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Made available in DSpace on 2022-04-28T19:47:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-01 Global Neoproterozoic glaciations are related to extreme environmental changes and the reprise of iron formation in the rock record. However, the lack of narrow age constraints on Cryogenian successions bearing iron-formation deposits prevents correlation and understanding of these deposits on a global scale. Our new multiproxy data reveal a long Cryogenian record for the Jacadigo Group (Urucum District, Brazil) spanning the Sturtian and Marinoan ice ages. Deposition of the basal sequence of the Urucum Formation was influenced by Sturtian continental glaciation and was followed by a transgressive interglacial record of >600 m of carbonates that terminates in a glacioeustatic unconformity. Overlying this, there are up to 500 m of shale and sandstone interpreted as coeval to global Marinoan glacial advance. Glacial outwash delta deposits at the top of the formation correlate with diamictite-filled pa-leovalleys and are covered by massive Fe and Mn deposits of the Santa Cruz Formation and local carbonate. This second transgression is related to Marinoan deglaciation. Detrital zircon provenance supports glaciostatic control on Cryogenian sedimentary yield at the margins of the Amazon craton. These findings reveal the sedimentary response to two marked events of glacioeustatic incision and transgression, culminating in massive banded iron deposition during the Marinoan cryochron. Faculdade de Tecnologia Universidade de Campinas Departamento de Geología Universidade Federal de Ouro Preto Instituto de Geociências Instituto de Astronomía Geofísica e Ciências Atmosféricas Universidade de São Paulo Departamento de Geologia Universidade Estadual Paulista Departamento de Geologia Universidade Estadual Paulista

Made available in DSpace on 2019-10-04T12:35:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) PROPE - UNESP The Itapucumi Group is recognized worldwide due to its well-preserved Ediacaran fossil assemblage. Despite its paleontological importance, this unit remains as the least studied South American Neoproterozoic sedimentary succession. Recorded at northern Paraguay, the Itapucumi Group is a similar to 400 m-thick siliciclastic and carbonate succession deposited on the Paleoproterozoic basement of the Rio Apa Craton. At west, this unit is deformed and metamorphosed, whereas the eastern domain constitutes an undeformed cratonic cover. The Itapucumi Group comprises, from base to top, siliciclastic rocks of the Vallemi Formation, succeeded by limestones and dolomites of the Camba Jhopo and Tagatiya Guazu formations, which are capped by marls and mudstones of the Cerro Curuzu Formation. The entire sedimentary succession consists of three depositional sequences deposited in a large rimmed carbonate platform open to the ocean westward: S.1, the lowermost predominantly terrigenous, and sequences S.2 and S.3, comprising carbonate and terrigenous facies associations. Carbon isotope data from limestones and dolostones show values of + 1.93 parts per thousand delta C-13 VPDB and Sr-87/Sr-86 ratios of 0.7084 and 0.7089, in agreement with a depositional age between 600 Ma and 550 Ma and coherent with the Cloudina biozone. These data support the paleogeographic correlation between the Itapucumi and Corumba groups at the margins of the Amazonian and Rio Apa Craton. The siliciclastic basal successions of both units, are interpreted as deposited in rift basins developed during the fragmentation of the Rodinia supercontinent (Cryogenian to Ediacaran). Later thermal subsidence led to the generation of a new accommodation space around 550 and 528 Ma, recording extensive carbonate platforms along the margins of Pampia, Amazonian and Rio Apa cratons. The deformation of the Itapucumi and Corumba basins started at around 528 Ma, and was controlled by the reactivation of listric and normal faults generated during the rift stage. The opposite tectonic vergence observed in the Vallemi and Paraguay fold-and-thrust belts can be ascribed to oppose master fault polarities in the precursor basins of this context, as well as to the rigid behavior of the Rio Apa Craton. The compressional phase ended around 484 Ma, and corresponding to the last stresses related to the Brasiliano Cycle and the closure of SW Gondwana. Univ Estadual Paulista, Dept Geol Aplicada, Inst Geociencias & Ciencias Exatas, Ave 24A,1515, BR-13506900 Rio Claro, Brazil Univ Estadual Campinas UNICAMP, Fac Tecnol, Rua Paschoal Marmo 1888, BR-13484332 Jd Nova Itdlia, Limeira, Brazil Univ Sao Paulo, Inst Energia & Ambiente, Ave Prof Luciano Gualberto 1289, BR-05508010 Sao Paulo, Brazil Univ Sao Paulo, Inst Geociencias, Rua Lago 562, BR-05508010 Sao Paulo, Brazil Univ Fed Sao Paulo, Dept Ecol & Biol Evolut, Rua Prof Artur Riedel 275, BR-09972270 Diadema, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Zool, BR-18618000 Botucatu, SP, Brazil Univ Brasilia, Inst Geociencias, ICC Ala Cent, BR-70910900 Brasilia, DF, Brazil Fac Ciencias, Dept Geol, Calle Igua 4225, Montevideo 11400, Uruguay UNLP, CONICET, Ctr Invest Geol, Calle 1,644, RA-1900 La Plata, Buenos Aires, Argentina Univ Fed Pernambuco, NEG LABISE, Ave Acad Helio Ramos, BR-50670000 Recife, PE, Brazil Univ Estadual Paulista, Dept Geol Aplicada, Inst Geociencias & Ciencias Exatas, Ave 24A,1515, BR-13506900 Rio Claro, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Zool, BR-18618000 Botucatu, SP, Brazil FAPESP: 2004/012330 FAPESP: 2010/19584-4 FAPESP: 2010/02677-0 FAPESP: 2015/24608-3 CNPq: 490234/2005-4 CNPq: 444070/2014-1

O crescente interesse pelo ecoturismo levou ao aumento no número de visitas a parques nacionais e estaduais, o que implicou na necessidade de organização dessa atividade. Pessoas locais, por conhecerem os lugares e trilhas, começaram a ser solicitadas para conduzir os visitantes. Com aumento progressivo dessa relação com os turistas, este profissional passou a ser formalmente reconhecido pelas instituições responsáveis pelas unidades de conservação, as quais passaram a cadastrar os condutores, e exigir sua formação através de cursos e treinamentos. Um dos temas abordados nos cursos de formação de condutor é as Geociências e se tem, através desses cursos, uma excelente oportunidade de divulgação dessa área. A correta formação dos condutores em Geociências possibilita a esses profissionais terem uma visão sistêmica da área de trabalho, o que se reflete na qualidade do serviço oferecido ao visitante ao mostrar a evolução geológica da região e como ela se relaciona com a biota e questões históricas e sócio culturais. Os cursos em Geociências devem apresentar o mínimo de 40 horas de aulas, teóricas, práticas e atividades de campo na região, com abordagem sistêmica do funcionamento do Planeta Terra, onde se procura mostrar a relação entre os processos da dinâmica interna com os da dinâmica externa, através da Tectônica Global e explanação dos processos formadores de rochas, com atividades práticas. O Tempo Geológico deve ser apresentado, junto aos conceitos de Paleontologia, de tal forma que o condutor se encontre preparado a apresentar sua versão pessoal da história geológica da região onde vai trabalhar. Ao instruir ainda os condutores com os resultados de pesquisas geológicas realizadas na região, estes se tornam os melhores divulgadores e propagadores das informações disponíveis tendo, assim, papel preponderante na divulgação das Geociências.

