Southeastern South America Research Articles

The \u201cstranger\u201d among Swedish \u201chomo academicus\u201d

This article deals with individuals of immigrant background in Swedish higher education—i.e., those who have a PhD and work in Swedish universities. The aim of the study is to examine whether and how factors other than academic qualifications—such as gender and migrant background—may affect the individual’s ability to find employment and pursue a successful career in a Swedish institution of higher education. The data used in the first section are Swedish registry data (LISA database and population), administered by Statistics Sweden. The second part of the paper is based on semi-structured interviews with 19 academics of migrant background. The results show that, given the same work experience and compared to the reference group (born in Sweden with at least one Swedish-born parent), individuals born in Eastern Europe, Asia, Africa, and South America are, firstly, more likely to be unemployed and, secondly, if they are employed, to have a lower income (lower position). The ways in which such gaps arises are also examined.

An evaluation framework to build a cost-efficient crop monitoring system. Experiences from the extension of the European crop monitoring system

This paper presents an evaluation framework followed to identify cost-efficient alternatives to extend the MARS Crop Yield Forecasting System (MCYFS), run by the European Commission Joint Research Centre since 1992, to other main producing areas of the world: Eastern European Neighbourhood, Asia, Australia, South America and North America. These new systems would follow the principles and components of the MCYFS Europe: a meteorological data infrastructure, a remote sensing data infrastructure, a crop modelling platform, statistical tools, a team of analysts and a crop area estimation component. The framework designed evaluates the performance of the possible MCYFS-like system realizations against six defined objectives and their costs. Possible monitoring systems are based on a combination of different technical solutions for each of the MCYFS components, and are evaluated through an automatic algorithm that calculates the expected system performance –relying on a priori expert judgement–, the costs, and possible risks to construct some technical solutions, to finally identify the cost-efficient ones. A baseline system, achieving the minimum required performance, was identified as the most efficient starting point for the MCYFS extension in all the geographical areas. Such system would be built upon: (i) near real-time reanalysis meteorological products; (ii) remote sensing data from low-resolution (~1 km) platforms with a long-term product archive; (iii) crop models based on crop-specific model calibration from experimental data published in scientific literature; (iv) statistical methods based on trend and regression analysis applied to national level; (v) a team of analysts with specific technical profiles (on meteorology, remote sensing, and agronomy); and (vi) digital classification of very high resolution imagery supported by non-expensive ground surveys for area estimation. In countries where accessibility to local data and resources is high the baseline system can be upgraded enhancing some of the components: sub-national statistical analysis with additional statistical methods like multiple regression or scenario analysis; recruitment of experts on local agricultural conditions in the team of analysts; local calibration of crop models with experimental data; and exploiting high and low resolution biophysical products from remote sensing for crop monitoring.

Identification of symmetric and asymmetric responses in seasonal streamflow globally to ENSO phase

The phase of the El Niño Southern Oscillation (ENSO) has large-ranging effects on streamflow and hydrologic conditions globally. While many studies have evaluated this relationship through correlation analysis between annual streamflow and ENSO indices, an assessment of potential asymmetric relationships between ENSO and streamflow is lacking. Here, we evaluate seasonal variations in streamflow by ENSO phase to identify asymmetric (AR) and symmetric (SR) spatial pattern responses globally and further corroborate with local precipitation and hydrological condition. The AR and SR patterns between seasonal precipitation and streamflow are identified at many locations for the first time. Our results identify strong SR patterns in particular regions including northwestern and southern US, northeastern and southeastern South America, northeastern and southern Africa, southwestern Europe, and central-south Russia. The seasonally lagged anomalous streamflow patterns are also identified and attributed to snowmelt, soil moisture, and/or cumulative hydrological processes across river basins. These findings may be useful in water resources management and natural hazards planning by better characterizing the propensity of flood or drought conditions by ENSO phase.

Agriculture and elevation are the main factors for Pampasic stream habitat and water quality.

