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RESEARCH

My research interests are diverse and include geochemistry of ore deposits, isotope geochemistry and geochronology, metallogenesis, and Andean geology.

My current research projects involve the formation and evolution of Cretaceous Iron Oxide Cu-Au (IOCG) and Iron Oxide-Apatite (IOA) deposits in Chile and the metallogenesis and magmatic evolution of the Coastal Cordillera in northern Chile. The goal of the latter is to study the evolution of the Early Jurassic to Late Cretaceous continental magmatic arc and determine the metal fertility of magmas as a function of time.

 

I have also recently started a research project on transition metal stable isotopes (i.e. Cu, Fe, Ag) to understand fractionation in the ore deposit environment and a project regarding the distribution of critical metals in sulfides. In addition to these projects, I collaborate on several other projects as Acting Director of the Millennium Nucleus for Metal Tracing Along Subduction (NMTM: http://www.trazadoresdemetales.cl/) and as an Associate researcher of CEGA. 


Since 2011 I am in charge of setting up and managing the new analytical facilities at the Geology Department, Universidad de Chile. I supervised the construction of a positive-pressure, metal-free, clean lab for chemical procedures, the acquisition and installation of a Neptune Plus MC-ICP-MS and a Teledyne Photon Machines Analyte G2 laser ablation system, the acquisition of a Thermo iCAP-Qc ICP-MS, the remodeling of the Mass Spectrometry Lab (LEM-CEGA; https://www.lemcegauchile.com/) and a wet chemistry lab (currently under construction). In this analytical facility under my direction, we have developed zircon U-Pb dating and Hf isotope analyses using LA-MC-ICP-MS, trace element analyses in several phases including sulfides (pyrite, chalcopyrite, bornite), oxides (magnetite), silicates (olivine, pyroxene, zircon), phosphates (apatite), and melt inclusions. Because this is a unique laboratory in this part of South America, we have built strong national and international collaborations with researchers from the US, Argentina, Australia, and Japan. In addition, we have supported researchers from other disciplines such as Ecology and Archeology by developing analytical procedures for the analysis of otoliths and human hair, respectively.       
 

My research lines include:

Geochemistry and Geochronology of Ore Deposits

 

During my career, I have developed a strong interest in the application of geochemistry to the study of mineral deposits, particularly the use of diverse geochronological tools to address questions such as:

- How long does it take to make a giant ore deposit and a small ore deposit?

- What is the duration of a hydrothermal system?

- Are giant ore deposits the product of multiple overlapping hydrothermal-mineralization events or a single large hydrothermal system?

- Are the deposits in a district formed simultaneously or over an extended period?

I have used the Re-Os system applied to molybdenite coupled with the single zircon U-Pb dating technique, and 40Ar/39Ar thermochronology to determine the temporal evolution of hydrothermal systems and try to provide some answers to these questions. 

In recent years we have also started investigating the distribution of trace elements in different mineral phases such as magnetite, pyrite, molybdenite and apatite, by using electron microprobe and laser ablation ICP-MS, in order to obtain clues regarding the origin and post-crystallization history of these minerals.

The trace element distribution in certain phases shows that most mineral grains have a complex history. Some minerals show overgrowth or evidence of DRP (dissolution and re-precipitation processes) caused by hydrothermal fluids of different or fluctuating chemical composition. The concentration of certain trace elements in some minerals can be used to infer formation parameters such as temperature and redox state.   

Re-Os Isotopes Applied to Ore Deposits

 

One of the fundamental questions in Economic Geology is: What is the source of metals in mineral deposits?

As a graduate student and postdoc at the University of Arizona, I worked with the Re-Os isotopic system to address this question. I applied this isotopic system in a variety of ore deposits around the world including porphyry Cu-Mo deposits in the US, Mexico, Peru, Chile and Iran, magmatic deposits in South Africa and Spain, stratabound Cu(-Ag) and IOCG deposits in Chile. 

All these projects were carried out in collaboration with researchers from around the world. 

Andean Geology and Metallogenesis

 

The Chilean Andes is a natural laboratory used by several researchers to understand geological processes such as the formation of continental crust and to the origin of magmatic-hydrothermal deposits among others. The Andean Cordillera and its wealth of mineral deposits are the results of the convergence of multiple processes, and where magmas, volcanoes, fluids and ores are the products formed in this "subduction factory". Understanding the evolution of these processes in the Chilean Andes is one of my research interests ranging from the early evolution of the western margin of Gondwana and the emplacement of serpentinized peridotites, the magmatic evolution of the Jurassic-Cretaceous Coastal Cordillera and the formation of Eocene-Oligocene porphyry Cu systems. 

Applications of Inorganic Mass Spectrometry

I'm the Director of the LEM-CEGA Mass Spectrometry Lab. The analytical facilities include a metal-free clean lab, a Neptune Plus MC-ICP-MS, a Teledyne Photon Machines Analyte G2 laser ablation system and a Thermo iCAP-Qc ICP-MS. This setup is unique in Chile and allows us to carry out different isotopic and elemental analyses of solutions and solid samples not only in support of earth sciences research but also other fields of science such as Ecology and Archeometry.

        

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Andacollo mine

Re distribution in molybdenite

Serpentinized olivine grain

Laser pits in apatite

Co distribution in pyrite