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The first chitinozoan assemblages from the middle–late Silurian and Early Devonian strata of the Copo Formation in the Rivadavia borehole, Salta province, Argentina, are described. The studied interval was considered deposited in an offshore shelf environment and composed of micaceous dark-gray shales with pyrrhotite intercalated with fine-grained quartzitic sandstones. Thirty-nine core samples were processed, and 11 yielded chitinozoan specimens that allowed taxonomic classification. Seven genera and 13 species were identified; four were retained in open nomenclature, and the new species Cingulochitina chacoparanaense sp. nov. is erected. Three chitinozoan assemblages were recognized: Chitinozoan assemblage I of a middle–late Silurian age, Chitinozoan assemblage II of a late Silurian age, and Chitinozoan assemblage III of a late Lochkovian (Early Devonian) age. A new upper Lochkovian chitinozoan concurrent range biozone of Cingulochitina striata and Ancyrochitina asterigis is proposed for northwestern Argentina. The chitinozoan assemblages support Gondwanan affinities from the middle Silurian to Early Devonian of the Chacoparaná Basin. Se han descripto las primeras asociaciones de quitinozoos del Silúrico medio–tardío y Devónico Temprano de la Formación Copo en el pozo Rivadavia, provincia de Salta, Argentina. El intervalo estudiado fue depositado en un ambiente marino de plataforma y está compuesto por lutitas micáceas de color gris oscuro con pirrotina e intercalaciones de areniscas cuarcíticas de grano fino. Se procesaron 39 muestras de testigo corona, de las cuales en 11 se obtuvieron especímenes de quitinozoos que permitieron el estudio taxonómico. Se identificaron siete géneros y 13 especies, cuatro de ellas en nomenclatura abierta y se creó la nueva especie Cingulochitina chacoparanaense sp. nov. Se reconocieron tres asociaciones de quitinozoos: Asociación de quitinozoos I del Silúrico medio–tardío, Asociación de quitinozoos II del Silúrico tardío, Asociación de quitinozoos III del Lochkoviano tardío (Devónico Temprano). Se propone la nueva biozona de quitinozoos, de extensión coincidente, Cingulochitina striata y Ancyrochitina asterigis para el Lochkoviano superior del noroeste argentino. Las asociaciones de quitinozoos sugieren afinidades gondwánicas desde el Silúrico medio al Devónico Temprano para la cuenca Chacoparaná. [ABSTRACT FROM AUTHOR]

Se presenta una nueva localidad paleontológica del Ordovícico del noroeste de España, ubicada en el flanco meridional del sinclinorio de Vega de Espinareda, al norte de Ponferrada (provincia de León). Se trata de la octava localidad con fósiles esqueléticos encontrada en la Formación Agüeira (Ordovícico Superior) del Dominio del Navia-Alto Sil de la Zona Asturoccidental-leonesa, y la primera ubicada en la mitad inferior de la formación. El nuevo yacimiento se sitúa muy próximo a su sección de referencia de la garganta fluvial entre las localidades de Congosto y Santa Marina del Sil, donde estos niveles eran interpretados como facies distales de un abanico submarino, en una sedimentación predominantemente turbidítica. Pero los trilobites, moluscos y braquiópodos encontrados, que por su escasa a nula desarticulación no parecen transportados, revelan una asociación propia de ambientes de plataforma mucho más someros, con fondos oxigenados como revela la alta concentración de galerías horizontales. La presencia de los trilobites Colpocoryphe grandis (Šnajdr) y Dalmanitina n. sp. (D. rabanoae Pereira, n. n.) indica una edad Berouniense temprano (= Sandbiense temprano), lo que abre la posibilidad de que el límite Ordovícico Medio/Superior se sitúe en los 400-450 m basales de la Fm. Agüeira en el sector estudiado.

