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This work proposes an analysis of pedagogical experiences developed in the context of university teacher education in dialogue with two different chronotopes: habitual face-to-face teaching modality and exceptional non-face-to-face teaching modality due to the COVID lockdown. We consider here two cases of Language and Literature teacher education courses in two universities in Argentina. Both experiences share the search for an equitable, dialogical interaction, in which there is a recovery of the students' opinions and criteria for the progressive and collaborative elaboration of knowledge. From a qualitative perspective, we resorted to autoethnographic narratives elaborated by the responsible teaching teams of the courses. In the approach we propose, there is a dialogue among different elements of our inquiry: a dialogue between the conceptions that we assume as teachers and researchers about teaching in face-to-face and virtual environments; a dialogue between the conceptualizations and concrete teaching-decisions; between the contexts of performance and the possibilities offered by virtuality; between the pedagogical experiences and the narratives; between the records and other materials that allow us to reconstitute these experiences; and between our voices and the voices of students and graduates who give us back evaluations and sustain the continuity of the dialogue. The analysis accounts for the definition of different chronotopes in the experiences and moments addressed. In both cases, the differences observed respond to contextual factors, particularities of the courses and the previous experiences that the teaching teams have had with ICT. Beyond the above-mentioned differences, for the exceptional non-face-to-face proposals, a greater stability in the proposed sequences and in the dynamics involved is observed in the two experiences, which seeks to generate greater predictability.

Copyright of Revista de la Facultad de Medicina Humana is the property of Instituto de Investigaciones en Ciencias Biomedicas de la Universidad Ricardo Palma and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Given the increasing number of immigrant students in the USA initially schooled in Mexico, Central America, and South America, and the dearth of investigations examining the beliefs of teachers from Mexico, Central America, or South America, an exploration of Latin American teachers' conceptions may inform policy-makers and researchers about teachers in different cultural contexts and provide insight into the types of instruction Latin American immigrants may have experienced before coming to the USA. Teachers' conceptions of reading comprehension and motivation to read across two cultural contexts (i.e. the USA and Argentina) were examined by analyzing responses from 21 US teachers and 23 Argentinean teachers. Both groups of teachers held views of reading comprehension in partial agreement with cognitive views of reading comprehension but differed in their views of instructional practices for "supporting" reading comprehension. Differences also emerged for conceptions of motivation and practices to support motivation to read. Knowledge of teacher views can be used by teacher educators to target misconceptions and further develop teachers' knowledge and skills related to reading comprehension and motivation to read. (Contains 8 tables.)

The Salí-Dulce basin is one of the main in the Northwest of Argentina and is affected by significant ecological changes due to the presence of polluting substances along its way. Diatoms are a prominent algal group in aquatic ecosystems. Their biology and taxonomy are suitable for their use in biomonitoring based on their specific responses to environmental changes. The objective of this study was to characterize the dynamic and composition of the taxocenosis of diatoms and their relationship with environmental variables in the Mista and Calimayo streams, belonging to the Salí-Dulce river basin (Tucumán-Argentina). For this, three sites were selected in each stream, and data on environmental and biological variables were collected according to conventional methodologies. Water quality was variable depending on the presence of pollutants and climatic seasonality. The diatom assemblage resulted as a sensitive taxocenosis bioindicator of the stream status. In this work, a total of 61 species were recorded, of which 11 could be good indicators for stream contamination. The use of two biotic indices makes it possible to affirm that the Pampean Diatom Index, modified on the basis of our data, resulted to be more sensitive and effective in determining water quality, which is why it could be considered as a tool for diagnosis, water quality monitoring and water planning that could provide valid information of easy application in basins of the Northwest of Argentina. [ABSTRACT FROM AUTHOR]

The common bean (Phaseolus vulgaris L.) is the most important grain legume in the human diet, mainly in Africa and Latin America. Argentina is one of the five major producers of the common bean in the world, and the main cultivation areas are concentrated in the northwestern provinces of this country. Crop production of the common bean is often affected by biotic factors like some endemic fungal diseases, which exert a major economic impact on the region. The most important fungal diseases affecting the common bean in Argentina are white mold caused by Sclerotinia sclerotiorum, angular leaf spot caused by Pseudocercospora griseola, web blight and root rot caused by Rhizoctonia solani, which can cause production losses of up to 100% in the region. At the present, the most effective strategy for controlling these diseases is the use of genetic resistance. In this sense, population study and characterization of fungal pathogens are essential for developing cultivars with durable resistance. In this review we report diversity studies carried out on these three fungal pathogens affecting the common bean in northwestern Argentina, analyzing more than 200 isolates by means of molecular, morphological and pathogenic approaches. Also, the screening of physiological resistance in several common bean commercial lines and wild native germplasm is reviewed. This review contributes to the development of sustainable management strategies and cultural practices in bean production aimed to minimize yield losses due to fungal diseases in the common bean. [ABSTRACT FROM AUTHOR]

This paper reports the findings of a project using research in co-labor carried out with secondary education teachers in Argentina. Our aim is to reconstruct tensions and challenges in situated writing teaching practices in contexts of advanced literacy from an ethnographic perspective. We retrieved various records produced by the participating teachers in the context of the experience, regarding their own teaching practices, as well as collective discussions regarding writing as theoretical object and as object of teaching and learning. The analysis shows three emerging tensions: between the prominence of writing in society and what is actually taught about writing at school; between a conception of writing as a complex social activity and a school-based conception; and between the objectives of advanced literacy and the pedagogical decisions taken. Furthermore, we highlight three potential actions that emerge strongly in the research records, the institutional approach to which may foster more equitable and democratic practices: (1) restoring the students' voices regarding the challenges of advanced literacy, (2) questioning "simulated" writing teaching, and (3) deficit discourses in schooling. [ABSTRACT FROM AUTHOR]

Since the reopening of the trials for the crimes committed by the last military dictatorship, new aspects have emerged on the scene, one of them being the age-impunity rhetoric. In its visual dimension, we understand this rhetoric to mean the representation of the perpetrators that has been taking shape in recent years, enabling them to be exempted from guilt and responsibility for the crimes committed by virtue of their advanced age. We argue that the visual configures a certain aesthetic that provides a scaffolding for impunity and its naturalization. In order to enter into the construction of this representation, we will put in tension the pair seen-unseen through photographs and editorials in the written press. [ABSTRACT FROM AUTHOR]

