Daniel G. Poiré

• PhD
• Emeritus Professor at National University of La Plata

made up of thick quartz arenite beds together with kaolinitic claystones and thin fine-grained conglomerates. The Balcarce Formation was formed in the nearshore and inner shelf environments of a tide-dominated and storm influenced open platform. It shows many features suggesting tidal sedimentation. Coarse-grained facies were formed by sand bar mig...

Palynological data on Piedra Clavada Formación (Albian) from its type area, Santa Cruz Province, Argentina. Two sections from the type area where Piedra Clavada Formación is found yielded pollen assemblages in which 70 palynomorphs have been determined, including Bryophytes/Pteridophytes, Gymnosperms, Angiosperms and terrestrial plancton. Few and b...

Sedimentological contrasts between coastal to shelf tidal barforms on ancient shorelines, particularly in tidally affected deltas, are relatively poorly understood. A comprehensive analysis of facies distribution and architectural attributes, complemented by virtual outcrop models (VOMs), has unveiled two different tidal barform archetypes in a san...

Vaca Muerta Formation. Diagenesis. --------------------------------------------------------------------------------- Las arcillas son un grupo de minerales dentro de los filosilicatos que presentan una estructura laminar y propiedades características. Diversos autores han utilizado estos minerales para realizar inferencias sobre las condiciones pal...

Systematic magnetic fabric and rock-magnetic studies on sedimentary rock specimens from the Neoproterozoic Villa Mónica (Cryogenian) and Loma Negra (Ediacarian) formations (Tandilia system, Buenos Aires Province, Argentina; Gómez-Peral et al., 2024) were carried out to elucidate the nature of a widespread remagnetization event which replaced primar...

South America figures as one of the most fruitful continents for paleontological research on the Ediacaran-Cambrian transition, with almost 100 years of studies on organisms preserved in carbonates and siliciclastic successions deposited during the birth of the Gondwana supercontinent. However, this scientific record is often scattered among local...

The initial peopling of South America is a topic of intense archaeological debate. Among the most contentious issues remain the nature of the human-megafauna interaction and the possible role of humans, along with climatic change, in the extinction of several megamammal genera at the end of the Pleistocene. In this study, we present the analysis of...

The Neoproterozoic (>1160 to~540 Ma) sedimentary record of the Tandilia System is reorganized into eight depositional sequences based on a detailed review of published sources and new lithological observations. The main compositional attributes compiled from the studied units were used to indicate changes in lithology regarding their origin. Epicla...

Anomalous paleomagnetic data have been found worldwide during the Ediacaran period, giving rise to several non-actualistic hypothesis. In order to get more information about this period, paleomagnetic, magnetic fabric and rock magnetic studies were carried out in the Avellaneda Formation ($570-560 Ma) from two drill cores of the Alicia quarry in th...

The final consolidation of southwestern Gondwana during the Ediacaran–Cambrian resulted in the formation of a large landmass originally surrounded by the newborn Panthalassic Ocean. The Río de la Plata Craton is one of the last pieces that complete the geotectonic puzzle along the austral part of this supercontinent. However, the sedimentary record...

Several studies on the Neoproterozoic sedimentary cover of the Tandilia System, Argentina, have been carried out in recent decades. The integration of this knowledge and new results have allowed us to carry out an integral analysis including backstripping technique, forward models, sedimentology, and stratigraphy to provide an integral , innovative...

The behavior of the Earth’s magnetic field during the Ediacaran Period (635-542 Ma) is intriguing. Paleomagnetic data suggest a hyperactive state characterized by a high frequency of polarity reversals and an apparent ultra-low field strength. These unusual activities seem likely to extend until the Ediacaran- Cambrian boundary, however, the scarci...

The Ediacaran apparent polar wander path (APWP) for the Rio de la Plata Craton was analyzed and a new alternative path is presented. This revised path was constructed considering an opposite polarity for poles older than ca. 590 Ma. This path is more consistent with that recently proposed for West Africa, whose large oscillations were attributed to...

Ignimbrites are deposits found in sedimentary basins globally, commonly linked with evolved volcanism. Understanding fractured ignimbrites in sedimentary basins is crucial for various economic applications, including hydrocarbon extraction, CO2 storage, fractured aquifers, and geothermal resources. Fractured ignimbrite reservoirs typically consist...

