El Gran Bajo de los Huesos, su tectónica en relación con la morfología: Chubut, Argentina

El área de trabajo se ubica en el N E de la provincia del Chubut. Dentro de la misma se han analizado dos secciones; una continental formada por mesetas, depresiones y acantilados y otra subácuea hasta una profundidad cercana a los 50m. Para realizar la interpretación estructural de las mismas, se aplicó una metodología que abarcó desde los relevamientos morfológicos y estratigráficos de campo hasta los análisis de fotografías aéreas. Con la información altibatimétrica se confeccionaron bloques de diagramas que permitieron relacionar las morfologías superficiales con las posibles estructuras profundas que les dieron origen. Se determinó que las geoformas continentales, positivas y negativas, se hallan controladas por fallas que siguen tres orientaciones principales correspondientes a los modelos morfológicos de escarpas y líneas de falla. La morfología subácuea se relaciona con un estilo estructural denominado de bloques fallados con desplazamientos de los mismos.The area under study is situated at the NE of Chubut Province. Two sections were analyzed in it; a continental one formed by plateaus, depressions and cliffs and a subaqueous one down to near 50 m depth. In order to carry out its structural interpretation, a methodology containing morphological and stratigraphical survey and aereal photography analysis was applied. Diagram blocks were made with alti-bathymetric information which allowed to relate superficial mhorphologies with the possible deep structures that originated them. It was determined that positive and negative continental geoforms are controlled by fractures following thee principal orientations corresponding to the morphological models of scarps and faults. Subaqueous morphology is related to a structural style called of fault blocks with displacemente.Asociación Argentina de Geofísicos y Geodesta

El Gran Bajo de los Huesos, su tectónica en relación con la morfología: Chubut, Argentina

El área de trabajo se ubica en el N E de la provincia del Chubut. Dentro de la misma se han analizado dos secciones; una continental formada por mesetas, depresiones y acantilados y otra subácuea hasta una profundidad cercana a los 50m. Para realizar la interpretación estructural de las mismas, se aplicó una metodología que abarcó desde los relevamientos morfológicos y estratigráficos de campo hasta los análisis de fotografías aéreas. Con la información altibatimétrica se confeccionaron bloques de diagramas que permitieron relacionar las morfologías superficiales con las posibles estructuras profundas que les dieron origen. Se determinó que las geoformas continentales, positivas y negativas, se hallan controladas por fallas que siguen tres orientaciones principales correspondientes a los modelos morfológicos de escarpas y líneas de falla. La morfología subácuea se relaciona con un estilo estructural denominado de bloques fallados con desplazamientos de los mismos.The area under study is situated at the NE of Chubut Province. Two sections were analyzed in it; a continental one formed by plateaus, depressions and cliffs and a subaqueous one down to near 50 m depth. In order to carry out its structural interpretation, a methodology containing morphological and stratigraphical survey and aereal photography analysis was applied. Diagram blocks were made with alti-bathymetric information which allowed to relate superficial mhorphologies with the possible deep structures that originated them. It was determined that positive and negative continental geoforms are controlled by fractures following thee principal orientations corresponding to the morphological models of scarps and faults. Subaqueous morphology is related to a structural style called of fault blocks with displacemente.Asociación Argentina de Geofísicos y Geodesta

Concreciones y rodados orgánicos presentes en el Golfo San José, Chubut, Argentina

Los trabajos referidos a la significación de concreciones y rodados de génesis orgánica tienen escasa difusión en nuestro país. El presente estudio permite inferir condiciones paleoambientales desarrolladas en los depósitos de origen de estas estructuras y durante su posterior evolución. Estos elementos fueron hallados en sedimentos de edad cuaternaria en el golfo San José, Chubut, Argentina. Corresponden a dos tipos genéticos: estructuras de precipitación (concreciones) y estructuras orgánicas rodadas (colonias de briozoarios removidas). Ambas estructuras fueron generadas en el tercio superior de la Formación Puerto Madryn (Mioceno marino), durante una facies regresiva litoral. Posteriormente fueron transportadas por acción fluvial durante el Cuaternario. Debido a su bajo índice de abrasión se puede inferir que el período de transporte fue corto y de rápida depositación. Este proceso habría sido sincrónico con la sedimentación continental acaecida durante el Cuaternario.Works about the meaning of concretions and pebbles of organic origin have limited diffusion in our country. This study allows to infer paleoenvironmental conditions developed in the original deposits of these structures and during their later evolutionary history. These elements were found in Quaternary sediments in the San José Gulf, Chubut, Argentina. They correspond to two different genetic types: precipitation structures (concretions) and organic pebbles (removed briozoary colonies). Both were generated in the upper third of the Puerto Madryn Formation (marine Miocene), during a regressive littoral facies. They were later transported by fluvial action during the Quaternary. Due to its low abrasion we can infer that its transport extended over a short period and had a rapid deposition. This process would have been synchronous with the Quaternary continental sedimentation.Asociación Argentina de Geofísicos y Geodesta