This article discusses the discovery of cryptospores, which are dispersed spores from the oldest terrestrial flora, in Colombia during the Late Ordovician to early Silurian period. The presence of these cryptospores suggests the existence of a land flora in northern South America during this time. The article also provides information on the paleoenvironment and age constraints of the samples based on palynological data. This research contributes to our understanding of the early terrestrialization of land plants in eastern Gondwana. Additionally, the article discusses the sedimentary sequence of the Llanos Basin in Colombia and the limited exploration of the Paleozoic unit in the region. The document is a compilation of scientific articles and studies related to palynology, covering topics such as the identification and classification of microfossils, biostratigraphy, and the paleogeographic significance of certain plant species. The studies primarily focus on regions such as Colombia, Argentina, Brazil, and Iran, providing insights into the evolution and distribution of early land plants during the Ordovician and Silurian periods. Lastly, the given text is a list of references and an annotated list of palynomorphs from a study on the Ordovician-Silurian cryptospores of Colombia. The list provides detailed descriptions and illustrations of the different palynomorphs identified in the study, which can be useful for researchers studying the paleogeography, paleoclimatology, and evolution of plant life during this time period [Extracted from the article]

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La formación Canoa se localiza en el sector El Mangle, cantón Montecristi, provincia de Manabí, costa de Ecuador. Esta presenta afloramientos que litológicamente consiste en areniscas, areniscas arcillosas, areniscas limosas y lodolitas limosas; subyace a la formación Tablazo y sobreyace a la formación Angostura. En este trabajo se describieron cinco afloramientos con el objetivo de determinar la litología, componentes mineralógicos esenciales, deposición, procedencia tectónica, bioestratigrafía y paleoambiente; y se lo realizó de la siguiente manera, diecinueve muestras para bioestratigrafía y litología, y tres secciones delgadas para petrotectónica y petrografía. Por la ocurrencia de foraminíferos planctónicos presentes y que se extinguen en dicho periodo, la edad relativa de la formación Canoa es Plioceno (Zona N18 – N19). El paleoambiente sedimentario es de plataforma interna debido a la abundancia de los foraminíferos bentónicos calcáreos y aglutinados

To understand the important significant climatic and paleoceanographic changes occurred in the Southern Hemisphere during the Paleogene, and especially those related to the opening of the Drake Passage, is essential to correlate the Eocene lithostratigraphic units in areas adjacent to this passage, such as those from the Austral-Magallanes and James Ross basins, to the north and to the south, respectively. For many years, there was no correlation between these units due to the absence of reliable chronostratigraphic and biostratigraphic information. Recently, other authors published U/Pb data for the Austral-Magallanes Basin and introduced important modifications to the previous stratigraphic scheme. Subsequently, due to reinterpretating the available isotope data together with U/Pb ages, the chronostratigraphic model has modified again, also including the James Ross Basin. In light of an updated quantitative dinoflagellate cyst dataset from the units adjacent to the Drake Passage, we performed a Principal Component Analysis (PCA) to discuss the correlation between the studied sections. The PCA groups assemblages with a high contribution of Antarctic taxa (e.g., Enneadocysta dictyostila, Deflandrea antarctica) containing in the Upper Member of the Río Turbio Formation (lower part), Man Aike, Leticia, and La Meseta formations, being Bartonian in age. The other group joined assemblages with younger ages, Priabonian, dominated by Antarctic species (Vozzhennikovia-Spinidinium) and cosmopolitan taxa, corresponding to the Upper Member of the Río Turbio Formation (upper part). This study reinforces the most recent chronostratigraphic proposal and proves the biostratigraphic useful of some taxa for sites near the Drake Passage. [ABSTRACT FROM AUTHOR]

Micropaleontological investigations performed at four sections in the Pucará Group, northwestern Peru, revealed the presence of late Triassic calcareous nannofossils. Recovered assemblages are poorly preserved and show low abundance and species richness. However, these findings represent one of the three records outside the Tethyan Realm and allow independent biostratigraphic constraints for the Pucará Group. In the Cantera Tello section, Chambará Formation, only the genus Prinsiosphaera was observed, suggesting a late Norian age for the lower part, and the occurrence of Eoconusphaera zlambachensis indicates a Rhaetian age for the upper part. In the Río Cocahuayco section, Chambará, and Aramachay formations, only the genus Prinsiosphaera was recovered, indicating the late Triassic. In Ricardo Palma section, Aramachay Formation, the presence of E. zlambachensis indicates a Rhaetian age. The Aguas Verdes section, Condorsinga Formation, yields an assemblage with P. triassica and E. zlambachensis, indicating that, at least in this part of the basin, the lower section of this Formation is Rhaetian. [ABSTRACT FROM AUTHOR]