La presencia de un espeso paquete de sedimentitas epiclásticas y carbonáticas intercalado en la Serie Tobífera y su equivalente en superficie Complejo El Quemado, ha sido reconocido en las últimas décadas. Recientemente De la Cal et al. (2022) han definido en subsuelo, el "Sistema Petrolero Tobífera-Tobífera", en donde la roca madre se encuentra en...

La Formación Vaca Muerta (Tithoniano-Berriasiano) es portadora de numerosas estructuras sedimentarias de origen orgánico, registradas tanto en subsuelo como en afloramientos. El objetivo de este trabajo es mostrar distintas formas de trazas fósiles y estromatolitos, y analizar su significado paleoambiental. Las secciones analizadas han sido las de...

La Formación Vaca Muerta (Tithoniano-Berriasiano) constituye la principal roca madre productiva del país. Se trata de una sucesión de grano fino caracterizada tanto por componentes carbonáticos (mayoritariamente micrita primaria) como siliciclásticos (cuarzo, feldespatos, arcillas), y en menor medida piroclásticos, materia orgánica, pirita y óxidos...

La Formación Ituzaingó son depósitos fluviales asociados a la evolución del río Paraná durante el Mioceno tardío-Pleistoceno. Aflora a lo largo de las barrancas de la margen izquierda del río Paraná en las provincias de Corrientes y Entre Ríos (Argentina), así como en diversos tributarios. En un principio se le asignaba una edad plio-pleistocena as...

The Neoproterozoic era (1000-539 Ma) encompasses drastic global changes, including extreme climatic events and transformative evolutionary transitions. Snowball Earth hypothesis (cf. Snowball vs Slushball Earth hypotheses) suggests that during Cryogenian the Earth was "completely" ice-covered Sturtian (~720-710 Ma) and Marinoan (635 Ma) events. In...

Las barras de marea ocurren tanto en estuarios y deltas como en costas abiertas donde varían sustancialmente en términos de dimensiones, arquitectura y orientación en respuesta a cambios en la altura de la columna de agua, la cantidad de sedimento disponible y la orientación y/o velocidad de las mareas. Ejemplos actuales de dichos ambientes, sujeto...

The terminal Ediacaran fossil record includes microbial mats and body fossils characterized by simple morphologies, which represents a challenge to understand several aspects related to the paleoecology of the emerging complex life. The marine siliciclastic deposits of the Cerro Negro Formation (~560-550 Ma) contain evidence of different styles of...

Omission surfaces represent a gap in the sedimentary record on a particular environment, constituting an important tool for basin analyses. Nevertheless, not always these surfaces constitute key sequence-stratigraphic surfaces, and their correct interpretation is highly important for the recognition of genetically related strata. Documentation and...

Magnetostratigraphy is a powerful technique for high-resolution stratigraphic correlation and accurate dating of the polarity history of the magnetic field. Up to now, magnetostratigraphic studies have been underutilized in Ediacaran successions. Here, we present a magnetostratigraphy coupled with a carbon isotope study in Ediacaran Avellaneda Form...

The Maastrichtian dinosaur-bearing Chorrillo Formation in southern Patagonia (⁓50° S, Austral-Magallanes Basin, Argentina) is a pedogenically modified fluvial succession, which records sediment deposition at mid-high paleolatitudes in the Southern Hemisphere. In order to reconstruct the paleoenvironment and paleoclimates for the Chorrillo Formation...

The sedimentary infill of the Tandilia Basin is characterised by at least four different stages of deposition during the Neoproterozoic (< 1160 to ~ 550 Ma), two of them recognisable in the Sierras Bayas Group and two in the La Providencia Group. The Villa Mónica Formation, representing the first stage of basin infill (< 1160 to < 720 Ma), consists...

Trace elements, particularly rare earth elements (REE), are widely used as proxies to reconstruct paleoenvironmental and taphonomic conditions. We traced these elements in fossil penguin bones collected along the Paleogene sequence exposed in Seymour Island (=Isla Marambio) to test them as indicators of the tectonic changes to which this region was...

A paleomagnetic and rock magnetic study was carried out in the Ediacaran Avellaneda (∼570 Ma) and Cerro Negro (∼555 Ma) Formations belonging to the La Providencia Group, in the upper part of the Neoproterozoic sedimentary cover of the Tandilia region, in the Río de la Plata craton. The Avellaneda Formation was studied at outcrop level and in three...

The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been reported from the Mata Amarilla Formation (Cenomanian), the Cerro Fortaleza Formation (Campanian–Maastrichtian), and the Chorrillo Formation (early Maastrichtian). In this contribution, we examined all the turtle remains recovered from six localities in the...