Copyright of Papeles del CEIC is the property of Centro de Estudios sobra la Identidad Colectiva, Facultas de Ciencias Sociales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Northwest Argentina has a wide variety of inland water systems including irregular ponds of variable dimensions, many of which have been formed by landslides. High-altitude ponds are scarce, of heterogeneous distribution and constitute fragile ecosystems, vulnerable to human intervention and natural effects. These lenitic ecosystems are unstable and shortlived, so their study is relevant for various purposes. Due to the accelerated loss of habitats and extinctions of biota, in recent years there has been an important interest in revaluing and studying biodiversity. In this global context and given the scarcity of research in the study area, an analysis of the richness and composition of phytoplankton was carried out in the Siambón pond, located in the Yungas of Northwest Argentina. 39 species were determined: 2 green algae, 5 green-blue algae (cyanobacteria) and 32 diatoms. Two new diatom citations are presented for Tucumán province (Nitzschia inconspicua and Stauroneis anceps). This first phycological contribution to this system will serve as a baseline for future limnological, phycological and palaeoenvironmental studies. Likewise, it constitutes a contribution to increase the knowledge of biological diversity in high altitude ponds. [ABSTRACT FROM AUTHOR]

Copyright of Lilloa is the property of Fundacion Miguel Lillo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Common bean web blight ( WB), caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris), is among the endemic fungal diseases of major impact in north-western Argentina ( NWA). This study aimed to analyse the genetic and pathogenic diversity of R. solani in Salta, NWA, where 97 isolates were recovered from commercial bean cultivars and wild beans showing WB symptoms in a major bean production area. The isolates were characterized on the basis of specific primers, rDNA- ITS sequences and morphological characteristics. All the isolates were identified as R. solani AG 2-2 WB, and they exhibited considerable intragroup variation. The phylogenetic tree generated with the ITS sequences confirmed the isolates identification. Aggressiveness of the isolates towards bean seedlings was assessed in the greenhouse. A great variability in virulence was observed among the isolates analysed. On the basis of the disease reaction on foliar tissues, the isolates were grouped into three virulence categories as follows: weakly virulent (30%), moderately virulent (38%) and highly virulent (32%). However, no correlation between virulence and geographical origin was detected. The information generated in this study provides initial data on the population variability of the WB pathogen in north-western Argentina and represents a valuable contribution to regional breeding programmes aimed to obtain cultivars with durable resistance. [ABSTRACT FROM AUTHOR]

Copyright of Romanica Olomucensia is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

New and previous fossil remains and resulting biostratigraphy of the El Imperial Formation at Arroyo del Imperial, Quebrada de La Horqueta, and Cañón del Atuel key sections are analyzed, while the faunal relationships among them are clarified. Two diachronnous faunas, the pTS and TSAIII associations, relatives to the Tivertonia-Streptorhynchus assemblage are recognized and constrained to early late Bashkirian and Moscovian ages, respectively. These age assignments are supported by statistical analyses and available palynological and radiometric dating. Previous mentions of brachiopods from Arroyo del Imperial and Quebrada de La Horqueta are elucidated with the identification of Buxtonia cf. riojanae (Leanza), Streptorhynchus inaequiornatus Leanza, Spiriferellina ? sp., Septosyringothyris (Precosyringothyris) aff. jaguelensis Lech, Septosyringothyris (Precosyringothyris) cf. feruglioi (Amos), Saltospirifer guevarai Cisterna and Archbold and Pericospira sp. A new marine fauna from the upper part of the Cañón del Atuel section (Cabecera del Cañón Member) is reported. It includes the brachiopods Argentiella cf. A. stappenbecki Archbold, Cisterna and Sterren, Oehlertella annae (Feruglio), Orbiculoidea saltensis Reed, Calytrixia piersoni Taboada, Coolkilella aredesi Taboada, Costatumulus sp. and Septosyringothyris ? sp. A bio-chronostratigraphic correlation scheme, including key lithostratigraphic units and biozones of central-western Argentina is updated. • Previous and new brachiopod records from the San Rafael Basin are identified and elucidated. • Two diachronic faunas of the El Imperial Formation, relatives to the Tivertonia-Streptorhynchus faunal assemblage, are distinguished and discussed. • Intrabasinal bio-chronological correlation among different sections of El Imperial Formation is clarified. • A bio-chronostratigraphic correlation scheme of lithostratigraphic units and biozones of central-western Argentina is updated. [ABSTRACT FROM AUTHOR]

A total of 286 lactic acid bacteria isolated from goat’s dairy products in northwest of Argentina were characterized. Lactobacilli (38%) and cocci (62%) were identified according to morphological, physiological, and relevant technological properties.L. plantarum(14%) andEnterococcus(34%) were the predominant species.S. thermophilus, PediococcusandL. plantarumwere the highest acid producers. Eight strains ofL. fermentumproduced bacteriocins or metabolites similar to bacteriocins. The API-ZYM test was applied to 39 isolates. Eight strains were selected from their both technological properties and enzymatic activities for use as starter or adjunct culture in the manufacture of artisanal goat cheeses. [ABSTRACT FROM PUBLISHER]