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The Arroyo Malo Formation represents the first marine ingression during the Late Triassic in the Neuquén Basin, west-central Argentina. The presence of calcareous nannofossils in this unit provides an independent age constraint of a late Norian to Rhaetian age for its lower and middle parts, in agreement with known fossil invertebrates. Furthermore, this represents one of the only three records of this group known so far outside the Tethyan Realm. The presence of monospecific assemblages of Prinsiosphaera triassica in the late Norian and assemblages characterized by P. triassica and Eoconusphaera zlambachensis in the Rhaetian, together with a review of other known records worldwide, allows the formal proposal of a global biozonation for the Late Triassic. Prinsiosphaera triassica Biozone, from middle Norian to late Norian, and Crucirhabdus primulus Biozone, spanning the Rhaetian (comprising two sub-biozones in the Tethys), are defined. Based on the new record from the Upper Triassic of the Neuquén Basin, we interpret that calcareous nannofossils originated during the middle Norian in the Western Tethys, and we suggest that they then rapidly dispersed to the Southeastern Tethys and from there to the Eastern Pacific across Panthalassa by southern mid-latitude easterly oceanic currents. [ABSTRACT FROM AUTHOR]

A Supersequência Bauru (SB), com cerca de 300 m no depocentro principal, refere-se ao pacote sedimentar continental cretáceo da Bacia do Paraná, incluindo os grupos Caiuá e Bauru. Estudos de superfície e de subsuperfície subdividiram a SB em várias unidades litoestratigráficas, mas seu arcabouço estratigráfico permanece instável, havendo, ademais, precária ponte entre a litoestratigrafia e a biocronologia, que é marcada por conflitos decorrentes de divergências taxonômicas. Discutimos este problema à luz de recentes dados palinológicos amarrados à bioestratigrafia aplicada ao Cretáceo das bacias costeiras do Brasil e de outras informações paleontológicas. O Grupo Caiuá é aqui atribuído ao Aptiano–Albiano. O Grupo Bauru, que tem na sua base sedimentos fluviais da Formação Santo Anastácio (Coniaciano?), apresenta em seu corpo lítico principal as formações Adamantina, Araçatuba, Uberaba, São Carlos, Itaqueri, Marília e Serra da Galga. Neste corpo, estudos palinológicos identificaram sedimentos neossantonianos e eocampanianos, respectivamente nas formações São Carlos e Araçatuba; a micropaleontologia de carófitas e ostracodes indicaram estratos maastrichtianos (neomaastrichtianos?) na Formação Serra da Galga. A combinação de tais datações com o arranjo estratigráfico-espacial das unidades permite-nos inferir uma idade neossantoniana–eocampaniana para as formações Adamantina e Uberaba e maastrichtiana para as formações Marília e Serra da Galga. Não se descarta que estratos santonianos mais velhos, ou mesmo pré-santonianos, componham as formações Adamantina/Araçatuba. A Formação Itaqueri, seguramente pós-santoniana, é tentativamente vinculada ao intervalo Campaniano inferior–médio. Cinco discordâncias erosivas, delimitando quatro sequências, associam-se à SB: a superfície da base, Pré-Caiuá, e os topos do Grupo Caiuá e das formações Santo Anastácio, Adamantina/Uberaba/Itaqueri e Marília/Serra da Galga. As lacunas temporais entre essas unidades são incertas pela imprecisão na datação do Santo Anastácio. O hiato máximo pré-Marília/Serra da Galga envolveria o intervalo Mesocampaniano a Eomaastrichtiano.

In Senado Formation, the knowledge about fossil diatoms flora is quite scarce; in Cuba, general speaking, studies are practically lacking. Determining Distephanosira architecturalis species represented a challenge due to its predominance in high latitudes. The aim of this research is to make public the first record of Distephanosira architecturalis for the Senado Formation in Central Cuba, providing its description based on biological microscopy. Distephanosira architecturalis was observed in sediments from Senado Formation, so its presence represents an extension of knowledge about distribution of taxon’s area and, in addition, allows us to consider the lower part of this unit with a stratigraphic distribution from the Middle Eocene.