Giant stromatolites are meter-scale laminated carbonate biosedimentary deposits formed by the action of benthic microbiota under very specific conditions. Although occurrences of giant stromatolites are relatively common in Precambrian deposits, the Phanerozoic record is still sparse. Here, we carried out an integrated analysis of the Lower Permian...

We present the first taphonomic analysis on basal sauropodomorph dinosaur remains from the Los Colorados Formation. We analyzed 22 bone samples with X-ray diffractometry, three of these in petrographic sections and one of them in SEM. In this article we recognize the taphonomic processes (biostratinomic and fossil-diagenetic) involved in the genesi...

Aggradational deltaic successions are uncommon in the stratigraphic record since deltas are progradational by nature. However, deltaic coastlines fed by multiple small distributaries rather than by a well-defined trunk fluvial distributary system might result in aggradational successions if the sediment is effectively redistributed from river mouth...

The Oligocene–early Miocene Tranquitas Formation in the southern Chaco foreland basin records the onset of Central Andean shortening. The aims of this contribution are to: (1) provide original data of the depositional conditions of the Tranquitas Formation, (2) to determine the role of tectonic and climate influence on the depositional conditions a...

The objective of this work is to determine the parent material of the area of Carlos Reyles, Durazno, as well as the rest of the area and its relation with the local geology. We studied four different places where geological survey was performed as well as sampling of horizons C. For the horizons C we estimated the size of the mineral particles by...

In recent decades, the growing interest in wetlands highlights the fundamental role of these complex ecosystems. Integrated sedimentological and geochemical studies that refer to wetlands appear more frequently in the literature, since such approaches provide a window into understanding the functions they have played through geologic time. The Mioc...

The deposits of the Chorrillo Formation (Maastrichtian) were accumulated during a ‘continental window’ that occurred during the Late Cretaceous in the Austral-Magallanes foreland basin, southern Patagonia, Argentina. The aim of the present contribution is to describe the depositional conditions as well as new vertebrate and plant fossils from this...

Wave-, tidal-, and fluvial-dominated deltas are important hydrocarbon reservoirs worldwide, and it is well known that depositional facies types, detrital composition and diagenetic products are key aspects when evaluating potential reservoir properties. Moreover, detrital composition and diagenetic products are controlled by external forces such as...

The wetlands and salt flats of the Central Andes region are unique extreme environments as they are located in high-altitude saline deserts, largely influenced by volcanic activity. Environmental factors, such as ultraviolet (UV) radiation, arsenic content, high salinity, low dissolved oxygen content, extreme daily temperature fluctuation, and olig...

La cobertura sedimentaria del Cratón del Río de La Plata en el Sistema de Tandilia inicia con las sedimentitas marinas de la Formación Villa Mónica. Esta formación (de ~80 m de espesor) se divide en dos secciones, una basal silicoclástica (conglomerados, areniscas y fangolitas) y otra superior esencialmente dolomítica rica en estromatolitos con mor...

The Salar de Atacama in the Chilean Central Andes harbors unique microbial ecosystems due to extreme environmental conditions, such as high altitude, low oxygen pressure, high solar radiation, and high salinity. Combining X-ray diffraction analyses, scanning electron microscopy and molecular diversity studies, we have characterized twenty previousl...

IMPLICANCE OF THE CRYOGENIAN SEAWATER GEOCHEMISTRY IN THE DOLOMITE ORIGIN, TANDILIA SYSTEM, ARGENTINA

The Río de la Plata craton is composed by the Piedra Alta and Tandilia terranes that achieved tectonic stability around 2.0 Ga. Paleomagnetic data are available for three short time spans. Nine pole positions for the Piedra Alta terrane in the interval 2.11 2.05 Ga suggest high latitudes with fast drift rates. Comparison with coeval poles from othe...

The well-preserved limestone succession, Loma Negra Formation (~40 m), in the Tandilia System was deposited in a shallow carbonate ramp under low energy conditions. The evolution in the depositional settings of the unit was indicated as deepening upwards varying from shallow-middle to outer ramp environment. The limestone fabric is assumed as the p...

The Cryogenian Period (720–635 Ma) is wide known by the occurrence of two global glaciations, Sturtian and Marinoan, responsible of dramatic climate and sea level changes as well as seawater oxygenation events. Constrained ⁸⁷Sr/⁸⁶Sr ratios from 0.7064 to 0.7071 and δ¹³C excursion are consistent with Cryogenian cap carbonates as documented in the up...

