Oppenheim (1935)_Petroleum in Gondwana

7/30/2019 Oppenheim (1935)_Petroleum in Gondwana

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V o l u m e 19 N u m b e r 1 2B U L L E T I Nof the

A M E R I C A N A S S O C I A T I O N O FP E T R O L E U M G E O L O G I S T SD E C E M B E R , 1935

P E T R O L E U M G E O L OG Y O F G O N D W A N A R O C K SO F S O U T H E R N B R A Z IL 1

V I C T O R O P P E N H E I M 2Rio de Janeiro, Brazi l

A B S T R A C TThis paper is a condensed version of a study made for the Brazi l ian Governmentand published as Boletim 5, "Rochas Gondwanicas e Geologia do Petroleo do Brasi lMeridional ," of the Servico de Fomento da Produccao Mineral of the DepartamentoNacional da Produ ccao M ineral , Ministr y of Agriculture. (Man y well logs and analysesnot given in the present paper may be found in the Portuguese bullet in.)It represents the results of a very extensive geological field study of SouthernBrazil , and covers the states of Sao Paulo, Parana, Santa Catharina, and Rio Grandedo Sul .The logs and locations of more than seventy borings drilled in this area were forthe first t ime careful ly analyzed and located on the accompanying map.The exist ing bibl iography was duly considered, as well as the wri ter 's previousstudies and knowledge of the Gondwana rocks of several South American countries.Th e paper gives a new interp retat io n of the structu ral characterist ics of the Paran aBasin, and sets forth many new geological observat ions and facts, besides making aclose correlat ion with the known Gondwana rocks of other continents.The strat igraphy of the Santa Catharina system of Southern Brazi l has beenslightly modified in accordance with the most recent data. The geological analysis ofthis part of Brazi l , as correlated with systems of Gondw ana rock s known in many o thercontine nts and co untries, perm its certain posi t ive conclusions regarding the petroleumgeology of Southern Brazil.The many geological cross sections of Southern Brazil and neighboring countries(drawn for the first t ime) clearly demonstrate the structural character of the basinand its relationship with any oil accumulations, if such exist.1 M anu script received, Augu st 24, 1935. Published by permission of the directorof the Department of Mines, Brazi l .2 Consult ing geologist , Department of Mines (Servico Fomento Produccao Mineral) . The wri ter 's thanks are due to Dr. Fleury da Rocha and Dr. Djalma Guimaraes,respectively director-general of the Departamento Nacional da Produccao Mineraland director of the Servico de Fomento da Produccao Mineral , for kind permission topublish this paper; to many engineers and geologists of the Departamento Nacionalda Produccao Mineral ; and to Dr. E. Terra Arocena, director of the Inst i tuto deGeologia y Perforaciones del Uruguay, for many useful data; also to I. Burbridge andM. C. Malamphy for useful help in presentat ion of this paper.

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GOXDWAXA ROCKS OF BRAZIL 1727PART 1

GONDWANA R OCKS OF SOUTHERN BRAZILI. GONDWANA SYSTEM

The continental masses of the Southern Hemisphere began to appear as one more or less united continent in early Paleozoic time.They are observable as connected lands through half of the Mesozoicage, and their development culminated at the end of the Triassic.

The surprising uniformity of stratigraphic and, in part, paleogeo-graphic conditions through widely separated areas, leads us to applythe conception of the Gondwana system to the geological areas of theAntarctic, Australia, Tasmania, New Zealand, India, Madagascar,South Africa, Central and West Africa, Patagonia, Falkland Islands,West and East Argentina, Southeast Bolivia, Paraguay, Uruguay, andSouthern Brazil.

The Gondw ana system is everywhere characterized by the greatdevelopment of terrestrial sediments, marine transgressions being fewand sporadic.

The two outstanding features of the Gondwana system are theGlossopteris flora and the early Permian glaciation in the SouthernHemisphere. These characteristics are invariably present in the dispersed fragments of the ancient Gondwana continent.

The glaciation which marked the beginning of sedimentation ofthe Gondwana system assumed proportions greater than any of theclimatic phenomena known in the earth 's history.The Gondwana rocks show considerable development in SouthernBrazil. The base of the system rests visibly and almost entirely onAlgonkian and Archean formations, the exception occurring in part ofthe State of Parana, where they rest on Devonian rocks. The considerable stratig raph ic hia tus a t the base of the system is consequentlyevident .

In the present article it is proposed to consider only the sedimentary basin, which is limited on the east by the Archean complex ofthe Serra do Mar or by the metamorphic formations (Minas andAssunguy series), and on the south and west by the extensive basaltictraps forming the Serra Geral.

A com parativ e stu dy of the stratigra phic co lumns, from the first,established by I. C. White, to our own field observations, leads us toadopt the column as presented in Table I .

I I . G L A C IA L S E D I M E N T S ( i T A R A R E S E R I E S )Geographic distribution.The base of the Gon dwana system in

Southern Brazil is formed by a glacial sedimentary series of consider-


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1 7 2 8 VICTOR OPPENHEIMT A B L E I

STRATIGRAPHIC COLUMN OP GONDWANA SYSTEM OF SOUTHERN BKAZIL

QuaternaryTert ia ryCretaceous

Rhaet ic

Uppe rTriassic

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Uppe rPermian

LowerPermian

Devonian

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Post -Gondwana sedimentsUnconformityCaiua sandstones (in Sao Paulo)

Serra Geral t rapsBotuca tu sandstonesLocal UnconformityRio do Rasto group: sandstones, red, and variegated clays. (Saurian remains at Santa Maria)UnconformityUpper Es trad a N ov a: yel low, red, and variegatedclay-stones and shalesTherezina, Rocinha, and Serrinha bedsAssumed UnconformityLower Estrada Nova: shales and gray sandstonesIraty group: shales and bi tuminous l imestonesPalermo and Rio Bonito groups: light-coloredsandstones and gray shales

Itarare: tillites and glacial sedimentsUnconformity Devonian sediments: Ponta Grossa shales andFurnas sandstonesUnconformity . . . . _Santa Catharina slates

Metamorphic rocks of Serie de Minas and Se'riede AssunguyGranites and basement rocks

able vertical and horizontal development, known as the Itarareseries.

Derby ( i ) 3 was the first to assume a glacial origin for these sediments, and proofs of glaciation were first found by G. B. Woodworth( 2 ) i n 1 9 1 2 .

On this continent, glaciation of Southern Brazil was apparentlycontemporary with that of Eastern and Western Argentina (Sierraof Buenos Aires, Sierras Pampeanas, and pre-Cordillera) (3), Southeast Bolivia (4 and 5) (Mandiyuti and Oquita formations), Uruguay(6 and 7), and Falklan d Islands (8). Other continents of Gondw ana

3 Numbers in parentheses refer to Bibliography at end of Part I


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GONDW ANA ROCKS OF BRAZIL 1 7 2 9origin present evidence of glaciation which probably also occurred atthe same time as that of Southern Brazil.

Owing to certain peculiarities, the characteristic remains of glaciation in Southern Brazil are less plentiful than in most of the areaspreviously mentioned. In spite of this, and although difficulty is experienced in the precise stratigraphic separation of the truly glacialbeds of Itarare from the post-glacial sediments of the Tubarao series,owing to the intimate connection between the two, it can be saidthat the area covered by glacial sediments in Brazil is limited tolatitudes between 21 0 and 31 0 S. and longitudes between 47 0 and 51 0W., that is, from a little north of Campinas, in the State of SaoPaulo, to Santo Antonio, on the borders of Uruguay.

The Itarare belt continues up to the south of Tubarao (State ofSanta Catharina), where it disappears below the eruptive cover of theSerra Geral. In Rio Grande do Sul, the Itarare appears sporadicallyin Sao Jeronymo and Santo Antonio, continuing well developed inUruguay, where, south of the Rio Negro, it closes the Gondwanasedimentary basin of Parana. Farther south, and on the eastern coast,the glacial sediments reappear in the Sierras de Buenos Aires, inArgentina. Although contemporary, the sediments of the FalklandIsland s are of a som ew hat different cha rac ter.

In the Parana Basin the Itarare is limited in the east by themetamorphic and Archean rocks of the Serra do Mar and EscudoRiograndense; only in the State of Parana and in Uruguay does it reston Devonian rocks (9). It seems to the writer that the northern limitpasses through Urutuba, in the State of Sao Paulo.

The most northerly sediments, observable west of Casa Brancaand Mococa, have the characteristics of Neo-Mesozoic fluvial deposits.The boulders are fluvial transport material of an erosion period laterthan the Itarare beds. In the writer 's opinion, these sediments arenot directly related to glacial deposition: they probably representmaterial of secondary sedimentation due to erosion of glacial Itararebeds.

The western limit of Itarare is much less clearly defined, and isconstituted by the sediments of the Tubarao seriesBonito andPalermo groups.

Although they have not been observed, it is assumed that thereare large transgressions of Neo-Gondwanic rocks above Itarare in theareas of the eruptive traps of the Serra Geral, as shown by the boringsat Paso Ulestie, in Uruguay.

Stratigraphy. Mo rphologically, the large area of glacial sed ime ntsis not distinguishable from the other sediments of the basin. The area


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173 2 VICTOR OPPENHEIMpresents a peneplaned, undulating surface without notable topographic relief, even in the eastern and western zones of contact.

The Harare sediments are composed chiefly of highly heterogeneous sandstones, and vary from coarse conglomeratic tillites to glacialclay and shales.

