Revista do Instituto Geológico, IG São Paulo, 20(1/2), 29-36, jan./dez./1999

QUATERNARY SEDIMENTATION, NEOTECTONICS AND THE EVOLUTION OFTHE DOCE RIVER MIDDLE VALLEY LAKE SYSTEM (SOUTHEASTERN BRAZIL)

Claudio Limeira MELLOCynthia Maria Soares METELO.

Kenitiro SUGUIOHeinz Charles KOHLER.

RESUMO

A região do Médio Vale do Rio Doce, situada no Estado de Minas Gerais, no Sudeste doBrasil, constitui uma das áreas mais importantes para o estudo da evolução quaternária dos tró-picos úmidos em território brasileiro. Esta área apresenta um sistema singular de lagos barra-dos, anteriormente investigados por diversos autores, particularmente na década de 70. Amaioria dos estudos anteriores referiu-se a condicionantes paleoc1imáticoscomo responsáveispela origem e evolução do sistema de lagos. Alguns autores reconheceram, ainda, evidênciasda atuação de mecanismos neotectônicos na sua formação e desenvolvimento. O presente estu-do discute uma nova abordagem acerca da evolução quaternária desta área, na qual a origem ea evolução do sistema de lagos são interpretadas com base em investigações estratigráficas eestruturais regionais. Dados geofísicos (sismoestratigráficos) fornecem novas evidências a res-peito da estratigrafia dos sedimentos lacustres. Análises estruturais detalhadas de juntas efalhas afetando os sedimentos quaternários sustentam interpretações neotectônicas. As análisesestratigráficasrealizadasconfirmam o inícioda sedimentaçãolacustrepor volta de 9.000 ,anosAP,simultaneamente a uma importante sedimentação aluvial regional. Análises sismoestratigráfi-cas realizadas na desembocadura do Lago Dom Helvécio documentam uma falha normal afe-tando sedimentos aluviais holocênicos, podendo explicar a barragem deste lago e sugerindomecanismos neotectônicos como o principal controle para a origem do sistema de lagos doMédio Vale do Rio Doce.

Palavras-chave: Quaternário, geomorfologia, neotectônicá, sistemas de lagos barrados,Vale do Rio Doce, Brasil de Sudeste.

ABSTRACT

.v

The Doce River Middle Valley (State of Minas Gerais, Southeastern Brazil) is one of themost important areas in Brazil in the study of Quaternary evolution of the humid tropics. Thisarea preserves a singular barred-Iake system which has been previously investigated byseveral authors, particularly on the 70's. Most previous studies have considered paleoc1imaticcontrols as responsible for the origin and the evolution of the lake system. Some authors havealso recognized evidences of neotectonic influence on the lacustrine development. In thepresent study, a new approach to the Quaternary evolution ofthis area is discussed. The originand the evolution of the lake system are interpreted according to regional stratigraphic andstructural investigations. Geophysical (seismic stratigraphic) data provide new insights aboutthe lake stratigraphy. Detailed structural analyses of joints and faults affecting Quaternarysediments support neotectonic interpretations. Stratigraphic analyses confirm the beginning ofthe lacustrine sedimentation around 9,000 years BP, simultaneously with an important regionalalluvial sedimentation. Seismic stratigraphic analysis performed at the dam of Dom HelvécioLake shows a normal fault affecting Holocene alluvial sediments. It explains the damming ofthis lake and suggests neotectonic mechanisms as the main control for the origin of the DoceRiver Middle Valley lake system.

Keywords: Quaternary, geomorphology, neotectonics, barred lake system, Doce RiverValley, Southeastern Brazil.

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Revista do Instituto Geológico, IG São Paulo, 20(1/2), 29-36, jan./dez./1999

1 INTRODUCTION

Remarkable geomorphologic andsedimentologic features observed in the DoceRiver Middle Valley (State of Minas Gerais,Southeastern Brazil) have been considered aspotentially important to explain the Quatemarypaleoenvironmental evolution of humid tropicsip.Brazil, especially with regard to paleoclimaticand neotectonic controls. The area is situated ina huge depressed topographic compartment(Figure 1), related by several authors toCenozoic tectonic mechanisms. Significantsedimentary deposits associated with well-developed recent geomorphic features arepreserved. The most impressive feature in theregion is a Quaternary barred-lake system(Figure 2). Since the area was not affected byQuaternary sea-Ievel variations, the regionallandscape evolution reflects fluvial networkresponses to paleohydrologic and/or base-leveIchanges.