The geological time scale before 720 Ma uses rounded absolute ages rather than specific events recorded in rocks to subdivide time. This has led increasingly to mismatches between subdivisions and the features for which they were named. Here we review the formal processes that led to the current time scale, outline rock-based concepts that could be...

The Austral-Magallanes Basin covers the southernmost region of Patagonia, South America. South of Lago Argentino, the Calafate Formation documents part of the foreland stage of the evolution of this basin. Here, sandstones from the Calafate Formation were characterized using petrographical, X-ray diffraction (XRD) and geochemical data in order to e...

In this contribution, multi-proxy geophysical methods have been used to analyze the subsurface Neoproterozoic limestone mantle configuration. We also evaluate the relationship between the sedimentary cover and the crystalline basement in order to propose an integrated geophysical model for the graben structures of the Olavarría-Sierras Bayas area,...

We describe isolated teleostean teeth found in no association with the jaw bone. The specimens have been recovered in Late Cretaceous marine deposits of the Vivian Formation in the Peruvian Sub-Andean Region. The deposition sequence from where the teeth come is interpreted as a shallowing-upward sequence of low salinity. The fish material is identi...

Geological studies in the northern sector of the Chaco foreland Basin, Bolivia, yielded new fossils coming from late Oligocene-late Miocene of the Petaca Formation. Few fossil mammals were known from the Subandean Region of Bolivia. We report a partially complete mandible of a hegetotheriid Hegetotheriinae (Notoungulata, Typotheria) from Abapó (Río...

In the Ediacaran marine succession of the Cerro Negro Formation (Tandilia System, NE Argentina), abundant microbially induced sedimentary structures indicate general conditions of substrate biostabilization. Numerous discoidal structures in this succession were previously interpreted as moulds of soft-tissue holdfasts of sessile organisms, within t...

This paper describes a petrified trunk collected from a conglomerate bed of the Springhill Formation (Berriasian– Valanginian) in the Estancia El Álamo locality, Santa Cruz Province, Argentina. The fossil trunk is classified within the ubiquitous genus Agathoxylon and the wood anatomy shows a close affinity to that of Araucariaceae. This Patagonian...

The Piedras de Afilar Formation (PAFm) is a late Neoproterozoic sedimentary succession autochthonous to the Tandilia Terrane, part of the Río de la Plata Craton. It overlies with erosional unconformity a Paleoproterozoic igneous and metamorphic basement. According to facies analysis and lithostratigraphy, the PAFm is divided into three members for...

The objective of this work is to discuss the paleoenvironment and age of the Los Monos Formation, in outcrop and subsurface, along a regional transect (west-east) in the southern sector of the Tarija basin. The lithofacies and ichnofacies of the Alarache, Angosto del Pescado and Balapuca outcrops and core-intervals of the Aguas Blancas xp-13, Ramos...

The South American tetrapod track record is highly diverse and well known mainly from Argentina, Brazil, Bolivia, Chile and Peru. To date, many tracksites are known from Bolivia, most studied during the past century. From the Jurassic-Cretaceous La Puerta Formation of the Tunasniyoj locality (Incapampa-Icla syncline) thyreophoran trackways have pre...

Four first-order (Hadean, Archean, Proterozoic and Phanerozoic eon) and nine second-order (Paleoarchean, Mesoarchean, Neoarchean, Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Paleozoic, Mesozoic and Cenozoic era) units continue to provide intuitive subdivision of geological time. Major transitions in Earth’s tectonic, biological and environme...

Representative rock-magnetic experiments and petrographic studies on remagnetized limestones and dolostones from the Upper Cambrian La Flecha Formation (Quebrada La Angostura, Precordillera of La Rioja, Argentina) carrying a pre-tectonic Permo-Triassic secondary magnetization are reported in order to improve the understanding of the pervasive Sanra...

The Tapes Complex crops out in the southeastern Nico Pérez Terrane (NPT) of the Río de la Plata Craton and forms part of a NE-trending Mesoproterozoic belt together with the Calymmian (1.48–1.43 Ga) Parque UTE and Mina Verdún groups. The complex is characterized by interbedded/tectonically interleaved metasedimentary (mainly siliciclastic) and meta...

