Neves, B.B., Carneiro, C.D.R., 2000. Origin and evolution of theSouth-American Platform. Earth-Science Reviews 50, 77111.

Almeida-Abreu, P.A., 1993. A Evoluo Geodinmica da Serra do Espinhao Meridional,Minas Gerais, Brasil. Ph. D. Thesis, Univ. Freiburg, Freiburg, Germany, 150 pp.

Almeida-Abreu, P.A., 1995. O Supergrupo Espinhao na Serra do Espinhao Meridional,Minas Gerais: O rifte, a bacia e o orgeno. Geonomos 3, 118.

Assumpo, M., James, D., Snoke, J.A., 2002. Crustal thicknesses in SE Brazilian shield byreceiver function analysis: implications for isostatic compensation. Journal ofGeophysical Research 107, 114. http://dx.doi.org/10.1029/2001JB000422 (ESE).

Barrel, J., 1917. Rhythms andmeasurement of geologic time. Bulletin Geological Societyof America 28, 745904.

Brito Neves, B.B., 1995. A Tafrognese Estateriana nos Blocos Paleoproterozicos daAmrica do Sul e Processos Subseqentes. Geonomos 3, 0121.

Brito Neves, B.B., Cordani, U.G., Kawashita, K., Delhal, J., 1979. A evoluo geocronolgicada Cordilheira do Espinhao; dados novos e integrao. Revista Brasileira deGeocincias 9, 7185.

Caby, R., Arthaud, M., 1987. Petrostructural evolution of the Lagoa Real subalcalinemetaplutonic complex (Bahia, Brasil). Revista Brasileira de Geocincias 17, 636.

Catuneanu, O., Abreu, V., Bhattacharya, J.P., Blum, M.D., Dalrymple, R.W., Eriksson, P.G.,Fielding, C.R., Fisher, W.L., Galloway, W.E., Gibling, M.R., Giles, K.A., Holbrook, J.M.,Jordan, R., Kendall, C.G.St.C., Macurda, B., Martinsen, O.J., Miall, A.D., Neal, J.E.,Nummedal, D., Pomar, L., Posamentier, H.W., Pratt, B.R., Sarg, J.F., Shanley, K.W.,Steel, R.J., Strasser, A., Tucker, M.E., Winker, C., 2009. Towards the standardizationof sequence stratigraphy. Earth-Science Reviews 92, 133.

Chaves, M.L. de S.C., 1997. Geologia e mineralogia do diamante da Serra do Espinhaoem Minas Gerais. Ph. D. Thesis, So Paulo, IG/Univ. So Paulo, 289 pp.

Chemale Jr., F., Dussin, I.A., Martins, M.S., Alkmim, F.F., Queiroga, G., 2010. TheEspinhao Supergroup in Minas Gerais: a Stenian Basin? 7th South AmericanSymposium on Isotope Geology, Braslia, pp. 552555.

Chemale Jr., F., Dussin, I.A., Alkmim, F.F., Martins, M.S., Queiroga, G., Armstrong, R.,Santos, M.N., 2012. Unravelling a Proterozoic basin history through detrital zircongeochronology: The case of the Espinhao Supergroup, Minas Gerais, Brazil.Gondwana Research 22, 200206.

Chorowicz, J., 2005. The East African rift system. Journal of African Earth Sciences 43,379410.

Dossin, I.A., Uhlein, A., Dossin, T.M., 1984. Geologia da Faixa Mvel Espinhao em suaporo meridional, MG. Congresso Brasileiro de Geologia, 33, Rio de Janeiro:Anais, Sociedade Brasileira de Geologia, 2, pp. 31183132.

Dossin, I.A., Garcia, A.J.V., Uhlein, A., Dardenne, M.A., Dossin, T.M., 1987. Fcies elico naFormao Galho do Miguel. Supergrupo Espinhao (MG). Simpsio sobre SistemasDeposicionais no Pre-Cambriano, Ouro Preto: Atas, Sociedade Brasileira deGeologia, pp. 8596.

Dossin, I.A., Dossin, T.M., Chaves, M.L.S.C., 1990. Compartimentao Estratigrca doSupergrupo Espinhao em Minas Gerais - os Grupos Diamantina e ConselheiroMata. Revista Brasileira de Geocincias 20, 178186.

Dossin, I.A., Dossin, T.M., Charvet, J., Chemale Jr., F., 1992. Tectonique du Protrozoiquesuprieur au sud-est du Craton So Francisco. Compts Rendus de L'Acadmie desSciences Serie II - Fascicule, Paris, 315, pp. 629636.