43'W

18'8

1° 1?Okm

'c/

FIGURE 1 - (a) Location map of the Doce Riverbasin (State of Minas Gerais, Southeastem Brazil).(b) Hypsometric map of the Doce River basinassigning the location of the lake system in the"Interplateau Lowlands of the Doce River MiddleValley" (after MEIS & MACHADO 1978).

PFLUG (1969) was the first author toperform geomorphologic studies in the area. Heproposed that the lake system was caused by thedamming of small tributary valleys of the DoceRiver due to intense alluvial accumulation.

According to him, this evolution occurred undersemi-arid climatic conditions, during a timeinterval contemporaneous with the Last Ice Ageof the Northern Hemisphere. Modern semi-humid tropical conditions were responsible for

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LEGEND:

iíi Rivers~ Paleochannels

.. LakesCJ Fluvial terraces

~O 2 4 km

FIGURE 2 - Map of alluvial forms and lacustrinebodies in the area of main concentration of lakes inthe Doce River Middle Valley - Doce River ForestPark (after BARBOSA & KOHLER 1981). Note thestring of lacustrine bodies associated withpaleochannels and infiUed valleys. In the presentwork, the Dom Helvécio Lake was studied in detail.

the posterior drowning of the dammed valleys.Meis and collaborators studied the Doce

River Middle Valley lake system with amorphostratigraphic approach (MEIS 1977,MEIS & MACHADO 1978, MEIS &MONTEIRO 1979), identifying sets of slopedeposits ("rampas" complexes) and fluvial andlacustrine deposits. Confirming PFLUG (1969),these authors recognized that a rapid fluvialaggradation of the main valleys at the endof thePleistocene resulted in the dammingof thesmaller creeks and originated the lakes. MEIS &MONTEIRO (1979) considered two phases oflacustrine submersion. The first one was datedat the Pleistocene/Holocene boundary and thesecondone was datedat 7,830 :l: 250yearsBPto 3,365 :l: 115years_BP.In their studies,Meis

Revista do Instituto Geológico, IG São Paulo, 20(1/2), 29-36, jan./dez./1999

and collaborators assumed paleoclimaticchanges as the main morphogenic controI.

Palynologic studies have led to otherpaleoc1imatic considerations (OVERLOOP1981, BEHLING 1995, YBERT et aI. 1997).According to these studies, Holocene humidconditions and a first lake submersion are onlyrecognizable after 9,000 years BP, whichsuggests a more recent age for the lake system.

BARBOSA & KOHLER (1981), SAADI(1991) and SUGUIO & KOHLER (1992)presented evidences of neotectonic processes onthe lake system formation. They discussedgeomorphologic aspects, such aslakealignments, lake margin straightness, infilledpaleovalleys and lake strings associated withabrupt fluvial migrations, as importantindicators of neotectonic controls on the lakesystem evolution.

The present paper aims to discuss theQuatemary evolution of the Doce River MiddleValley lake system based on a new approach thatintegrates regional stratigraphic and structuralanalyses. The lacustrine depressions arespecifically investigated in terms of stratigraphyand possible deformational structures.

2 REGIONAL SETTING

The study area is inserted in the occidentalportion of the Mantiqueira StructuralProvince, asdefinedby ALMEIDA et aI. (1977), comprisingacomplex set of Precambrian gneisses, migmatites,granites and granodiorites. Remnants ofgreenstone belts are also present. The lithologicunits are distributedalong NNE-SSW belts. Mostof the area is constituted by banded biotite-richgnêisses, which are locally migmatitic(MantiqueiraComplex-DNPM 1978).

The area is geomorphologically part of the"""Interplateau Lowlands of the Doce RiverMiddle Valley" (IGA-MG 1977) - Figure 1, thatcorrespond to an important physiographic featureof Southeastem BraziI. It represents a 200 kmlong and 50 km wide depressed area, striking ona NNE-SSW direction. This feature is stronglycontrolled by Precambrian structures and itsevolution is related to Cenozoicbrittle tectonics.

Inside this depressed area, the morphology ischaracterized by hilly lowlands with altitudesbetween 200 m and 500 m. There is a remarkable

zone, approximately20 km wide and 80 km long,

accompanying the Doce River course, that ismarkedby infilledvalleys and barred lakes.

The lakes have irregular dimensions, up tomore than 5 km long and more than 4 km2 inarea (MEIS & TUNDISI 1986). Their digitate ordendritic shapes confinn their origin associatedwith the drowning ofancient tributary valleys.