An integrated study combining sedimentological and ichnological data has been conducted in the lower wave-dominated deposits of the Calafate Formation. The study aimed to assess the variation in fair-weather and storm processes, tidal flux, and the coast configuration to correctly constrain sedimentary dynamics in complex depositional systems. The...

Maichnus wetkaroae igen. isp. nov., from the Albian of Patagonia, is composed of two or three ellipsoidal oblate chambers connected to shafts that show swellings and concentrically laminated linings. Such laminated linings are also present in chambers, and probably originated by radial backfilling and/or the successive discharges of liquid organic...

Lake sediments are key archives for paleoenvironmental investigation as they provide continuous records of the depositional history of the lake and its watershed. Lake Futalaufquen (42.8°S) is an oligotrophic waterbody located in Los Alerces National Park in the Andes of northern Patagonia, South America. A sedimentary sequence covering 1600 years...

Objetivos generales ✓ Ponderar los estudios de superficie para la industria petrolera. ✓ Conocer los conceptos básicos de la sedimentación carbonática actual y en el registro geológico. ✓ Detallar con ejemplos la metodología de estudio en superficie. ✓ Hacer hincapié en alguno de los estudios complementarios, que se inician con un adecuado muestreo...

Glyptodontidae are a conspicuous lineage of Cingulata with a long evolutionary history (late Eocene to the late Pleistocene-Holocene). Quaternary forms are the best known, but in recent years the knowledge of Neogene taxa, particularly from southern South America has been greatly improved. This is especially evident for the late Miocene-Pliocene (M...

Despite the absence of metazoans, structures resembling animal traces are common in a soda lake from the western Brazil Pantanal wetland. Pantanal soda lakes are ecologically extreme environments that preclude complex life, allowing extremophiles to flourish. Direct observation indicates that these structures are pseudotraces, representing groove m...

Abstract: Here we describe the spore and pollen assemblages recovered from the La Anita Formation, Late Cretaceous, Austral-Magallanes Basin (~50°S). This unit shows a high diversity of spores, with subordinate gymnosperms (mainly represented by Podocarpaceae) and angiosperms (mainly represented by Proteaceae and Arecaceae). The abundance of these...

The Austral-Magallanes is an oil-producing basin located in southern Argentina and Chile, containing a siliciclastic stratigraphic record ranging from the Late Jurassic to late Cenozoic. This short paper finalize the two special volumes of the Latin American Journal of Sedimentology and Basin Analysis dedicated to the basin, and aims to provide a c...

We present the first record of an extinct procyonid for Bolivia (Tariquía Formation, La Angostura, Santa Cruz de La Sierra; Late Miocene). It corresponds to Cyonasua, the first Carnivore taxon to enter South America from North America before the Paniamian Isthmus raised and as a part of the “proto Great American Biotic Interchange” (GABI). Cyonasua...

The Maastrichtian shallow marine deposits exposed at the south margin of the Lago Argentino within the Austral-Magallanes Basin are known as the Calafate Formation. In order to interpret the depositional systems and reconstruct the sequence stratigraphic architecture for this unit at its type locality (Cerro Calafate), we acquire new data from seve...

The Maastrichtian shallow marine deposits exposed at the south margin of the Lago Argentino within the Austral-Magallanes Basin are known as the Calafate Formation. In order to interpret the depositional systems and reconstruct the sequence stratigraphic architecture for this unit at its type locality (Cerro Calafate), we acquire new data from seve...

The limestones of the Loma Negra Formation provide an excellent opportunity to examine the behaviour of rare earth elements plus yttrium (REY) due to the near-zero diagenetic alteration of the carbonate system. The terrigenous supply to this unit was minimal or scarce in relation to the depth of seawater in which the limestones accumulated. The int...

Scelidotheriinae (Mammalia, Pilosa) is a xenarthran mylodontid clade recorded in much of South America from the middle Miocene to the early Holocene. However, studies of their Neogene representatives are still scarce compared to their Quaternary representatives. The main goal of this contribution is to report new remains of Proscelidodon rothi (Ame...

During the Early Cretaceous important changes occurred in South-western Gondwana related to its fragmentation, and South Atlantic Ocean opening. Then, two basins developed in southernmost Patagonia: the Austral-Magallanes Basin and the Rocas Verdes-Magallanes Basin. The Río Mayer Formation corresponds to the initial sedimentary stages of the Austra...