The Tamengo Formation (Corumbá Group) is an important Ediacaran stratigraphic unit in South America due to the presence of metazoan fossils and geochemistry data of carbonate rocks, with excellent geochronological delimitation (between 555–541 Ma) obtained by U–Pb dating on volcanic zircons. The present work shows three new species of macroalgae found as carbonaceous compressions and studied for their morphology and taxonomy. All new taxa are characterized as centric macroalgae; Tamengophyton espinosa sp. nov. is a fan-shaped alga with striated thalli, dichotomous branches, trichomes with perpendicular growth, and a connecting membrane. Ladariella hidria sp. nov. is formed by a set of striated and branched thalli in a cylindrical form with almond-shaped structures in the top. Ladariophyton veinosa sp. nov. is characterized by the main growth thallus and an enlarged longitudinal structure at the center. These new occurrences of macroalgae add to the largest life assemblages in the Neoproterozoic of South America, which contributes to documentation of the evolutionary history of macroalgae and the paleoecological settings of the Late Ediacaran.

The interest in geoparks in Brazil began after the inclusion of the Araripe Geopark into the Global Geopark Network (GGN) in 2006. After that, several areas within Brazil were proposed as potential geoparks, two of which were then formalized—the Quadrilatero Ferrifero (Minas Gerais) and Bodoquena-Pantanal (Mato Grosso do Sul), and formal applications were submitted to GGN in 2010 but not accepted. In spite of the relevance in the geology and paleontology of both areas, the refusals were due to being only a project and not an actual functioning structured geopark yet working. No kind of inventory or quantification of the geological sites was carried out to both of the proposed geoparks. Furthermore, the purpose of the present work is to present an inventory of the sites of the area proposed for the Geopark Bodoquena-Pantanal (GBP) in an effort to demonstrate the significance of the geological heritage of the area. The area of the GBP includes Ediacaran animal fossils, which provide information about the geological record just before the Cambrian Explosion. This record created international interest in the area, together with sections with that record of global changes that characterized the end of the Neoproterozoic Eon, such as the iron formations of the Urucum Massif (Rapitan type) and Marinoan glacial sediments and limestone (Tamengo Formation). The present inventory was compiled by the GEOSSIT platform of the Geological Survey of Brazil (CPRM), which is based on the method of Brilha (2016), with modifications. The 51 sites investigated were distributed among 6 geological frameworks, defined to represent the geological history of the region, and 26 sites were considered as geosites, of which 12 present international relevance, specifically the sites of Corumba Group, due to the importance for the investigation of the Ediacaran period. The inventory and its numerical result show the scientific importance of the area, as already recognized by international meetings and publications on the geology, and is useful to future plan and revision of the proposed geopark.

We present enigmatic toroidal carbonate concretions retrieved from 700 m water depth from two sites in the upper plateau of the Rio Grande Rise. The concretions have a diameter of ~15 cm and a central hole of ~5 cm, and were observed on top of loose bioclastic sand over an area of ~30 m2 at 0.5–1.5 m from one another. They consist of brown, porous, bioclastic grainstone, lacking internal structures. Grains consist of sand (

O Vale do Ribeira, no Estado de São Paulo, é conhecido por importantes terrenos cársticos o qual, apesar de relativa grande extensão em área, possui poucos depósitos de tufas, restrito a algumas drenagens. Neste trabalho, são descritas duas novas ocorrências de tufas no Vale do Ribeira: os depósitos da Cachoeira de Taquaruvira situada no Córrego Taquaruvira-Bombas (Iporanga - SP), e os depósitos de afluente do rio Catas Altas (Ribeira - SP). Estas novas ocorrências de tufas, somadas às da Serra do André Lopes, são as únicas conhecidas na região e consideradas as de posição mais meridional dentre os depósitos descritos no Brasil. O primeiro depósito está associado a área cárstica de Bombas (a montante) e apresenta depósitos em cachoeira já erodidos. O segundo depósito situa-se próxima a um pequeno corpo carbonático sem informações sobre carste, e apresenta dois depósitos, um ativo, de tufas em cachoeira, que ocorre onde a drenagem possui maior gradiente hidráulico, e recarga totalmente autogênica; e o outro inativo, de ruditos cimentados, mais a jusante, que ocorre sobre uma superfície de baixa inclinação, e com contribuição de recarga alogênica. Os depósitos descritos são caracterizados por depósitos de represas e cachoeiras, depositados em rios de vertente, com bacia de drenagem com predomínio de recarga autogênica.

Brazil is a natural laboratory for the application of isotope stratigraphy tools on the study of Precambrian sedimentary successions, with excellent registers of Archean, Paleo, Meso, and Neoproterozoic age. Those successions witnessed the most extreme and unidirectional events in Earth's history, such as the Paleoproterozoic and Neoproterozoic oxygenation events (GOE and NOE), the main stages of iron formation deposition, the global Cryogenian glaciations and the explosive diversification of metazoans near the Precambrian/Cambrian border. Chemical sedimentary rocks such as carbonates, iron formations and evaporites that can act as natural recorders of seawater composition are present in all of those successions and furnish important pieces of evidence in order to reconstruct the chemostratigraphic record. The field of isotope stratigraphy keeps expanding in Brazil and novel information from developing isotopic systems will surely add to the growing database and provide important information on Earth's ancient biogeochemical cycles in the years to come.