Irrefutable evidence of the glacial origin of the beds is furnishedby the striated or rolled boulders and typically glacial fine clays inassociation with boulders (tillites). Varve clays were first observedand described by Washburne (10) in Sao Paulo; these are depositscarried by ice sheets in standing water and are found in successivegray or black beds of a few millimeters up to centimeters in individualthickness, although they may form beds many meters thick, as hasbeen recorded in wells in the State of Sao Paulo. The deposits ofglacial dust, called loessites by Woodworth (2) may be cited asfurther evidence.The glacial boulders sporadically disseminated throughout thesedimentary mass are fragments of granites, gneiss, phyllites, quart-zites, limestones, diabase, et cetera, and vary in size from grains of afew millimeters to erratic blocks of 1-3 meters in diameter, examplesof the latter being found at Campinas. In most outcrops, bouldersof 15-30 centimeters in diameter predominate.

In spite of the extensive area of glacial deposits, there are comparatively few boulders with two striated surfaces, such as are typicalof boulders from the base of a glacier. There is an abundance ofrolled but unstriated tillites of Eo-Paleozoic and Archean rocks, anda notable distribution of limestone, which probably originated frommigratory infiltration through the Harare.

The pigmentation of the sediments varies with different localitiesand depths, though greenish gray coloration predominates. The coloring may be red, as in the State of Sao Paulo and in Uruguay, due toferruginous infiltrations from the overlying eruptives, or even black,which is the color of the shales of the glacial series in S anta Ca tha rina .In deep wells, the Itarare reveals beds of fine white sandstones notobservable in the outcrops.Mo raes Rego ( n ) me ntions the following places in the S tate ofSao Paulo where the beds are best exposed: the sections north ofCampinas; close to Cosmopolis; around Santa Barbara, branch ofPiracicaba; between Iracy and Rio das Pedras; the sections beyondSoracaba and the district around Ipanema; in the Itarare Rivervalley. The writer observed that the tillites of Pitanga, west of RioClaro, are also characteristic.

In Parana, Eusebio de Oliveira (12) describes in detail typical oc-


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CON D WAN A ROCKS OF BRAZIL x 7 3 3currences of sedimentarv rocks. In Parana the Itarare attains itsmaximum superficial development, and rests above the Devoniansed im enta ry rocks in a wide belt b etween Sao Luiz de Pu run a andFaxina, in the State of Sao Paulo. At the other points of contact, theItarare rests above the metamorphic or granitic rocks of the Basement complex.

The wells in the State of Parana have not reached the base ofItarare, with the exception of the recently finished well at Sao Josedo Paranapanema, which reached the base at 471 meters and continued through fossiliferous Devonian sediments to a depth of 597meters. Beds of tillites and successions of varve clays were also recorded at this well.

In the State of Santa Catharina the Itarare is much less developed.It narrows toward the south and ends south of the Tubarao, in theUrussunga River. South of Mafra, the Itarare is characterized by theabu nda nce of tillites, and excellent sections may be seen in the Itaj ah yRiver valley and on the Florianopolis-Lages road, where a thicknessof 300 meters of Itarare was recorded.

Many of the lower beds, in contact with the granites, are finelytextured dark or black shales. Boulders of granite of varying sizes,mica schists, and quartzite are common here, but no varve clays havebeen observed in these sections.

Fa rthe r south, in the Tu bar ao basin, the m easured thickness ofthe glacial sediments was only 32 meters, including the "Orleans conglomerate" of I . C. White (13).

South of Lauro Muller, erratic blocks of granite are found. Theseblocks appear to be related to the subjacent granites, and do notshow the characteristics of glacial boulders.

In the State of Rio Grande do Sul typical Itarare occurs onlysporadically, as in the Sao Jeronymo well, on the Cacequi road, andin the zone of Santo Antonio. The thicknesses measured in SaoJeronymo vary from 1.8 to 16 meters of shales and tillites which restdirectly on the crystalline basem ent. T he occurrence at Santo Antoniois also in superficial contact with the basement.Almost the whole of the western extension of the Escudo Rio-grandense is bordered by the sediments of the Tubarao series, thelatter resting transgressively on the rocks of the complex.

In no part of Southern Brazil did the writer notice surfacesstriated or otherwisetypical of glacial erosion, apart from thegranite protuberances near Campinas (Sao Paulo), which are roundedbut not str ia ted.

The thickness of the glacial beds varies considerably; in the State


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1734 VICTOR OPPENHEIMof Rio Grande do Sul and in the southern part of Santa Catharina thebeds are shallow.

None of the wells in the State of Sao Paulo has so far reached thecrystalline basement of the Itarare. According to Washburne (10),maximum thickness was attained in the Pitanga well, where a depthof 460 meters was registered, giving a total depth of Itarare of about500 meters, taking into account the overlying beds.

A thickness of approximately 1,000 meters of glacial beds may beassumed for certain areas of the basin, but it is necessary to bear inmind the unpredictable nature of the Basement complex. In the Stateof Par ana , the boring at S. Jose de Para nap ane m a reached the base ofItarare at 471 meters, penetrating the underlying Devonian shalesdown to a depth of 597 meters.

In Uruguay, the true glacial sediments are not particularly welldeveloped. They have been classified by Uruguayan geologists as being intimately related to the Bonito group of the Tubarao series,forming the Bonito-Itarare series. The first evidence of glaciation inthis region was found near Fraile Muerto. Du Toit (14) mentions theexistence of various glaciation horizons, and beds of Bonito-Itarareare known in several places. In contact with post-glacial rocks, thesebeds exhibit considerable transgression s of U pper P erm ian an d Tri-assic. The occurrence of Itarare in the well at Paso Ulestie (Uruguay)is of special interest. It occurs at a depth of 720 meters, below erup-tives and Triassic sediments, apparently demonstrating a hiatus in thePassa Dois and Tubarao series. The tillites observed in the cores appear as a red clay-sandstone material with small boulders of graniteand quartzi te .

At present, there is no positive knowledge regarding the occurrence of glacial beds west and northwest of the Parana Basin, thatis , in the State of Matto Grosso and in Paraguay.

Glacial sediments contemporary with Itarare.In the Argentine,glacial sediments contemporary with Itarare are known in the following regions north of Lat. 38 0 S.: Sierra de la Ventana (Province ofBuenos Aires), conglomerate of Pillahuinco (15); Pre-Cordillera ofSan Juan and Mendoza; Sierras Pampeanas-Sierra de Umango andPre-Cordillera do Norte (Province of Salta) (4); and the Tontal beds.

These beds rest transgressively on granites, Devonian rocks, orUpper Carboniferous, and appear in small outcrops along the Andes,extending north and south. With the exception of the Pillahuincoconglomerates, all these sediments are probably of marine glaciation.The outcrops at the Sierra de la Ventana are lithologically similar tothe greenish gray tillites, with striated boulders, of Itarare, and liediscordantly on a bed of Devonian rocks.


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GOXDW .IKA ROCKS OF BRAZIL 1735In the Sierras Pampeanas region the Permian glacial sediments

have been studied by Bodenbe nder, H ausen, R assmuss, Keidel, andothers. Together with the occurrences previously mentioned, in thePre-Cordillera, these sediments are known as "Umango beds" of theLa Rioja system of Lower Permian (3).In the Falkland Islands, Halle (8) studied glacial sediments withtillites from the Lafonian series in the central part of the easternisland. The boulders described by Halle are of pre-existent rocksoriginating from a zone now submerged. The glacial beds are in discordant contact with the subjacent Devonian rocks.

In Southeast Bolivia and the northern part of the Argentine Pre-Cordillera, a well developed system of glacial sediments has been observed between Lat. 18 and 23 S.; they are the sediments comprisingthe Bermejo series of Heald and Mather, or the "Areniscas Inferiores"of Guido Bonarelli (4), of the North Argentine. Both the lower andmiddle parts of the Bermejo seriesOquita formation and Mandiyuticonglomerateare typically glacial.

The Oquita formation (16) rests discordantly on the Devonian ofthe Totora series. It is of heterogeneous composition, with a coarsesandstone at the base, overlain by somewhat micaceous black shalesand gray or reddish clay-sandstones, with small striated boulders offluvio-glacial origin. The bed is 700 meters thick.

Overlying the Oquita is the compact Mandiyuti conglomerate,composed of vividly colored massive sandstone beds, intercalatedwith red shales. Topographically, they form extensive escarpmentsand cuestas in Southeast Bolivia. The polished and striated bouldersare of granite, gneiss, quartzite, and basic rocks. They are also, apparently, fluvio-glacial or lacustrine deposits. The conglomerates are500-1,000 meters thick, and are overlain by the non-glacial sedimentsof Macharetti , the total thickness of the beds being approximately1,000-1,700 meters. They are considered as belonging to the LowerPermian, and may constitute two different glaciation horizons.

Several geologists admit a certain contemporaneity between theDwyka of Africa, Talchir of India, and Itarare of Brazil, on the onehand, and the glaciation of Australia, Tasmania, and WesternArgentina, on the other. However, confirmatory evidence is lackingand in the writer's opinion the relationship is doubtful, and can besought only in the correlation of the probable centers of glaciation.These centers are apparently common for the sediments north ofLat . 38 0, embracing the areas of South Africa and South America;other centers should be assumed for the areas south of this latitude,and for the other continents.

Structure and character of deposition.The Itarare rests dis-


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1736 VICTOR OPPENHEIMcordantly on granites and metamorphic rocks of the S. Roque andAssunguy series, except in the State of Parana, where it covers shalesand Devonian sandstones. In spite of detailed study of the numeroussections and outcrops, no signs of diastrophism or folding of thesesediments were observed. The dips found in some parts of the basinare local in character and are due chiefly to the intrusion of igneousrocks abundantly distributed throughout the basin.

In Uruguay alone, in the Departamento de Cerro Largo, Falconertold the writer that he had found anticlinal folds of the Bonito-Itarare series resulting from the local action of basement masses inreciprocative compressive isostatic movement.