The regional climate is classified astropical, warm and semi-humid (NIMER 1989).The annual mean temperature varies between20°C and 22°C, and the annual mean rainfallvaries from 1,250 mm to 1,500 mm. Rainfall isconcentrated in the summer.

A tropical Atlantic forest and a vegetationtransitional between forest and cerrado were

present until the beginning of 20thcentury. Thenative vegetation has been almost destroyed andhas been replaced by pasture and eucalyptusplantations. It is locally preserved in the DoceRiver Forest Park (IEF-MG). There are swampyareas with corresponding vegetation.

3 METHODS

In this work, regional stratigraphic andstructural analyses were carried, out. A specialattention was given to the area where the lakesare preserved.

The stratigraphic analyses inc1udedmorphostratigraphic and allostratigraphicperspectives, emphasizing the reconnaissance ofdepositional surfaces and discontinuities in thestratigraphic recordo The main are as ofsedimentary accumulation were mapped usingaerial photos since they are characterized bywell-developed Quaternary features, such asfluvial terraces and "rampas" complexes. Themost representative morphologic features wereinvestigated by stratigraphic reconstruction ofnatural exposures (roadcuts and alluvial cliffs).

A high-resolution seismic analysisaccompanied by drilling was performed in orderto study the stratigraphy of the lacustrinebodies. The Dom Helvécio Lake, the largest onein the Doce River Middle Valley lake system,was selected for this analysis (Figure 2).

The stratigraphic studies werecomplemented by radiocarbon datings that werecarried out by Beta Analytic Inc. (USA).

Joints and faults affecting the sedimentswere carefully measured.A rigorous stratigraphic

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Revista do Instituto Geológico, IG São Paulo, 20(112), 29-36, jan.ldez.ll999

control and the analysis of kinematic indicatorssupport a discussion of their chronology. Faultplanes with slickensides were analyzed by theANGELIER & MECHLER (1977) method.

4 ALLUVIAL SEDIMENTATION ANDNEOTECTONICS

As discussed by some previous authors(PFLUG 1969, MEIS 1977, BARBOSA &KOHLER 1981), the Doce River Middle Valleylake system is characterized by a significantrelationship between the lacustrine bodies andgeomorphic features such as infilled valleys andpaleochannels.

The map of alluvial forms and lacustrinebodies presented by BARBOSA & KOHLER(1981) for the area of the Doce River ForestPark (Figure 2) documents a well-developedfluvial terrace surface bordered by lacustrinebodies in the Doce, Mombaça, Turvo and Belém

river valleys. The highest concentration of lakesis found along a paleochannel trace.

In order to discuss the relation between theQuaternary alluvial sedimentation and thelacustrine evolution, a regional stratigraphicanalysis was performed. Several stratigraphicsections were studied and a seismic profile and adrill hole at the mouth of an important lacustrinedepression (Dom Helvécio Lake) were alsoperformed.

The regional stratigraphic analysis resultedin identification of four major depositionalevents during the Cenozoic sedimentaryevolution of the Doce River Middle Valley(Figure 3). One of these events corresponds toan intensive and widespread alluvial-colluvialsedimentation, responsible for the filling-up ofheadwaters and valleys (Santo Antônio doRequerente Alloformation), and dated at theear1y to middle Holocene. The alluvial surfaceassociated with the lacustrine bodies wasproduced by this Holoc,enesedimentation.