Show caves provide tourists with the opportunity to have close contact with natural underground spaces. However, visitation to these places also creates a need for management measures, mainly the definition of tourist carrying capacity. The present work describes the results of climate monitoring and atmospheric profiling performed in Santana Cave (Alto Ribeira State and Tourist Park – PETAR, Brazil) between 2008 and 2011. Based on the results, distinct preliminary zones with different levels of thermal variation were identified, which classify Santana Cave as a warm trap. Two critical points along the tourist route (Cristo and Encontro Halls) were identified where the temperature of the locality increased by 1.3 °C when tourists were present. Air flow from the inner cave to the outside occurs during the austral summer, and the opposite flow occurs when the outside environment is colder than the air inside the cave during the austral winter. The temperature was used to establish thresholds to the tourist carrying capacity by computing the recovery time of the atmospheric conditions after the changes caused by the presence of tourists. This method suggests a maximum limit of approximately 350 visits per day to Santana Cave. The conclusion of the study is that Santana Cave has an atmosphere that is highly connected with the outside; daily variations in temperature and, to a lesser extent, in the relative humidity occur throughout the entire studied area of the cave. Therefore, the tourist carrying capacity in Santana Cave can be flexible and can be implemented based on the climate seasonality, the tourism demand and other management strategies.

The genus Cloudina Germs, 1972 includes seven species restricted to Ediacaran strata: 1. Cloudina lucianoi (Beurlen and Sommer, 1957) (Tamengo Formation, Brazil); 2. Cloudina hartmanae Germs, 1972 (Nama Group, Namibia); 3. Cloudina riemkeae Germs, 1972 (Nama Group, Namibia; 4. Cloudina waldei Hahn and Pflug, 1985 (Tamengo Formation, Brazil); 5. Cloudina lijiagouensis Zhang et al., 1992 (Yangtze Platform, China), 6. Cloudina sinensis Zhang et al., 1992, (Yangtze Platform, China); and 7. Cloudina carinata Cortijo et al., 2010 (Spain). Cloudina lucianoi was originally attributed to Aulophycus Fenton and Fenton, 1939 and was later suggested to represent a species of Cloudina . Briefly, Cloudina differs from Aulophycus in having a lamellar sessile benthic funnel-within-funnel skeleton instead of a tube-shaped skeleton. Additionally, Aulophycus has been considered restricted to the Cambrian, whereas all Cloudina species have been recorded only in the Ediacaran, with extinction of all species at the end of this period being observed. The results of taxonomic studies of Cloudina lucianoi are presented, as well as a revision of type-section, morphometric analysis, stratigraphic distribution and biostratigraphy. For this focal species, a new description, new diagnosis and morphometric analyses are included. Regarding taxonomy, a brief history is given of the Genus Cloudina , with remarks comparing Cloudina lucianoi with four other species. Additionally, new illustrations of type-material of Cloudina lucianoi , Cloudina hartmanae and Cloudina riemkeae are presented. The aforementioned species are revised in this report; additionally, an up-to-date stratigraphic approach and illustrations of the type-horizon of this species are included. A detailed comparison of the seven species is conducted to present a clearer diagnosis for this species described with material recovered from Brazil.

The massive Fe and Mn deposits of the Urucum district (Banda Alta Formation) and the iron formations from Fazenda Sao Manoel (Puga Formation) in Mato Grosso do Sul, Brazil, are associated with glacigenic deposits and represent the youngest and largest sedimentary Fe and associated Mn formation (IF;MnF) deposits of Cryogenian age in the world. The Urucum district IFs studied are predominantly composed of pure classical plane-parallel and stratified hematite–chert–iron - and intercalated manganese (cryptomelane) micro- and mesobands, whereas the IFs at Fazenda Sao Manoel are closely associated with diamictites and shales. Although the precise depositional age is unknown, maximum age constraints for the Puga IFs are defined by the youngest detrital zircon with an U-Pb age of 706 ± 9 Ma ( Babinski et al., 2013 ), a result which we here confirm by a U-Pb age of the youngest zircon of 695 ± 17 Ma from within shaly beds in the Urucum district IF succession. Redox-sensitive trace element signatures and tendency to hump-shaped Rare Earth Element + Yttrium (REY) patterns with negative Ce- but without Eu anomalies support the presence of an oxic surface water layer, fertilized by low temperature hydrothermal fluids injected from submarine thermal springs and/or, alternatively, by significant fresh water input directly derived from glacial meltdown. Strongly positively fractionated, authigenic chromium isotope signatures (average δ 53 Cr = 1.10 ± 0.4‰; n = 16; 2σ) prevailing throughout the entire stratigraphic section indicate that riverine supply of continentally-derived Cr, remained more or less constant throughout the glacier meltdown and IF depositional period. Cycling across a redoxcline and predominant deposition of the IF in anoxic deeper seawater of the Jacadigo basin is supported by the peculiar presence of subchondritic Y/Ho ratios, by decreased negative Ce anomalies and by shifts of LREE patterns towards higher values in the Urucum district IFs that are independent of detrital contamination. The strongly positively fractionated Cr isotope signatures measured in these iron formations are compatible with those from other iron formations and black shales deposited during the late Neoproterozoic and Precambrian-Cambrian transition worldwide and are in support of prevailing high atmospheric O 2 levels following the late Neoproterozoic glaciations that accompanied the evolution of macroscopic multicellular organisms.

The evolutionary events during the Ediacaran–Cambrian transition (~541 Myr ago) are unparalleled in Earth history. The fossil record suggests that most extant animal phyla appeared in a geologically brief interval, with the oldest unequivocal bilaterian body fossils found in the Early Cambrian. Molecular clocks and biomarkers provide independent estimates for the timing of animal origins, and both suggest a cryptic Neoproterozoic history for Metazoa that extends considerably beyond the Cambrian fossil record. We report an assemblage of ichnofossils from Ediacaran–Cambrian siltstones in Brazil, alongside U–Pb radioisotopic dates that constrain the age of the oldest specimens to 555–542 Myr. X-ray microtomography reveals three-dimensionally preserved traces ranging from 50 to 600 μm in diameter, indicative of small-bodied, meiofaunal tracemakers. Burrow morphologies suggest they were created by a nematoid-like organism that used undulating locomotion to move through the sediment. This assemblage demonstrates animal–sediment interactions in the latest Ediacaran period, and provides the oldest known fossil evidence for meiofaunal bilaterians. Our discovery highlights meiofaunal ichnofossils as a hitherto unexplored window for tracking animal evolution in deep time, and reveals that both meiofaunal and macrofaunal bilaterians began to explore infaunal niches during the late Ediacaran. Trace fossils from the Ediacaran–Cambrian transition of Brazil are interpreted as the remains of burrows made by a nematoid-like organism moving through sediment: these organisms are interpreted as the oldest known fossil meiofaunal bilaterians.

