Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de... more Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de la ruta nacional 7 en la provincia de Mendoza. La zona se ubica en la Cordillera Frontal, proxima al limite con la Precordillera. Se realizo un mapa geomorfologico detallado, sobre la base de una imagen Quickbird del ano 2006. Ademas, se hicieron calculos de volumenes,velocidades y caudales, con mediciones en el campo y con ayuda de un sistema de informacion geografico (SIG). Elestudio de la geomorfologia permitio proponer tres escenarios para el caso de un nuevo evento, a partir de los cuales secreo un mapa de susceptibilidad a los flujos de detritos para el tramo de ruta analizado. Finalmente, se proponen medidasde proteccion y de mitigacion ante la posibilidad de recurrencia de estos eventos en el sector.
Fil: Marengo, Hugo. Ministerio de Planificacion Federal, Inversion Publica y Servicios. Secretari... more Fil: Marengo, Hugo. Ministerio de Planificacion Federal, Inversion Publica y Servicios. Secretaria de Mineria. Servicio Geologico Minero Argentino (SEGEMAR); Argentina.
Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de... more Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de la ruta nacional 7 en la provincia de Mendoza. La zona se ubica en la Cordillera Frontal, próxima al límite con la Precordillera. Se realizó un mapa geomorfológico ...
The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile b... more The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border. Crossing the Andes Cordillera, it is exposed to numerous natural hazards, such as avalanches, rockfalls and debris flows. This study focuses on a catchment prone to debris flows above the International Road n°7 between Potrerillos and Uspallata (Mendoza Province, Argentina) and is part of a regional study that assesses the hazard along the mountainous section of this road. The catchment measures 4.7 km2 and is constituted of three main torrents that unite a few meters above the International Road. Heavy rainfalls triggered debris flows in each of these torrents during the evening of 11 January 2005, reaching the road apparently at a very short interval of time. A car was hit by one of these debris flows and two people were injured. The study has been realized from Quickbird satellite imagery and field data principally. The conditions that triggered the debris flows in this catchment were established from meteorological data, as well as particle size and mineralogy of the material. Satellite imagery and a digital elevation model showed that the debris flows initiated mainly at the top of the catchment. Erosion of a highly altered granite produced abundant sandy material. The debris flows were classified as granular matrix with a collisional-frictional behavior. Various calculations of volumes, peak discharges and velocities (∼ 7 m/s) were realized using different approaches. It appears that important volumes could be mobilized, especially in the longest torrent. A new event could imply more than 65'000 m3 of material. A detailed geomorphologic study shows the effect of mitigation works on the debris flows hazard. Indeed, the torrents were deviated towards a more adequate place for the construction of a road bridge. Three propagation scenarios show the limited efficiency of these works. The road bridge is under-dimensioned and deposits of the 2005 event have not been completely evacuated. The road can be hit even in case of much smaller events than the 2005 debris flows. The results permit to propose improved protection measures, including the evacuation of debris flows deposits and the continuation of the protection dam further towards the bridge.
Resumen: La superficie del centro de la provincia de Santa Fe está dominado por extensos depósito... more Resumen: La superficie del centro de la provincia de Santa Fe está dominado por extensos depósitos de loess y limos loessoides muy homogéneos, con muy bajos contenidos de fracción arena, siendo muy difícil diferenciar los diferentes tipos según sus características macroscópicas. Asociados a éstos se encuentran los depósitos fluviales, más arenosos, de los ríos Salado y Paraná. Un intensivo programa de muestreo y de análisis mineralógicos y texturales, ayudó a definir diferentes tipos de loess retrabajados derivados del loess primario o típico. Los procesos fluviales y palustres que actuaron en el retrabajo del loess original, favorecieron principalmente la remosión de una parte del vidrio volcánico y de la fracción arcillosa, produciendo depósitos empobrecidos en estos componentes, pero que conservaron sus características macroscópicas. La composición mineralógica, tanto de la fracción arenosa como de la arcillosa, indica claramente que los sedimentos detríticos del Cuaternario de la región, fueron aportados principalmente desde el oeste o sudoeste, con una muy escasa contribución de materiales procedentes del Macizo Brasileño transportados por el río Paraná. Abstract: The surface of central Santa Fe Province is dominated by large deposits of homogeneous loess and loess like sediments, with very low percentage of sand; therefore is very difficult to distinguish between them according to their macroscopic features. Also, there are fluvial sandy deposits from the Salado and Paraná riv-ers. An intensive program of sampling and mineralogical and textural analysis help to define different kinds of reworked loess deposits, derived from the typical or primary loess. Fluvial and lacustrine processes that reworked the original loess, led to the partial wasting of the volcanic glass shards and the clay fraction. The mineralogic composition of the sandy and clay fraction, show that the Quaternary detrital sediments of the region were mainly provided from the west or the southwest, with a very low contribution of sediments from the Brazilian Shield, transported through the Paraná river.
