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Papers by Ubiratan Faccini

AAPG Bulletin

Ten allomembers, labeled J-A, have been mapped in the deltaic Dunvegan Formation using 2340 wells... more Ten allomembers, labeled J-A, have been mapped in the deltaic Dunvegan Formation using 2340 wells and 63 outcrop sections. Each allomember spans about 200 k.y., is bounded by regional transgressive surfaces, and consists of 3-10 component shingles, apparently of autogenic origin. Allomembers H-E are discussed in this article. Their internal stacking patterns and bounding surfaces permit interpretation as depositional sequences. Sequences H-F have a sigmoidal-prismatic geometry, downlap to the southeast, and thin northwest onto the coastal plain. No differential thickening exists toward the orogen in the southwest. In contrast, sequence E thickens markedly toward the northwest. The tabular geometry of sequences H-F suggests accommodation was controlled by sea level change, whereas the wedge geometry of sequence E suggests significant tectonic tilting. Subaerial unconformities that bound valleys and extend onto adjacent interfluve paleosols can be traced 120-330 km updip into outcrop....

Apatite fission track thermochronology studies are applied to unravel the tectonic history of the... more Apatite fission track thermochronology studies are applied to unravel the tectonic history of the onshore southernmost Brazilian margin. Analyzed samples are collected in the Sul-rio-grandense Shield to address the Phanerozoic morphotectonic evolution of the margin, which included the intracratonic Paraná Basin and Mesocenozoic rocks. The Sul-rio-grandense southern shield, southern Brazil, is a major geotectonic feature of southernmost Brazil that includes Paleoproterozoic basement areas and Neoproterozoic fold belts linked to Brasiliano/Pan-African cycle. Crustal reworking and juvenile accretion events related to this cycle were positioned in the region between 900 and 500 Ma1 and were responsible for the assembly of southwestern Gondwana in southeastern South America. This shield is surrounded by the Paleozoic to Triassic sedimentary rocks of the Paraná Basin, which is in turn covered by the Cretaceous magmatic rocks of the Serra Geral Fm., so-called Paraná basalts. The shield is ...

The study area is located in the Southern Brazilian Shield of southernmost Brazil that includes P... more The study area is located in the Southern Brazilian Shield of southernmost Brazil that includes Paleoproterozoic basement areas and Neoproterozoic fold belts linked to Brasiliano/Pan-African cycle. sedimentary deposits that filled a preferential NE orogenic stages. Apatite fission track the tectonic history of the Camaquã performed followed two approximately NW Camaquã Basin and adjacent basement morphotectonic evolution. The FT samples. The confined FT lengths FT ages from the Camaquã Basin sediments 41Ma for samples that contain only one population of ages. There are some samples that two populations of ages: an older lengths in these samples vary from compared to the tracks from basement samples. recognized two cooling episodes Carboniferous and a second one that start paleotemperatures around 60°C continuing show a single, slower cooling trend from show us that AFT ages from Camaquã Basin and for adjacent indistinct. However, the track lengths more rapid cooling of this region C...

Águas Subterrâneas, 2011

Águas Subterrâneas, Vol. 25, No 1 (2011). ...

Journal of South American Earth Sciences, 2014

Two ash fall beds (tonstein) sampled from the post-glacial Permian deposits of the Paran a Basin ... more Two ash fall beds (tonstein) sampled from the post-glacial Permian deposits of the Paran a Basin have provided new UePb radiometric age constraints for this stratigraphic interval. The zircon grains were recovered from tonstein layers interbedded with fine-grained and carbonaceous lithologies in the middle portion of the Rio Bonito Formation. In both samples, the dominant population is interpreted as generated by explosive volcanism, as having formed immediately before the eruption. Based on 238 U/ 206 Pb, the selected zircon grains from the dominant population have weighted mean ages of 290.6 ± 2.8 Ma and 281.7 ± 3.2 Ma, corresponding to the Sakmarian and Kungurian ages in the Cisuralian epoch, respectively. These ages constrain the time of the deposition of the tonstein horizons and have important stratigraphic implications for the Late Paleozoic evolution of both the Paran a Basin and the southwestern region of Gondwana. The results presented here and the radiometric data already published suggest that deposition of the post-glacial coal-bearing deposits of the Rio Bonito Formation was probably initiated before the Early Permian. Thus, we infer that the climate had already ameliorated by this period in order to allow for the formation and accumulation of peat in this region of Gondwana.