Streams of the Pampasic plain in Southeastern South America are ecosystems affected by both water pollution and habitat alteration mainly due to agricultural activity. Water quality is influenced by the quality of habitats and both depend on land use and watershed morphology. The objective of this study was to determine the relationship between the variables of four factors: (1) the morphology of the watershed, (2) land use in the watershed, (3) river habitat, and (4) water quality of wadeable streams in Uruguay, as well as to determine the most representative variables to quantify such factors. We studied 28 watersheds grouped into three ecoregions and four principal activities, which generated seven zones with three to five streams each. Correlations between the variables of each factor allowed reducing the total number of variables from 57 to 32 to perform principal component analyses (PCA) by factor, reducing the number of variables to 18 for a general PCA. The first component was associated with water quality and elevation. The second was associated with the stream and watershed size, the third with habitat quality, and the fourth to the use of neighboring soils and objects in the channel. Our results indicate that agricultural intensity and elevation are the main factors associated with the habitat and water quality of these lowland streams. These factors must be especially considered in the development of water quality monitoring programs.

South American monsoon response to iceberg discharge in the North Atlantic

Heinrich Stadials significantly affected tropical precipitation through changes in the interhemispheric temperature gradient as a result of abrupt cooling in the North Atlantic. Here, we focus on changes in South American monsoon precipitation during Heinrich Stadials using a suite of speleothem records covering the last 85 ky B.P. from eastern South America. We document the response of South American monsoon precipitation to episodes of extensive iceberg discharge, which is distinct from the response to the cooling episodes that precede the main phase of ice-rafted detritus deposition. Our results demonstrate that iceberg discharge in the western subtropical North Atlantic led to an abrupt increase in monsoon precipitation over eastern South America. Our findings of an enhanced Southern Hemisphere monsoon, coeval with the iceberg discharge into the North Atlantic, are consistent with the observed abrupt increase in atmospheric methane concentrations during Heinrich Stadials.

Maps of wind hazard over South Eastern South America considering climate change

Wind is one of the most dangerous natural phenomena for the built environment in South Eastern South America. The hazard posed by wind depends on the extreme wind speeds on the surface and can be quantified by calculating the Average Recurrence Interval—more commonly known as return period—of these winds. Maps of return period of extreme wind speeds are used by planning authorities to enforce appropriate standards for infrastructure construction in most countries of the world. These maps are usually built up from wind speeds recorded at a network of weather stations. In some countries, however, the quality of the records is poor or the stations have not been in operation for long enough to give appropriate data for wind hazard studies. In this paper, we discuss an alternative approach based on wind speeds calculated by climate models. The approach provides longer datasets and facilitates assessment of the impact of climate change on wind hazard, a matter of great of importance for planning and emergency authorities. Map quality is evaluated by comparing results from the climate simulations with results from reanalysis. The comparison shows that the climate simulations produce results close enough to the reanalysis and hence they can be used for wind hazard assessment. The results also show that we could expect little variation in wind hazard in South Eastern South America during most of this century.

New record of lithic blades in Brazil: The Picão site, São Paulo state

Lithic blades are long and narrow flakes produced from prepared cores which form part of different technological complexes all around the world. In South America, the production and use of blades has been reported in different settings which include early hunter-gatherer occupations of the Pleistocene-Holocene transition, as well as Middle and Late Holocene occupations. Until now, the only reference to blade technology in Brazil comes from the south and corresponds to Early Holocene hunter-gatherer assemblages. This paper presents a second record of lithic blades in Brazil, which includes one fragment and three refitted artifacts manufactured from fine-grained silicified sandstone recovered from a surface site (Picão), which is located in the Dourado Municipality, central São Paulo state. Analysis undertaken on the blades involved the collection of metric data, including longitudinal curvature, and the elaboration of diacritic schemes which consider the direction and order of the observed remnant scars for interpreting the chronological sequence of removals. Results indicate the production of ³70.5 mm-long, softly curved blades, with evidence of preparation of the point of impact prior to extraction from the core, as well as the presence of unidirectional, parallel scars related to blade production from a single striking platform. These reduction characteristics resemble those encountered in the nearest contexts of southern Brazil and northern Uruguay, although differences also exist. In spite of the lack of chronological data, this new record of blades in central São Paulo state calls for more research into the origins and dispersion of this technology in southeastern South America.