A substantially improved reconstruction of the Late Pleistocene-Holocene morphological and geolog... more A substantially improved reconstruction of the Late Pleistocene-Holocene morphological and geological history of the Paraguayan Chaco and the Argentine Pampa Plain (Chaco-Pampa Plain) is presented. Due to the vast extension of the area, satellite images are the clue to synthesize previous and new multidisciplinary geoscientific results to set up a more reliable regional picture. For this synoptic view the interpretation of remote sensing data was complemented by ground investigation and physical age determinations. Luminescence ages (75 IRSL and 12 TL) of loess, loessoids and sands were determined to reconstruct the climatic history of the study area in the Marine Isotopic Stages (MIS) 3 to 1. Loess deposition dominated the period prior to MIS 2. For MIS 2 and MIS 1 the numerical ages of lacustrine and alluvial sediments intercalating the loess provide evidence for alternating humid and dry periods in the Chaco-Pampa Plain. Prevailing dry climate lasted from 8.5 to 3.5 ka (middle MIS 1) when sandy sediments deposited as dunes or filled palaeoriver beds. Temporarily limited phases of palaeoriver activity were related to sporadic torrential rainfall in the Andes Mountains. Source regions of loess, loessoid and sandy deposits were localized in the south-western Pampa and the neighbouring Andean slopes and the Altiplano. These sediment were transported towards east and later northeast as reconstructed by the morphological features and remnants of past aeolian activity periods.
RESUMEN
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedime... more RESUMEN Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas. Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad. Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions. Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features. As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
RESUMEN
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedime... more RESUMEN Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas. Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad. Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions. Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features. As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile b... more The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border. Crossing the Andes Cordillera, it is exposed to numerous natural hazards, such as avalanches, rockfalls and debris flows. This study focuses on a catchment prone to debris flows above the International Road n° 7 between Potrerillos and Uspallata (Mendoza Province, Argentina) and is part of a regional study that assesses the hazard along the mountainous section of this road. The catchment measures 4.7 km2 and is constituted of three main torrents that unite a few meters above the International Road. Heavy rainfalls triggered debris flows in each of these torrents during the evening of 11 January 2005, reaching the road apparently at a very short interval of time. A car was hit by one of these debris flows and two people were injured. The study has been realized from Quickbird satellite imagery and field data principally. The conditions that triggered the debris flows in this catchment were established from meteorological data, as well as particle size and mineralogy of the material. Satellite imagery and a digital elevation model showed that the debris flows initiated mainly at the top of the catchment. Erosion of a highly altered granite produced abundant sandy material. The debris flows were classified as granular matrix with a collisional-frictional behavior. Various calculations of volumes, peak discharges and velocities (~ 7 m/s) were realized using different approaches. It appears that important volumes could be mobilized, especially in the longest torrent. A new event could imply more than 65'000 m3 of material. A detailed geomorphologic study shows the effect of mitigation works on the debris flows hazard. Indeed, the torrents were deviated towards a more adequate place for the construction of a road bridge. Three propagation scenarios show the limited efficiency of these works. The road bridge is under-dimensioned and deposits of the 2005 event have not been completely evacuated. The road can be hit even in case of much smaller events than the 2005 debris flows. The results permit to propose improved protection measures, including the evacuation of debris flows deposits and the continuation of the protection dam further towards the bridge.
The National Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border... more The National Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border. This road is an extremely important corridor crossing the Andes Cordillera, but it is exposed to numerous natural hazards, such as rockfalls, debris flows and snow avalanches. The study area is located in the Mendoza Province, between Potrerillos and Las Cuevas in the Chilean border. This study has for main goals to achieve a regional mapping of geohazards susceptibility along the Road 7 corridor using modern remote sensing and numerical modelling techniques completed by field investigations. The main topics are: - Detection and monitoring of deep-seated gravitational slope deformations by time-series satellite radar interferometry (InSAR) methods. The area of interest is mountainous with almost no vegetation permitting an optimized InSAR processing. Our results are based on applying the small-baseline subset (SBAS) method to a time-series of Envisat ASAR images. - Rockfalls susceptibility mapping is realized using statistical analysis of the slope angle distribution, including external knowledge on the geology and land cover, to detect the potential source areas (quantitative DEM analysis). The run-outs are assessed with numerical methods based on the shallow angle method with Conefall. A second propagation is performed using the alpha-beta methodology (3D numerical modelling) with RAS and is compared to the first one. - Debris flow susceptibility mapping is realized using DF-IGAR to detect starting and spreading areas. Slope, flow accumulations, contributive surfaces, plan curvature, geological and land use dataset are used. The spreading is simulated by a multiple flow algorithm (rules the path that the debris flow will follow) coupled to a run-out distance calculation (energy-based). - Snow avalanches susceptibility mapping is realized using DF-IGAR to map sources areas and propagations. To detect the sources areas, slope, altitude, land-use and minimum surfaces are needed. DF-IGAR simulates the spreading by means of the "Perla" methodology. Furthermore, RAS performs the spreading based on the "alpha-beta" method. All these methods are based on Aster and SRTM DEM (grid 30 m) and observations of both optical and radar satellite imagery (Aster, Quickbird, Worldview, Ikonos, Envisat ASAR) and aerial photographs. Several field campaigns are performed to calibrate the regional models with adapted parameters. Susceptibility maps of the entire area for rockfalls, debris flows and snow avalanches at a scale of 1:100'000 are created. Those maps and the field investigations are cross-checked to identify and prioritize hotspots. It appears that numerous road sectors are subject to highly active phenomena. Some mitigation works already exist but they are often under-dimensioned, inadequate or neglected. Recommendations for priority and realistic mitigation measures along the endangered road sectors identified are proposed.
