In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile
Iron-oxide apatite (IOA) deposits are mined for iron (Fe) and can also contain economically exploitable amounts of Cu, P, U, Ag, Co, and rare earth elements (REE). Recently, it has been proposed based on trace element zonation in magnetite grains from the Los Colorados Kiruna-type IOA deposit, Chile...
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Online Access: | https://doi.org/10.2138/am-2019-6623 https://repositorio.uchile.cl/handle/2250/172048 |
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ftunivchile:oai:repositorio.uchile.cl:2250/172048 2023-05-15T17:04:10+02:00 In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile Knipping, Jaayke L. Fiege, Adrián Simon, Adam C. Oeser, Martín Reich Morales, Martín Bilenker, Laura D. 2019 application/pdf https://doi.org/10.2138/am-2019-6623 https://repositorio.uchile.cl/handle/2250/172048 en eng De Gruyter American Mineralogist, Volume 104, pages 471–484, 2019 19453027 0003004X doi:10.2138/am-2019-6623 https://repositorio.uchile.cl/handle/2250/172048 Attribution-NonCommercial-NoDerivs 3.0 Chile http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ CC-BY-NC-ND American Mineralogist Chilean Iron Belt From Magmas to Ore Deposits Iron isotopes Iron oxide-apatite deposits Kiruna-type deposits Los Colorados Magnetite flotation Artículo de revista 2019 ftunivchile https://doi.org/10.2138/am-2019-6623 2023-01-22T00:59:43Z Iron-oxide apatite (IOA) deposits are mined for iron (Fe) and can also contain economically exploitable amounts of Cu, P, U, Ag, Co, and rare earth elements (REE). Recently, it has been proposed based on trace element zonation in magnetite grains from the Los Colorados Kiruna-type IOA deposit, Chile, that ore formation is directly linked to a magmatic source. The model begins with the crystallization of magnetite microlites within an oxidized volatile-rich (H2O+Cl) andesitic magma reservoir, followed by decompression, nucleation of fluid bubbles on magnetite microlite surfaces, segregation of a Fe-Cl-rich fluid-magnetite suspension within the magma reservoir, and subsequent ascent of the suspension from the magma chamber via pre-existing structurally enhanced dilatant zones that act as conduits. Emplacement and precipitation of the suspension results in the formation of magnetite grains with core-to-rim features that record a transition from purely igneous to magmatic-hydrothermal conditions within IOA deposits. Here we test this model by using in situ femtosecond laser ablation MC-ICP-MS measurements of Fe isotopes to determine grain-to-grain and intra-grain Fe isotope variations in magnetite grains from the Los Colorados IOA deposit. All in situ δ56Fe values (56Fe/54Fe relative to IRMM-14) plot within the magmatic range (0.06 to 0.50‰), in agreement with previously published bulk Fe isotope analyses in magnetite from the Los Colorados IOA deposit. Different trace element signatures of these magnetite grains indicate an igneous or magmatic-hydrothermal origin, respectively. Although data partly overlap, the assigned igneous magnetites yield on average higher δ56Fe values (0.24 ± 0.07‰; n = 33), when compared to magmatic-hydrothermal magnetites (0.15 ± 0.05‰; n = 26). Some magnetite grains exhibit a distinct core-to-rim trend from higher toward lower δ56Fe signatures. Furthermore, the δ56Fe of the igneous magnetites correlate negatively with trace elements contents typical for igneous formation (Ti, Al, Ga, V, ... Article in Journal/Newspaper Kiruna Universidad de Chile: Repositorio académico Kiruna American Mineralogist 104 4 471 484 |
institution |
Open Polar |
collection |
Universidad de Chile: Repositorio académico |
op_collection_id |
ftunivchile |
language |
English |
topic |
Chilean Iron Belt From Magmas to Ore Deposits Iron isotopes Iron oxide-apatite deposits Kiruna-type deposits Los Colorados Magnetite flotation |
spellingShingle |
Chilean Iron Belt From Magmas to Ore Deposits Iron isotopes Iron oxide-apatite deposits Kiruna-type deposits Los Colorados Magnetite flotation Knipping, Jaayke L. Fiege, Adrián Simon, Adam C. Oeser, Martín Reich Morales, Martín Bilenker, Laura D. In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile |
topic_facet |
Chilean Iron Belt From Magmas to Ore Deposits Iron isotopes Iron oxide-apatite deposits Kiruna-type deposits Los Colorados Magnetite flotation |
description |
Iron-oxide apatite (IOA) deposits are mined for iron (Fe) and can also contain economically exploitable amounts of Cu, P, U, Ag, Co, and rare earth elements (REE). Recently, it has been proposed based on trace element zonation in magnetite grains from the Los Colorados Kiruna-type IOA deposit, Chile, that ore formation is directly linked to a magmatic source. The model begins with the crystallization of magnetite microlites within an oxidized volatile-rich (H2O+Cl) andesitic magma reservoir, followed by decompression, nucleation of fluid bubbles on magnetite microlite surfaces, segregation of a Fe-Cl-rich fluid-magnetite suspension within the magma reservoir, and subsequent ascent of the suspension from the magma chamber via pre-existing structurally enhanced dilatant zones that act as conduits. Emplacement and precipitation of the suspension results in the formation of magnetite grains with core-to-rim features that record a transition from purely igneous to magmatic-hydrothermal conditions within IOA deposits. Here we test this model by using in situ femtosecond laser ablation MC-ICP-MS measurements of Fe isotopes to determine grain-to-grain and intra-grain Fe isotope variations in magnetite grains from the Los Colorados IOA deposit. All in situ δ56Fe values (56Fe/54Fe relative to IRMM-14) plot within the magmatic range (0.06 to 0.50‰), in agreement with previously published bulk Fe isotope analyses in magnetite from the Los Colorados IOA deposit. Different trace element signatures of these magnetite grains indicate an igneous or magmatic-hydrothermal origin, respectively. Although data partly overlap, the assigned igneous magnetites yield on average higher δ56Fe values (0.24 ± 0.07‰; n = 33), when compared to magmatic-hydrothermal magnetites (0.15 ± 0.05‰; n = 26). Some magnetite grains exhibit a distinct core-to-rim trend from higher toward lower δ56Fe signatures. Furthermore, the δ56Fe of the igneous magnetites correlate negatively with trace elements contents typical for igneous formation (Ti, Al, Ga, V, ... |
format |
Article in Journal/Newspaper |
author |
Knipping, Jaayke L. Fiege, Adrián Simon, Adam C. Oeser, Martín Reich Morales, Martín Bilenker, Laura D. |
author_facet |
Knipping, Jaayke L. Fiege, Adrián Simon, Adam C. Oeser, Martín Reich Morales, Martín Bilenker, Laura D. |
author_sort |
Knipping, Jaayke L. |
title |
In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile |
title_short |
In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile |
title_full |
In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile |
title_fullStr |
In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile |
title_full_unstemmed |
In-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the Los Colorados Kiruna-type iron oxide-apatite deposit, Chile |
title_sort |
in-situ iron isotope analyses reveal igneous and magmatic-hydrothermal growth of magnetite at the los colorados kiruna-type iron oxide-apatite deposit, chile |
publisher |
De Gruyter |
publishDate |
2019 |
url |
https://doi.org/10.2138/am-2019-6623 https://repositorio.uchile.cl/handle/2250/172048 |
geographic |
Kiruna |
geographic_facet |
Kiruna |
genre |
Kiruna |
genre_facet |
Kiruna |
op_source |
American Mineralogist |
op_relation |
American Mineralogist, Volume 104, pages 471–484, 2019 19453027 0003004X doi:10.2138/am-2019-6623 https://repositorio.uchile.cl/handle/2250/172048 |
op_rights |
Attribution-NonCommercial-NoDerivs 3.0 Chile http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ |
op_rightsnorm |
CC-BY-NC-ND |
op_doi |
https://doi.org/10.2138/am-2019-6623 |
container_title |
American Mineralogist |
container_volume |
104 |
container_issue |
4 |
container_start_page |
471 |
op_container_end_page |
484 |
_version_ |
1766058214566133760 |