Assessing the Risk of Establishment of Rhagoletis cerasi (Diptera: Tephritidae) in the United States and Globally.

The European cherry fruit fly, Rhagoletis cerasi (L.) (Diptera: Tephritidae), is a highly destructive pest of cherries (Prunus spp.) (Rosaceae) in Europe and Asia. In 2016, R. cerasi was detected in Ontario, Canada, and in 2017 in New York State, USA, the first records of this pest in North America. The initial detections in Canada caused concern for the major cherry-growing states of Michigan, Washington, Oregon, and California in the United States. Establishment of R. cerasi in the United States could restrict cherry exports to other markets and increase costs needed for fly control, but it is unknown if R. cerasi can establish in U.S. commercial cherry regions. Here, we used the CLIMEX ecological niche model to determine the risk of establishment of R. cerasi in the United States and globally. Within the United States under a no-irrigation scenario, R. cerasi would establish in the East and West Coasts; however, under an irrigation scenario, its distribution would expand to the major cherry-growing regions in the interior of central and eastern Washington and in California. Results also showed that if introduced, R. cerasi would likely establish in eastern China, Japan, the Koreas, Australia, New Zealand, South America, South Africa, Mexico, and Canada. Host plant (Prunus spp. and Lonicera spp. [Caprifoliaceae]) presence, although not included in models, would affect fly establishment. Our results stress the importance of surveying for R. cerasi to prevent its spread and establishment within the United States and other countries.

Diversification patterns of the grasshopper genus Zoniopoda Stål (Romaleidae, Acridoidea, Orthoptera) in open vegetation biomes of South America

AbstractThe open vegetation biomes, within the limits of the Chacoan subregion, occur along a diagonal in eastern South America covering a large range of environmental conditions. In order to contribute to the knowledge on the biodiversity of these open biomes, we analysed the phylogenetic relationships of the grasshopper genus Zoniopoda to the remaining South American Romaleinae, and examined the biogeographical patterns of diversification of the genus. The study is based on morphological and molecular (COI and H3) evidence, including 12 species of Zoniopoda and 17 species of four tribes of South American Romaleinae. We describe a new species of Zoniopoda, and test its taxonomic placement within the group. Results of our phylogenetic analyses recovered Zoniopoda as a monophyletic group with high support values. According to the dispersion–vicariance analysis, the ancestor of Zoniopoda may have been distributed in an area corresponding to the Chacoan and Cerrado provinces. A vicariant event, that could be explained by the uplift of the Brazilian Plateau and the subsidence of the Chaco, is hypothesized to have occurred splitting the ancestral distribution of Zoniopoda, resulting in the independent evolution of the Tarsata group within the Cerrado and the Iheringi group in the Chacoan subregion.This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:act:FCFB4C5D-1741-46F1-8E25-B37ED2B9D872.

Single nucleotide polymorphisms in native South American Atlantic coast populations of smooth shelled mussels: hybridization with invasive European Mytilus galloprovincialis