Concreciones y rodados orgánicos presentes en el Golfo San José, Chubut, Argentina

Los trabajos referidos a la significación de concreciones y rodados de génesis orgánica tienen escasa difusión en nuestro país. El presente estudio permite inferir condiciones paleoambientales desarrolladas en los depósitos de origen de estas estructuras y durante su posterior evolución. Estos elementos fueron hallados en sedimentos de edad cuaternaria en el golfo San José, Chubut, Argentina. Corresponden a dos tipos genéticos: estructuras de precipitación (concreciones) y estructuras orgánicas rodadas (colonias de briozoarios removidas). Ambas estructuras fueron generadas en el tercio superior de la Formación Puerto Madryn (Mioceno marino), durante una facies regresiva litoral. Posteriormente fueron transportadas por acción fluvial durante el Cuaternario. Debido a su bajo índice de abrasión se puede inferir que el período de transporte fue corto y de rápida depositación. Este proceso habría sido sincrónico con la sedimentación continental acaecida durante el Cuaternario.Works about the meaning of concretions and pebbles of organic origin have limited diffusion in our country. This study allows to infer paleoenvironmental conditions developed in the original deposits of these structures and during their later evolutionary history. These elements were found in Quaternary sediments in the San José Gulf, Chubut, Argentina. They correspond to two different genetic types: precipitation structures (concretions) and organic pebbles (removed briozoary colonies). Both were generated in the upper third of the Puerto Madryn Formation (marine Miocene), during a regressive littoral facies. They were later transported by fluvial action during the Quaternary. Due to its low abrasion we can infer that its transport extended over a short period and had a rapid deposition. This process would have been synchronous with the Quaternary continental sedimentation.Asociación Argentina de Geofísicos y Geodesta

Carta hidrogeomorfológica de la cuenca superior de los arroyos Pillahuincó Grande y Pillahuincó Chico, Buenos Aires, Argentina

Intense rainfall produces flooding in the Quequén Salado river basin (Buenos Aires, Argentina). To analyze the causes, a hydrogeomorphologic study was performed in the Pillahuincó Grande and Pillahuincó Chico creeks upper basin, located in the Quequén Salado river basin. The main characteristics, dynamics and processes that influence the different courses of the hydrographic basin are described. The drainage is dendritic produced by its geological structure. The sinclinals and anticlinals on the SW side have a high slope, whereas on the east side, are expressed as smooth slopes. The typical infiltration of the area is between 12 and 25 mm/h. In shallow sectors of the main streams, flow coming from the upper basin that result in floods downstream because creeks can not contain water volumes.En época de intensas precipitaciones se producen inundaciones importantes de terreno en la cuenca del río Quequén Salado (Buenos Aires, Argentina). Para analizar las causas, se ha elaborado la carta hidrogeomorfológica para la cuenca alta de los arroyos Pillahuincó Grande y Pillahuincó Chico, localizados en la cuenca del mencionado río, con el fin de determinar sus características, dinámica y procesos prevalecientes. El drenaje predominante es el dendrítico, que guarda relación con la estructura geológica que controla los cursos. Los anticlinales y sinclinales del flanco sudoriental poseen escasa amplitud y flancos apretados, mientras que los del sector oriental son más amplios y de pendiente reducida. Dentro de las características hidrológicas de los terrenos predominan os índices de infiltración entre 12 y 25 mm/hora. En sectores poco profundos de los arroyos principales se producen frecuentes anegamientos del terreno debido a que estos no alcanzan a contener los caudales almacenados en sus cabeceras

Paleoambientes holocénicos en el paraje Playa Chica, costa norte del río Negro, Provincia de Buenos Aires, Argentina