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Se presenta una nueva sección bioestratigrafica de la parte basal de la Formación Sueve. La nueva sección se suma a las nueve secciones descritas en estudios previos, relativos al sector septentrional del manto de Laviana. Los horizontes fosilíferos muestreados se integran en la Biozona del graptolito Didymograptus murchisoni, indicativo de una edad Oretaniense tardío o Darriwiliense tardío no terminal según las respectivas escalas regional y global. Entre los resultados paleontológicos destaca el hallazgo de algunos fósiles raros o desconocidos en la Fm. Sueve. El graptolito Pseudoclimacograptus cf. scharenbergi (Lapworth) se cita por vez primera en el SO de Europa a través de un ejemplar conservado tridimensionalmente; el rostroconcha Ribeiria apusoides Schubert y Waagen se identifica por segunda vez en el Ordovícico de España (tras un primer registro centroibérico en Almadén); y el trilobites Crozonaspis morenensis Hammann confirma su presencia en el Oretaniense superior de la Fm. Sueve con un material más abundante y mejor conservado. Finalmente, el descubrimiento de un trilobites rafiofórido en el afloramiento estudiado abre la posibilidad de encontrar nuevos ejemplares de estos rarísimos trilobites a escala del Ordovícico ibérico.

In Senado Formation, the knowledge about fossil diatoms flora is quite scarce; in Cuba, general speaking, studies are practically lacking. Determining Distephanosira architecturalis species represented a challenge due to its predominance in high latitudes. The aim of this research is to make public the first record of Distephanosira architecturalis for the Senado Formation in Central Cuba, providing its description based on biological microscopy. Distephanosira architecturalis was observed in sediments from Senado Formation, so its presence represents an extension of knowledge about distribution of taxon's area and, in addition, allows us to consider the lower part of this unit with a stratigraphic distribution from the Middle Eocene. [ABSTRACT FROM AUTHOR]

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As amostras utilizadas para este estudo de nanofósseis calcários foram cedidas pelo Deep Sea Drilling Project (DSDP) e referem-se ao Site 354, Leg 39. O poço está situado na borda noroeste da Elevação Ceará, em uma feição topográfica distante cento e cinquenta metros do cone amazônico (Atlântico Equatorial). A partir da distribuição estratigráfica das espécies, a seção investigada foi refinada bioestratigraficamente e, posteriormente, intervalos cronoestratigráficos foram identificados. Foram descritas um total de seis biozonas, referentes ao intervalo Eoceno/Oligoceno. Dentre os nanofósseis calcários descritos e registrados destacam-se: Isthmolithus recurvus, Sphenolithus pseudoradians, Sphenolithus ciperoensis, Discoaster barbadiensis, Discoaster saipanensis, Sphenolithus intercalaris, Clausicoccus subdistichus, Sphenolithus distentus, Sphenolithus predistentus, Cyclicargolithus abisectus, Helicosphaera recta, Discoaster tanii, Coccolithus pelagicus, Helicosphaera euphratis e Triquetrorhabdulus milowii. Todas as principais espécies foram devidamente fotografadas e mensuradas, a fim de ilustrar o estudo e construir um biozoneamento de detalhe no intervalo em questão. A partir do comportamento da associação de nanofósseis, inferências paleoclimáticas foram sugeridas.

We present the palynoflora recovered from the Pescado Formation in the Subandean Range, Salta Province, Argentina. The palynological assemblage comprises well-preserved marine and terrestrial palynomorphs, including cryptospores (one species), trilete spores (16 species), acritarchs (six species), prasinophytes (three species), and chlorophytes (three species). Based on the quantitative analysis and stratigraphic distribution of palynomorphs, two palynological associations are recognized (RC1, RC2). The presence of Dictyotriletes emsiensis morphon and Acinosporites apiculatus, together with Duvernaysphaera angelae and D. tenuicingulata, suggests a late Emsian-Eifelian age for RC1 and RC2. The studied assemblages contain many taxa in common with other coeval assemblages of Gondwana that confirm the paleogeographical relationships among the Argentine Precordillera, the Tarija Basin, and the southern Chacoparaná Basin in Uruguay. The relative abundance of the palynomorphs encountered suggests a marine depositional environment close to the paleo-shoreline for the RC1, and a more distal marine setting for the RC2, possibly nearshore, reflecting the Eifelian transgression. This event, already documented by different authors, is also recognized in the southern portion of the Tarija Basin. [ABSTRACT FROM AUTHOR]

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Copyright of Spanish Journal of Palaeontology is the property of Socieadad Espanola de Paleontologia 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.)