BackgroundThroughout the world, harvesting of mussels Mytilus spp. is based on the exploitation of natural populations and aquaculture. Aquaculture activities include transfers of spat and live adult mussels between various geographic locations, which may result in large-scale changes in the world distribution of Mytilus taxa. Mytilus taxa are morphologically similar and difficult to distinguish. In spite of much research on taxonomy, evolution and geographic distribution, the native Mytilus taxa of the Southern Hemisphere are poorly understood. Recently, single nucleotide polymorphisms (SNPs) have been used to clarify the taxonomic status of populations of smooth shelled mussels from the Pacific coast of South America. In this paper, we used a set of SNPs to characterize, for the first time, populations of smooth shelled mussels Mytilus from the Atlantic coast of South America.ResultsMytilus spp. samples were collected from eastern South America. Six reference samples from the Northern Hemisphere were used: Mytilus edulis from USA and Northern Ireland, Mytilus trossulus from Canada, and Mytilus galloprovincialis from Spain and Italy. Two other reference samples from the Southern Hemisphere were included: M. galloprovincialis from New Zealand and Mytilus chilensis from Chile. Fifty-five SNPs were successfully genotyped, of which 51 were polymorphic. Population genetic analyses using the STRUCTURE program revealed the clustering of eight populations from Argentina (Mytilus platensis) and the clustering of the sample from Ushuaia with M. chilensis from Chile. All individuals in the Puerto Madryn (Argentina) sample were identified as M. platensis × M. galloprovincialis F2 (88.89%) hybrids, except one that was classified as Mediterranean M. galloprovincialis. No F1 hybrids were observed.ConclusionsWe demonstrate that M. platensis (or Mytilus edulis platensis) and M. chilensis are distinct native taxa in South America, which indicates that the evolutionary histories of Mytilus taxa along the Atlantic and Pacific coasts differ. M. platensis is endangered by hybridization with M. galloprovincialis that was introduced from Europe into the Puerto Madryn area in Argentina, presumably by accidental introduction via ship traffic. We confirm the occurrence of a native M. chilensis population in southern Argentina on the coast of Patagonia.

Sub‐monthly variability of the South American summer precipitation under El Niño and La Niña backgrounds during the 1998–2012 period

ABSTRACTThe sub‐monthly intra‐seasonal 8–24‐day period (SIS8‐24) timescale variability of the summer (1 November to 31 March) rainfall over South America (SA) under distinct inter‐annual (IA) backgrounds was analysed using the Tropical Rainfall Measure Mission (TRMM) based daily total precipitation data for the 1998–2012 period. The IA backgrounds refer to the El Niño (EN) and La Niña (LN) years. First, the summer daily precipitation anomaly fields were subject to the empirical orthogonal function (EOF) analysis. Using the first and the second principal component time series filtered at the SIS8‐24 timescale, positive and negative events were selected. The first SIS8‐24 mode features a precipitation anomaly dipole with centres over southeastern SA (SESA) and central and eastern tropical SA both extending southeastwards into the adjacent Atlantic Ocean. The second mode features a precipitation anomaly pattern similar to that previously documented for the oceanic South Atlantic convergence zone (SACZ). The SIS8‐24 precipitation anomaly patterns for the positive (negative) events show differences in the anomaly intensities between EN and LN years, but with almost the same locations of the anomaly centres. These differences result from the variability inter‐SIS8‐24 events, as indicated by the distinct paths of the SIS8‐24 Rossby wave train patterns in the subtropics, although they are regionally locked over tropical SA. The relation between the SIS8‐24 and IA variabilities might occur through variations in the Rossby wave train patterns. The Rossby wave trains of both timescales, depending on their phases, reinforce or weaken the rainfall anomalies over SA, in such a way that the rainfall anomalies over SA show similar patterns but with distinct magnitudes for EN and LN composites. The South American precipitation responses to the combined SIS8‐24 and IA variability timescales stratified according to the IA backgrounds have not been studied before and might be useful for operational forecasting services.

Late Quaternary environmental dynamics inferred from marine sediment core GeoB6211-2 off southern Brazil