Abstract: Brachiopod faunas from western Argentina are reviewed to improve the current understanding of their biostratigraphic and paleobiogeographic value for intercontinental correlation and paleoclimatic reconstruction, especially for middle to high paleolatitudes. The oldest faunal assemblage, the late Tournaisian–early Viséan Malimanian fauna, indicates an incipient biogeographic segregation of southwestern South America from contemporaneous peri-Gondwana and northern hemisphere regions, likely due to the enhanced thermal gradient that predated the pronounced latest Viséan global cooling and the major latitudinal biotic differentiation on a global scale. Paleogeographical distribution of key brachiopod taxa provides evidence of faunal interchange along western Gondwana during late Early Carboniferous. The paleoclimate of the region by this time has been interpreted as temperate preglacial conditions, in a higher paleolatitudinal setting. Global cooling and strong differentiation between marine biota of circum-polar and paleoequatorial regions occurred after late Viséan. The Barrealian fauna (Rugosochonetes-Bulahdelia and Levipustula assemblages), represents the oldest faunal record in western Argentina of this major latitude-related biotic segregation linked with the onset of the mid-Carboniferous glaciation. The Barrealian fauna appeared during a major late Viséan–Serpukhovian glacial episode with short-lived glacial and interglacial stages. Climatic fluctuations were probably related to local faunal changes and marine biotic exchange between higher and middle paleolatitudes of southwestern and eastern Gondwana. Widespread postglacial deposits bearing Bashkirian faunas demonstrate the beginning of a progressive climatic amelioration trend until early Permian times, barely affected by short-lived colder paleoclimatic fluctuations. The incoming of the late Bashkirian–early Moscovian Marginovatia-Maemia fauna was linked to a climatic change in the region following the disappearance of glacial conditions in westernmost Argentina. Ocean currents from the north, that reached the region bringing boreal brachiopods, were warm enough since Bashkirian times to build a thermal barrier for the biotic interchange with peri-Gondwana regions under subpolar settings and a faunal disconnection was established. In addition, asymmetrical climatic record between western Argentina and regions still under strong glacial influence, such as Patagonia and eastern Australia, reflect the clockwise rotation of Gondwana and consequent migration of western Argentina to lower latitudes. After a preceding mainly regressive depositional interval, the marine incursion bearing the Tivertonia-Streptorhynchus fauna accompanied the most extensive transgression that covered western Argentina. It was probably linked with the beginning of a thalassocratic regime by the global major sea level rise of late Asselian–Sakmarian times. The Tivertonia-Streptorhynchus assemblage represents a middle paleolatitude temperate and mixed fauna, which migrated toward southern Gondwana regions, indicating a marine faunal connection during a climatic amelioration trend. The last marine incursion in western Argentina brought the Costatumulus fauna, linked to a brief interruption of the mostly temperate paleoclimatic conditions established since the Pennsylvanian. A short-lived minor glacial pulse associated with the Costatumulus fauna reflected local mitigated climatic fluctuations, by the paleolatitudinal gradient to circumpolar areas where a major glacial pulse occurred during Sakmarian–Artinskian times. [Copyright &y& Elsevier]

Abstract: Argentina is a special place to study Late Palaeozoic life and environmental change because of the excellent exposures of Late Palaeozoic sedimentary sequences. In particular, Patagonia has an almost continuous Late Palaeozoic succession containing well-preserved faunal assemblages characterized by both strong endemism and distinctive palaeobiogeographic links to Australia and northeast Asia. In this contribution an overview of the current knowledge of the invertebrate faunas of Patagonia and their biostratigraphic and palaeobiogeographic significance are presented, along with comments on the future prospects of research in the light of new findings. The Late Palaeozoic outcrops in central-western Patagonia belong to the Tepuel–Genoa Basin (Chubut province, Argentina), then located in southwestern Gondwana during the Late Palaezoic. In this basin the succession is >6000m thick, and constitutes a continuous and complete succession from the Lower Carboniferous to lower Permian. As such, it has the potential to serve as an important reference section for regional and intercontinental correlations. The marine Late Palaeozoic of Patagonia has yielded abundant and well-preserved representatives of most invertebrate groups: brachiopods, bivalves, gastropods, cephalopods, hyolithids, pelmatozoans, ostracods and cnidarians. Recently, studies of the Patagonian faunas have resulted in different opinions on the ages of the faunas. Biostratigraphic correlation is complex due to strong faunal provincialism. For this reason, there are several hypotheses concerning the biostratigraphic zonation in the basin. Since 1920, when studies of Late Palaeozoic strata in Patagonia were first carried out, numerous papers on stratigraphic, palaeogeographic and taxonomic subjects have been published, but our knowledge of Carboniferous–Permian fossils from the Tepuel–Genoa Basin is still incomplete. At present, we are attempting to integrate and calibrate the different faunal associations with a view to achieving a unified biostratigraphic biozonation scheme and hence a much improved understanding of the palaeobiogeographic relationship of Patagonian faunas with those from western Argentina and other continents. Currently, detailed stratigraphic and palaeontological research is being done in the type section of the Tepuel–Genoa Basin. The aim of our studies is to integrate all partial sequences exposed throughout the basin and to propose a biostratigraphic chart based on key invertebrate taxa. Once this goal is achieved, a global correlation can be conducted, especially with other sections in Gondwana and the Arctic. [Copyright &y& Elsevier]

The article focuses on the Argentinean Pampas, a fertile region located in the south cone of South America whose temperate agricultural land serves as the backbone of Argentinean agriculture. It notes that the region is suffering from soil degradation and erosion as well as negative nutrient balance. It examines the importance of the region, such as being a significant resource for grain production, and the need to maintain the region's productivity through soil and water conservation.

Improved topsoil structural quality is expected under no-till farming, but soil physical constraints can develop under continuous no-till. Our objectives were: to evaluate the properties of loam, silty loam, and silty clay loam soils under various management practices on a regional scale; to clarify the relationship between soil organic matter pools and soil physical properties; and to find a minimum set of topsoil properties to characterize trends established by tillage. Thirty-nine loam, silty loam, and silty clay loam soils were sampled from cropped fields managed using conventional tillage (CT) and no-till (NT) as well as six undisturbed soils (uncropped). The A horizon thickness did not differ among soil textural groups and was 4 cm thicker in uncropped soils. Total and particulate organic C were significantly affected by management (uncropped > CT = NT, P 0.00 1). Soil structural instability of uncropped soils (0.3 17 mm) differed from CT soils (0.723 mm) but not from NT soils (0.573 mm). Soil structural instability was negatively related to total and particulate organic C, and no relation was found with the resistant organic C pool. Water infiltration rate was the only topsoil property affected by a significant texture x management interaction. Lower infiltration rates in NT silty soils were caused by platy structural forms with horizontal pores. Soil penetration resistance (0-5 cm) was 0.77 MPa higher in NT than in CT soils. A minimum set of topsoil properties to evaluate tillage management includes structural instability, total or particulate organic C, infiltration rate, and penetration resistance. [ABSTRACT FROM AUTHOR]

Abstract: In the humid Pampas of Argentina soybean is cultivated in different soil types, which were changed from conventional- to zero tillage systems in the last decade. Little is known about the response of soybean roots to these different soil physical environments. Pasture, and conventionally- and zero-tilled field lots cropped to soybean (R1 and R2 ontogenic stages) were sampled in February–March 2001 in a sandy clay loam and two silty clay loam Mollisols, and in a clayey Vertisol. In the 0–0.05m layer of conventionally- and zero-tilled lots soil organic carbon represented 53–72% of that in pasture lots, and showed an incipient recovery after 4–11 years of continuous zero tillage. Soil aggregate stability was 10.1–46.8% lower in conventionally-tilled than in pasture lots, and recovered completely in zero-tilled lots. Soil relative compaction ranged 60.8–83.6%, which was below the threshold limit for crop yields (>90%). In change, soil porosity>50μm ranged 0.91–5.09% soil volume, well below the minimum critical limit for root aeration and elongation (>10%, v/v). The threshold of soil resistance (about 2–3MPa) was only over passed in an induced plough pan in the conventionally-tilled Bragado soil (5.9MPa), and in the conventionally- and zero-tilled Ramallo soils (3.7–4.2MPa, respectively). However, neither the low macroporosity nor the high soil resistances impeded soybean roots growth in any site. According to a fitted polynomial function, root abundance was negatively related to clay content in the subsoil (R 2 =0.84, P <0.001). Soybean roots were only abundant in the subsoil of the sandy clay loam Mollisol, which had <350gkg−1 clay. Results show that subsoil properties, and not tillage systems, were the primary effect of root growth of soybean. [Copyright &y& Elsevier]