Revista de la …, 2008

728 Revista de la Asociación Geológica Argentina 63 (4): 728 - 753 (2008) ... DEPOSITS IN THE LOS... more 728 Revista de la Asociación Geológica Argentina 63 (4): 728 - 753 (2008) ... DEPOSITS IN THE LOS MOLLES FORMATION (CUYO GROUP ... - JURASSIC) AT LA JARDINERA REGION, NEUQUÉN BASIN ... Paulo SG PAIM1, Ariane S. SILVEIRA1, Ernesto LC ...

The article presents a model based on the use of free tools aiming at the publication of socioeco... more The article presents a model based on the use of free tools aiming at the publication of socioeconomic and environmental data and dissemination of information on the internet. The structure of this model makes it possible to present information as tables, graphs, pictures or web maps. The choice of a particular presentation format is determined according to the goals of the developer. As a result of this work the user will create a virtual geographic database for the generation of static information and interactive web maps. The main tools used are the Spring geographic information system, MySQL relational database, PHP script and Apache HTTP server.

Águas Subterrâneas, 2004

RESUMO Uma porção estratigraficamente complexa do Sistema Aqüífero Guarani foi investigada a part... more RESUMO Uma porção estratigraficamente complexa do Sistema Aqüífero Guarani foi investigada a partir de uma abordagem metodológica integrada. Foram individualizados dois aqüíferos, denominados Passo das Tropas (principal aqüífero) e Caturrita, ...

Águas Subterrâneas, 2010

Limites ao fluxo regional no Sistema Aquífero Guarani (SAG), produzidos por dois lineamentos, den... more Limites ao fluxo regional no Sistema Aquífero Guarani (SAG), produzidos por dois lineamentos, denominados Rio das Antas (LRA) e Rio Forqueta (LRF), foram identificados no NE do Rio Grande do Sul, Brasil. Termometria e hidroquímica, foram diagnósticos para a caracterização das barreiras de fluxo. O bloco do SAG a NE dos lineamentos possui águas hiper a hipotermais (46,7ºC a 28,6ºC) e condutividades elétricas elevadas. Os blocos a sul do LRA e a oeste do LRF apresentam águas frias (19ºC a 21ºC) e hidroquímica relacionável ao aquífero captado, respectivamente Botucatu e Passo das Tropas. A potenciometria não define as compartimentações produzidas pelos lineamentos. Ao sul do LRA, a distribuição de cargas hidráulicas do SAG sugere existência de fluxo divergente, direcionado aos vales dos Rios das Antas e Caí. A barreira de fluxo representada pelo LRA se deve ao escalonamento de blocos de aquífero em zona de falhas, a hidroestratigrafia sendo constante; enquanto que aquela representada pelo LRF é devida à supressão da Formação Botucatu do registro estratigráfico, as Formações Serra Geral e Santa Maria estando em contato direto. Quando considerados os limites definidos pelos dois lineamentos propostos, são eliminadas as discrepâncias entre as cargas hidráulicas modeladas e observadas ao sul do vale do Rio das Antas.

Revista de la Asociacion Geologica Argentina

The Pliensbachian to Early Callovian Cuyo Group in the Arroyo La Jardinera area reflects a shelf-... more The Pliensbachian to Early Callovian Cuyo Group in the Arroyo La Jardinera area reflects a shelf-slope-basin plain physiography. A major unconformity defines the onset of a thick turbidite succession and represents a 2nd order sequence boundary. The older 2nd order depositional sequence comprises the base of Los Molles Formation and includes a transgressive-regressive cycle ascribed to basin plain and slope rise strata. The younger one, which includes the rest of the Cuyo Group, consists of a regressive succession punctuated by several abrupt shifts of physiographic elements (3rd order sequence boundaries). The 3rd order depositional sequences include Aalenian slope rise and slope deposits in the Los Molles Formation, Early Bajocian shelfal facies at the transition of the Los Molles and Lajas formations, and Middle to Late Bajocian inner shelf to nearshore strata in the Lajas Formation that are overlain by Bathonian alluvial deposits of the Challacó Formation. Higher frequency cycle...