Ceonozoic Paleontology. The fossil record of the Cenozoic in Córdoba Province (Argentina) is very... more Ceonozoic Paleontology. The fossil record of the Cenozoic in Córdoba Province (Argentina) is very extensive and historically significative, given that the first fossil findings in this province date from the second half of the XVIth century. They comprise some Eocene remains, and are abundant and diverse from Miocene to Holocene. The principal remains of the fossil record include invertebrate and vertebrate icnites, root traces or rhizoliths, biodepositional structures, carophytes, diatoms, phytoliths, foraminifera, porifera, gastropods, ostracods, anurans, reptiles and mammals. Today, investigation also includes study of pollen, holocene megaflora and the isotope content of organic material. The Paleogene and Neogene fossiliferous outcrops occur in the mountain areas and near mountain regions of Córdoba (the Cosquín, Saguión, Brochero, Casa Grande and La Playa formations) or lie in the sub-soil of the Chaco Pampeana plain (Laguna Paiva and Paraná formations). The Quaternary paleontological deposits are principally found in the valleys, in the eastern foothills of the sierras, in the fluvial belts of the main channels of the Córdoba plain and southwestern plain of the province. The principal quaternary fossiliferous formations are Toro Muerto, Pampeano, General Paz, La Invernada, Río Primero, Chocancharava, Mina Clavero, Lagunilla del Plata and Tezanos Pinto. A summary of the principal results obtained in recent decades on the fossil record from Córdoba Province is presented with updated taxonomic assignments. Biostratigraphic and biogeographic aspects, in comparison with other regions of Argentina are analysed.
MIOCENO AL PLEISTOCENO DEL CENTRO Y NORTE DE ARGENTINA, 2019
The main tectonic, stratigraphic
and paleontological features of the Early and Middle Miocene,
in... more The main tectonic, stratigraphic and paleontological features of the Early and Middle Miocene, in the center and North of Argentina, are reviewed. The advances made in the last years in the dating of the main stratigraphic columns, allow to provide a consistent evolutionary scheme for the whole region. The stratigraphic record of the Paleogene can be considered small, mainly limited to the Andean region. On the other hand, the deposits of the Early and Middle Miocene possess a great vertical and superficial development, and correspond to a great variety of environments, from piedmont to shallow marine deposits. The main conditioners in the distribution and variation of these deposits are of tectonic origin, related to the migration of the Andean orogenic front towards the Argentine territory, with clear latitudinal differences, and to the variations in the rate and obliquity of convergence between Nazca and South America plates throughout the Miocene. Another important factor was the global eustatic variations, which generated two large marine ingressions of Atlantic origin, coinciding with periods of strong subsidence increase. The uplift of the Andes favored the formation of environments with marked aridity in the Andean area. On the other hand, the eastern plains were dominated by prairie and shallow marine environments. In general, throughout the Miocene, there would have been a gradual decrease in temperature in continental and marine environments, and an increase in aridity.
Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de... more Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de la ruta nacional 7 en la provincia de Mendoza. La zona se ubica en la Cordillera Frontal, proxima al limite con la Precordillera. Se realizo un mapa geomorfologico detallado, sobre la base de una imagen Quickbird del ano 2006. Ademas, se hicieron calculos de volumenes,velocidades y caudales, con mediciones en el campo y con ayuda de un sistema de informacion geografico (SIG). Elestudio de la geomorfologia permitio proponer tres escenarios para el caso de un nuevo evento, a partir de los cuales secreo un mapa de susceptibilidad a los flujos de detritos para el tramo de ruta analizado. Finalmente, se proponen medidasde proteccion y de mitigacion ante la posibilidad de recurrencia de estos eventos en el sector.
Fil: Marengo, Hugo. Ministerio de Planificacion Federal, Inversion Publica y Servicios. Secretari... more Fil: Marengo, Hugo. Ministerio de Planificacion Federal, Inversion Publica y Servicios. Secretaria de Mineria. Servicio Geologico Minero Argentino (SEGEMAR); Argentina.
Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de... more Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de la ruta nacional 7 en la provincia de Mendoza. La zona se ubica en la Cordillera Frontal, próxima al límite con la Precordillera. Se realizó un mapa geomorfológico ...
The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile b... more The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border. Crossing the Andes Cordillera, it is exposed to numerous natural hazards, such as avalanches, rockfalls and debris flows. This study focuses on a catchment prone to debris flows above the International Road n°7 between Potrerillos and Uspallata (Mendoza Province, Argentina) and is part of a regional study that assesses the hazard along the mountainous section of this road. The catchment measures 4.7 km2 and is constituted of three main torrents that unite a few meters above the International Road. Heavy rainfalls triggered debris flows in each of these torrents during the evening of 11 January 2005, reaching the road apparently at a very short interval of time. A car was hit by one of these debris flows and two people were injured. The study has been realized from Quickbird satellite imagery and field data principally. The conditions that triggered the debris flows in this catchment were established from meteorological data, as well as particle size and mineralogy of the material. Satellite imagery and a digital elevation model showed that the debris flows initiated mainly at the top of the catchment. Erosion of a highly altered granite produced abundant sandy material. The debris flows were classified as granular matrix with a collisional-frictional behavior. Various calculations of volumes, peak discharges and velocities (∼ 7 m/s) were realized using different approaches. It appears that important volumes could be mobilized, especially in the longest torrent. A new event could imply more than 65'000 m3 of material. A detailed geomorphologic study shows the effect of mitigation works on the debris flows hazard. Indeed, the torrents were deviated towards a more adequate place for the construction of a road bridge. Three propagation scenarios show the limited efficiency of these works. The road bridge is under-dimensioned and deposits of the 2005 event have not been completely evacuated. The road can be hit even in case of much smaller events than the 2005 debris flows. The results permit to propose improved protection measures, including the evacuation of debris flows deposits and the continuation of the protection dam further towards the bridge.