Silty loams of the rolling Pampa of Argentina are affected by different soil degradation levels. It is still poorly understood how soil degradation affects the regeneration of a desirable topsoil structure in pampean silty loams. A greenhouse pot experiment was carried out to evaluate changes in soil aggregation after 4 and 12 months exposure to varying: (i) soil management regimes: pasture, conventional tillage (CT) and eroded conventional tillage (CTer); (ii) water regimes: constant field capacity (FC) and wetting–drying cycles (W/D); and (iii) vegetation: sterilized and ryegrass. After 4 months (October–January), the size of aggregates measured by their mean weight diameter (MWD) after dry sieving, varied from 1.78 to 3.54 mm. This was significantly increased by soil degradation level (pasture

The soils of the Pampas are thought to be generally non-contaminated but there is growing evidence of trace element accumulation at some specific sites. The goal of this study was to measure the current levels of the main Potentially Toxic Elements (PTE) in the top horizon and in specific soil profiles so that we would establish the baseline concentrations of these elements. Eighty-eight top soils and three soil profiles were sampled. The samples were acid digested. Arsenic, boron, barium, cadmium, cobalt, chromium, copper, lead, manganese, mercury, molybdenum, nickel, silver, selenium and zinc were determined with inductively coupled argon plasma emission spectrometry (ICPES). All of the values found are within the normal range for uncontaminated soils as reported from several continents. Elements with high environmental risk potential are lower than the admissible range of the European Union and some of them are orders of magnitude lower than those of the United States Environmental Protection Agency (US-EPA) 501 levels. Potentially Toxic Elements contents increased with depth or showed a maximum concentration at the B2 horizon. This is related to the parent material and the pedogenetic processes but not to recent contamination. Soil profiles showed higher concentrations of PTE in clayey horizons. However, these relationships did not appear in top soil samples in any soil Great Group studied. The shown data establishes a baseline for PTE concentrations for Pampas soils. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age (LPIA) was the longest and most extensive glacial interval during the Phanerozoic, lasting from the Late Devonian to the late Permian (362–254 Ma). Numerous questions remain on the spatial and temporal extent of the ice centers, the timing of expansion and contraction of the ice sheets, and the distribution of ice across Gondwana through time. The Tepuel–Genoa Basin, in Patagonia (Argentina) was situated within the paleo South Polar Circle and contains a nearly continuous lower Carboniferous (Tournasian) to lower Permian (Artinskian) succession. The Mojón de Hierro Formation has been described as both non-glacial and glacial in origin, but lacks detailed sedimentological descriptions. This research investigates a ∼50 m succession with sedimentological and geochemical analysis within strata in the upper portion of the Mojón de Hierro Formation at Arroyo Garrido (Chubut Province). Five stratigraphic sections were measured and the strata were categorized into five lithofacies: 1) deformed sandstones, 2) thin-bedded diamictites, 3) graded rhythmites, 4) laminated mudstones with dispersed clasts, and 5) laminated mudstones. Deposition occurred in a slope environment from debris flows, turbidity currents, mass-movements, hemipelagic sedimentation, and ice rafting. The Chemical Index of Alteration (CIA) indicates values similar to average marine shales, which suggests that the muds were supplied from temperate terrestrial sediment sources. This indicates that icebergs from a distant source transited the basin and grounded glaciers were not present in the catchment area. Vanadium/chromium ratios (V/Cr) indicate dysoxic (restricted water circulation) values in samples between the mass-transported blocks and oxic values (well circulated water) in samples stratigraphically above the filled/leveled ponded mini basin. These oxygenation conditions suggest that the mass-transport deposit formed a topography on the sea floor, resulting in a mini basin that ponded sediments within the blocks. A local glacial source was not substantiated for the upper Mojón de Hierro Formation at Arroyo Garrido neither through the detailed facies analysis nor through geochemical proxies. [ABSTRACT FROM AUTHOR]

The westernmost Carboniferous Gondwanan deposits in Argentina recorded the Late Paleozoic Ice Age (LPIA) and the subsequent sea level changes in different fossiliferous stratigraphic units. One of them, the Retamito Formation, located at the southern extreme of the Paganzo Basin in the San Juan Province, contains the first Carboniferous paleoflora described in the country at the end of the 19th century. A recent revision of the outcrops allowed the recognition of invertebrates in marine strata linked to the Moscovian postglacial sea level rise characterized by the Tivertonia jachalensis-Streptorhynchus inaequiornatus (TS Biozone). These deposits overlie Bashkirian coal beds bearing plant remains of the Nothorhacopteris-Botrychiopsis-Ginkgophyllum flora (NBG Biozone), and both sequences provide abundant palynological assemblages. The palynofloras reveal the presence of Subzones B and C of the Raistrickia densa-Convolutispora muriornata (DM) Biozone. Subzone B is represented in the coal beds, and diagnostic palynological species indicate the presence of Subzone C in the transgressive event bearing the invertebrate fauna and microplankton elements. Approximately two tens of meters above the marine strata were recognized seeds linked to the Ferugliocladus Superzone of early Cisuralian age. The continuous succession, bearing palynological assemblages of the two subzones, spans the Bashkirian-Moscovian interval and allows comparisons with coeval palynofloras from Argentina and Brazil. • Two transgressive events characterize the Bashkirian-Moscovian in western Gondwana. • Existence of marine invertebrates confirms a transgression in the Retamito Formation. • Palynofloras are a key tool for correlating the two marine floodings in the region. [ABSTRACT FROM AUTHOR]