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 Geológicas

In central Brazil there are continental carbonate rocks in three different geological contexts – the Pleistocene wackestones in the Corumba city (Xaraies Formation), the mid-Holocene limestones lenses in the Pantanal Plain (Pantanal do Miranda) and old and modern tufas in the Serra da Bodoquena (Serra da Bodoquena Formation). We present here a systematic and taphonomic study of the molluscs found in the carbonate deposits in the Serra da Bodoquena and the limestones lenses of the Pantanal do Miranda, which provide information concerning the carbonate palaeoenvironments of these two distinct areas. Seven molluscan species were found: the gastropods Marisa sp., Pomacea canaliculata, an unidentified hydrobiid, Idiopyrgus sp., Biomphalaria sp. and Megalobulimus sp., and the bivalve Pisidium sp. The gastropods include species still living in the area today, which supports a Holocene age for the limestones, as indicated by published 14C dates. Overall, the data obtained from the Serra da Bodoquena carbonates suggest a freshwater environment with minimal current-wave action, in an area probably fed by springs, close to a terrestrial environment, in view of the assemblage composed of Pomacea canaliculata, the unidentified hydrobiid, Idiopyrgus sp., Biomphalaria sp. and Megalobulimus sp. The lacustrine palaeoenvironment in the Pantanal do Miranda area was different, as indicated by the presence of Marisa sp. and absence of shallow-water species such as Biomphalaria sp. The gastropods from Serra da Bodoquena and Pantanal do Miranda are predominantly aquatic and amphibious; they are probably younger than the terrestrial gastropods reported from fine-grained limestones in the Corumba area.

Stable isotope ratios combined with elemental compositions and molecular biomass data provide a powerful tool in Neoproterozoic palaeoenvironmental interpretations. Here, we report the results of an extensive organic and inorganic geochemical study performed in the Ediacaran sedimentary succession of the Corumba Group (CG) from SW-Brazil, deposited in a shallow marine basin in southwestern Gondwana. This sedimentary succession and in particular the Tamengo Formation, a unit bearing metazoan fossils, has been investigated by means of stable isotopes from carbonates (delta C-13(car) and delta O-18) and associated organic matter (delta C-13(ker) and delta N-15(ker)) together with hydrocarbon distribution and concentrations of major, trace and rare earth elements (REE). A short post-glacial delta C-13(car) negative excursion, interpreted as a period of water mixing, is recorded in the cap carbonates overlying diamictites of the Puga Formation, related to Gaskiers or end-Cryogenian glaciation. The overlying Tamengo Formation by contrast, represents a return to redox-stratified conditions in the basin before the Precambrian-Cambrian boundary. Two distinct biogeochemical modes alternate during deposition of Tamengo sediments: 1) an eutrophic, redox-stratified basin well defined by carbonaceous marls from the middle part of the unit but also recorded upwards, at the transition between bioclastic limestones and calcisiltites. 2) An anoxic basin well characterized in the shallow facies, particularly by bioclastic limestones of the upper Tamengo Formation. A positive Delta C-13(car-ker) (Delta C-13(car-ker) = delta C-13(car) - delta C-13(ker)) excursion of similar to 5% in the carbonaceous marls is explained by enhanced primary productivity in surface waters probably related to an increase of pCO(2), nutrient supply and possibly also changes of the primary producer communities. Abundant pyrite, a biomarker distribution characterized by the occurrence of gammacerane and a low Pr/Ph ratio (similar to 0.7) are also remarkable signatures of these facies, most probably associated with a sulfate-reducing microbial consortium in an anoxic and sulfidic (euxinic) environment. However, low concentrations in redox-sensitive trace elements in these fades suggest a largely oxygenated water column, thus constraining the euxinic setting to the sediments and/or bottom waters. The shallow-water bioclastic limestones record higher concentrations of redox-sensitive elements and Sigma REE as well as a positive Ce anomaly supporting reducing conditions. Oxygenated conditions and dominance of eukaryotic algae characterize the overlying Guaicurus Formation. Principal component analysis (PCA) was used to assess the major geochemical associations. The most significant component combines parameters involved in primary production, such as P concentrations and delta C-13(ker) values. The bio-chemostratigraphic variations in this part of SW-Gondwana point to a stratified ocean with oxic surface waters, alternating periods of high and low bioproductivity and anaerobic conditions at the bottom waters, in the aftermath of younger Neoproterozoic glaciations and close to the Precambrian-Cambrian boundary. (C) 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Speleoclimate studies about Brazilian caves are still incipient and restricted to monitoring and getting some localized measurements focused on the management of tourist caves, as well as to be used as a basis for paleoclimate studies. The present study reflects the development of these studies in Brazil, presenting one of the most complete and detailed climatic monitoring of a cave until it is finished (2011), aiming to define the dynamics of the atmosphere of the cave in different climatic seasons. The research was conducted in the Santana cave, one of the most important tourist caves in Brazil. The field research about the monitoring of atmospheric parameters focused the air temperature and the relative humidity. The data were submitted to a statistical treatment and an analysis which showed that the atmosphere of the Santana cave is characterized as a warm trap, which maintained the air in the upper galleries. Therefore, scientific parameters may be established to its management and conservation, as well as the use of the obtained information in future studies in the field of climate, paleoclimate and tourist management.

The emergence of soft-bodied metazoans and the radiation of the earliest skeletal organisms substantially changed the ecological dynamics of Ediacaran environments, leading to the genesis of biogenic hard-part deposits for the first time in Earth’s history. The impact of bioclast origin on sedimentary processes is analyzed herein, focusing on the sedimentology and taphonomy of shell concentrations dominated by the Ediacaran index fossil Cloudina from the Itapucumi Group, Paraguay. Skeletal concentrations include both dense accumulations of parautochthonous, disarticulated specimens (“Type 1 deposits”) and in situ specimens preserved as loosely packed assemblages (“Type 2 deposits”). At that time, Cloudina was the critical source of durable biomineralized hard parts in an environment nearly free of other bioclasts. The simple fabric and geometry of these accumulations are typical of Cambrian-style shell beds. Despite their Precambrian age, these deposits indicate that the establishment of the Phanerozoic style of marine substrates and preservation in early shell beds was determined more by the acquisition of hard parts than by environmental changes.