Erythrosuchid archosauriforms are quadrupedal carnivorous reptiles with a proportionally huge skull. They represent one of the first evolutionary radiations of medium to large predatory diapsids after the Permo–Triassic mass extinction. Erythrosuchids are known from Lower– Middle Triassic rocks of South Africa, Russia, and China, and there have been preliminary reports from the Middle Triassic Yerrapalli Formation of south-central India. Here we describe, compare and figure for the first time these Indian erythrosuchid remains. We erect the new genus and species Bharitalasuchus tapani based on a holotype and paratype that preserve tooth-bearing cranial fragments, at least 17 presacral vertebrae, some ribs and probable intercentra, and partial shoulder and pelvic girdles and hindlimb and allow recognizing a series of autapomorphies and unique combination of character states among erythrosuchids. Our phylogenetic analysis recovered Bharitalasuchus tapani most closely related to Shansisuchus shansisuchus and Chalishevia cothurnata from the late Anisian of China and Ladinian of Russia, respectively. The phylogenetic affinities of this new taxon and a revision of the tetrapod assemblage of the Yerrapalli Formation shed light on the age of this unit. The presence of the Wadiasaurus-Rechnisaurus-Bharitalasuchus association in the Yerrapalli Formation closely resembles the Sinokannemeyeria- Shansisuchus dicynodont-erythrosuchid association of late Anisian to early Ladinian Chinese units. This evidence supports a post-early–middle Anisian age, even possibly early Ladinian, for the Yerrapalli Formation. The presence of possibly one of the last erythrosuchids in India would indicate that the clade still retained both a northern and southern Pangean distribution before its extinction. [ABSTRACT FROM AUTHOR]

El lapso Neoproterozoico/Cámbrico temprano en la región noroeste de Argentina se encuentra representado por una potente secuencia sedimentaria que se destaca por su escaso metamorfismo y gran tectonización. Bajo la denominación de Formación Puncoviscana (s.l.) se unifican una serie de unidades rocosas escasamente fosilíferas con esquistos, areniscas, calizas y conglomerados con amplios afloramientos en la Cordillera Oriental de las provincias de Tucumán, Jujuy y Salta. Si bien la secuencia fue originariamente considerada como perteneciente al "basamento Precámbrico" de la región, el hallazgo de trazas fósiles eocámbricas permitieron su reasignación cronológica posteriormente ratificada por medios isotópicos. Análisis petrológicos y geoquímicos corroboran su asignación asociada al margen continental con el desarrollo de series metamórficas de un orógeno reciclado. Paleoambientalmente se reconocen una amplia variedad de contextos sedimentarios con sectores someros dominados por oleaje, secuencias turbidíticas, facies emipelágicas y calizas que denotan variados paleoambientes en el protomargen del Gondwana. La distribución de los elementos icnológicos en las unidades de la cuenca de Puncoviscana se presenta en fajas subparalelas con un sector este caracterizado por Nereites, y un sector oeste por Oldhamia. Esta distribución espacial representaría tanto caracteres morfológicos de la cuenca como niveles temporales distintos en la evolución del mar de Puncoviscana y su biota. La presente contribución provee un análisis actualizado de la Formación Puncoviscana y las unidades vinculadas en la región, aportando nuevas líneas de evidencia sobre las ideas más recientes desarrolladas sobre la transición Neoproterozoico/ Cámbrico temprano del noroeste de Argentina.

Introduction: The present work constitutes the first record of Ubaghsicystis Gil-Cid & Domínguez-Alonso (Echinodermata-Eocrinoidea) in the El Gavilán Formation, exposed in the El Sahuaral Hill, a new Cambrian locality of central Sonora, Mexico. The El Gavilán Formation is a sedimentary sequence mainly made up of shale interbedded with limestone, with abundant invertebrate fossils, deposited in an open shelf marine environment. Objective: The main objective of this research work is to describe the species Ubaghsicystis cf. U. segurae for the first time in Mexico, in addition to biostratigraphic and paleoecological considerations. Methods: A composite stratigraphic section of the El Gavilán Fm. was measured in central Sonora, where samples corresponding to eocrinods were collected, the material was examined in the Microscope Leica MZ10. Results: The biotic association is composed of reticulosan sponges, chancelloriids (Chancelloria eros, Allonnia tintinopsis, Archiasterella sp.), hyolithids, brachiopods, trilobites (Quadragnostus depressa, Peronopsis sp., Tonkinella valida, and Elrathina sp.), and echinoderms (Ubaghsicystis cf. U. segurae). Regarding the age, the trilobite association establishes a chronostratigraphic position from the middle Cambrian (Miaolingian, Wuliuan), Altiocculus Subzone, Ehmaniella Zone. The material studied is constituted by isolated echinoderm plates, which probably represent various cycles of theca plates assigned to Ubaghsicystis cf. U. segurae. The genus Ubaghsicystis has been scarcely recorded in a few Cambrian regions (e.g., Burgess Shale in Canada and Los Barrios de Luna in Spain), so that the information about this taxon is limited. Conclusions: The Cambrian succession of Sonora, where Ubaghsicystis occurred, was part of the border from the Laurentia craton during this period, located near the Paleoequator during this period, where ideal conditions for increasing diversity and abundance of species were developed, including echinoderms. [ABSTRACT FROM AUTHOR]