A sedimentary profile located on the north bank of the Negro river (Argentina) about 7 km from its mouth is studied. The column, 5 m of thickness, is composed by four differential units. The first unit shows a net domain of the clayey silt fraction, in brown reddish color, with good stratification. It possesses a fossil content of stem concretions and polihalobious to mesohalobious diatoms with Paralia sulcata domain. Depositional environment would be a tidal flat, formed under seasonal cold weather with temperate to warm oscillations. The second section, with sands lithology in pinkish grey to greenish grey colour, has a laminate structure with high organic matter and calcium carbonate content. Fossil algae are represented by polihalobious to mesohalobious species as Paralia sulcata, Cocconeis  scutellum and Rhaphoneis surirella. This unit ends with a deposit with palustrine characteristics. The depositional environment is considered a high tidal flat with sporadic marine influence. The climate would have oscillated from humid cold to warm arid. The third section dominated by sandy fractions, has brown yellowish color, with thick stratification and high percentage of organic matter and calcium carbonate. Fossil content is represented by similar diatoms to that of the previous section. The sedimentary environment begins with a swamp, little developed, continuing with an alluvial plain to conclude with a buried floor, under a variable climate between humid and arid. The fourth section of continental origin, presents massive sands of greyish color and with diatomologic contents dominated by oligohalobious indifferent species. Depositional environment would correspond to an eolic of interdune with cold and arid climate and interdigitation in west direction with deposits fluvial marine clayey silt, limited in their roof and bottom by sandy levels with fine stratification. The comparative age of the group is assigned to Holocene, and it would represent a marine–continental cycle that would have begun about 6.500 years ago.Se analiza un perfil sedimentario ubicado en la margen norte del río Negro (Argentina), a unos 7 km de su desembocadura. La columna, de unos 5 m de espesor, está compuesta por 4 unidades diferenciales. La primera muestra un neto dominio de la fracción limo-arcillosa, en colores pardo rojizos con buena estratificación. Posee un contenido fósil de bioconcreciones y diatomeas polihalobias a mesohalobias con dominio del género Paralia  sulcata. Su ambiente depositacional correspondería a una planicie de marea, formada bajo un clima frío estacional con intercalaciones templadas a cálidas. La segunda sección, con litología de arenas, en colores gris rosado a gris verdoso, posee una estructura laminar característica y alto contenido de materia orgánica. Las algas fósiles están representadas por las especies polihalobias a mesohalobias, como Paralia sulcata, Cocconeis  scutellum y Rhaphoneis surirella. El ambiente depositacional se considera de planicie de marea alta con ingresiones marinas esporádicas. Esta unidad finaliza con un depósito con características palustres. El clima habría oscilado de frío húmedo a cálido árido. La tercera sección dominada por fracciones arenosas, posee un color pardo amarillento, con estratificación gruesa y alto porcentaje de materia orgánica y carbonato de calcio. El contenido fósil está representado por diatomeas similares a las de la sección anterior. El ambiente sedimentario se inició con una marisma, poco desarrollada, continuando con una planicie aluvial para finalizar con un suelo enterrado, bajo un clima variable entre húmedo y árido. La cuarta sección, de origen continental, presenta arenas masivas, de color grisáceo y con un contenido diatomológico dominado por especies oligohalobias indiferentes. El ambiente depositacional correspondería a un eólico de interduna, bajo clima frío y árido, digitándose en dirección oeste, con depósitos fluviales limoarcillosos, limitados en su base y techo por niveles arenosos con fina estratificación. La edad comparativa del conjunto se asigna al Holoceno, y representaría un ciclo marino–continental que se habría iniciado hace nos 6.500 años AP

Paleoambientes holocénicos en el paraje Playa Chica, costa norte del río Negro, Provincia de Buenos Aires, Argentina