Vegetation and climate changes in southern Brazil, as well as the dynamics of the adjacent South Atlantic were investigated through the analyses of pollen, spores and dinocysts from marine sediment core GeoB6211-2 that covers the last 19.3 kyr. The pollen record indicates the dominance of grassland (campos) in southeastern South America (SESA), reflecting cold and/or dry conditions during the Last Glacial Maximum. Forests, mainly gallery forests, expanded slightly during Heinrich Stadial 1, suggesting slightly wetter conditions. A stronger expansion of the Atlantic lowland rainforest is noticed in the record after ca. 5.5 cal kyr BP, likely due to wetter conditions. The relatively high amount of exotic Nothofagus pollen, transported by wind, rivers and then by oceanic currents northwards to the study site, as well as the dinocyst Brigantedinium spp., indicate a noticeable influence of the Brazilian Coastal Current from the south between 19.3 and 14.8 cal kyr BP. After that, the decrease in Nothofagus and Brigantedinium spp. together with the increase in dinocyst Operculodinium centrocarpum indicate that the Brazil Current from the north dominated the coring site. The abundance of freshwater algae between ca. 19.3 and 17.0 cal kyr BP suggests that the Rio de la Plata mouth was located close to the coring site during this period, and its discharge of nutrient-rich freshwaters strongly affected the upper water column. Sea level rise decreased this impact during the late glacial phase by moving the coastline further away from the core site. The presence of the Brazil Current at the core site became stronger after ca. 15 cal kyr BP and strongest after 9 cal kyr BP. In summary, the pollen, spores and dinocyst records from core GeoB6211-2 provide important climatic records to reconstruct the environmental changes in SESA.

Activity of the Southern Annular Mode during 2015–2016 El Niño event and its impact on Southern Hemisphere climate anomalies

ABSTRACTPrevious studies documented that El Niño (EN) events are in general associated with negative phases of the Southern Annular Mode (SAM). EN 2015–2016 (EN15–16) was one of the three strongest events ever recorded. However, it was associated with a SAM positive phase of extreme intensity. Furthermore, while the negative linear relationship between ENSO and SAM during the most recent period (1986–2014) was significant and associated with a narrow uncertainty band, the combined condition of both climate patterns in the EN15–16 event was an outlier. The EN15–16 influence on the austral summer circulation anomalies at the extratropical and polar regions of the Southern Hemisphere was considerably altered by the strong SAM positive phase, which was evident not only at the troposphere but also at the stratosphere. Such circulation changes resulted in unusual regional impacts, such as negative anomalies of surface air temperature in western Antarctic Peninsula and negative precipitation anomalies in southeastern South America, ever recorded for previous strong EN events. Further research is needed to better understand the mechanisms explaining the SAM behaviour during 2015–2016 and its implication for climate predictability on seasonal timescales.

New Paleoindian Finds, Further Fell Points Data, and Technological Observations from Uruguay: Implications for the Human Peopling in Southeastern South America

Mainly represented by “fishtail” or Fell points (~11,000 - 10,000 uncalibrated years BP), Paleoindian remains in Uruguay are distributed over a wide area. However, just a few stratified sites have yielded evidence of the earliest settlers in this part of South America. Cueva Amarilla was discovered as a result of an intensive survey conducted in the Lavalleja department. Because cave sites in Uruguay are scarce, an evaluation of its archaeological potentiality was performed. Lithic artifacts and charcoal were exhumed from its sedimentary deposits. A sample of the latter yielded a conventional radiocarbon date of 10,000 uncalibrated years BP. This date suggests that Cueva Amarilla witnessed an occupation during the Pleistocene-Holocene transition, which was thus Paleoindian. This date agrees well with the time-span of the Fell occupation in South America in general, and particularly in southern Uruguay. Therefore, this level might have belonged to hunter-gatherer colonizers who used “fishtails” as part of their weaponry. In this regard further “fishtail” points data as well the specimens coming from neighboring departments are reported. In the study area, and around the cave, there are ubiquitous primary and secondary sources of lithic raw materials, mainly significant outcrops of a yellowish/pale-brown siliceous rock, commonly called “opal” or “jasper”, which was used since Paleoindian times. Related to the stone tool reduction systems, this material along with other finds from Cueva Amarilla is discussed from a technological perspective. The finds from this cave along with the Fell point finds from the region, are discussed within the framework of the colonization process of South America.

