Fluid-Assisted Aggregation and Assembly of Magnetite Microparticles in the Giant El Laco Iron Oxide Deposit, Central Andes

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dc.contributor.authorOvalle, J. Tomais
dc.contributor.authorReich, Martin
dc.contributor.authorBarra, Fernando
dc.contributor.authorSimon, Adam C.
dc.contributor.authorGodel, Belinda
dc.contributor.authorLe Vaillant, Margaux
dc.contributor.authorPalma, Gisella
dc.contributor.authorDeditius, Artur P.
dc.contributor.authorHeuser, Gert
dc.contributor.authorArancibia, Gloria
dc.contributor.authorMorata, Diego
dc.date.accessioned2025-01-20T20:09:36Z
dc.date.available2025-01-20T20:09:36Z
dc.date.issued2023
dc.description.abstractThe El Laco iron oxide mineral deposit in the CentralAndes ofChile has attracted significant attention because of its uniquelypreserved massive magnetite orebodies, which bear a remarkable similarityto volcanic products. To date, the outcropping highly vesicular andporous massive magnetite orebodies have received little attentionfrom a microtextural point of view, limiting our understanding aboutthe role of volcanogenic processes on iron mineralization. Here, wereport the chemical composition of vesicular magnetite at El Lacousing EPMA and LA-ICP-MS methods and provide detailed 2D and 3D imagingof the internal structure of these texturally complex magnetite oresby combining SEM observations, synchrotron radiation micro-X-ray fluorescencechemical mapping, and high-resolution X-ray computed microtomography.Our observations reveal the presence of abundant magnetite microsphereswith diameters ranging from & SIM;100 to & SIM;900 & mu;m, aswell as dendritic microstructures forming interconnected networksup to a few millimeters in size. Two-dimensional microtextural andgeochemical imaging of the microspheres show that these features areformed by multiple euhedral magnetite crystals growing in all directionsand occur immersed within a porous matrix conformed by smaller-sized(& SIM;2-20 & mu;m) and irregularly shaped magnetite microparticles.These types of morphologies have been reported in hydrothermal ventsassociated with hydrovolcanic processes and commonly described inhydrothermal synthesis experiments of magnetite microspheres, suggestingprecipitation from iron-rich fluids. A hydrothermal origin for themagnetite microparticles reported here is further supported by theirgeochemical signature, which shows a strong depletion in most minorand trace elements typical from magnetite precipitated from hydrothermalfluids in ore-forming environments. We propose that decompression,cooling, and boiling of fluids triggered massive iron supersaturation,resulting in the nucleation of magnetite microparticles or colloids,followed by self-assembly into larger and more complex microstructures.Our data from El Laco deposit agree with models invoking magmatic-hydrothermalfluids to explain the origin of the deposit and provide new insightson the potential role of iron colloids as agents of mineralizationin volcanic systems.
dc.fuente.origenWOS
dc.identifier.doi10.1021/acsearthspacechem.3c00036
dc.identifier.issn2472-3452
dc.identifier.urihttps://doi.org/10.1021/acsearthspacechem.3c00036
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/92012
dc.identifier.wosidWOS:001018209700001
dc.issue.numero7
dc.language.isoen
dc.pagina.final1387
dc.pagina.inicio1378
dc.revistaAcs earth and space chemistry
dc.rightsacceso restringido
dc.subjectiron oxide-apatite deposits
dc.subjectvolcanic systems
dc.subjectmagnetite microspheres
dc.subjectdendrites
dc.subjectmicrotextures
dc.subjectore-forming processes
dc.subject.ods13 Climate Action
dc.subject.odspa13 Acción por el clima
dc.titleFluid-Assisted Aggregation and Assembly of Magnetite Microparticles in the Giant El Laco Iron Oxide Deposit, Central Andes
dc.typeartículo
dc.volumen7
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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