Resumen: La superficie del centro de la provincia de Santa Fe está dominado por extensos depósito... more Resumen: La superficie del centro de la provincia de Santa Fe está dominado por extensos depósitos de loess y limos loessoides muy homogéneos, con muy bajos contenidos de fracción arena, siendo muy difícil diferenciar los diferentes tipos según sus características macroscópicas. Asociados a éstos se encuentran los depósitos fluviales, más arenosos, de los ríos Salado y Paraná. Un intensivo programa de muestreo y de análisis mineralógicos y texturales, ayudó a definir diferentes tipos de loess retrabajados derivados del loess primario o típico. Los procesos fluviales y palustres que actuaron en el retrabajo del loess original, favorecieron principalmente la remosión de una parte del vidrio volcánico y de la fracción arcillosa, produciendo depósitos empobrecidos en estos componentes, pero que conservaron sus características macroscópicas. La composición mineralógica, tanto de la fracción arenosa como de la arcillosa, indica claramente que los sedimentos detríticos del Cuaternario de la región, fueron aportados principalmente desde el oeste o sudoeste, con una muy escasa contribución de materiales procedentes del Macizo Brasileño transportados por el río Paraná. Abstract: The surface of central Santa Fe Province is dominated by large deposits of homogeneous loess and loess like sediments, with very low percentage of sand; therefore is very difficult to distinguish between them according to their macroscopic features. Also, there are fluvial sandy deposits from the Salado and Paraná riv-ers. An intensive program of sampling and mineralogical and textural analysis help to define different kinds of reworked loess deposits, derived from the typical or primary loess. Fluvial and lacustrine processes that reworked the original loess, led to the partial wasting of the volcanic glass shards and the clay fraction. The mineralogic composition of the sandy and clay fraction, show that the Quaternary detrital sediments of the region were mainly provided from the west or the southwest, with a very low contribution of sediments from the Brazilian Shield, transported through the Paraná river.
A substantially improved reconstruction of the Late Pleistocene-Holocene morphological and geolog... more A substantially improved reconstruction of the Late Pleistocene-Holocene morphological and geological history of the Paraguayan Chaco and the Argentine Pampa Plain (Chaco-Pampa Plain) is presented. Due to the vast extension of the area, satellite images are the clue to synthesize previous and new multidisciplinary geoscientific results to set up a more reliable regional picture. For this synoptic view the interpretation of remote sensing data was complemented by ground investigation and physical age determinations. Luminescence ages (75 IRSL and 12 TL) of loess, loessoids and sands were determined to reconstruct the climatic history of the study area in the Marine Isotopic Stages (MIS) 3 to 1. Loess deposition dominated the period prior to MIS 2. For MIS 2 and MIS 1 the numerical ages of lacustrine and alluvial sediments intercalating the loess provide evidence for alternating humid and dry periods in the Chaco-Pampa Plain. Prevailing dry climate lasted from 8.5 to 3.5 ka (middle MIS 1) when sandy sediments deposited as dunes or filled palaeoriver beds. Temporarily limited phases of palaeoriver activity were related to sporadic torrential rainfall in the Andes Mountains. Source regions of loess, loessoid and sandy deposits were localized in the south-western Pampa and the neighbouring Andean slopes and the Altiplano. These sediment were transported towards east and later northeast as reconstructed by the morphological features and remnants of past aeolian activity periods.
RESUMEN
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedime... more RESUMEN Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas. Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad. Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions. Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features. As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
RESUMEN
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedime... more RESUMEN Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas. Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad. Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions. Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features. As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile b... more The International Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border. Crossing the Andes Cordillera, it is exposed to numerous natural hazards, such as avalanches, rockfalls and debris flows. This study focuses on a catchment prone to debris flows above the International Road n° 7 between Potrerillos and Uspallata (Mendoza Province, Argentina) and is part of a regional study that assesses the hazard along the mountainous section of this road. The catchment measures 4.7 km2 and is constituted of three main torrents that unite a few meters above the International Road. Heavy rainfalls triggered debris flows in each of these torrents during the evening of 11 January 2005, reaching the road apparently at a very short interval of time. A car was hit by one of these debris flows and two people were injured. The study has been realized from Quickbird satellite imagery and field data principally. The conditions that triggered the debris flows in this catchment were established from meteorological data, as well as particle size and mineralogy of the material. Satellite imagery and a digital elevation model showed that the debris flows initiated mainly at the top of the catchment. Erosion of a highly altered granite produced abundant sandy material. The debris flows were classified as granular matrix with a collisional-frictional behavior. Various calculations of volumes, peak discharges and velocities (~ 7 m/s) were realized using different approaches. It appears that important volumes could be mobilized, especially in the longest torrent. A new event could imply more than 65'000 m3 of material. A detailed geomorphologic study shows the effect of mitigation works on the debris flows hazard. Indeed, the torrents were deviated towards a more adequate place for the construction of a road bridge. Three propagation scenarios show the limited efficiency of these works. The road bridge is under-dimensioned and deposits of the 2005 event have not been completely evacuated. The road can be hit even in case of much smaller events than the 2005 debris flows. The results permit to propose improved protection measures, including the evacuation of debris flows deposits and the continuation of the protection dam further towards the bridge.