This report reviews and incorporates new elemental and isotope chemostratigraphic data for correlation of Neoproterozoic carbonate-dominated successions in South America (Argentina, Bolivia, Brazil, Paraguay and Uruguay). These thick mixed carbonate/siliciclastic successions were largely deposited in epicontinental basins or accumulated on passive margins on the edges of cratons (e.g. São Francisco, Amazonia, Rio Apa Block, Pampia and Río de la Plata paleocontinents) during extensional events related to the rifting of the Rodinia Supercontinent. From the stratigraphic point of view, these successions occur as three mega-sequences: glaciogenic, marine carbonate platform (above glaciomarine diamictites or rift successions), and dominantly continental to transitional siliciclastics. In the orogenic belts surrounding cratons, carbonate-dominated successions with important volcanoclastic/siliciclastic contribution have been, in most cases, strongly deformed. The precise ages of these successions remain a matter of debate, but recently new paleontological and geochronological data have considerably constrained depositional intervals. Here, we report high-resolution C, O, Sr, and S isotope trends measured in well-preserved sample sets and mainly use Sr and C isotopes in concert with lithostratigraphic/biostratigraphic observations to provide detailed correlations of these successions. The establishing of a high-level and definite chemostratigraphic correlation between Neoproterozoic basins in South America is the main goal of this work. RESUMO: Esta revisão incorpora novos dados isotópicos e químicos para correlação quimioestratigráfica de sucessões, predominantemente carbonáticas, na América do Sul (Argentina, Bolívia, Brasil, Paraguai e Uruguai). Estas sucessões, depositadas durante eventos de extensão, aparecem como espessos estratos carbonáticos/siliciclásticos em bacias epicontinentais ou foram acumulados sobre margens passivas em bordos de cratons (ex.: São Francisco, Amazonas, Bloco Rio Apa, Pampia e Río de La Plata) como três megasequências: glaciogênica, plataforma marinha carbonática (sobre diamictitos glacio-marinhos) e predominantemente continental siliciclástica. Em cinturões circunjacentes a cratons, sucessões carbonáticas contendo material vulcanoclástico/siliciclástico foram, na maioria dos casos, fortemente deformados. A idade precisa de sedimentação destas sucessões permanece em debate, mas recentes dados paleontológicos e geocronológicos têm consideravelmente restringidos os intervalos de deposição. Neste trabalho, reportamos trends isotópicos de alta resolução de C, O, Sr e S medidos em amostras bem preservadas e usamos principalmente isótopos de Sr e C em consonância com observações litostratigráficas/biostratigráficas, para estabelecer correlações detalhadas destas sucessões. Propor uma correlação quimioestratigráfica entre bacias Neoproterozoicas na América do Sul é o principal objetivo deste trabalho.

The restriction of tubestone structures tomicrobialitic laminites in cap carbonates associated with the Marinoan glacial event in North and South America, Namibia, Australia and Oman makes them an important stratigraphic marker for the base of the Ediacaran system. This association has been recognized in the Mirassol D'Oeste Formation (635 Ma) adjacent to the northern Paraguay Fold Belt, and are reported here in isolated outcrops at Morraria do Sul and Forte de Coimbra in the southern Paraguay Fold Belt, west-central Brazil. The tubestone-microbialite associations at all localities reveal very similar macro- and microstructures, mineralogy, textures and fabrics. The microbialites consist of microbial laminites made up of dolomicrite clustered in microclots with dolospar-filled fenestrae. Lamination is defined by alternation in the relative abundance of these two components, suggestive of simple oscillations within a relatively uniform depositional environment and paleoecological setting. In the two new localities the tubestone fillings consist mainly of massive dolomicrite, although subordinate portions with concave lamination defined by concentrated very fine siliciclastic grains also occur. The presence of both massive and laminated tube fillings indicates variation in the processes responsible for their formation. These results extend the occurrence of the post-Marinoan tubestone-microbialite association at least 600 km southward from Mirassol D'Oeste in the north and document minor variations among the localities, which is what one would expect over such a broad distribution of this feature. The results also indicate that the isolated dolostones at Morraria do Sul and Forte de Coimbra do not belong to the Bocaina Formation (Corumba Group), with which they have previously been correlated.

Recent molecular clock studies place the origin of phylum Cnidaria within the Cryogenian Period (ca. 850–635 Ma), with the split between the two subphyla (Anthozoaria and Medusozoa) likewise occurring during this time interval. However, the oldest cnidarian macrofossils, all medusozoans, occur in rocks of the late Ediacaran Period (ca. 560–541 Ma). Lightly skeletonized Corumbella werneri, currently known from late Ediacaran strata of Brazil, Paraguay and Nevada (USA), has been allied with coronate and conulariid scyphozoans, but it also shares gross morphological similarities with Carinachites spinatus, a possible conulariid from Cambrian Stage 1 (China), and it may be compared with Sinotubulites and Wutubus annularis from the late Ediacaran Dengying Formation (China). The strongest evidence of affinity with coronate scyphozoans is exhibited by Paraconularia sp. from a Corumbella-bearing shale interval in the latest Ediacaran Tamengo Formation of central Brazil. Furthermore, Paraconularia sp. from this rock unit establishes conulariids as a cnidarian clade that crossed the Proterozoic-Phanerozoic boundary. Finally, Haootia quadriformis from the late Ediacaran lower Fermeuse and Trepassy formations (southeastern Newfoundland, Canada) exhibits intriguing gross morphological similarities to extant staurozoans and may represent the earliest record of metazoan musculature. Together, C. werneri and latest Ediacaran Paraconularia sp. fix the split between the medusozoan classes Cubozoa and Scyphozoa at no later than ca. 543 Ma. If H. quadriformis was indeed a staurozoan or stem staurozoan, then this fossil taxon fixes the split between the class Staurozoa and all other medusozoan cnidarians at no later than ca. 560 Ma.

Microfossils present in Quaternary micrites from Serra da Bodoquena, Mato Grosso do Sul State, Brazil, are here described for the first time. The studied taxa are: a) ostracods: Candona sp., Candonopsis sp., Cyclocypris sp., Cypria sp., Cypridopsis sp., Notodromas sp., Ilyocypris sp., Cyprideis sp., Wolburgiopsis cf. chinamuertensis (Musacchio 1970), Darwinula sp. and 5 morphotypes; b) microgastropod Acrobis sp., and c) Characeae remains and gyrogonites Chara sp.. The presence of these microfossils suggests clear-water shallow lacustrine paleoenvironments and the presence of aquatic vegetation. Similarities between microfossils and the living taxa suggest possible Holocene ages for these deposits, which is in accordance with previous C14 dates.Diversos microfósseis provenientes de micritos quaternários da Serra da Bodoquena, estado de Mato Grosso do Sul, Brasil são aqui descritos pela primeira vez. Os taxa descritos são os seguintes: a) ostracodes: Candona sp., Candonopsis sp., Cyclocypris sp., Cypria sp., Cypridopsis sp., Notodromas sp., Ilyocypris sp., Cyprideis sp., Wolburgiopsis cf. chinamuertensis (Musacchio 1970), Darwinula sp. e 5 morfotipos; b) microgastrópode Acrobis sp., e c) restos de Characeae e girogonites de Chara sp.. A presença destes microfósseis sugere paleoambiente lacustre raso de águas límpidas e presença de vegetação aquática. As semelhanças dos microfóssseis com taxa viventes sugerem idades possivelmente holocênicas para estes depósitos, concordando com datações prévias por C14.

