Conglomeratic deposits of the Paleo Tietê River: event of fluvial aggradation during the evolution of the São Paulo peripheral depression

Os depósitos conglomeráticos situados nos arredores do distrito de Laras, São Paulo, capeiam colinas amplas de topo aplainado com altitudes entre 500 e 570 m. Ocorrem em discordância sobre as formações Piramboia e Teresina da Bacia do Paraná. São constituídos de fácies de ortoconglomerados polimíticos com matriz arenosa, mal selecionada. A análise de proveniência realizada evidenciou o predomínio de clastos de silexito, quartzito e quartzo de veio, bem arredondados e oblatos, sugerindo longo transporte. A análise estatística revelou maior frequência de litotipos resistentes ao transporte na porção sudeste da área. Na porção noroeste predominam clastos menos resistentes, representados por oólito e coquina, sugerindo erosão da Formação Teresina e transporte curto a partir de terrenos paleozoicos existentes na Depressão Periférica Paulista. Dados de Luminescência Opticamente Estimulada (OSL) possibilitaram conferir idade mínima de 371.4 ± 27.5 ka para a unidade. Os depósitos conglomeráticos são interpretados como produto de deposição em canais fluviais tributários de grande porte, ou mesmo de um canal tronco principal, de um extenso sistema deposicional fluvial com paleomergulho deposicional para sudoeste do Estado de São Paulo. Esse sistema fluvial antecessor do atual Rio Tietê, com proveniência de nordeste, tinha área de drenagem em terrenos pré-cambrianos situados ao leste da área de ocorrências das unidades paleozoicas. Devido à localização e ao porte, os depósitos descritos registram importante fase de agradação fluvial na história geológica do Rio Tietê, evento de sedimentação ocorrido durante o longo processo de denudação que deu origem à Depressão Periférica Paulista durante o Cenozoico.The conglomerate deposits located near the district of Laras, São Paulo, cover wide flat-topped hills with altitudes between 500 and 570 m. They occur in discordance on older Piramboia and Teresina formations of the Parana Basin and are consisted of poorly selected sandy matrix polymeric orthoconglomerates. The provenance analysis performed showed the predominance of well-rounded and oblate silex clasts, quartzite and quartz vein clasts, suggesting long-distance transport. Statistical analysis revealed a higher frequency of transport-resistant lithotypes in the southeastern portion of the area. In the northwest portion, less resistant clasts predominate, represented by oolite and coquina, suggesting erosion of the Teresina Formation and short transport from Paleozoic terrains existing in the São Paulo Peripherical Depression. Optically stimulated luminescence (OSL) data allowed for a minimum age of 371.4 ± 27.5 ka for the unit. Conglomerate deposits are interpreted as the product of deposition in large tributary fluvial channels, or even of a main trunk channel, of an extensive fluvial depositional system with depositional paleomoving diving to the southwest of São Paulo State. This predecessor river system of the current Tietê River, coming from the northeast, had drainage area in precambrian lands located to the east of the occurrence area of the Paleozoic units. Due to their location and size, these deposits represent an important phase of fluvial alluviation in the geological history of the Tietê River, a sedimentation event that occurred during the long-term denudation process that gave rise to the São Paulo Peripherical Depression during the Cenozoic

Análise de lineamentos estruturais no Domo de Lages (SC) com uso de imagens de satélite e mapas de relevo sombreado

Este trabalho apresenta o estudo dos lineamentos estruturais na região do Domo de Lages, porção centro-sul do Estado de Santa Catarina, e sua relação com as diferentes unidades estratigráficas da Bacia do Paraná que ocorrem na região. Os lineamentos estruturais foram interpretados a partir da análise digital de imagens de satélite e de mapas de relevo sombreado, com o uso de técnicas de geoprocessamento. Os resultados mostram lineamentos estruturais com orientações NW, NNE, NE, ENE e E-W. Os lineamentos maiores (4 - 50 km) foram interpretados a partir dos mapas de relevo sombreado, enquanto os menores (1 - 3 km) foram interpretados a partir da imagem de satélite. De acordo com os dados de campo, estes lineamentos afetam rochas vulcânicas da Formação Serra Geral da Bacia do Paraná e rochas alcalinas associadas ao domo. Em todas estas direções estruturais são encontradas evidências de falhas transcorrentes. A formação das falhas transcorrentes destrais NNE tem sido relacionada a uma tensão compressiva orientada NE-SW. Considera-se que a idade máxima de geração dessas orientações estruturais situa-se no limite do Cretáceo Superior ao Paleógeno. A formação dessas estruturas tem sido relacionada à reativação de estruturas mais antigas presentes na bacia e no seu embasamento.This work focuses on the study of structural lineaments in the Domo de Lages region, central-south area of Santa Catarina State, and their relationship with the different stratigraphic units of the Paraná Basin that are present in this area. The lineaments were interpreted from Landsat and shaded relief images, using geoprocessing techniques. The results show structural lineaments with NW, NNE, NE, ENE and E-W trends. The larger lineaments (4 - 50 km) were interpreted using shaded relief maps, whereas the smaller lineaments were interpreted using satellite images (1 - 3 km). According to field data, these lineaments affect the volcanic rocks of Serra Geral Formation (Paraná Basin) and alkaline rocks associated with the dome. In all these structural trends, evidences of transcurrent faults were found. The formation of transcurrent faults with NNE trend has been related to compressive NE-SW stress. Late Cretaceous/Paleogene is the maximum age considered for the development of these structural trends associated with transcurrent faults. The formation of this structural pattern has been linked to the reactivation of older structures present in the basin and its basement