The observable stratification is generally cross-bedded. N eve rthe less, in the majority of the outcrops, the sediments appear in thickunstratified beds of irregular deposition. The dark and black shalesof the base are markedly horizontal, and in Santa Catharina they canbe seen with vertical fissures and faults.

An examination of the well cores suggests generalized faults ofconsiderable horizontal development. Drilling at Jaguariahyva (Stateof Parana) indicates a possible fault in the contact between theItarare and the underlying Devonian. In the areas between Jacare-zinho and Jaguariahyva, several faults are also assumed between theItarare and the Upper Permian and Triassic sediments, as shown bythe wells at Wenceslau Braz, Barbosas, and elsewhere. The contact byfaults is also known in Uruguay, between granites and the Bonito-Itarare series.The varvites found in the wells are horizontally stratified. Theoccurrence of boulders in the clastic mass is sporadic, and they donot occur in specific stratigraphic horizons.

As has already been men tioned, in certain areas the Sao B entoseries and Triassic sediments are in supposed transgression abovethe Itarare. It is well to mention the horst, of fair projection, whichappears in the zone of Xarqueada (Pitanga), in the State of SaoPaulo, and which may also be characteristic of other areas.

In general, the glacial sediments of Brazil, like those of Karroo,'did not suffer horizontal folding movements in the course of theirdeposition. This is contrary to what happened in certain parts ofSouth Africa, the western part of Argentina and the Sierra de laVentana, where strong inter-Permian tectonic movements werecommon (17).

As regard s the ir cha racte ristics a nd glacial facies, the D wy ka ofSouth Africa and the Talchir of India are contemporary with Itarare.In the Hunter River district of New South Wales, however, the


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CONDWAXA ROCKS OF BRAZIL 1737lower horizons of glaciation are of Carboniferous age, as is proved bythe Rhacopteris flora, and it is only in the Allandale conglomeratethat Permian beds appear. This suggests that glaciation in this areabegan in pre-Gondwana time.

Character of glaciation.The absence of striated surfaces on thepre-glacial rocks, the relative scarcity of striated, and the predominance of rolled boulders, the deposits of varvites and, finally, theexistence of Mollusca in the series, lead us to conclude that theItarare is not only of terrigenous fluvial glaciation, but is also in greatpart due to marine glaciation. It originated in the deposits from floating glaciers as well as in the sed ime nts carried by the rivers and wa tersunder the moving ice.

Based on certain striated surfaces observed in Uruguay and theArgentine, Du Toit (14) assumes that the glaciers descended from acontinental mass situated in some part of the area now occupied bythe Atlantic Ocean.

Halle (8) recorded the glacial sediments of the Falkland Islandsas dipping south, with boulders of rocks which could only have comefrom a region outside those islands, thus showing the existence ofglaciated areas at present unknown.

We must admit the existence of various large Permian glaciationcenters at the beginning of the Gondwana era. Apparently, theglaciers moved from south to north, in the present territories ofIndia and Australia, and from north to south, in Africa. The SouthAmerican Continent (17) shows two glaciation centers, one in thenortheast, comprising the glacial beds of Brazil, Uruguay, Argentina,and Bolivia, where there are signs of glacier movement toward thewest, and the other in the south or southeast, connected with theFalkland Islands glaciation and the northward movement of theAntarctic glaciers.

It should be noted that the small folds described by Washburne(10) as evidence of glacier movement were also observed by thewriter in various places in other formations, as in the beds of Riodo Rasto and Estrada Nova, and in Lages (Santa Cathar ina) . Consequently such folds can not be directly related to glaciation: they wouldprobably result from the local action of intrusive rocks.

Glaciation age (paleontologic observations). As a whole, Ita rarehas yielded no fossils which will permit a precise chronogeologicalclassification of the series to be made. Euzebio de Oliveira (12) foundfossil Mollusca in 1908 in the Passinho well (State of Parana), identifying them as Lingula imbituvensis (E.O.) , Orbiculoidea gnaranensis(E.O.), Leda Woodworthi (E.O.). Several remains of wings of insects


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1738 VICTOR OPPENHEIMand plants were also found here. The same species of Lingula andCkonetes were subsequently found in the same shales west of TeixeiraSoares . Euzebio de Oliveira (18) describes four new species of Molluscafound a t Bella Vista, 6 kilom eters south of Mafra (Santa Ca tha rina );these are species of Lingula imbituvensis, Orbiculoidea sp., Ckonetesrionegrenses, fish scales, sponges, and som e unde term ine d fossils.These fossils were somewhat bituminous; they were examined by W.L. Bryant, who assigned them to the Paleoniscidae family.

The collection of marine Mollusca, found in Santa Catharina byBastos and described by C. Reed as Permo-Carboniferous, containthe following spe cies of pa rtic ula r intere st (W ash burn e, 19,30, page 36).

Aviculopecten (Delopecten) catharinea ReedAiicttlopecten (Delopec ten) relegates ReedAmcidopectcn (Detopeclen) unions ReedAviculopecten (Detopeclen) crassicoslatus ReedPseiidamusium sp .Stuchburria brasilicnsis ReedEdmodia sp .Malomia cf. cuneata D a n aSolenopsis sp .Schizodus occidentalis ReedSchizodus (?) sp.Agalherias cf. micromphalus MorrChoneles (o r Chonelella?)In the Argentine Pre-Cordillera, several species of brachiopods,

gastropods, and bivalves of the Productus-S'pirifer and Pleurotomariaorders were found in the marine glacial deposits of the Tontal beds.In the Appendix to Du Toit 's work (14), Cowper Reed (19) attributesthis fauna to the Carboniferous, relating it to the Carboniferousfauna of Russia and Asia. This thesis is based mainly on the work ofTchernischev, whose conclusions have been questioned by Schuchert.Schuchert 's interpretation is the more acceptable to-day.

Du Toit unhesitatingly places the glaciation of Southern Brazil,together with that of Dwyka in Africa, in the Upper Carboniferous,and the same age must therefore be attributed to the marine andglacial sediments of Argentina. The latter, however, show a closerrelationship with the analogous Permian sediments of Australia andTasmania. Keidel (3), a leading authority on Argentine geology, isdecidedly in favor of accepting the Permian as the age of glaciationof that country, while the recent studies of glaciation in the Sierrasof Buenos Aires confirm the Permian age of the Pilhauinco sediments (15) .

Detailed studies supported by additional paleontologic evidenceare indispensable for a definitive chrono-geological classification. Considering the connection of the glaciation of the Parana Basin with


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GONDWANA ROCKS OF BRAZIL 1739that of Argentina and Uruguay, at present attributed to the Permian,the same age should be given to the Itarare. Nevertheless, we mustconsider the possibility that glaciation in the Southern Hemispheremay have begun in the Upper Carboniferous and continued into theLower Permian. To justify this conception, it is sufficient to bear inmind the very large marino-continental masses affected by glaciation,and the existence of glaciation centers geographically widely separated. However, until more paleontologic proofs are available, weshall retain the conception of the Permian age for the Itarare glacialbeds of Southern Brazil (20 and 21).

I I I . T U B A R A O S E R I E SStratigraphy and structure.Resting conformably on the glacial

tillites is a series of dark sedimentary sands and shales containing theGlossopteris and Gangamopteris flora. These beds were given the nameof the Tubarao series by I. C. White (13). The series is composed oftwo groups : the lower, known as the Rio B onito group, and the upper,the Palermo group.

The Bonito group is characterized by gray and yellow sands withseveral bands of dark-to-black shales, and contains the Coal measures of Southern Brazil.

The Palermo group consists principally of gray shales, light incolor and with bands of sandstones; the upper part of the grouppasses gradually into the black bituminous shales of the Iraty. Thisseries has been described by White (13) and others.The Tubarao sediments are well developed from the State of SaoPaulo to Uruguay, but they do not everywhere appear in their typicalstratigraphic sequence, the Bonito beds predominating in some areasand the Palermo beds in others.

There is no definite dividing line between the top of the Itarareand the Bonito group and it is the writer's opinion that the latter isalso, in pa rt, of glacial origin. We believe tha t the presence of bouldersof older rocks should be used as the criterion for the division of theTubarao series, sensu stricto, of immediate post-glacial sedimentationof fluvial character from the Itarare and lower Bonito that are composed of glacial sediments.

Coal beds have been located below the tillites of the Itarare invarious places. Although some authors tend to attribute this apparentanomaly to "charriage" of the Itarare sediments over the Tubarao,tillites overlying the coal beds south of Campinas, in Sao Paulo, inthe valley of the Rio do Peixe and at Wenceslau Braz in Parana, aswell as in the southern part of the State of Rio Grande do Sul, all


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1 7 4 0 VICTOR OPPENHEIMappear to lie in situ. Remains of the Clossopkris flora in the glacialsediments prove the existence of temperate climatic conditions duringcertain periods of the Permian glaciation. These phenomena can beexplained as resulting from the periodic advance and retreat of theglaciers during the last stages of the glacial period. Such recessions,some of protracted duration, would permit the development of a florawhich would be destroyed by the subsequent advance of the ice, andto them may be attributed the formation of the coal beds found between the glacial sediments. Similar advances and retreats of glaciershave been observed in regions both of recent and of contemporaryglaciation.

FIG. 2.State of Sao Paulo. Beds of Palermo group (Lower Permian) onPi rac icaba-Tatuhy road.The total thickness of the Tubarao series is variable. The only

extensive outcrops are found in the State of Santa Catharina. Theaverage thicknesses may be given as follows: Sao Paulo, ioo meters;Parana, 90 meters; Santa Catharina, 250 meters; and Rio Grande doSul, 150 meters. As a general average for all Southern Brazil, we maygive the limits of 100-180 meters.