Terra Nova, 23, 382–389, 2011 Abstract An in situ assemblage of Cloudina, thrombolites and an ichnofossil (cf. Archaeonassa), together with fragments of Corumbella werneri, is reported here, from a tidally influenced, shallow, lagoonal setting on a carbonate ramp within the Itapucumi Group, Paraguay. The association of Cloudina with thrombolites is comparable to other terminal Neoproterozoic occurrences, but the coexistence of shelly fossils in situ with trace fossils and microbially induced sedimentary structures is apparently unique. This discovery extends the record of Cloudina and Corumbella in South America and further elucidates the diversity, distribution and palaeoecology of shelled organisms in late Ediacaran time.

Discontinuous exposures of diamictite (>1000 km) termed the Puga Formation (Fm.) and interpreted as being related to a late Cryogenian glacial event are known in the Paraguay Belt (Brazilian–Pan-African Orogeny) and part of the Amazon craton and Rio Apa Block. These diamictite units and a mixed assemblage of sandstone, conglomerate and claystone were first named the Jangada Group. Recent interpretations have shown that the diamictite of the Puga Formation passes laterally into metasediments of the Cuiaba Group, interpreted as glacially influenced turbidites. The correlative Jacadigo Group in the southern Paraguay Belt includes a thick succession of banded iron formation (BIF) bearing large boulders that have been interpreted as recording glacially influenced sedimentation. The diamictite of the Puga Fm. is overlain by two different carbonate-bearing successions, the Corumba Group (Cadieus, Cerradinho, Bocaina, Tamengo and Guaicurus formations) in the south and the Araras Group (Mirassol d9Oeste, Guia, Nobres formations) in the north. Evidence of glaciation in the Puga Fm. consists of striated and faceted pebbles and blocks, and dropstones in the turbidites. Sedimentary and geochemical data from the associated carbonate reinforce the interpretation of a glacial origin. C, O and Sr isotope data from the northern Paraguay Belt are consistent with the proposed late Cryogenian age for the Puga Fm. sedimentation.

The Neoproterozoic (Ediacaran) Itapucumi Group in northern Paraguay is composed of carbonate and siliciclastic rocks, including ooid grainstones, marls, shales and sandstones, containing Cloudina fossils in the eastern region. It is almost undeformed over the Rio Apa Cratonic Block but shows a strong deformational pattern at its western edge. A detailed structural analysis of the Itapucumi Group was conducted in the Vallemi Mine, along with a regional survey in other outcrops downstream in the Paraguay River and in the San Alfredo, Cerro Paiva and Sargento Jose E. Lopez regions. In the main Vallemi quarry, the structural style is characterized by an axial-plane slaty cleavage in open to isoclinal folds, sometimes overturned, associated with N–S trending thrust faults and shear zones of E-vergence and with a low-grade chlorite zone metamorphism. The structural data presented here are compatible with the hypothesis of a newly recognized mobile belt on the western side of the Rio Apa Cratonic Block, with opposite vergence to that of the Paraguay Mobile Belt in Brazil. Both belts are related to the Late Brasiliano/Pan-African tectonic cycle with a Lower Cambrian deformation and metamorphism age. The deformation could be due to the late collision of the Amazonian Craton with the remainder of Western Gondwana or to the western active plate boundary related to the Pampean Belt. The structural and lithologic differences between the western Itapucumi Group in the Vallemi and Paraguay River region and the eastern region, near San Alfredo and Cerro Paiva, suggest that this group could be divided into two lithostratigraphic units, but more stratigraphic and geochronological analyses are required to confirm this possibility.

The Corumba Group, cropping out in the southern Paraguay Belt in Brazil, is one of the most complete Ediacaran sedimentary archives of palaeogeographic, climatic, biogeochemical and biotic evolution in southwestern Gondwana. The unit hosts a rich fossil record, including acritarchs, vendotaenids (Vendotaenia, Eoholynia), soft-bodied metazoans (Corumbella) and skeletal fossils (Cloudina, Titanotheca). The Tamengo Formation, made up mainly of limestones and marls, provides a rich bio- and chemostratigraphic record. Several outcrops, formerly assigned to the Cuiaba Group, are here included in the Tamengo Formation on the basis of lithological and chemostratigraphical criteria. High-resolution carbon isotopic analyses are reported for the Tamengo Formation, showing (from base to top): (1) a positive δ13C excursion to +4‰ PDB above post-glacial negative values, (2) a negative excursion to −3.5‰ associated with a marked regression and subsequent transgression, (3) a positive excursion to +5.5‰, and (4) a plateau characterized by δ13C around +3‰. A U-Pb SHRIMP zircon age of an ash bed interbedded in the upper part of the δ13C positive plateau yielded 543 ± 3 Ma, which is considered as the depositional age ( Babinski et al., 2008a ). The positive plateau in the upper Tamengo Formation and the preceding positive excursion are ubiquitous features in several successions worldwide, including the Nama Group (Namibia), the Dengying Formation (South China) and the Nafun and Ara groups (Oman). This plateau is constrained between 542 and 551 Ma, thus consistent with the age of the upper Tamengo Formation. The negative excursion of the lower Tamengo Formation may be correlated to the Shuram–Wonoka negative anomaly, although δ13C values do not fall beyond −3.5‰ in the Brazilian sections. Sedimentary breccias occur just beneath this negative excursion in the lower Tamengo Formation. One possible interpretation of the origin of these breccias is a glacioeustatic sea-level fall, but a tectonic interpretation cannot be completely ruled out.

Since the creation of the Global Geopark Network by UNESCO in 2004, 58 geoparks have been already established around the world, among them the first Brazilian geopark, Araripe Geopark (CE), created in 2006. The topic has increasing interest in Brazil, although there are many doubts concerning the creation process, and the obtaining of UNESCO recognition. On the other hand the role of the universities should be the promotion of debates about the many aspects which must be considered during the implantation of geoparks, such as the protection of geological heritage, the rational management of natural resources, support for the economic and cultural improvement of the communities, and most importantly, the great potential of educational projects which can be elaborated, with benefits for the formation of human resources. To achieve all this it is necessary to adopt strategies for the implantation and maintenance of these projects so that they help in conserving the geological heritage and the sustainability of the geoparks.