A DIVERSIDADE CENOZÓICA DOS BIVALVES ANTÁRTICOS NÃO REFLETE AS MUDANÇAS AMBIENTAIS DO OCEANO AUSTRAL APÓS O ISOLAMENTO TÉRMICO DA ANTÁRTICA.

Environmental changes occurred in Southern Hemisphere in response to the separation of Antarctica from Australia, around Eocene/Oligocene boundary, and from South America, during the late Oligocene, greatly affected biodiversity in Southern Ocean. Although it is generally accepted that the Antarctic thermal isolation affected the Cenozoic biodiversity by changing environmental conditions, there is no available study concerning the Cenozoic dynamics of Antarctic bivalve diversity in relation to climatic changes. In this study, an assembling of all available bivalve family and genera described from Antarctic Cenozoic deposits as well as modern bivalve family and genera were analyzed in order to evaluate possible effects of Cenozoic environmental changes on Antarctic bivalve diversity along the Cenozoic. The main conclusion of this work is that the currently known Cenozoic record of the Antarctic bivalves does not reflect Cenozoic environmental changes. This is probably related to the restricted record of Antarctic bivalves, and therefore to the scarce knowledge on the Cenozoic diversity of the group. The analysis also revealed that Cenozoic intervals of highest diversity are attributed to few areas in Antarctica that are available for paleontological exploration. Besides, the large number of recorded bivalve taxa in some Cenozoic intervals may be related to the stratigraphic control of deposits.As mudanças ambientais ocorridas no Hemisfério Sul em resposta à separação da Antártica e a Austrália, no limite Eoceno/Oligoceno, e da Antártica e a América do Sul, durante o final do Oligoceno, afetaram profundamente a biodiversidade das regiões do Oceano Austral. Muito embora seja amplamente aceito que o isolamento térmico da Antártica influenciou a biodiversidade ao alterar as condições ambientais da região, não há estudos relacionados à dinâmica de diversidade dos bivalves antárticos frente às mudanças climáticas ao longo do Cenozóico. No presente estudo, foi analisado o números de famílias e gêneros de bivalves fósseis descritos em depósitos cenozóicos da Antártica, bem como o número de famílias e gêneros de bivalves modernos, com o objetivo de avaliar possíveis efeitos das mudanças ambientais ocorridas ao longo do Cenozóico na diversidade dos bivalves antárticos. Como principal conclusão deste trabalho, o conhecimento atual sobre os bivalves cenozóicos da Antártica não reflete as mudanças ambientais ocorridas ao longo do Cenozóico. Isto provavelmente está relacionado ao registro limitado dos bivalves antárticos e, conseqüentemente ao conhecimento incipiente da diversidade cenozóica do grupo. A análise revelou também que os intervalos de tempo de maior diversidade são, na realidade, resultantes de estudos realizados nas poucas áreas de rochas aflorantes disponíveis para exploração paleontológica na Antártica. No entanto, o grande número de táxons de bivalves registrados em alguns intervalos do Cenozóico pode estar relacionado ao controle estratigráfico dos depósitos

Late Cretaceous insect trace fossils from the Capacete Formation, Sanfranciscana Basin, Brazil

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The missing mats: MISS diversity and influence on life preservation in the late Ediacaran of the Tandilia System, Argentina

