Artículos y presentaciones en Congresos
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Examinando Artículos y presentaciones en Congresos por Autor "Aguirre, Marina Laura"
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Embargado Coastal landscape evolution and sea-level change: a case study from Central Patagonia (Argentina)(2015) Pappalardo, Marta; Aguirre, Marina L.; Bini, Mónica; Consoloni, Ilaria; Fucks, Enrique; Hellstrom, John; Isola, Ilaria; Ribolini, Adriano; Zanchetta, GiovanniThe coastal fringe of Central Patagonia preserves a unique and spectacular succession of landforms discontinuously formed since MIS 11 up to the Holocene. The study area, stretching from 44° 34′ to 44° 54′ S of latitude, is crucial to analyze the complexity of multitemporal shorelines formation and preservation along the Atlantic coast of South America. We used depositional and erosional landforms to get reliable and well chronologically constrained sea level markers. In particular, multistoried swale infillings, produced by a complex relationship between river discharge and marine activity, were considered the most accurate sea level markers. Palaeo sea level elevation was assessed cross checking evidence obtained from different marker types and considering the original position of each of the measured features with respect to its contemporary sea level. A dedicated field measurement of the markers current elevation was necessary, considering the macrotidal regime that currently affects this coastal area. Literature and new data provide an excellent set of dating, useful to chronologically constrain all the palaeo shorelines that have been identified. On the whole five sea level highstands have confidently been referred to Holocene (maximum transgression peak), MIS 5, 7, 9 and 11. Sea level elevation for each of them was stated respectively at 2.5, 7.5, 10.5, 22.5 and 32.5 m a.s.l., but different error bars and levels of accuracy are assigned to each of these estimates, based on innovative criterions that are widely discussed in the text. Our work enabled us to obtain new, self-consistent values of the last 400 ka uplift rates for this coastal tract and to compare them with those calculated by other authors, suggesting for the investigated time span a moderate coastal uplift. - Artículo
Acceso Abierto Evolución geológica-geomorfológica de la cuenca del río Areco, NE de la provincia de Buenos Aires(2011) Fucks, Enrique; Blasi, Adriana Mónica; Carbonari, Jorge; Huarte, Roberto; Pisano, Florencia; Aguirre, Marina L.La cuenca del río Areco integra la red de drenaje de la Pampa Ondulada, NE de la provincia de Buenos Aires. Los procesos geomórficos marinos, fluvio-lacustres y eólicos actuaron sobre los sedimentos loéssicos y loessoides de la Formación Pampeano (Pleistoceno) dejando, con diferentes grados de desarrollo, el registro sedimentario del Pleistoceno tardío y Holoceno a lo largo de toda la cuenca. En estos depósitos se han reconocido, al menos, dos episodios pedogenéticos. Edades14C sobre MO de estos paleosuelos arrojaron valores de 7.000 ± 240 y 1.940 ± 80 años AP en San Antonio de Areco y 2.320 ± 90 y 2.000 ± 90 años AP en Puente Castex, para dos importantes estabilizaciones del paisaje, separadas en esta última localidad por un breve episodio de sedimentación. La cuenca inferior en la cañada Honda, fue ocupada por la ingresión durante MIS 1 (Formación Campana), dejando un amplio paleoestuario limitado por acantilados. El retroceso de la línea de costa y la continentalización del ambiente permitió la formación de un suelo datado en 3.070 ± 90 años14C AP cubierto por sedimentos aluviales. Los sedimentos litorales son en general de baja energía, asociados a tres litofacies diferentes, cuyas edades fluctúan entre los 4.270 ± 70 años14C AP en esta cuenca y 6.000 ± 8014C años AP, 6.370 ± 90 años14C AP, 3.640 ± 70 años14C AP, 5.630 ± 100 años14C AP y 5.420 ± 110 años14C AP, en cuencas aledañas. La ingresión durante MIS 5e también entró por el río Areco evidenciando ya la existencia de esta depresión. El límite externo de esta cuenca lo constituye el delta del Paraná cuya progradación ha dejado expuesto morfologías y depósitos de ambientes fluviales, observándose que el contacto entre ambas unidades morfológicas (delta y paleoestuario) está determinado por los cursos de agua, que con cambio bruscos de dirección, acompañan el sentido de avance del complejo deltaico. - Artículo
Embargado Holocene Beach Ridges and Coastal Evolution in the Cabo Raso Bay (Atlantic Patagonian Coast, Argentina)(2011) Ribolini, Adriano; Aguirre, Marina L.; Baneschi, Ilaria; Consoloni, Ilaria; Fucks, Enrique; Isola, Ilaria; Mazzarini, Francesco; Pappalardo, Marta; Zanchetta, Giovanni; Bini, MonicaThe Holocene evolution of the Cabo Raso bay (Atlantic Patagonian coast) was reconstructed by means of geomorphological, stratigraphic, and palaeontological analyses, assisted by radiocarbon dating. Six beach ridges were individuated and mapped in the field, as well as some rocky erosional landforms,e.g.,inner margins of marine terraces. Thanks to quarry sections, the internal structure of beach ridges, their relationship with continental deposits, and the fossil contents were determined. Two specimens ofAulacomya atraandBrachidontes purpuratuswere radiocarbon dated at 6055 and 