Dossin, I.A., Dossin, T.N., Charvet, J., Cocherie, A., Rossi, P., 1993. Single-zircon dating bystep-wise Pb-evaporation of Middle Proterozoic magmatismo in the Espinhaorange, southeastern So Francisco Craton. Minas Gerais, Brazil. Simpsio sobre oCrton do So Francisco, 2, Salvador, 1993: Anais, Sociedade Brasileira deGeologia/Superintendncia de Geologia e Recursos Minerais da Bahia, 1, pp. 3942.

Dupont, H., 1995. O Grupo Conselheiro Mata no seu quadro paleogeogrco eestratigrco. Simpsio de Geologia de Minas Gerais, Diamantina: Anais, SociedadeBrasileira de Geologia, 13, pp. 910.

Dussin, T.M., 1994. Associations plutono-volcaniques de lEspinhaoMeridional (SE-Brsil):um exemple dvolution de la crote protrozoque. Ph. D. Thesis, Orleans, Universite dOrleans, 177pp.

Dussin, I.A.,1994. Evolution Structurale de la pertie mridional de L'Espinhao sur labordure orientale du Craton So Francisco. Minas Gerais Brsil: Um exemple detectonique protrozoique superpos. Tese de Doutoramento. Universit d'Orlans,200pp.Dussin, I.A., Dussin, T.M., 1995. Supergrupo Espinhao: modelo de evoluo geodinmica.Geonomos 3, 1926.

Emery, D., Myers, K.J., 1996. Sequence Stratigraphy. Blackwell Science, Oxford (297 pp.).Fordham, A.M., North, C.P., Hartley, A.J., Archer, S.G., Warwick, G.L., 2010. Dominance of

lateral over axial sedimentary ll in dryland rift basins. Petroleum Geoscience 16,299304.

Garcia, A.J.V., Uhlein, A., 1987. Sistemas deposicionais do Supergrupo Espinhao na Regiode Diamantina (MG). Simpsio sobre Sistemas Deposicionais no Pre-Cambriano,Ouro Preto: Atas, Sociedade Brasileira de Geologia, pp. 113136.

Gawthorpe, R.L., Leeder, M.R., 2000. Tectono-sedimentary evolution of active exten-sional basins. Basin Research 12, 195218.

Knauer, L.G., Schrank, A., 1994. A origem dos litos hematticos da Serra do EspinhaoMeridional, Minas Gerais. Geonomos 1, 3338.

Li, Z.X., Bogdanova, S.V., Collins, A.S., Davidson, A., De Waele, B., Ernst, R.E., Fitzsimons,I.C.W., Fuck, R.A., Gladkochub, D.P., Jacobs, J., Karlstrom, K.E., Lu, S., Natapov, L.M.,Pease, V., Pisarevsky, S.A., Thrane, V.K., 2008. Assembly, conguration, and break-up history of Rodinia: a synthesis. Precambrian Research 160, 179210.

Ludwig, K.R., 2003. Using Isoplot/Ex, version 3.00, a geochronological toolkit forMicrosoft Excel. Berkeley Geochronology Center Special Publication, 1 (43 pp.).

Machado, N., Schrank, A., Abreu, F.R., Knauer, L.G., Almeida-Abreu, P.A., 1989. Resultadospreliminares da geocronologia U/Pb na Serra do Espinhao Meridional. Boletim daSociedade Brasileira de Geologia, Ncleo Minas Gerais, 10, pp. 171174.

Martins-Neto, M.A., 1996. Lacustrine fan-deltaic sedimentation in a Proterozoic riftbasin: the Sopa-Brumadinho Tectonosequence, southeastern Brazil. SedimentaryGeology 106, 6596.

Martins-Neto, M.A., 1998. O Supergrupo Espinhao em Minas Gerais: Registro de umaBacia Rifte-Sag do Paleo/Mesoproterozico. Revista Brasileira de Geologia 48,151168.

Martins-Neto, M.A., 2009. Sequence stratigraphic framework of Proterozoic succes-sions in eastern Brazil. Marine and Petroleum Geology 26, 163176.

Miall, A.D., 1977. A review of the braided river depositional environment. Earth-ScienceReviews 13, 162.

Morley, C.K., 1999. Patterns of Displacement Along Large Normal Faults: Implicationsfor Basin Evolution and Fault Propagation, Based on Examples from East Africa.AAPG Bulletin 83, 613634.

Nanson, G., Croke, J., 1992. A genetic classication of oodplains. Geomorphology 4,459486.

Pedrosa-Soares, A.C., Noce, C.M., Alkmim, F.F., Silva, L.C., Babinski, M., Cordani, U.,Castaeda, C., 2007. Orgeno Araua: sntese do conhecimento 30 anos apsAlmeida 1977. Geonomos 15, 116.

Pug, R., 1968. Observaes sobre a estratigraa da Srie Minas na regio de Diaman-tina, Minas Gerais. Boletim da Diviso de Geologia e Mineralogia do DepartamentoNacional de Produo Mineral: Notas Preliminares, 142 (20 pp.).