Long-range Transport of Aerosols from Biomass Burning over Southeastern South America and their Implications on Air Quality

ABSTRACT The long-range transport of aerosols is a global issue since it may significantly affect the air quality of regions without high concentrations of fine particulate matter (PM2.5). Two significant occurrences of long-range transport of aerosols over the state of Parana in Brazil, which occurred during the periods Aug. 16–18 and Sep. 10–14 of 2016, were studied in order to characterize the atmospheric synoptic conditions of these events and to estimate their contribution to the air quality conditions in the northern region of the state. The South American Low Level Jet (SALLJ) was the key meteorological component used to define the origin of the air mass trajectories over the region. In the first event, the SALLJ lost its configuration, bringing air masses from the western part of Sao Paulo (state), while in the second event, the SALLJ formed over southern Brazil and brought air masses from the northern and central parts of the nation. The significant number of fires from biomass burning in central Brazil associated with synoptic conditions contributed to the increase in PM2.5 concentrations by approximately 70–87% in the region. The transport of aerosols was a determining factor in PM2.5 exceeding the air quality standard in the region. Therefore, to minimize this problem, it is imperative to control biomass burning in Brazil.

Phylogeographic analyses of the pampas cat (Leopardus colocola; Carnivora, Felidae) reveal a complex demographic history.

The pampas cat is a small felid that occurs in open habitats throughout much of South America. Previous studies have revealed intriguing patterns of morphological differentiation and genetic structure among its populations, as well as molecular evidence for hybridization with the closely related L. tigrinus. Here we report phylogeographic analyses encompassing most of its distribution (focusing particularly on Brazilian specimens, which had been poorly sampled in previous studies), using a novel dataset comprising 2,143 bp of the mitogenome, along with previously reported mtDNA sequences. Our data revealed strong population strutucture and supported a west-to-east colonization process in this species’ history. We detected two population expansion events, one older (ca. 200 thousand years ago [kya]) in western South America and another more recent (ca. 60-50 kya) in eastern areas, coinciding with the expansion of savanna environments in Brazil. Analyses including L. tigrinus individuals bearing introgressed mtDNA from L. colocola showed a complete lack of shared haplotypes between species, indicating that their hybridization was ancient. Finally, we observed a close relationship between Brazilian/Uruguayan L. colocola haplotypes and those sampled in L. tigrinus, indicating that their hybridization was likely related to the demographic expansion of L. colocola into eastern South America.

The unusual case of the widely distributed fiddler crab Minuca rapax (Smith, 1870) from the western Atlantic: an exemplary polytypic species

A classic dilemma in taxonomy is distinguishing intraspecific from interspecific variation. In order to better comprehend the process of divergence and speciation, we examine morphological, genetic, developmental and behavioural variation among related fiddler crab populations from eastern North America, the Caribbean and South America. We chose geographically remote populations that appear related to Minuca rapax (Smith, 1870). First, using females from across the range of the species, we use geometric morphometric techniques to identify regional differences in carapace shape. Second, in the northern portion of the range, the Caribbean into the Gulf of Mexico, we report variation in the relationship between corporal size and cheliped length in males. Third, we examine the major components of the courtship waves produced by males from several locations in the western Gulf of Mexico. Fourth, we compare the structure of the gastric mill between different populations in the Gulf of Mexico, the Caribbean and the Atlantic Ocean. And, fifth, we use mitochondrial 16S rDNA and cytochrome oxidase subunit I as genetic markers to define the phylogeographic relationship among specimens from more than 20 populations. From these studies, we find discrete, distinct populations across the original range of the species. In particular, populations in the northern Gulf of Mexico appear to represent a lineage that has resulted from limited gene flow and sustained selection pressures. On the basis of the observed degree of divergence, it is apparent that some separated populations in M. rapax should be recognised as evolutionary significant units. The geographic range of these populations is consistent with the historical range for Minuca virens (Salmon & Atsaides, 1968), a putative species that otherwise cannot be consistently distinguished from M. rapax based on discrete external morphological characters. This study provides evidence for M. virens as an emergent but possibly not completely isolated subclade of the M. rapax species complex.

