Browsing by Author "Joaquin Jara, Jose"

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    Evaluation of econometric models of secondary refined copper supply
    (2021) Rivera, Nilza; Ignacio Guzman, Juan; Joaquin Jara, Jose; Lagos, Gustavo
    Copper is essential in attaining a sustainable development path due to its prominent role in the electromobility and renewable energy industries. In 2019 refined copper usage was 23.5 million tons, of which primary copper supplied 86.3%, and the remaining 13.7% was provided by secondary metal. In the future, copper recycling would increase significantly concerning primary copper supply to meet the goal of decreasing greenhouse gases emissions. Secondary copper production reduces energy consumption by 85% and greenhouse gas emissions by 65% compared to average primary sources.
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    Evolution of the Surface Area of Critical Lagoon Systems in the Salar de Atacama
    (2022) Ignacio Guzman, Juan; Retamal, Candelaria; Faundez, Patricio; Joaquin Jara, Jose
    The Salar de Atacama in northern Chile hosts the biggest lithium reserves globally. However, concerns have arisen regarding the environmental impact of lithium extraction on its basin; in particular, the possible drought of its lagoons that sustain unique natural ecosystems. This investigation implemented an image processing and statistical methodology to assess the area evolution and dynamic behavior of these main water bodies between 1986 and 2018. Results showed that these lagoon systems have not presented significant changes despite increasing lithium production, even for the years of large brine extraction. The analysis indicated that the total surface area of the lagoons varied within a restricted range at 95% confidence level: on average, of the total area covered by these systems 0.03% could have been lost or 0.01% could have been gained per year. Moreover, a multivariate analysis indicated that brine extraction did not have a negative impact on the evolution of the surface areas of the lagoons during the last three decades.
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    Geochronology and petrogenesis of intrusive rocks in the Coastal Cordillera of northern Chile: Insights from zircon U-Pb dating and trace element geochemistry
    (2021) Joaquin Jara, Jose; Barra, Fernando; Reich, Martin; Morata, Diego; Leisen, Mathieu; Romero, Rurik
    Two models have been proposed to explain the early Andean evolution of the southwestern margin of Gondwana; a model that assumes continuous subduction-related magmatism since the Carboniferous and a second involving subduction cessation during the pre-Andean stage (similar to 280-200 Ma) followed by subsequent reactivation at ca. 200 Ma. Here we provide new constraints regarding the onset of the Andean tectonic cycle and the transition between pre-Andean and early Andean stages (210-100 Ma) by performing a comprehensive study of the geochronology and petrogenesis of plutonic complexes from the Coastal Cordillera of northern Chile. We present the first zircon U-Pb geochronology and trace element dataset of intrusive rocks combined with whole-rock geochemistry for the early Andean stage. The oldest unit identified is a syenogranite dated at 246.7 +/- 3.9 Ma with a subduction signature, i.e., slightly peraluminous, enriched in LILE over HFSE, negative Nb-Ta and positive Pb anomalies, and strong REE fractionation, but also shows anorogenic features with an alkali-rich composition and high enrichment in rare earth and HFS elements compared to chondritic values. These characteristics are interpreted as representing a transitional, anorogenic event from the pre-Andean stage. In contrast, the second oldest magmatic eventwas dated at 211.4 +/- 1.2Ma and has a chemical composition consistent with Andean-related magmatismand its zircon composition is similar to those fromLate Triassic-Early Cretaceous units. Consequently, we conclude that the Andean orogeny started at ca. 210 Ma, before earlier estimates. Our study also supportsworks that indicate episodic high-flux magmatism and the eastward migration of themagmatic arc during the Mesozoic. Furthermore, the whole-rock Th/Yb and zircon U/Yb ratios show a trend fromthe Late Triassic to Late Jurassic of increasing depletion of themantle source. However, during the Early Cretaceous more variable and enriched signatures are observed, possibly related to changes in the tectonic regime. (C) 2021 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.