The Ansilta Formation is located 5 km southeast of the Astronomical Observatory El Leoncito near Barreal, San Juan Province, Argentina. It consists of glacimarine, nearshore, and fluvial systems deposited during the Late Paleozoic Ice Age along the eastern margin of the Calingasta-Uspallata Basin. Glacial environments are unique in that facies changes occur because of glacial ice margin fluctuations that may be independent from changes of eustatic sea-level. For this reason, an alternative conceptual framework outside of the traditional sequence stratigraphic approach is necessary to understand the genesis of these strata. The lower glacially influenced succession (0–427 m) records at least five glacial advances, where glacial dynamic signatures are interpreted using glacial sequence stratigraphy and glacial systems tracts (GST). The upper succession of the Ansilta Formation (427–700 m) consists of progradational shallow marine shelf, deltaic, and fluvial strata. This assemblage shows no direct evidence of ice contact deposition in the outcrop belt due to an absence of glacially shared diamictites and glacially modified clasts, representing a major deglaciation phase in western Argentina and is part of the stepped deglaciation across Gondwana that ended elsewhere during the late Permian. • We provide a stratigraphic analysis of the lower Ansilta Formation in the Calingasta-Uspallata Basin of Argentina. [ABSTRACT FROM AUTHOR]

The Retamito Formation is located at the southernmost of Oriental Precordillera, San Juan, Argentina. This contribution defines eight facies associations: FA1 (breccias and conglomerates) linked to initial valley fills by a chaotic basal colluvium fan and/or karst collapse. FA2 (sandstones and gravelly sandstones) is interpreted as deposits of coastal shoreface systems. The FA3 (coal and coaly mudstones) could be attributed to a paralic environment and represent the first record of plant remains of Argentina (NBG Biozone). FA4 (gravel-bed) is interpreted as a proximal alluvial system. FA5 (shales) contains the first record of brachiopods and a new taxa Komiellanetes cesariae sp. nov, probably representing an eastward extension of the TS fauna in a brief marine incursion. FA6 (mudstones and sandstones) is deposited in a delta front system. The FA7 (red mudstones) are linked to lagoons deposits, where they preserved a floristic assemblage of megaflora remains (Ferugliocladus Superbiozone) composed of seeds, stems, and leaves that are most likely of Permian age. Finally, the FA8 (interbedded sandstones and mudstones) is interpreted as deposited by an anastomosed fluvial system. We present paleoenvironmental and paleontological data of the Retamito Formation correlated with the neighboring Andapaico and Ansilta formations in an east-west transect. This correlation parsimoniously linked the Paganzo and Calingasta-Uspallata Basins in seven filling scenarios (temporal stages Ts). From Ts1 to Ts5, both basins were separated by the Protoprecordillera. Common paleoenvironments on both basins suggest unification of them in Ts6 and Ts7. These temporal stages are paleontologically controlled by two new fossil levels and the corresponding sedimentary paleoenvironments that contain them. Thus, it could be demonstrated that the positive element of the Protoprecordillera was active until the Upper Carboniferous and collapsed towards Early Permian, unifying both basins in this sector of Gondwana. • The first discovery of invertebrates from the TS biozone in the Eastern Precordillera (new genus and species). • The first discovery of the Superzone Ferugliocladus in the Eastern Precordillera. • An east-west correlation model between the Paganzo and Calingasta-Uspallata basins is presented. • The presence and subsidence of the Protoprecordillera that divided both basins were determined. [ABSTRACT FROM AUTHOR]

Cattle trampling during grazing of crop residue may cause physical soil damage that may be repaired when animals are excluded. Understanding the interplay between soil deterioration and natural recovery of the soil physical condition allows for a better understanding of grazing management systems. Various soil physical properties (i.e., bulk density (BD), penetration resistance (PR), infiltration rate, structural instability) were determined up to 20 cm depth in a silty loam Typic Argiudoll and a sandy loam Typic Hapludoll of the Argentine Pampas from 2005 to 2008. Sampling was carried out before and after grazing, and at different moments of the crop cycle including harvest event. Grazing winter residues and weeds did not lead to the expected compaction processes (e.g., in average BD difference between after grazing and before grazing was from −0.072 to +0.137 Mg m −3 for both soils under grazing). In general, physical soil conditions improved during winter, independently of grazing. This might be related to the intrinsic soil characteristics (organic matter content, moisture, clay content) or grazing system (stocking rate, duration of grazing period), which prevented soil physical damage, suggesting that recovery forces were greater than grazing stress. Cropping to maize and soybean showed similar value or improved soil physical properties respect to the after grazing (e.g., in average PR difference between before harvest and after grazing was from +409 to −2561 kPa for both soils), acting as biotic a recovery factor. However, massive damage was harvest operation led to the highest soil deterioration (e.g., in average PR difference between before harvest and after harvest was 985 kPa). [ABSTRACT FROM AUTHOR]

Cover crops (CC) provide many benefits to soils but their effect on decomposition of previous crop residues and release of nutrients in continuous no-tillage soybean [Glycine max (L.) Merr.] production are little known. Our objective was to quantify CC effects on decomposition and phosphorus (P) release from soybean residue using litterbags. Three CC species (oat, Avena sativa L.; rye, Secale cereal L.; and rye grass, Lolium multiflorum L.) and a no CC control were evaluated. Temperature, moisture content, microbial biomass and microbial activity were measured in the surface 2 cm of soil and residues. Cover crops increased soybean residue decomposition slightly both years (8.2 and 6.4%). Phosphorus release from soybean residue did not show any significant differences. Cover crops increased microbial biomass quantity and activity in both soil and residue samples (p < 0.001, p = 0.049 for soil and residue microbial biomass; p = 0.060, p = 0.003 for soil and residue microbial activity, respectively). Increased residue decomposition with CC was associated with higher soil and residue microbial biomass and activity, higher near-surface (0-2 cm) moisture content (due to shading) and soil organic carbon enrichment by CC. Even though CC increased soybean residue decomposition (233 kg ha-1), this effect was compensated for by the annual addition of approximately 6500 kg ha-1 of CC biomass. This study demonstrated another role for CC when calibrating models that simulate the decomposition of residues in no-tillage systems. [ABSTRACT FROM AUTHOR]