Abstract Abstract This paper is about an almost uninterrupted exposure of the Jurassic Los Molles... more Abstract Abstract This paper is about an almost uninterrupted exposure of the Jurassic Los Molles Formation in the Arroyo La Jardinera region in the southern Neuquén Basin (western Argentina). It is based on the analysis of a high-resolution satellite images linked with extensive field data. Its main goal is to present a conceptual model for the studied turbidite system capable of explaining how sand and gravel were brought into and removed from the shelf margin and how these coarse-grained sediments were transported along and deposited on the slope and basin plain. The facies tract ascribed to this turbidite system represents high-frequency, lowstand systems tracts. From proximal to distal it includes the record of fluvial channels incised into mid to outer shelf deposits, turbidite channels scoured on slope strata, turbidite lobes resting on slope rise facies, and poorly-developed turbidite lobe fringes enclosed within basin plain strata. These gravity flow strata were assigned to...

Brazilian Journal of Geology, 2014

Turbidites have captioned the attention of sedimentologists during the last decades due their imp... more Turbidites have captioned the attention of sedimentologists during the last decades due their importance as hydrocarbon reservoirs. However, their relationship to delta systems still deserves further studies. This paper presents examples from a late deglacial to early post-glacial deltaic and turbidite strata exposed in the surroundings of Vidal Ramos (Santa Catarina State, Brazil), southern portion of the Paraná Basin. There, the uppermost part of the Mafra Formation and the Rio do Sul Formation onlap the Proterozoic basement and comprises an up to 360 m thick package. It includes (base to top) black shales, mass transport deposits (MTD) and sandy turbidites (Mafra Formation) as well as thin bedded turbidites (tbt), including one interval of black shales and sandy turbidites, overlain by proximal delta front sandstones (Rio do Sul Formation). The analysis of the succession shows two more than 150 m thick coarsening-upwards deltaic successions composed of turbidite sand sheets at their base (prodelta), followed by partially collapsed thin bedded turbidites (delta slope wedge) and delta front sandstones. Both turbidite sand-sheets abruptly overlay black shale intervals related to maximum flooding surfaces and therefore record correlative conformities. A detailed stratigraphic section elaborated from the correlation of four logs (1/100) suggests that distal delta front sands includes both thin bedded turbidites and wave reworked sands whereas the proximal delta front was dominated by long-lived underflows (hyperpycnal flows). The succession suggests that the most expressive turbidite beds (base of the delta systems) have resulted from relative sea-level falls (early lowstand) whereas the thin-bedded turbidites were related to the development of the late lowstand wedge. Black shales represent the transgressive systems tract and HST were not deposited or preserved in the area. High sediment supply associated with lowstand tracts could explain the occasional (Vidal Ramos) to common occurrence of slope failures (slumps and diamictites) involving thin bedded turbidites and delta front sandstones. This situation is quite logical in terms of deglacial periods, and resulting high sediment supply, within a long-term icehouse context, with prevalence of lowstand to transgressive settings.

The Talacasto paleovalley is situated in the Central Precordillera of San Juan, Argentina, where ... more The Talacasto paleovalley is situated in the Central Precordillera of San Juan, Argentina, where upper Carboniferous-Permian rocks (Paganzo Group) rest on Devonian sandstones of the Punta Negra Formation. This outcrop is an excellent example of a glacial valley-fill sequence that records at least two high-frequency cycles of the advance and retreat of a glacier into the valley. The paleocurrent analysis shows transport predominantly to the south, indicating that at this site the ice flow differs from the other nearby paleovalleys. Evidence of the glacial origin of this valley can be seen in the glacial striae on the valley's sides, as well as the U-shape of the valley, indicated by very steep locally overhanging valley walls. Deglaciation is indicated by a set of retransported conglomerates deposited in a shallow-water environment followed by a transgressive succession, which suggests eustatic rise due to meltwater input to the paleofjord. The complete sedimentary succession records distinct stages in the evolution of the valley-fill, represented by seven stratigraphical units. These units are identified based on facies associations and their interpreted depositional setting. Units 1 to 5 show one cycle of deglaciation and unit 6 marks the beginning of a new cycle of glacier advance which is characterized by different types of glacial deposits. All units show evidence of glacial influence such as dropstones and striated clasts, which indicates that the glaciers were always present in the valley or in adjacent areas during sedimentation. The Talacasto paleofjord provides good evidence of the Late Paleozoic Gondwana glaciation in western Argentina and examples of sedimentary successions which have been interpreted as being deposited by a confined wet-based glacier in advance and retreat cycles, with eventual release of icebergs into the basin. The outcrop is also a key for reconstructing the local glacial paleogeography, and it suggests a new interpretation that is not in agreement with previous studies. Finally, the importance of the Talacasto paleovalley for the Paganzo basin lies in its orientation, because it allows the reconstruction of the ice paleoflow and indication, for the first time, that marine ingressions into this area were not taking place along the Jachal trough, as expected, but along a different connection to the sea, which for this work we will call the San Juan Paleotrough.