The coal beds are th in, vary ing from a few centim eters to 2 or 3meters in some localities. They alternate with beds of sands andshales. Beds of limestone are commonly included, particularly in thePalermo group. Inclusions of silica "chert" are found throughout theentire series, being more common in the upper beds and graduallydiminishing w ith depth. These "c he rt" occurrences are not syngenetic;


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GONDWANA ROCKS OF BRAZIL 1 7 4 1they are apparently due to infiltrations of silica-bearing solutionsoriginating in the upper formation.

The Tubarao sediments are generally cross-bedded, and are offluvial, and probably estuarine, deposition, as is shown by the composition and character of the coal-bearing beds and fossil plants.

In extensive areas, particularly in Rio Grande do Sul, and inUruguay, the Tubarao occurs transgressively and directly on thegranites and metamorphic rocks of the basement.

As in the Itarare, there are no indications of diastrophic orogenicmovements in the Tubarao series. The structure is characterized bysmall faults and vertical dislocations of the component beds. Thesefaults are easily observable in the coal mines of Barro Branco and inthe numerous wells drilled in search of coal in Southern Brazil, aswell as in the cores themselves.

Paleontologic aspect.- The typical fossils described by Zeiller (23),D . White (24), and others are found throughout the series. The lowerbeds are characterized by the "genera austral," for example, thefollowing.

Gangamopteris cyclopkroidcsGangamopteris obovala (White)Glossoplcris brownianaCordiatcs hislopiPhyttoteca griesbachiLepidopholios lariciniusSigilaria bradriiLepidodendrum pedroanumPec.opteris s p p .

Disseminated through various beds are found: Neuropteridiumvalidum, Anularia anstralis, and others; also there are sporadic occurrences of Glossop teris indica, G. ampla, and G. occidentalis in theupper beds. The occurrence of the latter leads one to believe that these"genera septentrional" of the Glossopteris flora em igrated from theNorthern Hemisphere during the latter half of the Permian, and thatthey are not indigenous to the series, as Du Toit (14) infers when heconsiders the Tubarao and Itarare series as the chronological equivalent of the Upper Carboniferous.Mention should also be made of the recent finding of fish remainsin the Palermo beds of the northern part of Santa Catharina. Theseremains are apparently related to those found in Uruguay and described by Walther.

The Permian age of the Tubarao is also strongly supported bythe paleobotanic classification of David White (24). Moreover, oncethe glacial period is referred to the Lower P erm ian, for reasons alrea dygiven the Tubarao must correspond with the Upper Permian.


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1 7 4 2 VICTOR OPPENHEIMFormations contemporary with Tubarao. -The so-called "Estratos

de Jejenes" of the Pampean series of Argentina, which follow theglacial sediments of the base of the "Estratos de Umango" are, apparently, contemporary with the Tubarao. Characteristic occurrencesof these formations are described as sandstones and clayey shales,grayish-to-yellow in color, with impregnations and inclusions of calcareous material. At the base of these beds are found carbonaceousshales and thin beds of coal. The beds called "Piso I" by Bodenbender(25) vary from 30-300 meters in thickness. They are characterizedby the inter-Permian diastrophism, which affected the Gondwanaformations of Argentina, this characteristic being observable in theoutcrops of the "Estratos de Jejenes."

Keidel cites the following as typical flora.Ncoggerathiopsis hislopiGlossopteris communisGangamopteroides cyclopteroidcsEuryphyllum whilianumNeuropteridium validum

According to the logs given by Stappenbeck (26) relating to thewells drilled between Alhuampa and Gualeguay, in Eastern Argentina, the Tubarao must be included (if it exists) in the heavy beds ofconglomerates cut at the bottom of the wells of Quimili, Alhuampa,Tostado, and San Cristobal. These logs demonstrate the considerabledepression of the Permian Basin west of the Parana River, and alsoshow that this region was not affected by the inter-Permian diastrophism as was the case in Southern and Western Argentina.According to Beder (27), carbonaceous shales are found at variousplaces in Paraguay, at Santa Marta and Asuncion, and these are apparently identical with the shales of the Bonito group.

In Uruguay south of the Jaguarao River, coal beds of the Bonitowere found in several wells drilled. The maximum thickness of theTubarao cut in the Melo well was 300 meters. The Palermo in Uruguay is very sandy and is hardly to be distinguished from the Bonitogroup in many localities.

In comparison with the Gondwana sediments of the other continents, the Upper Permian Tubarao corresponds with the Karhabariand possibly the Ba raka r of Easte rn Ind ia; with the Ecca coal-bearingbeds of South Africa, and, finally, with the Greta coal beds of NewSouth Wales.

The distribution of the Glossopteris and Gangamopteris, both inthese territories and in the Antarctic Continent, is universal in character, although the various genera did not reach their maximumdevelopment and territorial distribution simultaneously.


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GONDWANA ROCKS OF BRAZIL 1743I V . P A S S A D O I S S E R I E S

Subdivision of series. -There is no evidence of unconformity between this series and the Tubarao, and we may consider the lowergroupIraty shalesas a continuation of the Palermo group.

To the present, there has been some confusion in the classification of the upper part of the series. Our own observations, togetherwith the data published by Du Toit (14), Moraes Rego (11), and E.Oliveira (28) and based on Cowper Reed's classification of a largenumber of Triassic MoUusca, make it necessary to divide the seriesinto three groups, of which the upper mem ber, or "Rocin ha lim e" ofWhite (13), must be separated from the two lower members andplaced in the Triassic. There is probably unconformity between theTriassic and the underlying Permian. In spite of paleontologic evidence, no supporting stratigraphic evidence has yet been observed inthe field.

In accordance with the aforementioned data, we divide the seriesas follows.

Permi an ( J r a t y g ? P H MILower Est rada Nova groupUnconformityTriass ic Upper Est rada Nova groupIRAT Y GROUP

Stratigraphy. This grou p forms th e base of the series and is welldeveloped in the Parana Basin. It can be observed from Rio Bonitoto Rio Verde, in Matto Grosso and Goyaz (28), and as far south asMelo, in Uruguay. Its thickness diminishes from the center of thesedimentary belt of Parana, on the north, and from the State ofSanta Catharina, on the south. The most characteristic developmentof the Iraty is found in Parana, in the southern part of Sao Paulo,and in Santa Cathar ina.

The Iraty has been described by I. C. White (13). In all its outcrops it is characterized by black bituminous shales, with thin bedsof limestone. It is definitely classified by the remains of the reptileMesosaurus brasiliensis (McGregor). In some outcrops, nodules ofblack silex are also found. This silex is impregnated with bituminousmaterial and, when broken, emanates an odor of petroleum. Thebituminous material of the Iraty shales in places amounts to approxim ately 100 liters per cubic meter, or 10 per cent by volum e. Ina great number of the wells, waters circulating below the limestoneand shales are highly saline. Salt-water springs are found in someplaces in Sao Paulo and Parana, while sulphurous water and gaseshave been found in some of the tests drilled in those states.


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1744 VICTOR OP PENH EI MOn weathering, the Iraty changes color to blue, light gray, or

violet. In almost all the wells drilled in this group, the Iraty wasfound to be associated with magmatic intrusions generally distrib-

F io . 3.State of Santa Catharina. Dark beds of Lower Estrada Nova(Upper Permian) on Lages-Bom Retiro road.

uted at one level or more along the planes of schistosity. It is thewriter's opinion that these intrusives are of Triassic age, and thatthey have risen along faults and structural fractures in the Iraty.


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GONDWANA ROCKS OF BRAZIL 1745The shales offered little resistance to the intrusives, which were injected in thin sheets of considerable horizontal extension and varyingthickness. Contact with the magma resulted in dehydration and distillation of the bituminous material, sometimes transforming it intoalber t i te and grahamite.

The group is found in its normal stratigraphic position in all thewells which have been driven in Southern Brazil. In Western Uruguay(Paso Ulestie), and still farther west, at Entre Rios in Argentina,there is a hiatus of apparently the entire group.

The thickness of the Iraty ranges from 30 to 97 meters, the latterbeing found in the wells at Marechal Mallet, in Parana. The Araquawell in Sao Paulo was drilled through 88 meters. The greatest average thickness, 70 meters, is found in the State of Parana, the averagefor the whole group ranging from 30 to 60 meters.

The beds are well stratified and are generally horizontal where notaffected by intrusive masses which in some places produce sharp dipsof purely local extension. The Iraty forms an excellent key bed forstructural studies. Data obtained from outcrops and well logs reveala structure of faults and fractures over considerable areas of thewhole basin.

Paleontologic considerations.The fossils Mesosanrus (McGregor)and Stereosternum (Cope) are found in this horizon. They are found inabundance in the states of Sao Paulo, Parana, Santa Catharina, andRio Grande do Sul, as well as in Uruguay. They are not commonnorth of Sao Paulo. Von Huene (29) claims that the Stereosternumtumidum is not a distinct genera from the Mesosaurus brasiliensis. H econsiders the two fossils as Mesosaurus tumidum and Mesosaurusbrasiliensis and classifies them with the South African species whichhe studied under the single name of Mesosaurus tenuidens,

Reptiles presumably inhabited waters of high salinity, little dep th,and lake-like character, in which the Iraty shales were deposited.These conditions, particularly the high salinity, explain the incomplete decomposition materials which gave rise to the genesis of thepetroliferous and bituminous materials found in this group. In certainoutcrops, such as at Lages, in Santa Catharina, the bitumen is foundfilling cavities formed in the shales by the impressions of the skeletonsof reptiles.