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Se presenta en este trabajo el análisis paleontológico de 26 especies fósiles muestradas en cinco cortes de las Formaciones de Tamengo y Guaicurus en las regines de Corumbá y Ladário: canteras de Corcal y Laginha, Porto Sobramil, Porto Figueiras y Ecoparque Cacimba. Además, se añaden varias interpretaciones paleoecológicas y ambientales, basadas en el registro fósil. Cloudina carinata Cortijo et al., 2010, previamente citada en España y Siberia, aparece por primera vez en el continente Americano, concretamente en limolitas de la Formación Tamengo en el corte de Porto Figueiras, Corumbá, Estado de Mato Grosso do Sul, Brasil. La biota de la Formación Tamengo incluye tres metazoos mineralizados, que incluyen espículas de poríferos, posibles gémulas de esponjas y una colonia sésil de procaiotas epibentónicos. Este trabajo se centra en la taxonomía y distribución estratigráfica de cuatro icnoespecies y tres especies de vendoténidos que forman la fauna bentónica de la parte superior del Grupo de Corumbá. La biodiversidad de la Formación Tamengo ha sido completada con el registro de 16 especies microfósiles que representan posiblemente una asociación plantónica marina. Se ha identificado un cambio drástico en las condiciones ambientales de las Formaciones Tamengo y Guaicurus, que culminan en un evento de extincinón masiva posiblemente relacionado con la extincición en masa que marca el tránsito global Ediácarico- Cámbrico. Por otro lado, se han extraído microfósiles de pared orgánica de varios afloramientos: nueve especies de la Formación de Nomtsas (Namibia), cuatro de la Formación Tagatiya Guazu (Paraguay) y seis de la Formación Dengying (China). Se propone un marco bioestratigráfico para el Ediacárico terminal que incluye seis biozonas y una biozona para el Cámbrico basal.

El presente trabajo aborda la estratigrafía del sector Morro-Bacuranao, zona perspectiva para producción de hidrocarburos. A la luz de recientes perforaciones que permitieron correlacionar estratigráficamente seis pozos ubicados en los municipios Habana del Este y Cojímar de la provincia de La Habana se confeccionaron los esquemas de correlación de los pozos y una columna geológica generalizada del área. Los nuevos datos estratigráficos y bioestratigráficos permiten concluir que en este sector el reservorio es del tipo Grupo Veloz, al ser una secuencia carbonatada donde predominan los mudstones calcáreos con una edad Jurásico Superior Tithoniano Superior-Cretácico Inferior. Estos resultados son de gran utilidad en la prospección petrolera al disminuir el riesgo de la exploración en la Franja Norte de Crudos Pesados, principal zona productora de hidrocarburos de Cuba.

ABSTRACT We review geological evidence on the origin of the modern transcontinental Amazon River, and the paleogeographic history of riverine connections among the principal sedimentary basins of northern South America through the Neogene. Data are reviewed from new geochronological datasets using radiogenic and stable isotopes, and from traditional geochronological methods, including sedimentology, structural mapping, sonic and seismic logging, and biostratigraphy. The modern Amazon River and the continental-scale Amazon drainage basin were assembled during the late Miocene and Pliocene, via some of the largest purported river capture events in Earth history. Andean sediments are first recorded in the Amazon Fan at about 10.1-9.4 Ma, with a large increase in sedimentation at about 4.5 Ma. The transcontinental Amazon River therefore formed over a period of about 4.9-5.6 million years, by means of several river capture events. The origins of the modern Amazon River are hypothesized to be linked with that of mega-wetland landscapes of tropical South America (e.g. várzeas, pantanals, seasonally flooded savannahs). Mega-wetlands have persisted over about 10% northern South America under different configurations for >15 million years. Although the paleogeographic reconstructions presented are simplistic and coarse-grained, they are offered to inspire the collection and analysis of new sedimentological and geochronological datasets.