Sedimentary …, 2003

The continental Triassic succession of southernmost Brazil comprises two second-order depositiona... more The continental Triassic succession of southernmost Brazil comprises two second-order depositional sequences-the Sanga do Cabral (Early Triassic) and the Santa Maria (Middle to Late Triassic) supersequences. The first one includes ephemeral, lowsinuosity fluvial deposits developed on a low gradient plain. Based on fossil tetrapods, especially procolophonids, an Upper Induan age is estimated for this sequence. Facies association of the Santa Maria Supersequence indicates low-sinuosity fluvial rivers, deltas and lakes. This supersequence can be further subdivided into three third-order sequences (age provided by palaeovertebrate biostratigraphic data) as follows: Santa Maria 1 (Ladinian), Santa Maria 2 (Carnian to Early Norian) and Santa Maria 3 (probably Raethian or Early Jurassic) sequences. The Gondwanides paroxysms I and II in the Sierra de la Ventana -Cape Fold Belt are directly related to the development of both supersequences. The source area of the Sanga do Cabral Supersequence was located to the south. It consisted of an uplifted peripheral bulge situated landward of the retro-foreland system, from where older sedimentary rocks were eroded. The source area of the Santa Maria Supersequence was also positioned southwards and related to the uplifted Sul-Rio-Grandense and Uruguayan shields. The Santa Maria Supersequence stratigraphic architecture is comparable to the Triassic rift basins of Western Argentina. Diagenesis, facies and palaeontology of the studied succession suggest a dominantly semiarid climate during the Triassic. D

Sedimentology, 1999

To date, discussion of changes in alluvial style and in the character of palaeosols in relation t... more To date, discussion of changes in alluvial style and in the character of palaeosols in relation to changes in accommodation and sediment supply on oodplains has primarily been from a conceptual standpoint: few case studies are available against which to test ideas. One hundred and thirty metres of nonmarine strata of the Dunvegan Formation were examined in 14 closely spaced sections in the canyon of the Kiskatinaw River, NE British Columbia, Canada. This site was located about 120 km inland from the transgressive limit of the contemporary marine shoreline and represents almost exclusively freshwater environments. Fluvial channels in the Kiskatinaw River section are of two types. Small, single-storey, very ®ne-to ®ne-grained sandstone ribbons with W/T ratios <30, encased in ®ne-grained¯oodplain sediments are interpreted as anastomosed channels. Fine-to medium-grained, laterally accreted point-bar deposits forming multistorey sand bodies with individual W/T ratios >30 are interpreted as the deposits of meandering rivers ®lling incised valleys. Interchannel facies include the deposits of crevasse channels and splays, lakes, oodplains and palaeosols. Floodplain palaeosols consist of laterally heterogeneous, simple palaeosol pro®les and pedocomplexes similar to modern Entisols, Inceptisols and hydromorphic soils. Inter¯uve, sequencebounding palaeosols adjacent to incised valleys are laterally continuous, up to 3 m thick and can be reliably identi®ed using a combination of (1) stratigraphic position; (2) ®eld observations, such as thickness, structure, colour, degree of rooting; and (3) micromorphological features, such as evidence of bioturbation, clay coatings, ferruginous features and sphaerosiderite. Inter¯uve palaeosols are similar to modern Al®sols and Ultisols. Correlation of the local stratigraphic succession with the regional sequence stratigraphic framework, based on 2340 well logs and 60 outcrop sections, shows that the vertical changes in coastal plain character (more coals and lakes vs. more pedogenesis) can be related to relatively high-frequency base level cycles (eustatic?) that are expressed as transgressive±regressive marine cycles in downdip areas. Regional isopach maps show that these cycles were progressively overprinted and modi®ed by an increasing rate of tectonic subsidence in the north and west. The character of palaeosols developed on aggrading¯oodplains primarily Present addresses: Sedimentology (1999) 46, 861±891 Ó 1999 International Association of Sedimentologists 861 re¯ects local sediment supply and drainage. In contrast, well-developed inter¯uve palaeosols record pedogenesis during periods of reduced or negative accommodation (base level fall). Vertical changes in¯oodplain palaeoenvironments and palaeosol types re¯ect changes in accommodation rate. The detailed micromorphological analysis of inter¯uve palaeosols represents a powerful application of an under-used technique for the recognition of key surfaces in the geological record. This has broad implications for non-marine sequence stratigraphy.