Other fossils found in the Iraty include an unclassified crustacean,fish teeth and scales, petrified wood, et cetera. According to Walther(30) the fish scales found near M elo, in Uru gua y, belong to the ganoidspecies. I t is possible tha t these scales can be correlated with thefish remains recently found in the Palermo group of northern SantaCathar ina .


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1746 VICTOR OPPENHEIMThe occurrence of Mesosaurus definitely places the age of the Iraty

formations as Permian.Geographic distribution. The only know n occurrence of Mesosaurus outside Brazil is in the "White band" of South Africa. According to Du Toit, there is a striking lithological similarity between theseformations and the Iraty group.

Contrary to other areas of Gondwana rocks, the equivalent of theIraty has yet to be found in Argentina. Nevertheless, contemporaryrocks must exist in that country.

According to Beder (27), remains of Mesosaurus have been foundin Paraguay, where the westernmost limit of the Iraty occurs. Fragments of remains of the same reptile found near Melo, in Uruguay,were shown to the author by Terra y Arocena.

LOWER ESTRADA NOVAThe sediments overlying the Iraty are also gray or dark shales

with sandy intercalations, but lacking the bituminous material. Remains of Mesosaurus have not been found in these sediments. Thethickness of this group is presumably between 50 and 70 meters.Owing to their lithologic similarity to the Triassic upper group, it isdifficult to establish the dividing line between the two groups.

The group is characterized, paleontologically, by scales, bones,and coprolites of fish. Various specimens of plants and fossil woodhave also been found in this group. David White (24) describes thewood as Dadoxylon numularium and Lycopodiopsis derbyi. The Phyl-lopodos Leaia of C. Reed (31) from Valloes, in Parana, must belongto this group, which is undoubtedly of the Permian age.

The overlying group corresponds with the "Rocinha" of White,and is cal led the "Therezina be ds" by Moraes Rego ( n ) . We thinkthe term Upper Estrada Nova more appropriate"Upper" becausethere is a liability to confuse sediments of a different age and separated by an assumed hiatus when using the term "Estrada Nova."However, there is no inconvenience in leaving these sediments in theclassic series created by I. C. White (13).In Uruguay, the Lower Estrada Nova combines with the Iratyto form a distinct group called "Melo"a classification well justified stratigraphically.

UPPE R E ST RADA NOVAStratigraphy. This group is composed of san dy clay shales, yel

low, brown, violet, or variegated in color, with intercalations of sandsof lighter color. The upper part is generally more clayey. The groupis characterized by the presence of various beds of Triassic Mollusca.


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GONDWANA ROCKS OF BRAZIL 1 7 4 7The "Rocinha lime" is not restricted to Santa Catharina. Its

equivalent may be observed at "Estancia Caleira," northwest of Sao

*sF^?5c*

FIG. 4.State of Santa Catharina. Sandstone dike in fault in Upper EstradaNova (Triassic), on road between Lages and Bom Retiro.Gabriel in Rio Grande do Sul; in siliceous limestones south of Canoin-has, in Santa Catharina; in the fossil beds of Serrinha and Therezinha,in Parana; and in the siliceous beds of Ferraz and Camaquan in Sao


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1748 VICTOR OP PEN HELMPaulo, described by Von Huene (31). These beds might correspondwith the base of the Upper Estrada Nova, marking the transgressionof the Triass ic sea. How ever, the limesto ne is not uniformly distributed, being absent in many of the well logs. It is probable that thisgroup does not exist in certain areas, the lower group only croppingout. The sediments of the two groups are well stratified and areessentially horizontal. The predominance of dark colors in the lowergroup is characteristic, the upper group showing brighter and reddish colors. This indicates a radical change in conditions at the timeof deposition of the sediments. Apart from the limestone and variousbeds of sandstones, the group also contains concretions and beds ofsilex. Owing to the great variation in color and texture between onelocality and ano the r, in various s tate s, it is difficult to establish auniform lithologic criterion for the group.

Paleontologic considerations.The essential argument for thesubdivision of the Estrada Nova rests on paleontologic as well aslithologic evidence. The Upper Estrada Nova includes a great faunaof lamellibranchs unquestionably of Triassic age. Found originallyby E. de Oliveira (12), and later by Du Toit (14), the Mollusca fromRio Claro, east of Marechal Mallet, in Parana, were studied by Cow-per Reed and classified as follows.

Zone I Pachycardia aft", mgosa Hauc rAnodontophora aff. trapcsoidalis MansuyTrigonodus aff. rabhnsis GredlerRadiolaria (undetermined)Zone II Pachycardia neotrcpica sp. nov.Myophoria (Myophoriopsis) aff.Myophoria carinata B i t t n .Myophoria aff. lincata M u n s t .Megalodus neotrepicus sp. nov. cf.Megalodus trigneter (Wulf)Gonodon (Schafthantlia) paranaense sp. nov.Modiola aff. subcarimta B i t t n .According to Reed there are no common species in zones I and

I I . The specimens from the two zones belong to the Upper Triassic.T he Mollusca of zone I occur in the siliceous beds and chert, those ofzone II being found above, in the beds of sandy limestone. The samebeds extend in the direction of Iraty Station (Sao Paulo-Rio GrandeRailway), and reappear at various points. At Serrinha, 7 kilometersnorthwest of Marechal Mallet, in the same place where Du Toit (14)found the aforem entioned fossils, K arl Ho ldha us (32) describes thefollowing species.

Solenomorpka similis sp. nov. H.Solenomorpha intermedia sp. nov. H.Solenomorpka allissima sp. nov. H.Solenomorpha reflexa sp. nov. H.


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CON DW ANA ROCKS OF BRAZIL 1749From the Agua Quente River he describes Sanguinolites alongatus sp.nov. H. and S. sp. Holdhaus considers them to be of Permian age,but Cowper Reed holds this classification to be doubtful. Subsequently, in the same locality, only Triassic fossils have been found,the species indicated by Holdhau s being un know n.

Beds of Triassic Myophoriopsis and Pachycardia Mollusca werealso found by Huen e in Ferraz and Ca ma qua n, in Sao Paulo, and theyare also particularly well developed at Therezina, in Parana. VonHuene is also of the opinion that the Serrinha Mollusca are Triassicspecies of the Myophoria genera. The same species were observed bythe writer at Lageado Piso, south of Canoinhas, and on the road toLages, in Santa Cathar ina. The Cuspidaria species was found atSerrinha.

A ppa ren tly, the fossil beds can be related to the R ocinha limestone in Santa Catharina and the Caleria in Rio Grande do Sul. Thelimestone ranges from 1 me ter to 3 me ters thick. T he Mollusca, Ter-raia, found at Cerro Hospital in Uruguay, appear to correspond withthe Triassic species from Therezina and other typical localities inBrazil.

Geographic distribution.The Es trad a Nova is known to extendfrom the Rio Bonito and Jatahy, in the southern part of the State ofGoyaz, to Aquidauana in Matto Grosso, and south as far as Uruguay.It is found in a belt approximately 10-20 kilometers wide along theolder sediments already mentioned.

Owing to the difficulty of establishing the lower limit of theUpper Estrada Nova from the well logs, the thickness of the formation appears to be nota bly variable and completes the thinner LowerEst rada Nova .

The lithologic characteristics, and the fossils found, suggest thatthe Upper Estrada Nova was deposited in epi-continental seas, orduring periods of ingression. This might explain the sporadic occurrence of the fossils, the irregular distribution, and the complete absence of the sediments of this group in certain areas.

Inasmuch as the Triassic referred to this group is the upper, corresponding with the Karnic or Lower Keuper of Germany (v. Huene)(31), and that the lower sediments are Permian, it is necessary to admit a hiatus of all the Lower and Middle Triassic.

In Paraguay, Beder refers to the same sediments at Villa Rica,where they appear with the outcrops of the Iraty.

In Uruguay, the Estrada Nova corresponds with this group, thatis , with the Upper Estrada Nova, the lower groups of Permian agebeing considered as forming the Melo group.


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i7S VICTOR OPPENIIEIMIn Argentina, Bodenbender (25) attempted to correlate the

Estrada Nova with the Piso II . Keidel (3), however, considers thePassa Dois series as being contemporary with the Estratos de Ca-tuna, and this may be correct as far as the Permian groups are concerned. The Upper Estrada Nova must, then, correspond with theEstratos Paganzo. As a matter of fact, a visible hiatus exists betweenthe Estratos Umango (Permian) and the Paganzo (Triassic).

In Patagonia, Myophoria neuquenesis is found in the marine sediments of the Triassic ingression {$$). The Vitiacua limestone of Southeastern Bolivia and the "Horizonte calcareo dolomitico" of Northeastern Argentina are presumed to be contemporary with the limestones and silex beds of the Upper Estrada Nova.

In eastern India, the Passa Dois series corresponds with the lowerpart , "Raniganj ," and the upper par t , "Panchet ," of the Damuda andPanchet series.In the Karroo system the groups known as Beaufort beds correspond, in their lower part, with the Permian, and in their upper partwith the Triassic, of the Passa Dois series.

S A O B E N T O S E R I E SAccording to I. C. White (13), this series was originally composed

of the sediments of the upper part of the Santa Catharina system, andthe superimposed and intercalated effusive diabases. Subsequently,E. de Oliveira (12) gave the following names to the elements forming the Sao Ben to series.

Rio do Rasto groupBotuca t i i sandstoneEruptives of the Serra GeralIn view of later, more detailed investigations, the limits and positionsof the sedim entary beds, hith erto interpreted in different ways bydifferent aut ho rs, should tak e a position which appe ars to us theclosest to their true cycle of deposition.