Pug, R., Hoppe, A., Brichta, A., 1980. Paleogeograa do Precambriano na Serra doEspinhao, Minas Gerais. In: Zeil, W. (Ed.), Nuevos resultados de la Investigacingeocientca alemana en Latinoamerica. Proyectos da DFG, Boppard (Boldt), pp. 3343.

Prosser, S., 1993. Rift-related linked depositional systems and their seismic expression.In: Williams, G.D., Dobb, A. (Eds.), Tectonics and Seismic Sequence Stratigraphy:Geological Society, London, Special Publications, 71, pp. 3566.

Saadi, A., 1995. A geomorfologia da Serra do Espinhao em MinasGerais e de suasmargens. Geonomos 3, 4163.

Santos, M.N., 2011. Evoluo sedimentolgica e paleogeogrca do sistema de riftes doEspinhao Meridional. MSc Thesis, Instituto de Geocincias, Universidade Federaldo Rio Grande do Sul, Porto Alegre, Brazil, 85 pp.

Schll, W.U., 1980. Estratigraa, sedimentologia e paleogeograa na regio de Diamantina(Serra do Espinhao, Minas Gerais, Brasil). Mnstersche Forschungen zur Geologieund Palontologie 51, 223240.

Schll, W.U., Fogaa, A.C.C., 1979. Estratigraa da Serra do Espinhao na regio deDiamantina. Simpsio de Geologia de Minas Gerais, Diamantina: Anais, SociedadeBrasileira de Geologia, pp. 5573.

Scholz, C.A., Moore, T.C., Hutchinson, D.R., Golmshtok, A.J., Klitgord, K.D., Kurotchkin,A.G., 1998. Comparative sequence stratigraphy of low-latitude versus high-latitude lacustrine rift basins: seismic data examples from the East African Basinsand Baikal rifts. Palaeogeography, Palaeoclimatology, Palaeoecology 140, 401420.

Sheldon, N.D., 2005. Do red beds indicate paleoclimatic conditions?: a Permian casestudy. Palaeogeography, Palaeoclimatology, Palaeoecology 228, 305319.

Silva, R.R., 1995. Contribution to the stratigraphy and paleogeography of the lowerEspinhao Supergroup (Mesoproterozoic) between Diamantina and Gouveia,Minas Gerais, Brazil. Ph. D. Thesis, Univ. Freiburg, Freiburg, Germany, FreiburgerGeowiss. Beitr., 8, 115 pp.

Silva, R.R., 1998. As bacias proterozicas do Espinhao e So Francisco emMinas Gerais:uma abordagem do ponto de vista da estratigraa de sequncias. Geonomos 6,112.

Trompette, R.R., Uhlein, A., Silva, M.E., Karmann, I., 1992. O crton brasiliano do SoFrancisco uma reviso. Revista Brasileira de Geocincias 22, 481486.

Uhlein, A., Chaves, M.L.S.C., 2001. O Supergrupo Espinhao em Minas Gerais e Bahia:correlaes estratigrcas, conglomerados diamantferos e evoluo geodinmica.Revista Brasileira de Geocincias 31, 433444.

Uhlein, A., Trompette, R., Egydio-Silva, M., 1995. Rifteamentos Superpostos e Tectnicade Inverso na Borda Sudeste do Crton do So Francisco. Geonomos 3, 99107.

Uhlein, A., Trompette, R., Egydio-Silva, M., 1998. Proterozoic rifting and closure, SE borderof the So Francisco Craton, Brazil. Journal of African Earth Sciences 11, 191203.

Van der Nat, D., Schmidt, A.P., Tockner, K., Edwards, P.J., Ward, V., 2002. Inundationdynamics in braided oodplains: Tagliamento river, northeast Italy. Ecosystems5, 636647.

Sedimentological and paleoenvironmental constraints of the Statherian and Stenian Espinhao rift system, Brazil1. Introduction2. Geological setting2.1. The Espinhao Rift System2.2. Dating background2.3. Stratigraphic background

3. Methodology3.1. Stratigraphic-sedimentological mapping3.2. UPb zircon dating

4. Results4.1. Unconformities identified4.2. Units identified4.3. Geochronological results

5. Discussion5.1. Stratigraphic position of the Datas Member5.2. Northsouth and eastwest faults and their sedimentological control5.3. Tectonic evolution, stratigraphy and paleogeography5.4. Lower Espinhao Basin5.4.1. Bandeirinha Formation5.4.2. So Joo da Chapada Formation

5.5. Upper Espinhao Basin5.5.1. Sopa-Brumadinho Formation5.5.2. Galho do Miguel Formation5.5.3. Conselheiro Mata Group

6. ConclusionsAcknowledgmentsAppendix A. Supplementary dataReferences