During the Carboniferous, western Gondwana was affected by numerous transgressions resulting from fluctuations in the ice sheet throughout the Late Paleozoic Ice Age. These sea level rises are well documented in western Argentina basins: Paganzo, Río Blanco, San Rafael, and Calingasta–Uspallata. Three transgressive events are recognized: The first corresponds to the post-glacial transgression of early Bashkirian age, which flooded the basins of western Argentina. The second transgression, the Pennsylvanian Transgression 1, is limited to the San Rafael, Río Blanco, western Paganzo, and Calingasta–Uspallata basins. This transgression facilitated the deposition of carbonaceous shales and thin coal beds in transitional estuarine-type environments. This stratigraphic interval is accompanied by megaflora of Nothorhacopteris – Botrychiopsis – Ginkgophyllum , microflora of Raistrickia densa – Convolutispora muriornata Subzone b, and an association of marine invertebrates that constitute the Marginovatia – Maemia Fauna. Finally, Pennsylvanian Transgression 2 or "Stephanian" transgression is more extensive and is associated with a Moscovian age invertebrate fauna. This contribution focuses on a sedimentological and paleontological analysis of the Pituil Formation. This unit comprises five facies associations: I, offshore; II, shoreface; III, deltaic systems; IV, barrier islands; and V, coastal lagoon. These sedimentological data and the fossil content of the Pituil Formation allow us to characterize the Pennsylvanian Transgression 1 in the Calingasta–Uspallata Basin and correlate it with other basins in western Gondwana. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to identify pore characteristics (quantity, distribution, stability and orientation of pores) that condition water dynamics under continuous zero tillage (ZT) on silty soils of the Argentinian Rolling Pampas. Soil properties were analyzed under continuous chisel plough (CP) and ZT treatments from three trials with different duration and crop sequence. The following soil properties of A horizon were analyzed from 0 to 0.05 and from 0.10 to 0.15m depths: bulk density, pore size distribution, pore origin distribution, aggregate stability index, infiltration rate and organic matter. Preferred pore orientation was carried out by introducing the sampling cylinders in vertical and horizontal direction and then discriminating by pore size. Total porosity of A horizon under CP was 3.5% higher than under ZT. This could be attributed to macro and mesopores as well as to structural porosity. Aggregates were 30% more stable in ZT than under CP in the top at 0.05m due to a 21% increase in organic matter. However, infiltration rate was not improved under ZT. Under ZT, there was a tendency of macropores to become orientated in parallel to the soil surface. This horizontal preferential macropore orientation was critical in determining water infiltration. The susceptibility to stratify the structure in the first centimeters of the soil under ZT was attributed to the predominance of soybean in the crop sequence. [Copyright &y& Elsevier]

• Results from 32 field experiment of subsoiling studies under no till were analyzed. • Deep no-inversion tillage decreased soil bulk density and penetration resistance and increased infiltration rate. • Effect of deep no-inversion tillage on soil penetration resistance persisted 17 months after labor. • Deep no-inversion tillage increased soybean yields (26 %) mainly when control yields were low. • Deep non-inversion tillage increased maize yields around 6%. No till is considered part of the good management practices recommended in conservation agriculture. Regardless of the benefits of this practice, shallow compaction or soil hardening by farm machinery traffic can lead to soil constraints to crop growth. Deep non-inversion tillage could be proposed together with other practices to alleviate this soil compaction. In this meta-analysis, we reviewed experimental results (32 field studies) obtained throughout the Pampas Region focused on the immediate effects and duration of soil mechanical alleviation measured by relevant soil physical properties and by the impact on maize and soybean yield. Treatments were classified in: a) Control (no tilled soils), and b) Subsoiled (no tilled soil subjected to mechanical compaction alleviation by deep non-inversion tillage). Data were analyzed by comparing pairs of the same experiment (t-paired test). The response to compaction alleviation (Δ Subsoiled - Control) for different soil variables was related to soil and climate and agricultural history management. Deep non-inversion tillage significantly decreased soil bulk density (0−0.20 m; P < 0.0001; -4.3 % in average), increased infiltration rate fivefold (Δ = +213 mm.h−1) and decreased soil penetration resistance in the 0−0.20 m layer 44 % in average (Δ = -0.86 MPa). Soil penetrometer resistance profiles (0 to 0.4 m) of Control situations peaked at 0.15−0.20 m. This peak disappeared in deep tillage, showing significant penetration resistance decreases at these layers. Soil compaction alleviation works had a durability of not more than 17 months (±2.8 months) after being performed. Deep non-inversion tillage enhanced soybean yields (26 % on average; Δ = +561 kg. ha−1; P < 0.0001), mainly in yields lower than 2000 kg. ha−1, usually associated with clay soils. In maize, mean responses to deep non-inversion tillage were only 6% (Δ = +567 kg. ha−1; P < 0.0001). Considering these results, deep non-inversion tillage could be a promising practice to close rainfed crop yield gaps in the region. Nevertheless, due to its low durability in time, it is strategic to incorporate further compaction prevention and structural regeneration practices such as cover crops, diversified crop rotations and controlled traffic according to soil and environment characteristics. [ABSTRACT FROM AUTHOR]

Context: In grazed pasture systems, most nitrogen (N) losses arise from N deposited in the form of ruminant excreta patches. However, during winter, when grassland stocking rate and soil nitrous oxide (N2O) emissions are expected to be low, N2O fluxes from excreta patches could be considered negligible for the calculation of the total emissions. Aims: The aims of the study were to quantify and compare N2O winter emissions in soils with and without grazing and to study some drivers of N2O emission during a low-temperature period. Methods: The experiment was performed in the Flooding Pampa, Argentina, in a completely randomised design with repeated measures over time. The treatments were urine, faeces, and control without excreta addition. During winter, 20 gas samplings were made for each treatment, and the results of N2O fluxes were extrapolated to 1 ha. Key results: Daily N-N2O emissions of the control were 0–10 mg/m2.h. The N-N2O emissions from the urine patches were higher (P < 0.05) than those from faeces and control treatments, with average respective treatment values of 26.13, 5.35 and 2.88 µg N-N2O/m2.h. The N-N2O emissions increased after urine application and fluxes from this treatment were intensified after rainfall. The cumulative N2O emission per chamber was almost 10 times higher in the urine treatment than in the faeces and control treatments. Conclusion: The air temperature influenced N2O emissions. The accumulated N2O per hectare arising from animal deposition was <5% greater than in the control. Implications: Although the contribution of animal excreta to soil N2O emissions seems to be low, it could be of relevance once extrapolated to the total area under grazing on the Argentinean pampas (principally Flooding Pampa) where the low-temperatures period is at least 15% of the year. In Argentina, livestock is the main source of greenhouse gas emissions, and nitrous oxide (N2O) emitted from excreta is an important contributor. This study of N2O emission was conducted in the main livestock region of the country, with cold winters; although the difference in gas emissions was only 5% between soils with and without livestock during winter, the difference could be important if extrapolated to the entire livestock area. Future studies, already under way, will allow to see their weight within the total annual emissions. [ABSTRACT FROM AUTHOR]