RIO DO RASTO AND B0TTJCATU GROUPSStratigraphy.The Rio do Ra sto group proper, whose stra ti-graphic position has not yet been denned with exactitude, rests discordantly above the Upper Estrada Nova, forming a natural continuation of the latter. In its most characteristic areas it is composedof red or alternately red and greenish or variegated sandstones andclays.Regional divergences.The sediments of the Rio do Rasto appearin their m ost ch arac teristic form in Rio Gra nde do Sul and San ta


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CON DW AN A ROCKS OF BRAZIL i 7 S iCatharina, occurring in a somewhat less pronounced form in Paranaand Sao Paulo. In the latter states the group appears much moresandy, and resembles more closely the sandstone of Botucatu overlying the Rio do Rasto sediments.

In Sao Paulo the group is known as Piramboia (in accordancewith the nomenclature adopted by the Geographical and GeologicalCommission of the State of Sao Paulo); it is incompletely developedand is even absent in certain places, such as Boa Esperanca in SaoPau lo. In Chiniqu a (M unicipa lity of Sao Ped ro), however, there existsa fossiliferous horizon with remains of saurian fauna (31).

In Parana, the group is of a much less sandy nature, mixing onthe top with the sandstone of Bo tucatu and passing imperceptibly intothe fossiliferous beds of the Upper Estrada Nova. Multi-coloredclayey banks of this group are easily seen on the road to G uara pav a,passing Prudentopolis.In Lageado Liso (Canoinhas), in the northern part of SantaCatharina, there is visible contact of this group in discordance withthe Upper Estrada Nova, the beds being sandy and yellowish incolor. In the district around Lages, the Rio do Rasto is very sandyand light in color, showing a clear angular discordance with theBotucatu sandstone, although its aspect is very similar to the latter.

The group appears in its clayey and most characteristic surfaceson the road between Bom Jardim and Lauro Muller. No reptilianfossils were found in these beds, however.

In Rio Gra nde do Sul the group presents its mo st complete aspect,and is described in detail by v. Huene and Stahlecker (34). Thebeds are clays and light sandstones, friable, successively superimposed, and becoming more sandy at the base. In Santa Maria anintercalated bed of the same material, 53 meters thick, yielded anotable collection of Triassic reptiles of this group.

In its extension south, from Santa Ana to Uruguay, the Rio doRa sto is very sa ndy in texture, closely resembling the Botuc atu sandstone. In Eastern Uruguay, in the Department of Cerro Largo, thesandstone outcrops bearing Triassic Mollusca should be related tothe Upper Estrada Nova.

Red sandy clay beds similar to those of the Rio do Rasto are alsoknown in Paraguay (Bella Vista), in Matto Grosso (Aquidauana), andin the southern part of Goyaz.Structure. The thickn ess of the group varies, the average beingbetween 70 and 150 meters. It attains its greatest development in RioGrande do Sul, where v. Huene (35) measured 380 meters, this figureundoubtedly including the Botucatu sandstone.


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i 7 5 2 VICTOR OPPENHEIMThe characteristic structure is cross-bedded, without signs of fold

ing apart from uplifts due to intrusive magmatic rocks.The character of the stratification and the texture of the material

presuppose a terrigenous eolian deposition, but the clayey beds of thebase and the common occurrence of thin lenticular limestone bedssuggest local aquatic conditions, probably fluvial, in Rio Grande doSul.

Paleontologic observations.The fossils associated with this groupcomprise reptiles and abundant remains of coniferous woods, chieflyof the Dadoxylon order. The lamellibranch Molliisca, usually connected with this group, should be attributed to the Upper EstradaNova, which displays the marine facies of the Upper Triassic.

In Santa Maria da Boca do Monte, in Rio Grande do Sul, thereare outcrops with numerous occurrences of saurian fossils such asScaphonix, Rhynchosaums, and Erythosucus. Some remains of thesame reptiles were also found at Chiniqua, in Sao Paulo, and Leme(36) mentions the finding of remains similar to those of Scaphonixat Cambumbe, in the northern part of the Chapada of Matto Grosso.

According to v. Huene (35) and other writers, the Rio do Rastoappears definitely to belong to the Upper Triassic.

In A rgentina, s trata identical with this group are assumed, according to Rassmuss (37) in Sierra de Velasco and in the Fre-Cor-dillera; they are calcareous clays, although not characterized by fossilfauna.

In the Pre-Cordillera and in Sanagasta these sediments rest abovethe crystalline rocks, disclosing a considerable transgression in thedeposition of the group. In Eastern Argentina, the wells from Al-huampa to San Cristobal show the presence of sediments of the seriesin varying depths. According to Stappenbeck (38), the lower levelof the series at Alhuampa is at a depth of 1,630 meters.

In Northeastern Argentina the "Areniscas superiores," above the"Horizonte calcareo-dolomitico," have the characteristic red, sandyclay beds of the Rio do Rasto.

The base of the Tacurii formation of Bolivia, composed of successive beds of shales and sandstones, has the characteristics of adeposition probably contem porary with the Rio do Ra sto. Nev ertheless, the former has not yet yielded fossils which would permit its definitive classification.

From the fossil fauna, the Rio do Rasto is apparently contemporaneous with the beds of Molteno sandstones in South Africa, withreptilian fossils corresponding with those described by v. Huene (29).

Botucatu sandstone.In spite of the fact that the sandy facies of


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GOXDWANA ROCKS OF BRAZIL T75 3the Rio do Rasto is with difficulty distinguished from the Botucatusandstone, there apparently exists an angular discordance of localcharacter on top of the group. Von Huene mentions it in several localities in Rio Grande do Sul, and the writer noticed such a discordanceon top of the group in Lages, Santa Catharina. Washburne also refers to a discordance with a hiatus in Sao Paulo. Nevertheless, mostof the outcrops of Botucatu sandstone lie concordantly above the Riodo Rasto. The bed consists of a sandstone varying in texture fromfine to coarse, with strongly pronounced diagonal stratification. Outcrops occur as massive banks ranging in color from orange red to aslightly grayish white. The sandstone is invariably related to the

FIG. 5.State of Santa Catharina. Counterforts of Botucatu sandstones(Rhaetic) on road from Lages to Bom Retiro.eruptive escarpment of the Serra Geral and accompanies the latterfor the whole of its extension, from Minas Geraes in the north, toUruguay, where it is known as "Arenisca de Tacuarembo."

The B otuc atu sandston e varies in thickness from 50 to 120 me ters,forming steep walls along the escarpment. In many places, due toerosion, the sandstone joins the eruptives, forming extensive counterforts with evidence of considerably eroded Botucatu. This shows theconsiderable development of Botucatu before profound erosion tookplace.

With the exception of some remains of fossil worms found byJoviano Pacheco in Sao Paulo, footprints of small reptiles in SaoPaulo, and some undetermined remains of a reptile found at PassoFundo, Rio Grande do Sul, by the same geologist, no other fossilsof this horizon are known in Brazil.


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i7S4 VICTOR OPPENUEIMSediments contemporary with Botucatii'. On the top of the "Aren-

isca de Tacuarembo," near the city of that name, Walther (30) recently found some remains of a ganoid fish which he classified asSeminotus. Without doubt, the sandstone of Botucatii has all thecharacteristics of eolian desert deposition. However, the remains ofthe Tacuarembo fish, if belonging to the Botucatu sandstone, implythe existence of an aquatic or lacustrine facies in the extreme southernpart of the Parana Basin. The basaltic rocks observable in this regionsupport this inference: these rocks are extremely amygdaloidal andsome of them suggest that they were ejected while submerged.

No sediments contemporaneous with those of Botucatu have beenobserved in A rgentina.

It is probable that the discordance between the Pampeanasseries and the Liassic sediments with plant remains, in Patagonia andin the Cordillera, corresponds with the deposition period of theBotucatu of Brazil.

Transgressions of eruptives with a hiatus of the lower sedimentaryand Triassic parts of the series are also observable in Uruguay.

The Cave sandstones of the Stromberg series in South Africa, andthe Mahadeva formation of India, are apparently contemporaneouswith Botucatu.

According to the stratigraphic evidence, the Botucatu is of theRhaetic or Upper Permian age.

Capping the Botucatu are enormous masses of effusive rocks covering the greater pa rt of the Paran a Basin.Caiud sandstones.In the western part of the State of Sao Paulothere exists a sedimentary bed related in age to the basaltic trap onwhich it rests: this is the Caiua formation, thus called by the State ofSao Paulo Geographical and Geological Commission, and describedin detail by Washburne (10). It is friable sandstone, bright red incolor, everywhere much decomposed in outcro ps, free of interpo lationsof clay or gravel of any kind, thus confirming its eolian origin. Thestratification shows pronounced deposition in dunes.

The Caiua. has certain affinities with the Botucatu sandstone, although it is mixed with the material resulting from the deep erosionof the traps. In certain places, its thickness reaches 50 meters. No fossil remains were found in this bed; nevertheless, its affinity with theBotucatu and its stratigraphic position above the basaltic trap suggest that its age is Jurassic. E. de Oliveira (28) places the Caiua sandstone of the western part of Sao Paulo and southern part of MattoGrosso, together with the eruptives of the Serra Geral, on top of theUpper Triassic (Rhaetic).


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GONDWANA ROCKS OF BRAZIL 1755No deposits of Caiu;i sandstones are known in the remaining statesof Southern Brazil.

V I . T R A P S O F S E R R A G E R A LGeographic and stratigraphic distribution.The basaltic traps of the

Parana Basin constitute a physiographic and morpho-geologic factorof the greatest significance in the geology of Southern Brazil. Thetraps cover Northwestern and Western Uruguay, a large part of theTe rritory of Missiones and N orthea stern Corrientes in Argentina, andthe whole of Western Para gua y.