The National Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border... more The National Road 7 crosses Argentina from East to West, linking Buenos Aires to the Chile border. This road is an extremely important corridor crossing the Andes Cordillera, but it is exposed to numerous natural hazards, such as rockfalls, debris flows and snow avalanches. The study area is located in the Mendoza Province, between Potrerillos and Las Cuevas in the Chilean border. This study has for main goals to achieve a regional mapping of geohazards susceptibility along the Road 7 corridor using modern remote sensing and numerical modelling techniques completed by field investigations. The main topics are: - Detection and monitoring of deep-seated gravitational slope deformations by time-series satellite radar interferometry (InSAR) methods. The area of interest is mountainous with almost no vegetation permitting an optimized InSAR processing. Our results are based on applying the small-baseline subset (SBAS) method to a time-series of Envisat ASAR images. - Rockfalls susceptibility mapping is realized using statistical analysis of the slope angle distribution, including external knowledge on the geology and land cover, to detect the potential source areas (quantitative DEM analysis). The run-outs are assessed with numerical methods based on the shallow angle method with Conefall. A second propagation is performed using the alpha-beta methodology (3D numerical modelling) with RAS and is compared to the first one. - Debris flow susceptibility mapping is realized using DF-IGAR to detect starting and spreading areas. Slope, flow accumulations, contributive surfaces, plan curvature, geological and land use dataset are used. The spreading is simulated by a multiple flow algorithm (rules the path that the debris flow will follow) coupled to a run-out distance calculation (energy-based). - Snow avalanches susceptibility mapping is realized using DF-IGAR to map sources areas and propagations. To detect the sources areas, slope, altitude, land-use and minimum surfaces are needed. DF-IGAR simulates the spreading by means of the "Perla" methodology. Furthermore, RAS performs the spreading based on the "alpha-beta" method. All these methods are based on Aster and SRTM DEM (grid 30 m) and observations of both optical and radar satellite imagery (Aster, Quickbird, Worldview, Ikonos, Envisat ASAR) and aerial photographs. Several field campaigns are performed to calibrate the regional models with adapted parameters. Susceptibility maps of the entire area for rockfalls, debris flows and snow avalanches at a scale of 1:100'000 are created. Those maps and the field investigations are cross-checked to identify and prioritize hotspots. It appears that numerous road sectors are subject to highly active phenomena. Some mitigation works already exist but they are often under-dimensioned, inadequate or neglected. Recommendations for priority and realistic mitigation measures along the endangered road sectors identified are proposed.
Ceonozoic Paleontology. The fossil record of the Cenozoic in Córdoba Province (Argentina) is very... more Ceonozoic Paleontology. The fossil record of the Cenozoic in Córdoba Province (Argentina) is very extensive and historically significative, given that the first fossil findings in this province date from the second half of the XVIth century. They comprise some Eocene remains, and are abundant and diverse from Miocene to Holocene. The principal remains of the fossil record include invertebrate and vertebrate icnites, root traces or rhizoliths, biodepositional structures, carophytes, diatoms, phytoliths, foraminifera, porifera, gastropods, ostracods, anurans, reptiles and mammals. Today, investigation also includes study of pollen, holocene megaflora and the isotope content of organic material. The Paleogene and Neogene fossiliferous outcrops occur in the mountain areas and near mountain regions of Córdoba (the Cosquín, Saguión, Brochero, Casa Grande and La Playa formations) or lie in the sub-soil of the Chaco Pampeana plain (Laguna Paiva and Paraná formations). The Quaternary paleontological deposits are principally found in the valleys, in the eastern foothills of the sierras, in the fluvial belts of the main channels of the Córdoba plain and southwestern plain of the province. The principal quaternary fossiliferous formations are Toro Muerto, Pampeano, General Paz, La Invernada, Río Primero, Chocancharava, Mina Clavero, Lagunilla del Plata and Tezanos Pinto. A summary of the principal results obtained in recent decades on the fossil record from Córdoba Province is presented with updated taxonomic assignments. Biostratigraphic and biogeographic aspects, in comparison with other regions of Argentina are analysed.
MIOCENO AL PLEISTOCENO DEL CENTRO Y NORTE DE ARGENTINA, 2019
The main tectonic, stratigraphic
and paleontological features of the Early and Middle Miocene,
in... more The main tectonic, stratigraphic and paleontological features of the Early and Middle Miocene, in the center and North of Argentina, are reviewed. The advances made in the last years in the dating of the main stratigraphic columns, allow to provide a consistent evolutionary scheme for the whole region. The stratigraphic record of the Paleogene can be considered small, mainly limited to the Andean region. On the other hand, the deposits of the Early and Middle Miocene possess a great vertical and superficial development, and correspond to a great variety of environments, from piedmont to shallow marine deposits. The main conditioners in the distribution and variation of these deposits are of tectonic origin, related to the migration of the Andean orogenic front towards the Argentine territory, with clear latitudinal differences, and to the variations in the rate and obliquity of convergence between Nazca and South America plates throughout the Miocene. Another important factor was the global eustatic variations, which generated two large marine ingressions of Atlantic origin, coinciding with periods of strong subsidence increase. The uplift of the Andes favored the formation of environments with marked aridity in the Andean area. On the other hand, the eastern plains were dominated by prairie and shallow marine environments. In general, throughout the Miocene, there would have been a gradual decrease in temperature in continental and marine environments, and an increase in aridity.
