Thermal evolution of Andean iron oxide-apatite (IOA) deposits as revealed by magnetite thermometry

Magnetite is the main constituent of iron oxide–apatite (IOA) deposits, which are a globally important source of Fe and other elements such as P and REE, critical for modern technologies. Geochemical studies of magnetite from IOA deposits have provided key insights into the ore-forming processes and...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Palma, Gisella, Reich Morales, Martín Herbert, Barra Pantoja, Luis Fernando, Ovalle, J. Tomás, Real, Irene del, Simon, Adam C.
Format: Article in Journal/Newspaper
Language:English
Published: Nature 2021
Subjects:
El-lacocopper-gold
Isotope signatures
Trace-elements
Kiruna
Geochemistry
Bearing
Origin
Reequilibration
Online Access:https://doi.org/10.1038/s41598-021-97883-3
https://repositorio.uchile.cl/handle/2250/183339
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Summary:Magnetite is the main constituent of iron oxide–apatite (IOA) deposits, which are a globally important source of Fe and other elements such as P and REE, critical for modern technologies. Geochemical studies of magnetite from IOA deposits have provided key insights into the ore-forming processes and source of mineralizing fuids. However, to date, only qualitative estimations have been obtained for one of the key controlling physico-chemical parameters, i.e., the temperature of magnetite formation. Here we reconstruct the thermal evolution of Andean IOA deposits by using magnetite thermometry. Our study comprised a > 3000 point geochemical dataset of magnetite from several IOA deposits within the Early Cretaceous Chilean Iron Belt, as well as from the Pliocene El Laco IOA deposit in the Chilean Altiplano. Thermometry data reveal that the deposits formed under a wide range of temperatures, from purely magmatic (~ 1000 to 800 °C), to late magmatic or magmatic-hydrothermal (~ 800 to 600 °C), to purely hydrothermal (< 600 °C) conditions. Magnetite cooling trends are consistent with genetic models invoking a combined igneous and magmatic-hydrothermal origin that involve Fe-rich fuids sourced from intermediate silicate magmas. The data demonstrate the potential of magnetite thermometry to better constrain the thermal evolution of IOA systems worldwide, and help refne the geological models used to fnd new resources. ANID through Millennium Science Initiative Program NCN13_065 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1190105 ANID-FONDAP project "Centro de Excelencia en Geotermia de Los Andes, CEGA" 15090013 Versión publicada - versión final del editor

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