TECTONIC EVENTSGEOCHRONOLOGY ALLOSTRATIGRAPHY

17.500yl'C14 AGEo

RIBEIRÃO MOMBAÇA ALLOFORMATION

~~~~~HOLOCE

~r17.500YI19.000yl

10.000y

SANTO ANTÔNIO DO REQUERENTEALLOFORMA TION

~Ic(E-WII

I' INw)1

GG1,8 million years

. RIBEIRÃOSANTAISÀBELALWFÓR'MÀTT6r\f.'h' '.u' ~,"';"'"',""":'O'o'''-a;'':''..'.':'''':';..o~

PLEIS.'OCENI

PLIOCENE

5,3 million years

=545 million yearsq

.,Q

~ GnelsSes,MIgmatites .-' '--- Schists,Quartzites , , .......-

FIGURE 3 - Cenozoic al10stratigraphicunits and tectonic events in the Doce River Midd1e Val1ey (after MELLO 1997).

Two stratigraphic sections are heredescribed aiming to represent the mainstratigraphic, sedimentologic and structuralrelationships regarding to the evolution of theinfilled valleys and lakes (figures 4 and 5).

The Fazenda Conquista (A) Section (Figure4) reproduces the main stratigraphic aspects ofthe infilled valleys. The sedimentary succession

32

is marked by the interbedding of tabular layersof very oxidized, horizontally stratified' sandydeposits (flashflood deposits) and massiveclayey deposits (mudflow deposits). Near thebottom of this section, an organic-rich clayeylayer was dated at 9,020 :I: 230 14Cyears BP(charcoal, Beta-9707l). This stratigraphic leveIseems to be very' dose to the beginning of the

Revista do Instituto Geológico, IG São Paulo, 20(1/2), 29-36, jan.ldez.l1999

alluvial sedimentation associated with the

widespread filling of the valleys. Thesedimentologic characteristics indicate that an

NW

1 O 1-=-=-

alluvial fan and low-sinuosity river system wasactive during the early to middle Holocene times.

The alluvial fan morphology can be still

9.020 +/- 230 years B.P.(charcoal)

(7) Reddish brown, massive clayey-sands

( 6) Reddish, horizontally stratified, coarse to very coarse sands

(5)' Reddish, horizontally stratified, sandy-silts and silty-sands with thin reddish clayey layers

(4) Yellowish, oxidized, horizontally stratified sands

( 3) Grayish, organic-rich clayey-silt

(2) Reddish to yellowish, massive sands

(1) Yellowish brown, massive sandy-clay

2m]

FIGURE 4 - Fazenda Conquista (A) Section reproduces the stratigraphic reconstruction of a typical infilledvalley ofthe study-area. The alluvial sedimentation is dated at ear1yto middle Holocene.

mapped on the present landscape, dissectingNW-SE oriented interfluves. It was verified that

these interfluves configure horsts.The Córrego Grande (B) Section (Figure 5)

exhibits the stratigraphic and structuralframework of one of those NW-SE interfluves.

sw

At this section, an organic-rich horizon dated at9,990 :I: 80 14Cyears BP (charcoal, Beta,..97068)is displaced by a NW-SE transtensional fault.This fault can be related to an E-W dextral

transcurrence that was regionally identified inthe study-area (Figure 3).

N~

',j (3) Yellowish brown, massive sandy-clay

(2) Dark brown, massive clayey-sand

( 1) Weathered basement rocks

N

~'--~\J

~.~..~

~(b)-'-"'-'-'---

2 1 o 2m

(a)

N

FIGURE 5 - Córrego Grande (B) Section. (a) Stratigraphic reconstruction, (b) stereographic projection of thefault planes measured in this site and (c) the analysis of them using the ANGELIER & MECHLER (1977)method. Note the displacement ofthe Holocene organic-rich horizon by a NW-SE nOlmal fault.

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Revista do Instituto Geológico, IG São Paulo, 20(112), 29-36, jan.ldez.ll999

In the present study it is proposed that thisfaulting process has conditioned the Holocenealluvial fan sedimentation (sin-sedimentarytectonics) suggesting that the early to middleHolocene alluvial sedimentary event was causedby neotectonic mechanisms related to an E-Wdextral transcurrent regime.

~ 5 LACUSTRINE SEDIMENTATION ANDNEOTECTONICS

The stratigraphic investigation carried out atthe mouth of the Dom Helvécio Lake providesnew insights about the evolution of the DoceRiver Middle Valley lake system. A seismicstratigraphic profile was obtained documentingthe sedimentary pattem at this site (Figure 6a). An8 meters long 0011hole was obtained, crossing themain seismic stratigraphic units (Figure 6b).

(a)

~ ~? 1'.~l~-~~

~

L §°m

(b)3

2220 ~60 B.P.

. Organic levels

i\IIIIGrayish olive andolive brown mudsDark yellow;shbrown muds