En el presente capítulo se sintetiza y actualiza el conocimiento que existe sobre el Paleógeno y ... more En el presente capítulo se sintetiza y actualiza el conocimiento que existe sobre el Paleógeno y Neógeno de la Provincia de Córdoba tanto en subsuelo como en superficie, en las Sierras de Córdoba, en sus valles y pie de montes. Exceptuando el registro marino representado por dos episodios transgresivos bien diferenciados en la región de la llanura (cuenca Chacoparanense), la generalidad de los sistemas depositacionales incluye ambientes continentales (abanicos aluviales, sistemas fluviales, fluvio-eólicos, lacustres y de llanuras). Las dos transgresiones no alcanzaron la región serrana ni interserrana actual, razón por la cual se interpreta una altura media de esta región por encima del nivel de base regional. Este hecho permite pensar en un cierto engrosamiento cortical relativamente persistente durante casi todo el Cenozoico para la región de las sierras. Si bien el registro paleógeno es bastante discontinuo y está poco documentado, una tectónica incipiente acompañada de estructuración de nuevos depocentros parece haberse iniciado en el Eoceno. El registro neógeno, en cambio, está mucho más distribuido regionalmente y se relaciona con el conocido levantamiento de las sierras (etapa de antepaís fragmentado) a partir del Mioceno tardío. A partir de esta nueva etapa de estructuración, con la inversión y reactivación tectónica de antiguas estructuras, se produjo en la región serrana una fuerte compartimentación con acomodación diferencial de sistemas aluviales, a diferencia de la llanura oriental, donde el registro sedimentario aunque con frecuencia condensado resulta mucho más continuo. Separando ambas etapas se desarrolló un calcrete regional que con diferentes características (de espesor y microfacies) refleja una etapa de condensación compleja asociada con peneplanización generalizada, escasa acomodación regional, pedogénesis y fluctuaciones climáticas que permitieron superponer notables efectos freatogénicos dentro de este nivel guía de carbonatos continentales. A grandes rasgos la evidencia paleontológica resulta consistente con esta interpretación.
La provincia de Corrientes forma parte de la Mesopotamia Argentina, región con muy escaso conocim... more La provincia de Corrientes forma parte de la Mesopotamia Argentina, región con muy escaso conocimiento sobre su actividad neotectónica. En varios sectores la red de drenaje sugiere un marcado control estructural, muy claro en numerosos tributarios de diversas magnitudes sobre la margen izquierda del Paraná. La cuenca del arroyo Toropí fue seleccionada para su investigación detallada. Una recorrida minuciosa permitió observar al menos tres localidades con fallas aflorantes, manifestadas en el desplazamiento vertical de niveles guía; se midieron las cotas de estos niveles y de la superficie del terreno en 46 estaciones, mediante un receptor GPS de alta precisión. Esta metodología permitió medir, con precisión de algunos centímetros, desplazamientos verticales de 3 a 5 m, mediante la construcción de perfiles a escala vertical y horizontal. Se estima que la mayor parte del desplazamiento se produjo durante el Pleistoceno Tardío, con movimientos menores en el Holoceno. Esta contribución constituye la primer observación directa y la medición precisa de estructuras cuaternarias aflorantes en Corrientes, y posiblemente en toda la región del Litoral.
Se discute en forma breve la diversidad de formas y orígenes para los depósitos de arena incluido... more Se discute en forma breve la diversidad de formas y orígenes para los depósitos de arena incluidos entre los basaltos de la Formación Serra Geral. El análisis de un corte estratigráfico en cercanías a Cerro Azul, permitió identificar, por primera vez en Argentina, depósitos originados por inyección de arena (inyectita) asociada a procesos hidrotermales. A su vez se describe el posible hallazgo de un depósito producido por extrusión (extrudita). El origen del material clástico en esta localidad es aún desconocido, pero podría provenir de depósitos arenosos intercalados entre flujos basálticos subyacentes (intertrap).
El territorio de Corrientes registra diversos ciclos tectónicos desde el Proterozoico. En los últ... more El territorio de Corrientes registra diversos ciclos tectónicos desde el Proterozoico. En los últimos años se ha determinado, mediante información geofísica, que las principales estructuras están asociadas a ciclos tectónicos subcontinentales, como la extensión del Ordovícico, o la compresión brasiliana y del Paleozoico Tardío. Los posteriores períodos extensivos y compresivos parecen haber actuado sobre las mismas estructuras. Nuevos relevamientos de superficie permiten modificar algunas de las conclusiones previas, y completar la evolución estructural de la provincia hasta el Holoceno.
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Papers by Hugo Marengo
La composición mineralógica, tanto de la fracción arenosa como de la arcillosa, indica claramente que los sedimentos detríticos del Cuaternario de la región, fueron aportados principalmente desde el oeste o sudoeste, con una muy escasa contribución de materiales procedentes del Macizo Brasileño transportados por el río Paraná.
Abstract: The surface of central Santa Fe Province is dominated by large deposits of homogeneous loess and loess like sediments, with very low percentage of sand; therefore is very difficult to distinguish between them according to their macroscopic features. Also, there are fluvial sandy deposits from the Salado and Paraná riv-ers. An intensive program of sampling and mineralogical and textural analysis help to define different kinds of reworked loess deposits, derived from the typical or primary loess. Fluvial and lacustrine processes that reworked the original loess, led to the partial wasting of the volcanic glass shards and the clay fraction.
The mineralogic composition of the sandy and clay fraction, show that the Quaternary detrital sediments of the region were mainly provided from the west or the southwest, with a very low contribution of sediments from the Brazilian Shield, transported through the Paraná river.
Chaco and the Argentine Pampa Plain (Chaco-Pampa Plain) is presented. Due to the vast extension of the area, satellite
images are the clue to synthesize previous and new multidisciplinary geoscientific results to set up a more reliable regional
picture. For this synoptic view the interpretation of remote sensing data was complemented by ground investigation and physical
age determinations. Luminescence ages (75 IRSL and 12 TL) of loess, loessoids and sands were determined to reconstruct
the climatic history of the study area in the Marine Isotopic Stages (MIS) 3 to 1. Loess deposition dominated the period prior
to MIS 2. For MIS 2 and MIS 1 the numerical ages of lacustrine and alluvial sediments intercalating the loess provide evidence
for alternating humid and dry periods in the Chaco-Pampa Plain. Prevailing dry climate lasted from 8.5 to 3.5 ka (middle MIS 1)
when sandy sediments deposited as dunes or filled palaeoriver beds. Temporarily limited phases of palaeoriver activity were
related to sporadic torrential rainfall in the Andes Mountains.