4500 ± 20 YBP, respectively. The bedrock outcrops at the base of an analysed section allowed us to associate the age of the samples collected to the elevation of the marine transgression surface upon which the entire deposit rests. Because a beach ridge is a regressive form, the elevation of the base of the dated deposit was assumed to be equivalent to or slightly lower than the maximum sea-level stationing, represented by the inner margin of the coheval marine terrace. The altimetric correlation between the base of the beach ridge dated at 6055 ± 20 YBP and the inner margin of the corresponding marine terraces allowed us to constrain the maximum Holocene marine transgression to about 3 to 2m above sea level. This elevation for the maximum Holocene transgression is lower than that shown by most of the previous data for Patagonian coast, but it shows a crude agreement with recent estimates coming from geophysical models that report, for this area, a departure from the eustatic value of sea level, mainly caused by glacioisostatic process. This means that the employment of marine erosional landforms, associated with other multisource field data, proved to be determinant for reconstructing the sea-level variation in the Patagonian coast. - Artículo
Acceso Abierto Nuevo ordenamiento estratigráfico de las secuencias marinas del sector continental de la Bahía Samborombón, provincia de Buenos Aires(2010) Fucks, Enrique; Schnack, Enrique Jorge; Aguirre, Marina L.Este estudio refleja las características geológicas-geomorfológicas de dos eventos transgresivo-regresivos acontecidos en el Pleistoceno tardío y Holoceno en el sector terminal de las cuencas de drenaje de los ríos Salado y Samborombón, este de la Provincia de Buenos Aires. Las variaciones del nivel del mar y un ambiente de costa baja, limitada hacia el norte y oeste por sectores positivos, han generado depósitos con unidades sedimentarias claramente individualizadas, proporcionando los elementos necesarios para establecer la evolución estratigráfica y geomorfológica del sector. Si bien esta región ha sido estudiada desde diversas disciplinas, la amplia y confusa nomenclatura existente determina la necesidad de denominar, agrupar y redefinir el conjunto de las unidades litológicas involucradas, a fin de establecer un marco estratigráfico y su relación con la evolución geomorfológica del área. En este sentido, a la ingresión del Pleistoceno tardío se la denomina Formación Puente de Pascua y a todos los depósitos de la ingresión postglacial se los involucra dentro de la Formación Canal de las Escobas, en la que se incluyen cuatro miembros: Destacamento Río Salado, Canal 18, Cerro de la Gloria y Canal 15. Esta nueva organización estratigráfica incluye criterios sedimentológicos y paleoecológicos y su asociación con la evolución geomorfológica de la región, discriminando ambientes de planicie de marea, lagunas costeras y cordones litorales. - Artículo
Embargado Taphonomic comparison between two bivalves ( Mactra and Brachidontes) from Late Quaternary deposits in northern Argentina: Which intrinsic and extrinsic factors prevail under different palaeoenvironmental conditions?(2011) Aguirre, Marina L.; Richiano, Sebastián M.; Farinati, Ester; Fucks, EnriqueQuaternary records of unique skeletal deposits studied at two coastal areas of the Bonaerensean littoral, Bahía Samborombón in the north (at Puente de Pascua and Canal 15 area) and Bahía Blanca southwards, are thick (4–5m) and exceptionally rich in molluscan assemblages (ca. 75–90% bivalve shells), indicating different high sea level episodes. Through taphonomical aspects of target bivalves (Mactra,Brachidontes) which differ in shell structure, life habit and habitat, abundantly present in the marine Late Quaternary from both areas, the aims were: 1) to establish quantitative grades of taphonomic alteration ofMactrafrom four lithostratigraphical units at Bahía Samborombón and identify which signature/s better discriminates palaeoenvironments; 2) test whetherMactrashows different alteration than doesBrachidontesin response to differences in intrinsic features and ecological requirements; 3) compare isotaphonomic assemblages complementing independent geological and palaeoenvironmental interpretations. Attributes (articulation, fragmentation, abrasion, colour, encrustation, bioerosion) were classified for about 5400 shells from 11 samples. Bar plots, ternary taphograms and Q-Mode Cluster analysis discriminate beach, beach ridges and tidal flat environments and two taphofacies: Late Pleistocene and Holocene high energy units; and low energy Holocene units. Only abrasion and colour allow discrimination between high and low energy conditions. Rules cannot be applied to the processes of deposition of shells, at least for the Late Quaternary marine deposits along the Buenos Aires Province coastal area. Despite the harder (Mactra) or more fragile (Brachidontes)shell architecture, in softer (Mactra,muddy substrates, infaunal) or harder (Brachidontes, varied sandy-rocky bottoms, epibyssate) and deeper (Mactra, infralittoral) or shallower waters (Brachidontes, intertidal to supratidal), the taphonomic grades of alteration are similar, a product mainly of long after-death exposure along the Taphonomically Active Zone in high to moderate wave energy conditions.