CJ Reddish brown muds

8230;:70 B.P.

60t80 B.P.

FIGURE 6 - (a) Seismic profile showing thestratigraphic pattern at the mouth of the DomHelvécio Lake. On the left side, a remarkablestructure is seen deforming the seismic reflectors. Itwas interpreted as a NE-SW normal fault. (b)Stratigraphic reconstruction of the drill hole indicatedin (a). First lacustrine conditions are recorded around9,060:1: 80 14Cyears BP. Modified from MELLO(1997).

It could be documented that the ancienttributary valley where the Dom Helvécio Lakeis now located was filled by alluvial depositssimilar to the sediments identified at Fazenda

34

Conquista (A) Section. This a11uvialdeposition ischaracterized by more than 2 meters thick,reddish brown muds that are present on the lowerpart of the drill hole. Overlying this alluvialmateriaIs there is a thin layer of grayish olive,organicmuddy sediments,dated at 9,060 :I:80 14Cyears BP (plants remnants, Beta-9706l), whichrepresents a first lacustrine sedimentation.Above this organic leveI, there are 3 metersthick, brownish muddy sediments, which areinterpreted as the record of a fluvial to lacustrinetransitional environment. Organic-rich, typica11ylacustrine sediments are only recorded on theupper part of the drill hole, after 8,230 70 :I:14Cyears BP (plant remnants, Beta-97060).

The alluvial to lacustrine sedimentarysuccession described at the Dom Helvécio Lakemouth is affected by a normal fault plane,probably NE-SW oriented. This plane isrecognized on the left side of the seismicprofile and can be related to a Holocene NW-SE extensional tectonic regime that wasregiona11yidentified in the study-area (Figure 3).It is a strong evidence for the recentneotectonic control of lake formation.

6 FINAL REMARKS

Stratigraphic and structural analyses carriedout in the present study suggest that theevolution of the Doce River Middle Va11eylakesystem can be divided in distinctive phasescharacterized by pat1icular sedimentary andneotectonic mechanisms. Dom Helvécio Lake isconsidered as a model for this evolution.

A first lacustrine submersion has occurred

simultaneously to an intense alluvialsedimentationduring early Holocenetimes. It canbe assigned by radiocarbon dates around 9,000years BP that were obtained from the analyses ofalluvial and lacustrine sediments. The early tomiddle Holocene alluvial deposition resulted inthe widespread filling of drainage basins and canbe related to an E-W dextral transcurrent tectonic

regime. This sedimentary event and this tectonicmechanism are identifiable in other places ofSoutheastem Brazil as discussed by MELLO etai. (1999). It is supposed that the beginning oflacustrine evolution was caused by concurrentaction of tectonic and sedimentary mechanisms.

At the beginning of the lacustrine evolution,the lakes were probably shallow and greatly

Revista do Instituto Geológico, IG São Paulo, 20(1/2), 29-36, jan.ldez.ll999

influencedby alluvialprocesses.It can be infeITedftom the relatively thick transitional lacustrine toalluvial sedimentationthat is recordedjust abovethe organic leveI dated at 9,000 years BP. Typicallacustrine sediments were only identified afterapproximately8,200years BP.

It is supposed that the final lacustrineevolution of the Doce River Middle Valley lakesystem was conditioned by the Holocene NE-SW extensional tectonic regime. The fault planeidentified at the mouth of the Dom HelvécioLake is strong evidence. This tectonicmechanism also explains the Doce Rivermigration and the consequent abandonment ofthe ancient infilled valley which is observed atthe main area of lake concentration, representedby the significant paleochannel trace. Asproposed by PFLUG (1969), MEIS (1977) andBARBOSA & KOHLER (1981), this fluvialmigration is directly associated with the lakesystem origin, but these two related geomorphicaspects are both apparently controlled by a moreimportant tectonic mechanism.

The present study discussed some newevidences of neotectonic controls on theevolution of the Doce River Middle Valley lakesystem indicating that is important to consider

the neotectonic mechanisms beside paleoclimatic

inferences to explain the Quatemary landscapeevolution of Southeastern Brazil. Discussions

about the relationships between neotectonic and