Journal of South American Earth Sciences, 2010

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j s a m e s (silc... more j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j s a m e s (silcificados), que estão associados ao início da formação de superfícies regulares, interpretados como resultado da precipitação química de carbonatos em ambiente palustre. O padrão de cores do marmoreado, bem como as acumulações de carbonatos não são, na sua maioria, produtos de processos pedogênicos, mas refletem predominantemente a atividade de águas subterrâneas e de variações do nível freático. Os intraclastos carbonáticos e os carbonatos bandados (silicificados) têm sua gênese relacionada a processos pedogênicos em sentido estrito. Deste modo é natural que as águas fluvial e meteórica sejam os fatores essenciais para que a evolução das paleoalterações na Formação Sergi acompanhe a tendência deposicional, já que ambos são controlados pelos mesmos fatores -clima, relevo e taxa de sedimentação.

Photolineaments and stream alignments, visible on radar and satellite images and on aerial photos... more Photolineaments and stream alignments, visible on radar and satellite images and on aerial photos of varied scales, define structural blocks in sedimentary rocks, characterized by a certain stratigraphic homogeneity, allowing the possibility of correlation on heavily vegetated areas. At the central portion of the Rio Grande do Sul State (Southern Brazil), six structural blocks were recognized (Santa Maria, São João do Polêsine,
Faxinal do Soturno, Agudo, Paraíso do Sul and Candelária), based on fault displacements on the order of 100 m, which is more than the average thickness of some lithostratigraphic units. At the Santa Maria block, groundwater wells and field data allowed to recognize five structural subblocks
(Cabeceira do Raimundo, Tancredo Neves, Cidade, Km 3, Camobi), with fault displacements averaging 30 m. The identified fault displacements, in lithofaciologically similar deposits, lead to a biostratigraphic discontinuity, from block to block, produced by the lateral juxtaposition of different biozones. The main alignments show distinct cenozones on each side, leading to difficulties on litho- and biostratigraphic correlations, at the regional scale. This study seeks to demonstrate that the advance on the comprehension of stratigraphic correlations at the central portion of the Rio Grande do Sul State must consider the structural compartmentalization of the region.

Five types of paleo-weathering and carbonate precipitation were recognized in fine-grained deposi... more Five types of paleo-weathering and carbonate precipitation were recognized in fine-grained deposits of the Alemoa Member, Santa Maria Formation, Middle to Upper Triassic of southern Brazil. The fauna and flora found in these lithologies are important dating tools, but only in a generic way, misleading the time involved in periods of deposition and non deposition. The identified types of deposits are (i) reddish mudstones, with none or little paleo-weathering, (ii) mottled mudstones, with incipient pedogenesis, mainly mottling, destratification, animal and vegetal colonization, (iii) carbonate veins, with more evidences of exposure and root action, (iv)
carbonate siltstones/sandstones, where restricted fluvial deposits are cemented by phreatic carbonate, and (v)
carbonate nodules and lenses, in which small lenses of a very compact calcrete are at the top and in the center of carbonated siltstone/sandstone beds, distinguished by its crystalinity, hardness and brighter color. The recorded microfacies point to a cyclic variation of the mainly high phreatic level, forming cracks and pedotubules (pedogenesis) filled with carbonate and Fe and Mn oxides (phreatic). The identification of five distinct pedofacies and the stratigraphic correlation in the sedimentary package of the Alemoa Member (base, middle or topmost
position) suggest a probable association of paleo-weathering processes and vertebrate preservation. Near channel facies, mainly at the base and top, present smaller exposure periods and higher variations on the phreatic level, and consequently, the best preserved vertebrate fossils. On the other hand, facies which are far from the channel, record more subaerial exposure and more significant phreatic variation, leading to more advanced (although still incipient) paleo-weathering and carbonate precipitation, and to a worst fossil preservation.