Abstract The terminal Ediacaran fossil record includes microbial mats and body fossils characterized by simple morphologies, which represents a challenge to understand several aspects related to the paleoecology of the emerging complex life. The marine siliciclastic deposits of the Cerro Negro Formation (~560–550 Ma) contain evidence of different styles of microbially induced sedimentary structures (MISS) and discoidal forms associated with them. Different types of MISS, such as Kinneyia and wrinkle structures, elephant skin, and Arumberia, are reported and related to shallow marine depositional environments. These morphologies are commonly associated with the high quality of preservation of body fossils in Ediacaran deposits. The preservation of Aspidella discoidal holdfast is related to biotic and abiotic processes involving substrate sealing by microbial mats, fluidization, and probably organic matter decay. Both abiotic factors (tidal currents and waves, added to liquefaction and sand injection) and biotic factors (substrate biostabilization by microbial mats favoring sediment cohesion) are considered the main ones responsible for the preservation style in the Cerro Negro Formation. This formation constitutes a remarkable example in SW-Gondwana of how preservation dynamics took place on a seabed sealed by microbial mats and is an important deposit conserving diverse Ediacaran forms of life in South America

Microbially induced pseudotraces from a Pantanal soda lake, Brazil : Alternative interpretations for Ediacaran simple trails and their limits

Despite the absence of metazoans, structures resembling animal traces are common in a soda lake from the western Brazil Pantanal wetland. Pantanal soda lakes are ecologically extreme environments that preclude complex life, allowing extremophiles to flourish. Direct observation indicates that these structures are pseudotraces, representing groove marks that result from the interaction of wave-transported floating rafts of epibenthic microbial mat fragments with the substrate. Variations in wind/wave direction and intensity result in marks of different size and morphology. The most common pseudotraces are simple and slightly curved, narrow grooves (type 1), whereas others are straight and present raised lateral ridges (type 2). Both are V-shaped in cross section. Type 3 comprises long, sinuous, shallow grooves, displaying internal crescentic laminated infill and U-shaped cross section. The similarity of these pseudotraces to Ediacaran structures usually interpreted as animal trace fossils suggests that care should be exercised in their analysis. A set of criteria is proposed to differentiate microbially induced pseudotraces from trace fossils. Analysis of Ediacaran structures needs to be performed on a case-by-case basis, taking into account morphology, orientation, and preservation style of the structure, sedimentary environment, and presence or absence of microbial mats.Centro de Investigaciones Geológica

Cloudina-Corumbella-Namacalathus association from the Itapucumi Group, Paraguay: Increasing ecosystem complexity and tiering at the end of the Ediacaran

The intriguing Ediacaran fossil Namacalathus is described from limestones of the Tagatiya Guazú Formation, Itapucumi Group, Paraguay. This is the fifth occurrence of the genus in the Ediacaran geological record. The Paraguayan Namacalathus specimens are preserved as partially complete spheroidal cups with an opening at the top and thin walled stems. The remains of this soft-calcified globe-shaped organism occur as sparse disarticulated parautochthonous fragments within bioclastic deposits dominated by Cloudina shells with subordinate Corumbella fragments. The co-occurrence of these three skeletal metazoan species in the same environmental context attests that the diversity of the Paraguayan accumulations is ecologically comparable to the typical skeletal assemblage of the Nama Group. The discovery of new samples of Namacalathus in the Itapucumi Group also indicates that this genus presented a broader paleobiogeographic distribution than previously thought and, in the same way as Cloudina, it represents a low latitude, shallow water metazoan of the Ediacaran Gondwana.Centro de Investigaciones Geológica

Shell beds from the Low Head Member (Polonez Cove Formation, early Oligocene) at King George Island, west Antarctica: new insights on facies analysis, taphonomy and environmental significance

Shell bed levels in the Low Head Member of the early Oligocene Polonez Cove Formation at King George Island, West Antarctica, are re-interpreted based on sedimentological and taphonomic data. The highly fossiliferous Polonez Cove Formation is characterized by basal coastal marine sandstones, overlain by conglomerates and breccias deposited in fan-delta systems. The shell beds are mainly composed of pectinid bivalve shells of Leoclunipecten gazdzickii and occur in the basal portion of the Low Head Member. Three main episodes of bioclastic deposition are recorded. Although these shell beds were previously interpreted as shelly tempestites, we present an alternative explanation: the low fragmentation rates and low size sorting of the bioclasts resulted from winnowing due to tidal currents (background or diurnal condition) in the original bivalve habitat. The final deposition (episodic condition) was associated with subaqueous gravity driven flows. This new interpretation fits with the scenario of a prograding fan-delta front, which transported shell accumulations for short distances near the depositional site, possibly between fair-weather and storm wave bases. This work raises the notion that not every shell bed with similar sedimentological and taphonomic features (such as geometry, basal contact, degree of packing and shell orientation in the matrix) is made in the same way.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection