Informe de Asistencia Técnica al Parque Nacional Iguazú

Fil: García Aráoz, Eduardo. Servicio Geológico Minero Argentino. SEGEMAR; Argentina.Fil: Celli, Alejandro E. Organismo Regulador de Seguridad de Presas. ORSEP; Argentina.El presente informe responde a la solicitud de asistencia técnica efectuada por la Administración de Parques Nacionales (APN) al Servicio Geológico y Minero Argentino (SEGEMAR), considerando el Convenio de Asistencia Técnica existente entre ambas instituciones.El presente informe responde a la solicitud de asistencia técnica efectuada por la Administración de Parques Nacionales (APN) al Servicio Geológico y Minero Argentino (SEGEMAR), considerando el Convenio de Asistencia Técnica existente entre ambas instituciones. Surge la preocupación por parte de las autoridades del Parque Nacional Iguazú (PNI), la ocurrencia de posibles eventos de remoción en masa que pudieran afectar el recorrido del circuito turístico denominado Circuito Inferior (CI). Cabe destacar que dicho circuito se encuentra actualmente cerrado al público (de manera provisoria y preventiva), debido al registro de una serie de acontecimientos de caída de bloques que han impactado sobre la pasarela en los últimos años. A raíz de esta solicitud, se designó un equipo de trabajo interinstitucional, integrado por los geólogos Eduardo García Aráoz, de SEGEMAR, y Alejandro Celli, de ORSEP (Organismo Regulador de Seguridad de Presas), quienes llevaron a cabo entre los días 14 y 20 de diciembre de 2020, un relevamiento geológico-geotécnico con el fin de analizar los peligros asociados con los procesos de ladera. Los resultados de los análisis efectuados, permiten en este informe, elaborar una zonificación del terreno en función del peligro de materialización de diferentes procesos de remoción en masa, y recomendar distintas alternativas de estabilización tendiente a disminuir dichos peligros y a concretar la pronta reapertura de este circuito tan importante para el turismo

Radiogenic heat production in granitoids from the Sierras de Córdoba, Argentina

Abstract One of the most important processes of heat generation from the Earth's interior is the radioactive decay of isotopes. The main hosts of the major radiogenic elements U, Th and K in the crust are granitoids. The Sierras de Córdoba are formed of dissimilar granitic intrusions emplaced by a series of magmatic events that occurred during the Paleozoic. The different granitoids are classified as A-type, I-type, and S-type, and there is also a magmatic expression corresponding to the Famatinian period which exhibits TTG-type characteristics. In this work, the geochemical concentrations of the radiogenic elements of the granitic intrusions making up the Sierras de Córdoba were compiled in a single database. The radiogenic heat production of the Sierras de Córdoba granitoids was evaluated, making this the first study of radiogenic heat generation in the area. The radiogenic heat production showed variability for the different events, with the highest values found in Achalian magmatism and early Carboniferous magmatism, which are represented by A-type granitoids. The Capilla del Monte pluton has the highest heat production rate, with a value of 4.54 ± 1.38 µW/m3. The lowest values were found in the TTG-type granitoids and in the S-type granitoids, all of which belong to the Famatinian magmatic event. The range of values for this magmatic event goes from 0.26 ± 0.05 µW/m3 for the San Agustin pluton to 1.19 ± 0.50 µW/m3 for the La Playa pluton. An empirical ternary model is presented for the Sierras de Córdoba that involves the concentrations of the elements U, Th and K, and the radiogenic heat production, with a distinction for the petrogenetic types according to the S-I-A-M classification. The thermal manifestations located on the Capilla del Monte pluton could be related to the radioactive heat generation of the intrusion, involving both the neotectonic activity of the area and the radiogenic heat production. The results provide new opportunities for studying temperature variation within some of these intrusions and to evaluate the geothermal potential of the granitoids of Córdoba

Granitic caves from the Achala Batholith in the Province of Córdoba, Argentina: A study on three particular stories with a common past

The igneous or magmatic rocks, especially those with granitic composition, constitute a special type of geomorphological substrate. As fromits exposure on the Earth´s surface and the modelling that eventually takes placeon them, different landscapes with specific characteristics emerge where inherited and present shapes coexist making possible to reconstruct the landscape evolution of the massif. Traditionally, in the studies of granitic landscapes,only the forms observed on the surface are described, where as those that develop underground are not often taken into consideration. In this paper three caves are analysed in order to specify their particular origins and classify it according to its morphological characteristics and the genetic processes involved. These caves are located on the same scarp of the rock massif and, therefore, share a geological and geomorphological common history, which is shown in their hypothesis of evolution. In addition, based on the type of cavityand certain observations of their environments it is possible to establish a relative chronological order in their ages of formation. In this context, it is proven that these underground environments (as the other geographical accidents andgranitic landforms) are not chaotic but - on the contrary- they are structured ingeological and geomorphological processes over time and they respond to acommon evolutionary framework to the entire rock massif. More detailed studies on these environments can develop in new methodological tools to understand the geological history of the granitic landscape they are located in.Fil: García Aráoz, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geología Aplicada; ArgentinaFil: Madelon, Nicolás. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Pleitavino, Micaela Natalí. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Boretto, Gabriella Margherita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Cioccale, Marcela Alejandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geología Aplicada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

South American mountain ecosystems and global change – a case study for integrating theory and field observations for land surface modelling and ecosystem management

Plot-based monitoring has yielded much information on the taxonomic diversity and carbon (C) storage in tropical lowland forests of the Amazon basin. This has resulted in an improved understanding of the relationship between lowland forest biomass dynamics and global change drivers, such as climate change and atmospheric CO2 concentration. Much less attention has been paid to the mountain ecosystems of South America that comprise montane forests and alpine vegetation (páramo, puna, high Andean grasslands, wetlands, and alpine heath). This vegetation complex provides a variety of ecosystem services and forms a natural laboratory along various physiographic, geological and evolutionary history/biogeography, and land use history gradients. Here we review existing empirical understanding and model-based approaches to quantify the contribution of mountain ecosystems to ecosystem service provision in the rapidly changing socioecological setting of the South American mountains. The objective of this paper is to outline a broad road map for the implementation of mountain vegetation into dynamic global vegetation models (DGVM) for use in Earth System Models (ESM), based on our current understanding of their structure and function and of their responsiveness to global change drivers. We also identify treeline processes, critical in mountain ecosystems, as key missing elements in DGVMs/ESMs, and thus explore in addition a treeline model. A stocktaking of availability of empirical data was undertaken from eight research sites along the Andes and in south-eastern Brazil. Out of eight sites, two (one each in Venezuela and Brazil) had some climate, ecological and ecophysiological data potentially suitable to parametrise a DGVM. Tree biomass data were available for six sites. A preliminary assessment of the Joint UK Land Environment Simulator (JULES) DGVM was made to identify gaps in available data and their impacts on model parametrisation and calibration. Additionally, the potential climate-determined elevation of the treeline was modelled to check the DGVM for its ability to identify the transition between the montane forest and alpine vegetation. Outcomes of the evaluation of the JULES land surface model identified the following key processes in montane forests: temperature-related decrease in net primary production, respiration, and allocation to above-ground biomass and increase in soil C stocks with elevation. There was a variable agreement between simulated biomass and those derived from field measurements via allometric equations. We identified major gaps between data availability and the needs of process-based modelling of South American mountain vegetation and its dynamics in DGVMs. To bridge this gap, we propose a transdisciplinary network, composed of members of the theoretical/modelling and empirical scientific communities to study the natural dynamics of mountain ecosystems and their responses to global change drivers locally, regionally and at the continent scale, within a social-ecological system framework. The work presented here forms the basis for the design of data collection from field measurements and instrumental monitoring stations to parametrise and verify DGVMs. The network is designed to collaborate with and complement existing long-term research initiatives in the region and will adopt existing standard field protocols. Complementary protocols will ensure compatibility between field data collection and data needs for process-based and empirical models.</p