Evaluación de escombreras de mármoles para su aprovechamiento como agregado en una estructura de pavimento, Córdoba, Argentina

In this contribution, 10,000 tonnes of marble waste dumps have been characterized in order to define the physico-mechanical and mineralogical parameters and determine their feasibility to be applied as main components in road bases and sub-bases. he Los Angeles abrasion values obtained (41-53%) exceeded those permitted for the standard technical specifications. However, particle-size distribution, plasticity and California Bearing Ratio (C.B.R.)(76, 83, 100% at 97, 98 and 100% of maximum density, respectively) satisfied, marginally, those specifications. Therefore, with a simple screening, these waste dumps would be applied as granular materials in roads. This is an alternative: a) environmentally sustainable, since future crushed stone exploitations would be reduced and removed a potential environmental passive; b) technically feasible, because the carrying capacity of the granular layers would not be affected; and c) economically profitable, because adds value to a currently non useful material and reduces the extraction and transportation costs.En este trabajo se caracterizaron 10.000 toneladas de escombreras de mármoles a fin de definir sus parámetros físico-mecánicos y mineralógicos y determinar su aptitud como componente principal en capas granulares de una estructura de pavimento. Aunque los coeficientes Los Ángeles (41-53%) exceden lo permitido en la especificación de referencia, la granulometría, plasticidad y California Bearing Ratio (C.B.R.) (76, 83, 100% al 97, 98 y 100% de la densidad máxima, respectivamente) satisfacen lo especificado, con condicionamientos. Por consiguiente, con un simple cribado, este material de escombrera podría ser utilizado en terraplenes, sub-bases y bases granulares de carreteras, constituyendo una alternativa: a) Ambientalmente sostenible: porque evita nuevas explotaciones y elimina un potencial pasivo ambiental; b) Técnicamente viable: ya que la capacidad portante de las capas granulares no se vería afectada; c) Económicamente conveniente: porque aporta un valor agregado a un sub-producto hoy desechado y reduce costos de explotación y transporte

Shear-assisted water-fluxed melting and AFC processes in the foreland of the Early Paleozoic Famatinian orogen: petrogenesis of leucogranites and pegmatites from the Sierras de Córdoba, Argentina

In the Comechingones pegmatitic field, central Argentina, leucogranite and pegmatite bodies crop out in a relatively narrow (25 × 10 km) belt, and were emplaced synkinematically with the main deformational event of the crustal-scale Guacha Corral shear zone during the Early Ordovician (~ 475 Ma). These leucogranites and pegmatites are geochemically evolved rocks with high silica and alkalis, low Fe2O3, MgO, TiO2 and CaO, and high ASI values. The leucogranites display quite variable Sr and Nd isotope compositions (initial 87Sr/86Sr ratios from 0.7048 to 0.7170, and εNd values from + 2.0 to − 3.1), some of which do not overlap with almost any other pre-Famatinian rock from the Sierras de Córdoba. The major and trace element geochemistry and the particular Sr and Nd isotope compositions of the leucogranites are here explained by the following processes: (1) water-fluxed partial melting of amphibolites at relatively low P–T conditions generating currently unexposed granodioritic melts with unradiogenic 87Sr/86Sr ratios and radiogenic εNd values; (2) fractionation of mostly plagioclase and monazite leading to compositions close to the leucogranite melts; and (3) assimilation of metasedimentary rocks with crustal isotopic signatures, modelled by assimilation and fractional crystallization processes. The major, trace and isotope compositions of the pegmatites suggest a derivation from partial melting of the same metasedimentary protoliths of the Sierras de Córdoba that were assimilated by leucogranite melts. We propose a feedback relationship among deformation, anatexis, magma evolution and mass transfer in the context of such a crustal-scale shear zone in the foreland of the Famatinian orogen