The geographic limits of the traps are: on the north, Lat. 18 0 S.,embracing the central areas of the State of Goyaz and Minas Geraes;on the south, Lat. 33 0 S., embracing Uruguay as far as the southernboundary of the Rio Negro valley; on the west, Long. 59 0 W., inArgentina, and on the east, Long. 4Q3o', forming the Serra Geral ofBrazil, with maximum extension reaching the Atlantic coast at Torres, in the State of Rio Grande do Sul.

The total visible surface area of the trap, together with its extensions under the po st-Go ndw ana sediments as observed in the wellsin Uruguay and Entre Rios, in Argentina, is approximately 1,200,000square kilometers. The area covered by the trap in Brazil is 900,000square kilometers, and embraces the states of Goyaz, Minas Geraes,Matto Grosso, and the larger part of the states of Sao Paulo, Parana,Santa Ca thar ina, and Rio Gran de do Sul. Th e whole of this huge areaextends northeast and southwest, and has a maximum longitudinalaxis of 1,700 kilometers, the east-west transverse axis measuring approximately 1,000 kilometers, at Lat. 28 0 S. This area forms the mostextensive effusion of basaltic rocks ever observed on earth.

Similar in characteristics, although smaller in area, are the Trias-sic and Jurassic traps of the Karroo, the Cretaceous traps of theDeccan, the 500,000 square kilometers of Tertiary basalts in Oregon, Nevada, and Idaho, the extensive effusions, 1,000 meters inthickness, of the lavas of Greenland, Spitzbergen, the Hebrides, andScotland, and the lava traps of Patagonia and the Antarctic Continent.

The absence of volcanic cones, the surprisingly uniform composition of the diabases throughout considerable areas, and the structuraluniformity of the various traps show that the effusions were quiet andsuccessive, but with ejections of extremely fluid lava.

The eastern margin of the trap in Brazil forms a continuousbasaltic escarpment extending from Uruguay to the State of MinasGeraes. In spite of its magnitude, however, little importance has


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1756 VICTOR OP PEN HELMh i the r t o been a t t ached t o t h i s ma jo r geograph i c f ea tu re o f Sou the rnB r a z i l .

T he morpho log i c s i gn i f i cance o f t he Se r r a Gera l name g iven byWhi t e (13) t o t he marg in o f t he t r ap i n San t a Ca tha r ina is comp a r a b l e w i t h t h a t o f t h e S e r r a d o M a r , p a r t i c u l a r l y c o n s i d e r i n g i t slength of near ly 1 ,500 ki lometers and i t s average e levat ion of 800m e t e r s w i t h p e a k s r e a c h i n g 2 , 0 0 0 m e t e r s ( C a m p o d o s F r a d e s , S a n t aC a t h a r i n a ) . T h e w e s t e r n , n o r t h e r n , a n d s o u t h e r n l i m i t s o f t h e t r a pa re no t so c l ea r l y de f i ned , due t o t he i r be ing ove r l a in by pos t -Gond-w a n a s e d i m e n t s . N e v e r t h e l e s s , t h e w el ls a t P a z o U l e s ti e ( U r u g u a y )a n d t h o s e f ro m G u a l e g u a i t o A l h u a m p a ( A r g e n t i n a ) , t o g e t h e r w i t ht h e o u t c r o p s of T r i a s s i c b a s a l t s i n P a r a g u a y a n d t h e S t a t e of M a t t oGrosso, make i t poss ible to es tabl i sh i t s l imi t s wi th fa i r accuracy(39)-

T he su rf ace of t he t r a p i s den ud ed and f ree f rom po s t -G on dw an ased im en t s t h ro ug ho u t la rge a r eas , a f fo rd ing ev idence of cons ide rab l ee ros ion and t opograph i c l ower ing o f t he a r ea f rom the Mesozo i c t oR e c e n t t i m e .

T h ere i s i n su ff ic i en t ev ide nce t o m ak e poss ib l e an ex ac t ch rono log i cc lass i f ica t ion of the t rap . In spi te of th i s , i t i s evident ly l imi ted by theUpper T r i a s s i c be low and t he L i a s s i c above . I n a l l p robab i l i t y , t heR h a e t i c a g e m a r k e d t h e p e r i o d o f m a x i m u m d e v e l o p m e n t o f t h et r aps , wh i l e t he p roces s o f e f fus ion may have begun i n t he T r i a s s i cand con t i nued i n to t he L i a s s i c .

Petrographic observations.Petrographically, th e t ra ps w eres tud i ed i n de t a i l i n t he exce l l en t work o f D ja lma Gu mara.es ( 4 0 ) ,an d by H au se n (41) an d K . W al th e r (42) a s r ega rds t he e ru p t ves ofA r g e n t i n a a n d U r u g u a y .

The microscopic physiography of the basalts of the south part of thecountry, forming its chief magmatic province, varies with the conditionsunder which the rocks were consolidated. The mineralogical composition ispractically uniform, with local variations characterized by the concentrationof magnetite-ilmenite in proportions which may exceed 20 per cent. All thesuccessive phases may be found among the representative types of theTriassic magma on the south, from holo-crystallines of ophitic and interstitial, to micro-crystallines of microlitic texture. (Djalma Guimaraes, op. cit.,page 9.)T h e na tu re of t he e ru p t i v es i s s i ngu l a r l y un i fo rm an d s 'mple . T he y

a re a lm os t a l l ba sa l t s f ree f rom o l i v ine -b asa l t i t e s (p l ag ioc l a se w i thp h e n o c r y s t a l s of a u g i t e a n d m a g n e t i t e ) , d i a b a s e s , a n d m e l a p h y r e s .T h e m e l a p h i t i c t y p e s a r e p a r t i c u l a r l y p l e n t i f u l i n t h e p e r i p h e r i ca r eas o f t he t r ap , w i th poor ly deve loped amygda lo ids i n t he com-
http://mara.es/http://mara.es/http://mara.es/


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GOND W.l.XA ROCKS OF BRAZIL '757pact basaltic mass of the Serra Geral (Bom Jardim, Santa Catharina)escarpment, and excessively vesicular and amygdaloidal types inUruguay and Argentina.

The predominating color is gray, but may vary from black toslightly violet, reddish, and slightly green. Coloration depends partlyon certain chloritic and hematitic impregnations, and partly, as regards the surface, on climatic conditions and atmospheric precipitations. The deep decomposition of the basalts is specially noteworthyin the State of Sao Paulo (terra roxa) and in the Missiones Territoryof Argentina.

With the exception of tufntes, volcanic breccia, and cineratic sediments existing in Minas Geraes (Triangulo Mineiro) (40), very fewremains of explosive eruptions have been found in the huge area ofthe trap.

Thickness of the trap.This varies considerably at different pointsin the basin, this being in part due to the considerable erosion alreadymentioned. The thickest basaltic body penetrated by drilling inBrazil was 147 meters (Boa Esperanca, Sao Paulo), in a laccolith notcompletely measured.

Morpho-geological g enesis.The Serra Geral escarpment belongsto the Cenozoic age. It originated from the differential erosion of theBotucatii sedimentary beds. These beds were contemporary with theescarpment, and probably formed a ridge of desertic accumulationsflanking the western border of the old mass of the Archean shield.The successive flows of lava were retarded in their advance towardthe east by this barrier of sediments of the Sao Bento series.

The intense Cenozoic erosion, and the isostatic raising of thecoast at this period, resulted in the disappearance of the large sedimentary beds of the Sao Bento series that formerly covered the areabetween the present Serra do Mar and Serra Geral. The erosion alsocut deeply into the subjacent Perm ian sedimen ts. Figure 6 shows theprocess schematically, it being particularly suggestive in certain placesin the states of Santa Catharina and Parana.

Most of the western border of the trap does not constitute aphysiographic feature of the topography of the region, since it dipsbelow the post-Gondwana sediments.

There is an erosion escarpment on the margin of the trap, inEastern Paraguay, west of this escarpment and south of Assuncion(27), where rocks of the Archean complex appear. As in Brazil, theprofound erosion has denuded the Permian sediments and uncoveredthe m argin of the t rap .

Contrary to what occurred in the east, where there were the con-


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1758 VICTOR OPPENHEIMsiderable sedimentary accumulations already mentioned, the lavasmet with no obstacles in their expansion toward the southern marginof the trap, and directly covered the rocks of the complex (State ofGoyaz) or, transgressively, theTermian sediments (Uruguay). In these

FIG. 6.Sketch of successive phases of erosion of sedimentary belt along easternflank of Serra do Mar. Phase 3 shows present aspect of escarpment of Serra Geral(left) and Serra do Mar (right).regions there is no pronounced escarpment, and the trap cover is thin.

In the southwestern part of Santa Catharina and northwest of RioGrande do Sul, the continental depression favored the westerly advance of the lava, which extends into the sea at Torres. Here also, thetrap escarpment closely follows the outline of the basement masses as


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UOXDWAXA ROCKS OF BRAZIL I7S9well as the borders of the depression on the north and south, wherethey gradually thin out.

Types of contact.- The contacts between the effusives and theBotucatu sandstones may be classified in the following three types:(a) in contact with the counterforts of the Botucatu sandstones,(b) in en dents d e scie form of contact, and (c) in the form of successive

FIG. 7.Forms of contact of Serra Geral traps with Botucatu sandstones.traps, with interposition of sedimentary beds of Botucatu of irregular thickness. Figure 7 shows these types of contact.

Th e meta mo rphis m of the sands tones of the Sao Be nto series in contact with the effusives may be seen in many places, and appears in theform of fusion of the sandstones, which are transformed into a highlycompact quartzite of conchoidal fracture. This metamorphic actionwas local and had very little effect on the deeper parts of the beds.