The protozoan parasite Leishmania (Viannia) braziliensis is among Latin America's most widespread Leishmania species and is responsible for tegumentary leishmaniasis (TL). This disease has multiple clinical presentations, with cutaneous leishmaniasis (CL) being the most frequent. It manifests as one or a few localized skin ulcers, which can spread to other body areas. Hence, early diagnosis and treatment, typically with pentavalent antimonials, is critical. Traditional diagnostic methods, like parasite culture, microscopy, or the polymerase chain reaction (PCR) for detection of the parasite DNA, have limitations due to the uneven distribution of parasites in biopsy samples. Nonetheless, studies have revealed high levels of parasite-specific anti-α-Gal antibodies in L. (V.) braziliensis- infected patients. Previously, we demonstrated that the neoglycoprotein NGP28b , consisting of the L. (Leishmania) major type-2 glycoinositolphospholipid (GIPL)-3-derived trisaccharide Gal p α1,6Gal p α1,3Gal f β conjugated to bovine serum albumin (BSA) via a linker, acts as a reliable serological biomarker (BMK) for L. (V.) braziliensis infection in Brazil. This indicates the presence of GIPL-3 or a similar structure in this parasite, and its terminal trisaccharide either functions as or is part of an immunodominant glycotope. Here, we explored whether extending the trisaccharide with a mannose unit would enhance its efficacy as a biomarker for the serological detection of L. (V.) braziliensis. We synthesized the tetrasaccharide Gal p α1,6Gal p α1,3Gal f β1,3Man p α(CH 2) 3 SH (G31 SH) and conjugated it to maleimide-functionalized BSA to afford NGP31b. When we assessed the efficacy of NGP28b and NGP31b by chemiluminescent enzyme-linked immunosorbent assay on a cohort of CL patients with L. (V.) braziliensis infection from Bolivia and Argentina against a healthy control group, both NGPs exhibited similar or identical sensitivity, specificity, and accuracy. This finding implies that the mannose moiety at the reducing end is not part of the glycotope recognized by the parasite-specific anti-α-Gal antibodies in patients' sera, nor does it exert a relevant influence on the terminal trisaccharide's conformation. Moreover, the mannose does not seem to inhibit glycan-antibody interactions. Therefore, NGP31b is a viable and dependable BMK for the serodiagnosis of CL caused by L. (V.) braziliensis. [Display omitted] • An α-Gal containing tetrasaccharide was synthesized and conjugated to a carrier protein resulting in neoglycoprotein NGP31b. • NGP31b can serve as a biomarker for New World cutaneous leishmaniasis and can distinguish from T. cruzi infection. • The reducing Man of the tetrasaccharide in NGP31b is not needed for the recognition by the patients' anti-α-Gal antibodies. [ABSTRACT FROM AUTHOR]

Agriculture is one of the key economic sectors in Argentina and, in the last decades, the increase in prices and competitiveness of some grains has imposed important changes. In this process, crop cultivation occupied significant extensions of land areas previously dedicated to livestock farming, which in turn have experienced intensification in terms of production through an increasing share of feedlot systems. The agriculture sector is the main NH 3 emitter in Argentina, however no inventory developed locally has been thus far available. We estimated the time series 2000–2012 of NH 3 emissions, both at national and spatially disaggregated levels. National NH 3 emissions in 2012 amounted to 0.31 ± 0.08 Tg, with the use of mineral fertilizers accounting for 43.0%, manure in pasture 32.5%, manure management 23.0% and agricultural waste burning 1.5%. Urea use was the major source of NH 3 emissions and its application on wheat and corn crops dominated the trend. Emissions from open biomass burning were estimated but not included in the national totals because of the difficulties in differentiating between agricultural (i.e., prescribed burning of savannas) and non-agricultural emission sources. Compared to this work, NH 3 emissions reported by EDGAR were 83% higher than our estimates. The time series of spatially distributed NH 3 emission estimates clearly showed the effect of the expansion of cropland, the displacement of planted areas of N-fertilizes crops by competing soybean cultivation and the relocation and intensification of beef cattle production. This new inventory constitutes a tool for policies concerning the impact of agricultural activities on air quality and contributes with more accurate and updated information useful for atmospheric chemical transport modeling. The accuracy and applicability of the inventory may be improved by local studies aimed at refining the spatial disaggregation by focusing in specific areas of fertilizer application, reflecting seasonal and monthly patterns in agricultural practices and climate conditions and addressing likely changes in diets, productivity and excretion rates over time. [ABSTRACT FROM AUTHOR]

Because of the increasing prices of commodities over the last decades, crops like maize (Zea mays L.) are being cultivated in lowland sodic soils with physical-chemical constraints, such as those having natric horizon (Btn); however, the magnitude of the reductions in maize productivity in the face of these limitations under different water regimes is not known. Maize is a highly water-demanding crop in midsummer, so the ability of the Btn horizon to provide enough water to the crop in times of high atmospheric demand is still unclear. The objectives were to evaluate (i) the contribution of the Btn horizon to water absorption by maize, and (ii) the effect of soil exchangeable sodium percentage (ESP) in the Btn horizon on leaf area index (LAI) and maize grain yield (GY) under contrasting imposed soil water conditions. Field trials were carried out during the growing seasons 2018/19 and 2019/20 at Chascomús, Argentina (35º 44′ S; 58º 03′ O), where sodic soils with natric horizons and high-water table are plentiful. Treatments included a bare soil without cultivation and maize crops under two water regimes: i) rainfed control (C), ii) drought (D), under a wide range of exchangeable sodium percentage (ESP) in the Btn horizon (from ESP 3–34 %). Maize crops could uptake water from the Btn horizon in both water regimes (C and D), but absorption decreased by ≈ 1 % for every 1 % increase in subsoil ESP. This increase in sodicity also decreased the LAI by 0.053 cm cm−2, and GY by 134.5 kg ha−1. In the treatment with imposed drought, maize roots passed down the Btn horizon and reached the groundwater from where they absorbed water. The Btn horizon can be considered a source of water for the maize crop, mainly with low levels of ESP. The detrimental effect of ESP in the GY was independent of water regimes in the crop cycle. SIGNIFICANCE: These results are useful for farmers to adjust crop management, considering the soil ESP, available water in the Btn horizon, and the groundwater depth, making use of water and soil resources more efficient and sustainable. [ABSTRACT FROM AUTHOR]