Source regions of loess, loessoid and sandy deposits were localized in the south-western Pampa and the neighbouring Andean
slopes and the Altiplano. These sediment were transported towards east and later northeast as reconstructed by the morphological
features and remnants of past aeolian activity periods.
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas.
Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad.
Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT
Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions.
Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features.
As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas.
Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad.
Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT
Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions.
Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features.
As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
significative, given that the first fossil findings in this province date from the second half of the XVIth century. They comprise some Eocene remains, and are abundant and diverse from Miocene to Holocene. The principal remains of the fossil record include invertebrate and vertebrate icnites, root traces or rhizoliths, biodepositional structures, carophytes, diatoms, phytoliths, foraminifera, porifera, gastropods, ostracods, anurans, reptiles and mammals. Today, investigation
also includes study of pollen, holocene megaflora and the isotope content of organic material. The Paleogene
and Neogene fossiliferous outcrops occur in the mountain areas and near mountain regions of Córdoba (the Cosquín,
Saguión, Brochero, Casa Grande and La Playa formations) or lie in the sub-soil of the Chaco Pampeana plain (Laguna
Paiva and Paraná formations). The Quaternary paleontological deposits are principally found in the valleys, in the eastern
foothills of the sierras, in the fluvial belts of the main channels of the Córdoba plain and southwestern plain of the
province. The principal quaternary fossiliferous formations are Toro Muerto, Pampeano, General Paz, La Invernada, Río
Primero, Chocancharava, Mina Clavero, Lagunilla del Plata and Tezanos Pinto. A summary of the principal results obtained
in recent decades on the fossil record from Córdoba Province is presented with updated taxonomic assignments. Biostratigraphic and biogeographic aspects, in comparison with other regions of Argentina are analysed.
Books by Hugo Marengo
and paleontological features of the Early and Middle Miocene,
in the center and North of Argentina, are reviewed.
The advances made in the last years in the dating of the
main stratigraphic columns, allow to provide a consistent evolutionary scheme for
the whole region. The stratigraphic record of the Paleogene can be considered small,
mainly limited to the Andean region. On the other hand, the deposits of the Early
and Middle Miocene possess a great vertical and superficial development, and correspond
to a great variety of environments, from piedmont to shallow marine deposits.
The main conditioners in the distribution and variation of these deposits are of
tectonic origin, related to the migration of the Andean orogenic front towards the
Argentine territory, with clear latitudinal differences, and to the variations in the rate
and obliquity of convergence between Nazca and South America plates throughout
the Miocene. Another important factor was the global eustatic variations, which
generated two large marine ingressions of Atlantic origin, coinciding with periods
of strong subsidence increase. The uplift of the Andes favored the formation of environments
with marked aridity in the Andean area. On the other hand, the eastern
plains were dominated by prairie and shallow marine environments. In general,
throughout the Miocene, there would have been a gradual decrease in temperature
in continental and marine environments, and an increase in aridity.
La composición mineralógica, tanto de la fracción arenosa como de la arcillosa, indica claramente que los sedimentos detríticos del Cuaternario de la región, fueron aportados principalmente desde el oeste o sudoeste, con una muy escasa contribución de materiales procedentes del Macizo Brasileño transportados por el río Paraná.
Abstract: The surface of central Santa Fe Province is dominated by large deposits of homogeneous loess and loess like sediments, with very low percentage of sand; therefore is very difficult to distinguish between them according to their macroscopic features. Also, there are fluvial sandy deposits from the Salado and Paraná riv-ers. An intensive program of sampling and mineralogical and textural analysis help to define different kinds of reworked loess deposits, derived from the typical or primary loess. Fluvial and lacustrine processes that reworked the original loess, led to the partial wasting of the volcanic glass shards and the clay fraction.
The mineralogic composition of the sandy and clay fraction, show that the Quaternary detrital sediments of the region were mainly provided from the west or the southwest, with a very low contribution of sediments from the Brazilian Shield, transported through the Paraná river.
Chaco and the Argentine Pampa Plain (Chaco-Pampa Plain) is presented. Due to the vast extension of the area, satellite
images are the clue to synthesize previous and new multidisciplinary geoscientific results to set up a more reliable regional
picture. For this synoptic view the interpretation of remote sensing data was complemented by ground investigation and physical
age determinations. Luminescence ages (75 IRSL and 12 TL) of loess, loessoids and sands were determined to reconstruct
the climatic history of the study area in the Marine Isotopic Stages (MIS) 3 to 1. Loess deposition dominated the period prior
to MIS 2. For MIS 2 and MIS 1 the numerical ages of lacustrine and alluvial sediments intercalating the loess provide evidence
for alternating humid and dry periods in the Chaco-Pampa Plain. Prevailing dry climate lasted from 8.5 to 3.5 ka (middle MIS 1)
when sandy sediments deposited as dunes or filled palaeoriver beds. Temporarily limited phases of palaeoriver activity were
related to sporadic torrential rainfall in the Andes Mountains.
Source regions of loess, loessoid and sandy deposits were localized in the south-western Pampa and the neighbouring Andean
slopes and the Altiplano. These sediment were transported towards east and later northeast as reconstructed by the morphological
features and remnants of past aeolian activity periods.
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas.
Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad.
Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT
Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions.
Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features.