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1760 VICTOR OPPENHEIMV I I . T E C T O N I C S O F P A R A N A B A S I N

Structure of the trap. Considered as a whole, the Parana Basin isundoubtedly a continental depression with the character of a "geo-synclinorium." The writer 's observations in this connection amplyconfirm the opinion of Baker (39):Structurally, all this region is a single vast downfold (geosyncline)and Walther (42):. . . es seguro por mas que faltan investigaciones detalladas que en muchospontos la disposicion tectonica de los estratos que yacen en posicion casihorisontal, obedece a la de bloques de falla (fault blocks).

The synclinal axis which crosses the basin northeast and southwest south of Lat. 2 70, clearly dips southwest. The western depression (west of the Serra Geral escarpment) inclines markedly northwest in the area north of Lat. 240, west between La ts. 240 and 28, andsouthwest between Lats. 28 and 32 0 S.

The general horizontality of the successive beds of the trap, observable in the greater part of the basin, does not permit the establishment of dips, even of local character. However, when the factors oftheir profound erosion are b orne in mind, the var ying elevations ofthe effusive mass above seal-level prove that it is composed of fractured blocks, faulted and extended en echelon from west to east. Byestablishing an altimetric relationship between the various trap areas,one deduces an averag e of 2 me ters per 1,000 for the westw ard d ip.

The Serra Geral reaches a height of 1,600 meters above sea-levelaround Bom Jardim (Santa Catharina); the rocks of the trap arefound at 300 meters below sea-level in the drilling at Pazo Ulestie(Uruguay), and at an elevation of 120 meters at the mouth of theIguassu, in Pa rana.

In the southern pa rt of M at to Grosso, and in Sao Pau lo, betweenLats . 18 0 and 240 S., the southern area of the basin reveals structuralcharacteristics of a graben whose axis clearly follows the course ofParana River. The eastern margin forms a monocline with theascending blocks reposing on the S erra do M ar.

The folding of the Andean Cordillera did not affect the Gondwanaof Southern Brazil, and the absence of other folding factors or oro-genic diastrophism in the post-Gondwana of this part of the continentcauses the G ondw ana to show a tectonic character som ewha t differentfrom the greater part of the other major effusions, such as those of theKarroo systems. In spite of the evident correspondence between thetraps of Karroo and those of the Parana Basin, which assumably are


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GONDWANA ROCKS OF BRAZIL 1761con tem por ary , the latte r suffered muc h less intense fractu ration anddiastrophic disturbance than the former.

Due to the acute erosion of the trap surface, and to the relativelyslight vertical projection of the faults, the latter are in general notconspicuously exposed. These faults are, however, well in evidence inthe river beds. The rivers, with numerous waterfalls, cut deeply intothe trap and form the extensive hydrographic system of the basin.

From the stair-like character of their banks in certain places, itseems probable that the valleys of the larger rivers, such as the Tiete,Paranapanema, Ivahy, Iguassu, and Uruguay, occupy the zones offaulting of separate blocks. These masses, en echelon, descended gradually from north to south, in the direction of the longitudinal axisof the basin. It is probable that the tectonic factors which caused the

FIG. 8.State of Sao Paulo. Escalonated escarpment of Itaquery Serra.faulting of this considerable area operated in post-Triassic time, andthat they were connected with the isostatic depression of the basin,possibly at the same time that the synclinal depression of the ChacoTerritory occurred. It is also possible that the fractures occurred atthe end of the Triassic, causing the effusion of magma, and that theypersisted after the latter had cooled and formed the solid mass of thetrap. The last hypothesis could be related to the mise en place readjustment of the separated epirogenic masses which, up to that time,formed the probably connected continental mass of Gondwana.

Structure of sedimentary basin.The narrow strip of sedimentarydeposits between the complex of the Serra do Mar on the east and theescarpment of the Serra Geral on the west is evidently the outcroppingmargin of the large sedimentary plain stretching toward the westin' Sou thern B razil. Ne arly the whole of this plain is covered withbasalts.


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1 7 6 2 VICTOR OPPENHEIMStructurally, this strip corresponds with the tectonic facies of the

trap, showing a tendency to depression toward the western quarterin Sao Paulo , Pa ran a, and S anta C atha rina, and toward the southernor southwestern qua rter in the southern part of Santa Ca tharina andin Rio Grande do Sul. In Sao Paulo, Parana, and Santa Catharinathe average elevation of th e sed im enta ry area is 700 m eters, and inRio Grande do Sul, Uruguay, Matto Grosso, and Paraguay theaverage elevation of the outcrop is 150 meters.

The sedimentary beds of the Parana Basin have not sufferedorogenic movements or pronounced diastrophism since their forma-

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/ F a l h a s F a u l t s ( as su m e d o r o b s e r v e d )/F I G . g. K ey t o s t r a t i g r a p h i c s e q u e n c e i n c r o s s s e c t i o n s ( F i g s . 10 , n , 1 2 ) .

tion in the Permian or Triassic, although the type of fracturing of thetra p and th roug hou t the basin also affected the bordering sedim entaryareas.

The structural and characteristic factors greatly affected thesedimentary belt. In the first place are the magmatic intrusions in theform of dikes, with extensive ramification, such as sills, necks, andeven intrusive batholiths. In the second place are the fractures andfaults, generally of low vertical displacement and covering a largeare a: these are chiefly related to the mag m atic intrusion s, for whichthey offered a means of penetration. Superficially, these faults do notform well marked contours, this being due partly to the same intensepeneplanation as was previously mentioned in connection with the
http://arenito.de/http://arenito.de/http://arenito.de/


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GONDWANA ROCKS OF BRAZIL 1763trap surfaces, and parti)- to the homogeneity of the clastic massescomposing the sedimentary rocks.

In general, the faults show low vertical projection, although drilling proves the subsurface presence of large faults with 200 meters ormore displacement, such as those verified in the small area of drillingat Sao Pedro, in the State of Sao Paulo. The presence of faults hasbeen proved in all those areas where there are a number of wells closeto one ano ther.

The fractures are apparently well developed along the line of thecontacts from north to south, this conclusion being supported by thestructure of the faults observable in the Serra do Mar, in Sao Paulo.The development of the system of east-west faults is much greater,and covers the whole basin. The numerous logs of wells throughoutthe sedim entary area supply considerable material for determining thestruc ture of the area.The Iraty shales appear as a key bed of unmistakable characteristics in the stratigraphic column. A continuous correlative study ofthis horizon fully confirms the tectonic character of the sedimentarybelt.

The diastrophism already mentioned affected the trap and thesubjacent sedimentary rocks simultaneously, as well as the base ofme tamo rphic and crystalline rocks of the complex.

The intrusives, which rest in considerable areas on top of thesedimentary series, apparently belong to various eruptive cyclessince, apart from the preponderant basalts, several intrusions of acidand nepheline rocks are known in the southern states, as for examplein Lages, Santa Catharina.

The intrusives greatly affect the form of the sedimentary rocks,creating structures of local character and, in some areas, of accentuated relief, and they may form conic or asymmetric domes, most ofwhich extend in the direction of the Serra Geral.

The orography of the belt has the character of a peneplain withintrusive protuberances and evidence of erosion, generally along theescarpment. Considerable areas of the intrusives have been baredby the acute erosion, thus creating extremely fertile areas of decomposed basalts (terra roxa).

Owing to the characteristic cross-bedding of the sediments, it isnot possible to consider the apparent stratification as of true tectonicvalue. The decisive factor in the structural study of a region with thepeculiar conditions of the Pa ran a B asin should be sought principallyin the correlation of the logs of the wells, as we have studied them.

Summary. Tectonically, and in a general way , the Pa ran a Basin


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1764 VICTOR OPPENHEIM

700

600

500

400-

300

200-

100-

0 ' N i v e l d o m a r

-100

-200

-300

CORTE ESTRUTURAL A-B NA ZONA DE SONDAGENS SAO PEDRO-XARQUEADAFIG. 10.Section AB of Sao Pedro-Xarqueada area, State of Sao Paulo. Location


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GONDWANA ROCKS OF BRAZIL I 7 6 5

400

3 0 0

E sc a la horizon tal 200I 2 3 < 5 6 7 6 9 10 Km

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S . P A U L O S E 6 U N D 0 V . O P P E N H E J M R I O O E J A N E IR O , J U L H O D E 1 9 M .shown in Figure 13. Vertical scale in meters above and below sea-level.


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CORTE ESTRUTURAL C - D N A ZONA DE SONDAGENS SAO PEDRO-XARQUEADAFIG. 11.Section CD of Sao Pedro-Xarqueada area, State of Sao Paulo. Location


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GONDWAXA ROCKS OF BRAZIL 1707

shown in Figure 13. Vertical scale in me ters above an d below sea-level.


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C O R T E E S T R U T U R A L E - F NA Z O N A D E S O N D A G E N S S A O P E D R O - X A R Q U E A D A - S . F jF I G . 12.Section EF of Sao Pedro-Xarqueada area, State of Sao Paulo. Location


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GONDWANA ROCKS OF BRAZIL 1769

I -700.^T^.^/.V.' .*.*.V/.' / / .' .VAV/iV.r.V/*V.*S^\

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f l f l o S E G U N D O V . O P P E N b B M' * | ~, ' ^ p m in Figure 13. Vertical scale in meters above and below-sea-level.

- * 0RIO DE JANEIRO, JULHO D E ,I9 3 4.


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GONDW AXA ROCKS OF BRAZIL 1771is a geo- sy nc l i no r ium of g r ab en ch a ra c t e r be tw een L a t s . 18 0 a n d24 0 S. , and a monoc l i ne on t he sou th , be tween L a t s . 24 0 a n d 33.T h e i n t e r n a l s t r u c t u r e c o m p r i s e s f a u l t s a n d

Documents

Oppenheim (1935)_Petroleum in Gondwana