A sedimentary profile located on the north bank of the Negro river (Argentina) about 7 km from its mouth is studied. The column, 5 m of thickness, is composed by four differential units. The first unit shows a net domain of the clayey silt fraction, in brown reddish color, with good stratification. It possesses a fossil content of stem concretions and polihalobious to mesohalobious diatoms with Paralia sulcata domain. Depositional environment would be a tidal flat, formed under seasonal cold weather with temperate to warm oscillations. The second section, with sands lithology in pinkish grey to greenish grey colour, has a laminate structure with high organic matter and calcium carbonate content. Fossil algae are represented by polihalobious to mesohalobious species as Paralia sulcata, Cocconeis  scutellum and Rhaphoneis surirella. This unit ends with a deposit with palustrine characteristics. The depositional environment is considered a high tidal flat with sporadic marine influence. The climate would have oscillated from humid cold to warm arid. The third section dominated by sandy fractions, has brown yellowish color, with thick stratification and high percentage of organic matter and calcium carbonate. Fossil content is represented by similar diatoms to that of the previous section. The sedimentary environment begins with a swamp, little developed, continuing with an alluvial plain to conclude with a buried floor, under a variable climate between humid and arid. The fourth section of continental origin, presents massive sands of greyish color and with diatomologic contents dominated by oligohalobious indifferent species. Depositional environment would correspond to an eolic of interdune with cold and arid climate and interdigitation in west direction with deposits fluvial marine clayey silt, limited in their roof and bottom by sandy levels with fine stratification. The comparative age of the group is assigned to Holocene, and it would represent a marine–continental cycle that would have begun about 6.500 years ago.Se analiza un perfil sedimentario ubicado en la margen norte del río Negro (Argentina), a unos 7 km de su desembocadura. La columna, de unos 5 m de espesor, está compuesta por 4 unidades diferenciales. La primera muestra un neto dominio de la fracción limo-arcillosa, en colores pardo rojizos con buena estratificación. Posee un contenido fósil de bioconcreciones y diatomeas polihalobias a mesohalobias con dominio del género Paralia  sulcata. Su ambiente depositacional correspondería a una planicie de marea, formada bajo un clima frío estacional con intercalaciones templadas a cálidas. La segunda sección, con litología de arenas, en colores gris rosado a gris verdoso, posee una estructura laminar característica y alto contenido de materia orgánica. Las algas fósiles están representadas por las especies polihalobias a mesohalobias, como Paralia sulcata, Cocconeis  scutellum y Rhaphoneis surirella. El ambiente depositacional se considera de planicie de marea alta con ingresiones marinas esporádicas. Esta unidad finaliza con un depósito con características palustres. El clima habría oscilado de frío húmedo a cálido árido. La tercera sección dominada por fracciones arenosas, posee un color pardo amarillento, con estratificación gruesa y alto porcentaje de materia orgánica y carbonato de calcio. El contenido fósil está representado por diatomeas similares a las de la sección anterior. El ambiente sedimentario se inició con una marisma, poco desarrollada, continuando con una planicie aluvial para finalizar con un suelo enterrado, bajo un clima variable entre húmedo y árido. La cuarta sección, de origen continental, presenta arenas masivas, de color grisáceo y con un contenido diatomológico dominado por especies oligohalobias indiferentes. El ambiente depositacional correspondería a un eólico de interduna, bajo clima frío y árido, digitándose en dirección oeste, con depósitos fluviales limoarcillosos, limitados en su base y techo por niveles arenosos con fina estratificación. La edad comparativa del conjunto se asigna al Holoceno, y representaría un ciclo marino–continental que se habría iniciado hace nos 6.500 años AP

Relationship between carotid intima-media thickness and non valvular atrial fibrillation type

Objective: Carotid intima-media thickness (cIMT) is a surrogate marker of subclinical atherosclerosis and it is able to predict both coronary and cerebral vascular events. No data exist on the association between cIMT and non valvular atrial fibrillation (NVAF) type. We conduct this study with the aim to analyze the association between abnormal cIMT and NVAF type. Methods: A cross-sectional study of the "Atrial fibrillation Registry for Ankle-brachial index Prevalence Assessment-Collaborative Italian Study (ARAPACIS)" has been performed. Among 2027 patients enrolled in the ARAPACIS, 673 patients, who underwent carotid ultrasound examination to assess cIMT, were included in the study. Results: Among the entire population, 478 patients (71%) had cIMT>0.90mm. Patients with an abnormal cIMT (>0.90mm) were significantly older and more likely hypertensive, diabetic and with a previous history of stroke than those with normal cIMT (≤0.90mm). These patients had more permanent/persistent NVAF and CHA2DS2-VASc score ≥ 2 (p<0.0001) compared to those with cIMT <0.90mm. Excluding all patients affected by previous cardiovascular disease, logistic regression analysis showed that independent predictors of abnormal cIMT were: age class 65-74 yrs. (p<0.001), age class ≥75 yrs. (p<0.001), arterial hypertension (p<0.001), calcium-channel blockers use (p<0.001) and persistent/permanent NVAF (p=0.001). Conclusion: Our findings show a high prevalence of abnormal cIMT in NVAF patients, reinforcing the concept that NVAF and systemic atherosclerosis are closely associated. Abnormal cIMT was particularly evident in persistent/permanent NVAF suggesting a more elevated atherosclerotic burden in patients with long-standing NVAF