paleoclimatic aspects are not attempted here, but

represent a future necessary task.

7 ACKNOWLEDGEMENTS

This study was supported by FAPESP,CAPES and CEPG-UFRJ. The authors wish tothank Isabela de Oliveira Carmo, Luiz FelipeRodrigues, Flávia Gonçalves de Castro, ClaudioValdetaro Madeira and Rute Maria Oliveira deMorais for the contributions on several stages ofthe study, particularly field work. Thanks are dueto Df. Cleverson Guizan Silva (LAGE-MAR/UFF) for collaboration on the seismicsurvey and to Dr. Paulo Eduardo de Oliveira forcollaboration on the drillings. The authors aremost grateful to the Instituto Estadual deFlorestas/IEF-MG, especially the technical staffof the Doce River Forest Park, for support andfacilities in the field. Editorial review andcomments are also gratefully acknowledged.

8 REFERENCES

ALMEIDA, F.F.M; HASUI, Y; NEVES, B.B.B;FUCK, R.A. 1977. Províncias estruturaisbrasileiras. In: SBG, Simpósio deGeologia do Nordeste, 8, Campina Grande(PB), Atas, 363-391.

ANGELIER, J. & MECHLER, P. 1977. Sur uneméthode graphique de recherche descontraintes principales également utilisableen tectonique et en seimologie: Ia méthodede diedres droits. Buletin SocietéGéologique France, 7:1309-1318.

,d BARBOSA, G. V. & KOHLER, H. C. 1981. O, sistema lagunar do Parque Estadual do Rio

Doce (MG). Boletim SBG/MG, 2:37-46.

BEHLING, H. 1995. A high resolutionHolocene pollen record from Lago doPires, SE Brazil: vegetation, climate andfire history. Journal of Paleolimnology,14: 253-268.

DNPM. 1978. Folha Geológica Belo Horizonte(SE-23). Projeto Carta Geológica doBrasil ao Milionésimo. MME/DNPM.

IGA-MG. 1977. Mapa geomorfológico

1: 500.000. Folha Belo HorizOnte.Secretaria de Estado de Ciência eTecnologia de Minas Gerais, (ProjetoRADAR-MG)

MEIS, M.R.M. 1977. As unidades morfoestrati-gráficas neoquatemárias do médio vale doRio Doce. Anais Academia Brasileira deCiências, 49(3):443-459.

& MACHADO, M.B. 1978. Amorfologia de rampas e terraços noPlanalto do Sudeste do Brasil (médio valedo rio Doce). Finisterra, 13(26):199-219.

MEIS, M.R.M. & MONTEIRO, A.M.F. 1979.Upper Quaternary "rampas": Doce rivervalley, Southeastem Brazilian plateau. Z.Geomorph., 23(2):132-151.

MEIS, M.R.M. & TUNDISI, J.G. 1986.Geomorphological and limnologicalprocesses as a basis for lake typology. Themiddle Rio Doce 1ake system. An. Acad.bras. Ciênc., 58(1):103-120.

MELLO, C.L. 1997. Sedimentação e TectônicaCenozóicas no Médio Vale do Rio Doce

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Revista do Instituto Geológico, IG São Paulo, 20(1/2), 29-36, jan.ldez.l1999

(MG, Sudeste do Brasil) e suasImplicações na Evolução de um Sistema,de Lagos. Instituto de Geociências,Universidade de São Paulo, São Paulo,Tese de Doutoramento, 275p.

MELLO, C.L; MADEIRA, C.V; MOURA,J.R.S. 1999. Ear1y to middle Holoceneenvironmental instability in SE Brazil(Manso Event) and its influence ondevelopment of infilled valleys. In: IGU,GEOVEG99 - Meeting on geomorphicresponses to environmental (vegetation)changes - problems and remedial work,Rio de Janeiro, Proceedings, 6p.

NIMER, E. 1989. Climatologia do Brasil. Riode Janeiro, IBGE, 421 p.

PFLUG, R. 1969. Quaternary lakes of EasternBrazil. Photogrammetria, 24:29-35.

OVERLOOP, E. 1981. Post-glacial to Holocene

Endereço dos autores:

transition in a peatlayer of Lake Jacare(Rio Doce Basin, Brasil). Bull. SocietéBelge de Géologie, 90(2):107-119.

SAADI, A. 1991.Ensaio sobre a Morfotectônicade Minas Gerais. Instituto de Geociências,UniversidadeFederalde Minas Gerais,BeloHorizonte,Tese de ProfessorTitular,285p.

SUGUIO, K; KOHLER, H.C. 1992. Quatemarybarred lake systems of the Doce river(Brazil). Anais Academia Brasileira deCiências, 64(2):183-191.

YBERT, lP; ALBUQUERQUE,A.L.S; TURCQ,B. 1997. Evolução paleoc1imática epaleambiental na região do vale médio dorio Doce (Minas Gerais, Brasil). In: ABE-QUA, Congresso da Associação Brasileirade Estudos do Quaternário, 6, Curitiba(PR), Resumos Expandidos, 511-514.

Claudio Limeira Mello e Cynthia Maria Soares Metelo - Departamento de Geologia, IGEO/UFRJ. CCMN,Bloco G, Cidade Universitária, Ilha do Fundão, CEP: 21.949-900, Rio de Janeiro (RJ). E-mail:limeira@igeo.ufrj.br

,j

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