D. J. Condon, P. Boggiani, D. Fike, G. P. Halverson, S. Kasemann, A. H. Knoll, F. A. Macdonald, A. R. Prave, and M. Zhu NERC Isotope Geoscience Facilities, British Geological Survey, Nottingham, UK Instituto de Geociencias, Universidade de Sao Paulo, Sao Paulo, Brazil Department of Earth & Planetary Sciences, Washington University, Washington, USA Department of Earth & Planetary Sciences, McGill University, Montreal, Canada Department of Geosciences, University of Bremen, Bremen, Germany Department of Earth & Planetary Sciences, Harvard University, Cambridge, USA Department of Earth & Environmental Sciences, University of St Andrews, St Andrews, UK State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China

This paper presents data from automatic stations which have been installed for monitoring climatic parameters in caves in two areas of Brazil. These devices, initially developed at the Royal Observatory of Belgium to monitor environmental parameters in geophysical observatories, were adapted in our study to operate under tropical cave conditions and to measure temperature, atmospheric pressure and drip rate of stalactites. Similar devices were installed at the surface near to the caves to measure air temperature, atmospheric pressure and rainfall. The results reveal that the drip rate at the tip of stalactites is related to the effective rainfall (water excess). The stable drip regime observed during the dry season seems to be reproducible from one year to the other and could be related to the infiltration of water which has a long residence time in the aquifer. Regular pressure oscillations, with amplitude ranging between 1 and 2 mb, are observed in both of the monitored caves. Spectral analysis of the data suggests that these oscillations are linked to the diurnal and semi-diurnal solar tides (S1 and S2). In one cave, very small temperature variations (0.02–0.05 °C) are also observed with a similar diurnal and semi-diurnal pattern, and we argue that the generating process of the thermal components of the S1 and S2 frequencies is a mixture of thermal convection produced by the surface meteorological variations and of an adiabatic induction of the S2 atmospheric pressure modulation. A very large annual thermal amplitude (13 °C) is observed in the other cave; this is a great motivation to study the stable isotope geochemistry of its speleothems as they probably have recorded past temperature fluctuations linked to paleoclimate variations in this area of south-western Brazil.

The present paper deals with the phlebotomine species captured during the period from January 1998 to June 2000 in 12 caves located in the Serra da Bodoquena, situated in the south central region of Mato Grosso do Sul State, Brazil. Three of the caves are situated further north (in Bodoquena county), seven in the central area (Bonito county) and two in the south (Jardim county). These last two caves and three of those in Bonito are located at the west side of the ridge. Eighteen species of phlebotomines were captured within the caves: Brumptomyia avellari (Costa Lima, 1932), Brumptomyia brumpti (Larrousse, 1920), Brumptomyia cunhai (Mangabeira, 1942), Brumptomyia galindoi (Fairchild & Hertig, 1947), Evandromyia corumbaensis (Galati, Nunes, Oshiro & Rego, 1989), Lutzomyia almerioi Galati & Nunes, 1999, Lutzomyia longipalpis (Lutz & Neiva, 1912), Martinsmyia oliveirai (Martins, Falcão & Silva, 1970), Micropygomyia acanthopharynx (Martins, Falcão & Silva, 1962), Micropygomyia peresi (Mangabeira, 1942), Micropygomyia quinquefer (Dyar, 1929), Nyssomyia whitmani (Antunes & Coutinho, 1939), Psathyromyia campograndensis (Oliveira, Andrade-Filho, Falcão & Brazil, 2001), Psathyromyia punctigeniculata (Floch & Abonnenc, 1944), Psathyromyia shannoni (Dyar, 1929), Pintomyia kuscheli (Le Pont, Martinez, Torrez-Espejo & Dujardin, 1998), Sciopemyia sordellii (Shannon & Del Ponte, 1927) and Sciopemyia sp. A total of 29,599 phlebotomine sandflies was obtained. Lutzomyia almerioi was absolutely predominant (91.5%) over the other species on both sides of the Bodoquena ridge, with the exception of the southern caves in which it was absent. It presents summer predominance, with nocturnal and diurnal activities. The species breeds in the caves and was captured during daytime both in the dark area and in the mouth of the caves. Martinsmyia oliveirai, the second most frequent sandfly, also presents a summer peak and only predominated over the other species in one cave, in which there were human residues.0

The recent discovery of ice-striated surfaces associated with the late Paleozoic Aquidauana Formation suggests that glaciers coming from southwest Africa reached westernmost parts of the Parana Basin in central Brazil. Abrasion features were developed by glaciers moving from SSE towards NNW, mainly on an unconsolidated bed. These records expand to about 1,050,000 km2, the coverage of the late Paleozoic glaciation in the region of the Parana Basin in Western Gondwana.

The remarkable occurrence of more than 4,500 conical siliceous mounds in an area of less than 1.5 square kilometres has been reported in the Parana basin, near Anhembi, Sao Paulo, in southeastern Brazil1. These structures, which are up to two metres high, are thought to have been formed at the margin of a very shallow, broad but waning internal sea1, and it was originally suggested that they are stromatolites2. Yet their restricted occurrence, unusual abundance and nearly pure siliceous composition have never been satisfactorily explained by this hypothesis. Here we report field and laboratory observations on their shape, construction, composition and mineralogy. On the basis of our data we suggest that the conical mounds are the result of subaqueous Late Permian vent activity in southwestern Gondwana. The present siliceous cone field differs considerably from other Palaeozoic siliceous hot spring deposits, such as those at Rhynie, Scotland3, and the Drummond basin, Australia4, and therefore represents an unusual occurrence of vent activity.

The Paraguay belt comprises a thick sedimentary succession deposited on the southwestern border of the Amazonian Craton and the Rio Apa Block. The base of the succession in the southern Paraguay belt is marked by a level of glacially derived deposits from the Puga Formation associated with banded iron formations, which has been assumed to be end-Cryogenian in age (635 Ma) by previous authors is spite of the lack of geochronological data. Here we present the first U–Pb SHRIMP ages on detrital zircon grains separated from the matrix of six samples of these diamictites two different localities (Puga Hill and Bodoquena area). U–Pb ages determined from two samples (ca. 130 grains) of Puga Hill show a large variation between 970 Ma and 2100 Ma. Rocks with these ages can be found in the Amazonian Craton suggesting that it is the most probable source of the sediments. Detrital zircons (ca. 230 grains) from the Bodoquena area (about 200 km south of Puga Hill) range from 706 to 1990 Ma. The 1760 Ma source is significantly more important in these samples, comprising more than 70% of analyzed grains, and indicates provenance from the adjacent Rio Apa Block. The youngest zircon was dated at 706 ± 9 Ma, thus constraining the maximum depositional age for the Puga Formation. Possible sources for this younger population could be either the juvenile Mara Rosa magmatic arc in the Brasilia belt, or the rocks from the Laurentian external fold belts located to the west of the sampled area in Neoproterozoic paleogeographic reconstructions. The maximum depositional age of the diamictites (and associated BIFs), together with cap carbonate carbon and strontium isotope data (δ 13 C = − 5.0 and 87 Sr/ 86 Sr = 0.7077) in Puga Hill, indicate that they were deposited after 700 Ma, suggesting that they may represent the end-Cryogenian event.