This paper presents the integration of micropaleontological (palynology and foraminifera) and isotopic (87Sr/86Sr) analysis of a selected interval from the well 2-TG-96-RS, drilled on the onshore portion of the Pelotas Basin, Rio Grande do Sul, Brazil. A total of eight samples of the section between 140.20 and 73.50 m in depth was selected for palynological analysis, revealing diversified and abundant palynomorph associations. Species of spores, pollen grains and dinoflagellate cysts are the most common palynomorphs found. Planktic and benthic calcareous foraminifera were recovered from the lowest two levels of the section (140.20 and 134.30 m). Based on the stratigraphic range of the species of dinoflagellate cysts and sporomorphs, a span age from Late Miocene to Early Pliocene is assigned. The relative age obtained from the 87Sr/86Sr ratio in shells of calcareous foraminifers indicates a Late Miocene (Messinian) correspondence, corroborating the biostratigraphic positioning performed with palynomorphs. Paleoenvironmental interpretations based on the quantitative distribution of organic components (palynomorphs, phytoclasts and amorphous organic matter) throughout the section and on foraminiferal associations indicate a shallow marine depositional environment for the section. Two palynologicals intervals were recognized based on palynofacies analysis, related to middle to outer shelf (140.20 to 128.90 m) and inner shelf (115.75 to 73.50 m) conditions.

The Aquidauana Formation is a Permo-Carboniferous sedimentary unit, widely stratigraphicaly distributed in the northwestern and northern portions of the Paraná Basin. However, little paleontological data is available from this formation, preventing accurate biostratigraphic and paleoecological interpretations. An abundant, diversified and well preserved assemblage of palynomorphs was recognized from sampling conducted in an outcrop section in Cipolândia District of Aquidauana Municipality, state of Mato Grosso do Sul, Brazil. A total of 35 indigenous palynomorph taxa was recognized, comprising 6 species of spores (related to 5 genera), 28 species of pollen grains (14 genera) and 1 species of chlorophycean algae. Monosaccate pollen grains are exceptionally dominant, representing 90.38% of the association, particularly constituted by species of the genera Cannanoropollis (30.41% of the total assemblage), Potonieisporites (28.14%) and Plicatipollenites (19.52%). This quantitative overrepresentation is not usual from Gondwana deposits, revealing a particular plant dominance of Cordaitales in the terrestrial flora. These results are interpreted as an upland ecology characterized by plants with a moisture-independent reproduction strategy, under a glacial climate influence. Certain species of pollen allow assignment of this assemblage to the Crucisaccites monoletus Zone (Late Pennsylvanian), which had been recognized only in the middle portion of the Itararé Group at the northeastern margin of the basin.

We review geological evidence on the origin of the modern transcontinental Amazon River, and the paleogeographic history of riverine connections among the principal sedimentary basins of northern South America through the Neogene. Data are reviewed from new geochronological datasets using radiogenic and stable isotopes, and from traditional geochronological methods, including sedimentology, structural mapping, sonic and seismic logging, and biostratigraphy. The modern Amazon River and the continental-scale Amazon drainage basin were assembled during the late Miocene and Pliocene, via some of the largest purported river capture events in Earth history. Andean sediments are first recorded in the Amazon Fan at about 10.1-9.4 Ma, with a large increase in sedimentation at about 4.5 Ma. The transcontinental Amazon River therefore formed over a period of about 4.9-5.6 million years, by means of several river capture events. The origins of the modern Amazon River are hypothesized to be linked with that of mega-wetland landscapes of tropical South America (e.g. várzeas, pantanals, seasonally flooded savannahs). Mega-wetlands have persisted over about 10% northern South America under different configurations for >15 million years. Although the paleogeographic reconstructions presented are simplistic and coarse-grained, they are offered to inspire the collection and analysis of new sedimentological and geochronological datasets. [ABSTRACT FROM AUTHOR]