Relationship between carotid intima-media thickness and non valvular atrial fibrillation type.

OBJECTIVE:Carotid intima-media thickness (cIMT) is a surrogate marker of subclinical atherosclerosis and it is able to predict both coronary and cerebral vascular events. No data exist on the association between cIMT and non valvular atrial fibrillation (NVAF) type. We conduct this study with the aim to analyze the association between abnormal cIMT and NVAF type.METHODS:A cross-sectional study of the "Atrial fibrillation Registry for Ankle-brachial index Prevalence Assessment-Collaborative Italian Study (ARAPACIS)" has been performed. Among 2027 patients enrolled in the ARAPACIS, 673 patients, who underwent carotid ultrasound examination to assess cIMT, were included in the study.RESULTS:Among the entire population, 478 patients (71%) had cIMT > 0.90 mm. Patients with an abnormal cIMT (>0.90 mm) were significantly older and more likely hypertensive, diabetic and with a previous history of stroke than those with normal cIMT ( 640.90 mm). These patients had more permanent/persistent NVAF and CHA2DS2-VASc score 65 2 (p < 0.0001) compared to those with cIMT <0.90 mm. Excluding all patients affected by previous cardiovascular disease, logistic regression analysis showed that independent predictors of abnormal cIMT were: age class 65-74 yrs. (p < 0.001), age class 6575 yrs. (p < 0.001), arterial hypertension (p < 0.001), calcium-channel blockers use (p < 0.001) and persistent/permanent NVAF (p = 0.001).CONCLUSION:Our findings show a high prevalence of abnormal cIMT in NVAF patients, reinforcing the concept that NVAF and systemic atherosclerosis are closely associated. Abnormal cIMT was particularly evident in persistent/permanent NVAF suggesting a more elevated atherosclerotic burden in patients with long-standing NVAF

Relationship between carotid intima-media thickness and non valvular atrial fibrillation type

OBJECTIVE: Carotid intima-media thickness (cIMT) is a surrogate marker of subclinical atherosclerosis and it is able to predict both coronary and cerebral vascular events. No data exist on the association between cIMT and non valvular atrial fibrillation (NVAF) type. We conduct this study with the aim to analyze the association between abnormal cIMT and NVAF type. METHODS: A cross-sectional study of the "Atrial fibrillation Registry for Ankle-brachial index Prevalence Assessment-Collaborative Italian Study (ARAPACIS)" has been performed. Among 2027 patients enrolled in the ARAPACIS, 673 patients, who underwent carotid ultrasound examination to assess cIMT, were included in the study. RESULTS: Among the entire population, 478 patients (71%) had cIMT > 0.90 mm. Patients with an abnormal cIMT (>0.90 mm) were significantly older and more likely hypertensive, diabetic and with a previous history of stroke than those with normal cIMT ( 640.90 mm). These patients had more permanent/persistent NVAF and CHA2DS2-VASc score 65 2 (p < 0.0001) compared to those with cIMT <0.90 mm. Excluding all patients affected by previous cardiovascular disease, logistic regression analysis showed that independent predictors of abnormal cIMT were: age class 65-74 yrs. (p < 0.001), age class 6575 yrs. (p < 0.001), arterial hypertension (p < 0.001), calcium-channel blockers use (p < 0.001) and persistent/permanent NVAF (p = 0.001). CONCLUSION: Our findings show a high prevalence of abnormal cIMT in NVAF patients, reinforcing the concept that NVAF and systemic atherosclerosis are closely associated. Abnormal cIMT was particularly evident in persistent/permanent NVAF suggesting a more elevated atherosclerotic burden in patients with long-standing NVAF. TRIAL REGISTRATION: http://clinicaltrials.gov/ct2/show/NCT01161251