Cavernas são feições geológicas que apresentam também aspectos bióticos e outros abióticos, não geológicos, que possibilitam enquadrá-las em diferentes categorias do patrimônio natural. Se forem considerados ainda aspectos históricos e culturais, outras formas de enquadramento como patrimônio são possíveis, além do paisagístico, no qual a maioria das cavernas do Brasil vem sendo classificada. Considera-se, no entanto, caverna como patrimônio geológico apenas as que apresentam registro paleoambiental ou paleoclimático raro ou diferente processo geológico de formação, de tal forma que nem toda caverna pode ser considerada patrimônio geológico. Definida a caverna que venha a ser enquadrada como patrimônio geológico, deve-se procurar formas de acesso a esse patrimônio pela sociedade, através do geoturismo e espeleoturismo, com destaque para os projetos educacionais e preocupação com a melhoria de qualidade de vida das comunidades locais. No sentido de subsidiar a definição futura de caverna como patrimônio geológico, panorama é apresentado sobre as cavernas no Brasil em comparação ao cenário espeleológico mundial.

Although the basic morphology of the Ediacaran metazoan Corumbella werneri (the type species of the genus) is well established, little is known about its skeletal tissue. Carbonaceous fragments of this fossil from the Itapucumi Group (Paraguay) reveal details of the ultrastructure of its carapace, providing an unprecedented opportunity to understand a paradigmatic issue of the evolution of skeletogenesis in early metazoans. Corumbella was a sessile predator whose carapace consisted of organic polygonal plates with pores and papillae similar to features observed in some conulariids. Its occurrence with the shelly fossil Cloudina suggests that the acquisition of protective structures in metazoans involved penecontemporaneous processes of biomineralization and secretion of organic walls.

Active tufas in the form of waterfalls and dams occur along drainage channels in the Serra do Andre Lopes region (State of Sao Paulo, southeastern Brazil) and are associated with the karst system that developed on a dolomitic plateau with a superhumid subtropical climate. The predominance of autogenic waters enables the groundwater to become enriched in calcium carbonate, with low terrigenous sediment content. The tufas that were studied are composed of calcite and have high calcium contents and low magnesium contents. Eroded tufa beds that originate from changes in the position of fluvial channels or river flow rates also occur in this region. In the Sapatu deposit, phytohermal tufas with complex morphologies are arranged in levels constituting various temporally repeated sequences that were deposited between 10,570 and 4,972 cal years BP. In the Frias deposit, distal fluvial deposits of tufa are massive with a relatively greater quantity of terrigenous material and show evidence of dissolution and reprecipitation. The base of this deposit is composed of a cemented breccia dated at 25,390 years BP, which is younger than the overlying tufas (>42,000 years BP). In the two deposits, the levels of terrigenous sediments (quartz sand and lithic pebbles) and terrestrial gastropod shells are interpreted as phases of increased flow rate of rivers during intervals of higher rainfall.

A Faixa Paraguai meridional evoluiu como um típico fold-and-thrust belt. Sua evolução principia por rifteamento, provavelmente no final do Criogeniano, evoluindo para mar restrito e transgressão marinha extensiva até o final do Ediacarano. O final do processo colisional ocorreu no início do Cambriano, com magmatismo pós-colisional no Cambriano Superior. O Grupo Corumbá é subdividido em cinco formações (Cadiueus, Cerradinho, Bocaina, Tamengo e Guaicurus), estratigrafia esta observada até nas porções mais deformadas no centro-leste da área. A Formação Puga é colocada como correlata às suas formações basais, Cerradinho e Cadiueus. No extremo oeste da área, o Grupo Corumbá está depositado em inconformidade sobre o bloco cratônico Rio Apa. Para os xistos do extremo leste da área, é proposto o nome local Xistos Agachi. Durante o Ediacarano, sincronicamente com a deformação, granitogênese de arco e metamorfismo do Grupo Cuiabá a leste, ter-se-ia a deposição das formações Tamengo e Guaicurus a oeste, provavelmente num contexto de bacia de ante país (foreland). São observadas até três fases de dobramento sobrepostas coaxiais, associadas a metamorfismo de fácies xisto-verde e sistemas de falhas de empurrão, com vergência tectônica para oeste. A convergência colisional em direção ao bloco Rio Apa não foi completamente frontal, existindo algum grau de obliquidade, com vetores de convergência em torno de WNW-ESE. A variação do estilo estrutural e metamórfico pode ser explicada pela migração do front deformacional de leste para oeste. As principais falhas de empurrão coincidem com limites bacinais importantes, sugerindo que estes empurrões reativaram falhas lístricas do estágio rifte.

The Jacadigo Group contains one of the largest sedimentary iron and associated manganese deposits of the Neoproterozoic. Despite its great relevance, no detailed sedimentological study concerning the unit has been carried out to date. Here we present detailed sedimentological data and interpretation on depositional systems, system tracts, external controls on basin evolution, basin configuration and regional tectonic setting of the Jacadigo Basin. Six depositional systems were recognized: (I) an alluvial fan system; (II) a siliciclastic lacustrine system; (III) a fan-delta system; (IV) a bedload-dominated river system; (V) an iron formation-dominated lacustrine or marine gulf system; and (VI) a rimmed carbonate platform system. The interpreted depositional systems are related to three tectonic system tracts. The first four depositional systems are mainly made of continental siliciclastics and refer to the rift initiation to early rift climax stage; the lake/gulf system corresponds to the mid to late rift climax stage and the carbonate platform represents the immediate to late post rift stage (Bocaina Formation deposits of the Ediacaran fossil-bearing Corumba Group). The spatial distribution of the depositional systems and associated paleocurrent patterns indicate a WNW-ESE orientation of the master fault zone related to the formation of the Jacadigo Basin. Thus, the iron formations of the Jacadigo Group were deposited in a starved waterbody related to maximum fault displacement and accommodation rates in a restricted continental rift basin. The Fe–Si–Mn source was probably related to hydrothermal plume activity that reached the basin through the fault system during maximum fault displacement phases. Our results also suggest a restricted tectono-sedimentary setting for the type section of the Puga Formation. The Jacadigo Group and the Puga Formation, usually interpreted as glacial deposits, are readdressed here as basin margin gravitational deposits with no necessary relation to glacial processes.