As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
Se estudió la composición micropaleontológica, la estratigrafía y algunos aspectos sedimentológicos de los testigos de unas 200 perforaciones, en las cuencas Chacoparanense y del Salado. Se reconocieron dos niveles marinos representados por asociaciones de foraminíferos, ostrácodos y nanoplancton calcáreo. El nivel marino inferior es casi desconocido, e incluido previamente en la Formación Mariano Boedo del Maastrichtiano-Daniano, es denominado Transgresión de Laguna Paiva (TLP) y posee microfósiles del Oligoceno tardío?-Mioceno temprano. El nivel marino superior corresponde a la Formación Paraná, y es tratado aquí como Transgresión del “Entrerriense-Paranense” (TEP), del Mioceno medio-tardío?. Ambas inundaron todo el territorio de la llanura Chacopampeana, alcanzando algunos sectores de las Sierras Pampeanas, Cuyo y Noroeste. Para la datación de las dos transgresiones se utilizaron criterios bioestratigráficos, eustáticos y tectónicos; se informan los primeros hallazgos de foraminíferos planctónicos y nanofósiles calcáreos para ambas.
Sobre la base de la datación y caracterización de ambos niveles marinos, se propone una nueva división litoestratigráfica para el Cenozoico de la cuenca Chacoparanense. Las Formaciones Laguna Paiva y Paraná, de origen marino, están intercaladas con los miembros Palermo, San Francisco y Pozo del Tigre de la Formación Chaco; estas unidades fueron reunidas en el Grupo Litoral. Se brinda una caracterización sedimentológica y mineralógica de cada unidad.
Como complemento se estudiaron los foraminíferos y algunos aspectos sedimentológicos de tres perfiles levantados en península Valdés.
ABSTRACT
Micropaleontologic composition, stratigraphy and some sedimentologic features were studied in samples from about 200 boreholes in Chacoparanense and Salado Basins. Two marine levels were recognized, each one is characterized by specific associations of foraminifers, ostracods and calcareous nannoplankton. The lower marine level was almost unknown, and was previously included in the Maastrichtian Danian Mariano boedo Formation; in this work it is called Laguna Paiva Transgression (TLP), and bears microfossils of late Oligocene?-early Miocene age. The upper marine level corresponds to the Paraná Formation, and is referred here as “Entrerriense-Paranense” Transgression (TEP), from the middle-early? Miocene. Both transgressions flooded the whole Chaco-Pampa Plains and reached some sectors in the Sierras Pampeanas, and Cuyo and Northwest regions in Argentina. The age of both transgressions was estimated using biostratigraphic, eustatic and tectonic poins of view; it is reported the first finding of planktonic foraminifers and calcareous nannoplankton in both transgressions.
Based in the datation and characterization of both marine levels, a new litostratigraphic division is proposed for the Ceonozoic in Chacoparanense Basin. Marine Laguna Paiva and Paraná Formations, are interbedded with Palermo, San Francisco and Pozo del Tigre Members of Chaco Formation; all those units are assembled in the Litoral Group. Each unit is characterized by mineralogic and sedimentologic features.
As a complement, foraminifers and some sedimentologic features are reported from three profiles of Península Valdés.
significative, given that the first fossil findings in this province date from the second half of the XVIth century. They comprise some Eocene remains, and are abundant and diverse from Miocene to Holocene. The principal remains of the fossil record include invertebrate and vertebrate icnites, root traces or rhizoliths, biodepositional structures, carophytes, diatoms, phytoliths, foraminifera, porifera, gastropods, ostracods, anurans, reptiles and mammals. Today, investigation
also includes study of pollen, holocene megaflora and the isotope content of organic material. The Paleogene
and Neogene fossiliferous outcrops occur in the mountain areas and near mountain regions of Córdoba (the Cosquín,
Saguión, Brochero, Casa Grande and La Playa formations) or lie in the sub-soil of the Chaco Pampeana plain (Laguna
Paiva and Paraná formations). The Quaternary paleontological deposits are principally found in the valleys, in the eastern
foothills of the sierras, in the fluvial belts of the main channels of the Córdoba plain and southwestern plain of the
province. The principal quaternary fossiliferous formations are Toro Muerto, Pampeano, General Paz, La Invernada, Río
Primero, Chocancharava, Mina Clavero, Lagunilla del Plata and Tezanos Pinto. A summary of the principal results obtained
in recent decades on the fossil record from Córdoba Province is presented with updated taxonomic assignments. Biostratigraphic and biogeographic aspects, in comparison with other regions of Argentina are analysed.
and paleontological features of the Early and Middle Miocene,
in the center and North of Argentina, are reviewed.
The advances made in the last years in the dating of the
main stratigraphic columns, allow to provide a consistent evolutionary scheme for
the whole region. The stratigraphic record of the Paleogene can be considered small,
mainly limited to the Andean region. On the other hand, the deposits of the Early
and Middle Miocene possess a great vertical and superficial development, and correspond
to a great variety of environments, from piedmont to shallow marine deposits.
The main conditioners in the distribution and variation of these deposits are of
tectonic origin, related to the migration of the Andean orogenic front towards the
Argentine territory, with clear latitudinal differences, and to the variations in the rate
and obliquity of convergence between Nazca and South America plates throughout
the Miocene. Another important factor was the global eustatic variations, which
generated two large marine ingressions of Atlantic origin, coinciding with periods
of strong subsidence increase. The uplift of the Andes favored the formation of environments
with marked aridity in the Andean area. On the other hand, the eastern
plains were dominated by prairie and shallow marine environments. In general,
throughout the Miocene, there would have been a gradual decrease in temperature
in continental and marine environments, and an increase in aridity.