The Lower Jurassic Huayacocotla Fm. (Upper Sinemurian), was first studied by several American and European geologist during the twentieth century (1948), whom eventually concluded that these rocks were not commercially productive. Consequently, the interest in this unit faded a long time ago. However, studies resumed in the 2000’s by Mexican researchers, this time including a wide range of paleontological, paleoenvironmental, paleoecological, geologic, and structural aspects, incorporating taphonomic, petrologic and geochemical techniques. They concluded that the Huayacocotla Fm. is not a condensed sequence, but can be better regarded as a single unit, including several facies rather than a complex unit of several formations. Today, it is well known that the Huayacocotla Fm. was deposited in a semi-restricted back arc paleobasin, with suboxic to euxinic conditions. Its protolith of igneous intermediate composition reveals tectonic features related to the Pangea collision phase and the first stages of the Gulf of Mexico opening. The paleobasin with high rate of sedimentation, generated this sequence siliciclastic, simultaneously with the process of expansion of the Gulf of Mexico. The modern biostratigraphical analyses developed in the 2000’s, accurate the biostratigraphic zonation proposed by Burckhardt and Erben. These new studies revealed that the deposition of the Huayacocotla Fm. spanned several Late Sinemurian diverse chronozones, especially Oxynotum, Densinodulum, and Raricostatum subzones. Nevertheless, some local divergences with respect to the standard biozonation were noticed, and these anomalies are tentatively explained to be the result of Early Sinemurian homotaxial events. There is a gap in the Lower Obtusum faunas, but the presence of Lower Sinemurian deposits was reported from at least one outcrop. This Jurassic field trip guide was written to lead and encourage interested researchers in this field to contribute to this subject, and maybe other related topics, as well as to encourage academic discussions about the knowledge of Early Jurassic marine paleobasins, in the context of the 10th International Jurassic Congress. [ABSTRACT FROM AUTHOR]

The Triassic and Jurassic geology of northern Sonora encompasses important events that are linked to the late Paleozoic history of the region. The fossiliferous El Antimonio Group in the Sierra del Álamo includes the upper Permian-Triassic Antimonio, and Río Asunción formations and the Hettangian-Sinemurian Sierra de Santa Rosa Formation. These formations consist of upward-fining sequences from I to XIV that represent fluvial to shallow and deep marine environments of deposition. The Triassic/Jurassic boundary in this region is a hiatus represented by a disconformity between sequence IX of the Río Asunción formations and sequence X of the Sierra de Santa Rosa Formation. The shallow to deep marine succession of the Sierra de Santa Rosa composes the upper part of the Sierra de Santa Rosa Formation that ranges in age from late Sinemurian to early Pliensbachian. Ages of the Permian to Triassic plutonic rocks of northwesternmost Sonora, the Mojave Desert and the Jurassic continental margin Nazas arc that crossed through northern Sonora, are also well recorded by igneous clasts and detrital zircon grains that have been dated from the El Antimonio Group and other Jurassic formations of this region. The upper Oxfordian-lower Tithonian Cucurpe Formation in north-central Sonora recorded the onset of continental extension and incursion of marine waters from the Gulf of Mexico into northwestern Mexico, once activity of the Jurassic magmatic arc ended. [ABSTRACT FROM AUTHOR]

In this study, biostratigraphy and paleoecology of the Asmari Formation have been investigated. The study area is located in the Izeh zone, Zagros Basin. Four outcrop sections (Halayjan, Kuh Shur, Kuh-e Bad and Gharibi Ha) have been sampled. Based on distribution of the larger benthic and planktonic foraminifera, five assemblage zones have been recognized. Assemblages 1 and 2 indicate Chattian; assemblage 3 is restricted to Aquitanian and assemblages 4 and 5 suggest Burdigalian. During the Chattian, the carbonate deposits of the Asmari Formation are mostly composed of coralline red algae and large and flat benthic foraminifera. The common components of the Aquitanian are abundant imperforate foraminifera and Favreina asmaricus. The Burdigalian is characterized by coral, coralline algae, and perforate and imperforate foraminifera. During the Burdigalian toward the SE of study area (Gharibi Ha section), the shallow water deposits are abruptly overlain by pelagic limestone. It is interpreted as the result of a regional tilting that started in the upper part of the Burdigalian. The biotic associations suggest that carbonate sedimentation occurred in tropical to subtropical waters under oligotrophic to mesotrophic conditions. The carbonate grain associations in the Asmari Formation suggest heterozoan association. According to paleoecological parameters (such as: nutrient, depth, light and salinity) in the study area, the Asmari Formation belongs to nannofor--foralgal to foramol association which were deposited in slightly hyper to normal saline environment. In the euphotic zone, abundant imperforate foraminifera are present. Basinward, lens shaped rotalids developed in mesophotic conditions, and large lepidocyclinid-nummulitids characterize the sediments of the deeper oligophotic zone. [ABSTRACT FROM AUTHOR]