Desfase en dirección única. Notas sobre los orígenes del videoarte en Uruguay y Eslovenia

Existe en la actualidad un creciente interés en establecer correspondencias y comparaciones entre Europa del Este y América del Sur en el campo de las artes visuales, especialmente durante el período comprendido entre 1960 y 1989, aproximadamente. Hay tres factores que contribuyen a justificarlo. El primero de ellos es el vínculo directo entre ambas regiones, en parte creado por las diferentes olas de migraciones en ambas direcciones y sus procesos históricos, y en parte por el intercambio cultural vinculado o no a ellas. El segundo es la constatación y análisis de una serie de puntos en común en el campo de la creación artística a partir de la década de 1960. El tercer factor es la «contemporaneidad» (Preda, 2015, 56) de «regímenes dictatoriales» en diversos países de ambas regiones en las décadas de 1970 y 1980, un contexto en el que «estrategias para lidiar con todo tipo de medidas políticas de represión fueron cultivadas simultáneamente» (Dressler, 2010).

Genesis, Pathways, and Terminations of Intense Global Water Vapor Transport in Association with Large‐Scale Climate Patterns

AbstractThe CONNected objECT (CONNECT) algorithm is applied to global Integrated Water Vapor Transport data from the NASA's Modern‐Era Retrospective Analysis for Research and Applications – Version 2 reanalysis product for the period of 1980 to 2016. The algorithm generates life‐cycle records in time and space evolving strong vapor transport events. We show five regions, located in the midlatitudes, where events typically exist (off the coast of the southeast United States, eastern China, eastern South America, off the southern tip of South Africa, and in the southeastern Pacific Ocean). Global statistics show distinct genesis and termination regions and global seasonal peak frequency during Northern Hemisphere late fall/winter and Southern Hemisphere winter. In addition, the event frequency and geographical location are shown to be modulated by the Arctic Oscillation, Pacific North American Pattern, and the quasi‐biennial oscillation. Moreover, a positive linear trend in the annual number of objects is reported, increasing by 3.58 objects year‐over‐year.

Detrital zircon geochronology (U-Pb LA-ICP-MS) of syn-orogenic basins in SW Gondwana: New insights into the Cryogenian-Ediacaran of Porongos Complex, Dom Feliciano Belt, southern Brazil

The Dom Feliciano Belt represents the major geotectonic unit in southeastern South America, being part of the Neoproterozoic western Gondwana. The Porongos Complex comprises the southernmost Brazilian supracrustal sequence of this belt, overlying the Paleoproterozoic Encantadas gneiss (c. 2.2–2.0 Ga). Until recently, these rocks were traditionally interpreted as a single early Neoproterozoic (Tonian, c. 790 Ma) basin.Here we present new U-Pb detrital zircon ages for the Capané Antiform, located in the northern part of the Porongos Complex. The central sector, interpreted as a basement domain, shows both pronounced Paleoproterozoic (2.2–2.0 Ga) and Neoproterozoic (Tonian, 830–780 Ma) age peaks. The latter accounted for the rift-related Porongos succession that is tectonically imbricated with basement rocks. In contrast, metavolcano-sedimentary units from the eastern and western sectors reflect predominant Cryogenian-Ediacaran provenance (peaks at 615–580 Ma).This new detrital zircon signature challenges the traditional view of a single Neoproterozoic depositional episode for the Porongos Complex by implying two different sequences termed Porongos I and II of Tonian and Ediacaran ages, respectively. The Porongos I sequence is made up of mica schist from the central sector, showing Tonian maximum depositional ages. On the contrary, the younger volcano-sedimentary units of the two peripheral sectors display the Porongos II sequence deposited in a Cryogenian-Ediacaran basin. The Porongos I sequence may have evolved in an extensional setting as a marginal basin with rift-related units, whereas Porongos II formed during compression related to active thrusting, which resulted from the collision with the Pelotas Batholith.Therefore, the present age data combined with previously published geochronological, stratigraphic, and tectonic data sets identify the Capané Antiform as a key area to understand the tectonic evolution of the Porongos Complex. Its protracted evolution has recorded a tectonic history of more than 200 million years, lasting from the break-up of Rodinia to the Gondwana amalgamation.