The sedimentary infill of the Austral-Magallanes Basin since the onset of its foreland stage in the Lago Argentino region is dominated by deep-marine and coastal deposits. However, during the Late Cretaceous the basin accumulated a thick and poorly known continental sedimentary succession, which has received different lithostratigraphic names. The...

Coastal depositional systems are commonly classified in terms of the relative interaction of wave, tide and fluvial processes. The La Anita Formation represents the opportunity to study and better understand coastal sedimentary systems. It is a poorly studied prograding siliciclastic deltaic-coastal wedge accumulated in the Campanian during the for...

En los últimos años se ha registrado la existencia de más de 30 lagos hipersalinos en la Puna de Argentina, Chile y Bolivia, con sistemas microbianos extremófilos, que generan distintos tipos de estromatolitos. De estos lagos se han elegido siete con productos microbiales muy disímiles, en los que se reconocen importantes variaciones en su composic...

La Formación La Anita forma parte del relleno sedimentario de la Cuenca Austral en su etapa de antepaís y se encuentra muy bien expuesta en los alrededores del Lago Argentino, provincia de Santa Cruz. A partir de la confección de perfiles sedimentológicos de detalle en esta unidad se definieron 9 Asociaciones de Facies (AF) en base a sus caracterís...

The Itapucumi Group is recognized worldwide due to its well- preserved Ediacaran fossil assemblage. Despite its paleontological importance, this unit remains as the least studied South American Neoproterozoic sedimentary succession. Recorded at northern Paraguay, the Itapucumi Group is a ~400 m-thick siliciclastic and carbonate succession deposited...

The objective of this work is the revision of the most conventional methods used to determine the thermal maturity of the Los Monos Formation in the Tarija Basin. For this, the thermal maturity of the formation was determined from multiple vitrinite reflectance analysis, programmed pyrolysis, index of thermal alteration and clay index. Work was don...

El levantamiento de perfiles sedimentológicos de detalle en superficie, llevados adelante en el área de Puerto Ocopa, Cuenca de Ene, han permitido reconocer de base a techo, cinco secuencias sedimentarias de bajo orden para la Formación Chonta. Estas secuencias responden a ascensos y descensos relativos del nivel del mar, que permiten reconocer lím...

The Berriasian–early Valanginian time interval is well represented in the Rio Mayer Formation in the Río Guanaco area (Austral Basin, Argentina). From this locality, well preserved belemnite shells of the genus Belemnopsis sp. and black shales are used to unravel the main palaeoenvironmental conditions of the seas at these high palaeo-latitudes (60...

Few fossil mammals were known from the Subandean zone or adjoining parts of Bolivia until recently. We report a partial mandible of Prohegetotherium (YPFB-LIT-PAL-002) from the outcrops of the Petaca Fm, in the Río Grande River (19°1’17” S - 63°33’25” W) near the town of Abapó, in the southwest of the department of Santa Cruz (Bolivia). This specim...

The Ediacaran Loma Negra Formation may be deposited in a platform environment related to the Clymene Ocean. This unit is exposed in the Olavarría and Barker areas within the Tandilia Basin, and composed entirely of lime mudstones (∼40m thick). The age of the Loma Negra Formation (LNF), the uppermost unit of the Sierras BayasGroup,hasbeendebated,but...

Neoproterozoic diamictite rocks as tillites or glaciomarine deposits have been recorded as the product of regional glaciations around the world, according to the "Snowball Earth" hypothesis. However, in some parts of the planet, contemporaneous non-glaciogenic sedimentary rocks have also been observed related to sedimentation in non-glacial environ...

The Tithonian–Valanginian period in the Mendoza Shelf (Neuquén Basin, Argentina) is well exposed in the Río Salado, Puesto Loncoche and Cuesta del Chihuido sedimentary sections. From those localities, more than fifty preserved oyster shells of the genus Aetostreon sp. were selected and sampled in order to perform the first δ13C curves for this part...

Based on new material from the uppermost Albian levels of Piedra Clavada Formation (Austral Basin, Argentina), the species Konijnenburgia alata (Matoniaceae) is re-examined, its diagnosis emended, and a formal lectotype from the historic type collection is here designated. A complete comparison with extant and fossil Matoniaceae is provided, with d...

Neoproterozoic successions in South America are recorded in many areas of Brazil, Paraguay, Bolivia, Uruguay and Argentina. Some of these units show glaciogenic formations like those represented in the Puga and Serra Azul formations in the Northern Paraguay Belt (Brazil) in agreement with their accumulation in a Snowball Earth context. However, in...