Favorable climate and soils for rainfed crop production, together with a relatively low population density, results in 70–90% of Argentina grain production being exported. No assessment to date has tried to estimate the potential for extra grain production for soybean, wheat and maize, which account for 78% of total harvested area, by yield gap closure on existing cropland area and its impact at a global scale. The objectives of this paper are (i) to estimate how much additional grain could be produced without expanding crop area by closing yield gaps in Argentina, (ii) to investigate how this production and yield gaps varies across regions and years, and (iii) to analyze how these inter-annual variations are related to El Niño—Southern Oscillation phenomenon (ENSO). Production increase on existing crop area was assessed for soybean, wheat and maize by quantifying the yield gap (Yg), that is, the difference between water-limited yield potential (Yw) and actual yield (Ya). A bottom-up approach was followed to estimate Yw and Yg, in which these parameters were first estimated for specific locations in major crop producing areas and subsequently up-scaled to country level based on spatial distribution of crop area and climate zones. Locally-calibrated crop simulation models were used to estimate Yw at each selected location based on long-term weather data and dominant soil types and management practices. For the analyzed period, the national level Yg represented 41% of Yw for both wheat and maize and 32% of the Yw for soybean. If farmers had closed Yg from these levels to 20% of Yw, Argentina could have increased soybean, wheat and maize production by a respective 7.4, 5.2, and 9.2 Mt, without expanding cropland area. This additional production would have represented an increase of 9%, 4%, and 9% of soybean, wheat, and maize global exports. This potential grain surplus was, however, highly variable because of the ENSO phenomenon: attainable soybean production was 12 Mt higher in favorable “El Niño” years compared with unfavorable “La Niña” years. Interestingly, Yg tended to be higher in wet years, suggesting that farmers do not take full advantage of years with favorable conditions for rainfed crop production. Regional variation in Yg was found in Argentina highlighting the usefulness of this work as a framework to target research and, ultimately, reduce gaps in areas where current yields are well below their potential. [ABSTRACT FROM AUTHOR]

Abstract: The grazing of crop residues during the winter in integrated crop–livestock systems can either increase soil bulk density (BD) by compaction or decrease BD by swelling, as a function of gravimetric soil water content (GW) during grazing. A field experiment was conducted from 2005 to 2008 to evaluate the BD response to grazing in a no-till silty loam soil (Typic Argiudoll) of the Pampas region of Argentina. Soil BD (core method), GW data and the calculated air volume (AV) were obtained from the 0–50mm and 50–100mm layers at different sampling times from ungrazed and grazed treatments. Over most of the study period (2006 through 2008) soil BD showed little impact from grazing, with minimal temporal variation (1.32–1.46Mgm− 3). This stable behavior was ascribed to low rainfall and relatively low GW values at the time when soil was trampled by livestock and routinely trafficked by machinery. Soil BD in the upper (0–50mm) layer was significantly (p<0.001) lower at the beginning of the study (2005 to early 2006), when the rainfall was higher (as was soil GW) during transit periods. Lower BD was not due to soil swelling but to air that was trapped by kneading in response to transit of livestock and machinery. Fitted straight lines indicated that this process became particularly prominent when GW was >330gkg− 1 in the ungrazed treatment and GW was >240gkg− 1 in the grazed treatments. Grazing accentuated the soil kneading process that promoted air entrapment. Our results suggest in this no-tilled silt loam soil that winter grazing of crop residues caused no deterioration of topsoil porosity in the no-tilled silty loam soil. [ABSTRACT FROM AUTHOR]

The provenance of sandstones deposited in the late Paleozoic Tepuel-Genoa Basin is analyzed in this paper. Five sections were sampled in Esquel, Sierra de Tepuel, Sierra de Tecka, El Molle, and Río Genoa areas for petrographic and geochemical studies. The sandstones in the Tepuel-Genoa Basin are dominated by feldspathic litharenites and litharenites, showing lithic fragments of volcanic and sedimentary rocks in the Valle Chico Formation and medium-to high-grade metamorphic rock clasts in the rest of the units. Detrital modes of seventy-five sandstones samples from the Valle Chico, Pampa de Tepuel, Mojón de Hierro, and Río Genoa formations were counted and analyzed. Seven modal components have discriminant value for identifying provenance areas (Qm, Qi, Lv, Lmm-h, Lm-Lp, Lm, Qpm). These modal components allow identification of three petrofacies: 1. Quartzose-lithic (Qm 69 Lv 2 Lm 29), 2. Quartzose (Qm 89 Lv 4 Lm 7) and 3. Volcanic-sedimentary (Qm 60 Lv 38 Lm 1). The quartzose-lithic petrofacies is mainly composed of monocrystalline quartz, medium- and high-grade metamorphic clasts and polycrystalline quartz with cataclastic texture, this assemblage is interpreted as being derived from the crystalline rocks that form the Deseado Massif. The quartzose petrofacies is composed of monocrystalline quartz with scarce contributions of metamorphic clasts and traces of volcanic fragments; the provenance area is ascribed to sedimentary terrains, which most likely covered part of the Deseado Massif. The volcanic-sedimentary petrofacies is comprised of volcanic (acidic and intermediate rocks) and sedimentary (sandstone and mudstone) clasts, with discrete amounts of quartz grains with idiomorph shapes and embayments. This assemblage may correspond to material supply from the Devonian-Early Carboniferous accretionary complex developed in Chile or the unroofing of the western volcanic arc located in the central part of Patagonia. The validity of the three defined petrofacies was evaluated using Principal Component Analysis and triangular compositional diagrams; both methods show good separation and lack of overlap between the three petrofacies. Major (Si, Al, Fe, Na, K) and trace-REE elements (Zr, Th, Sc, Hf) were used to improve the petrographic information. The relation SiO 2 against K 2 O/Na 2 O indicates that the Pampa de Tepuel and the Mojón de Hierro formations correspond to a passive margin, while the Valle Chico and Río Genoa formations represent different types of active continental margins. The Th/Sc and Zr/Sc ratios and the Th-Hf-Co distributions indicate that the sandstones of the Tepuel Group were formed from rocks compatibles with the average composition of the upper continental crust. • Detrital modes of the late Paleozoic Tepuel-Genoa Basin in Patagonia (Argentina) are analyzed. • Geochemical data of sandstones of this basin are presented. • Three petrofacies (Quarztoze, Quarztose-lithic, and Volcanic-sedimentary) are defined. • The basement of the Macizo del Deseado and Chilean accretionary complexes are proposed as the main source areas. [ABSTRACT FROM AUTHOR]