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Orthopyroxenite hosted chromitite veins anomalously enriched in platinum-group minerals from the Havana-Matanzas Ophiolite, Cuba

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doi: 10.18268/BSGM2020v72n3a110620
Authors:Farré de Pablo, Júlia; Pujol-Solà, Núria; Torres-Herrera, Harlison; Aiglsperger, Thomas; González-Jiménez, José María; Llanes-Castro, Angélica Isabel; Garcia-Casco, Antonio; Proenza, Joaquín A.
Author Affiliations:Primary:
Universitat de Barcelona, Departament de Mineralogia, Petrologia i Geologia Aplicada, Barcelona, Spain
Pontifical Catholic University of Peru, Peru
Recursos del Caribe, United States
Fundación Universitaria del Area Andina, Colombia
Lulea University of Technology, Sweden
Universidad de Granada, Spain
Instituto de Geología y Paleontología, Cuba
Volume Title:Mineral deposits of Latin America and the Caribbean
Volume Authors:Proenza, Joaquín Antonio, editor; Torró, Lisard; Nelson, Carl E.
Source:Mineral deposits of Latin America and the Caribbean, edited by Joaquín Antonio Proenza, Lisard Torró and Carl E. Nelson. Boletín de la Sociedad Geológica Mexicana, 72(3). Publisher: Sociedad Geológica Mexicana, Mexico, D.F., Mexico. ISSN: 0366-1784
Publication Date:2020
Note:In English with English and Spanish summaries. 71 refs.; illus., incl. geol. sketch maps, sects., 4 tables
Summary:The Havana-Matanzas Ophiolite contains one of the few examples of ophiolitic platinum group minerals (PGM)-rich chromitites associated with orthopyroxenites in the mantle section of ophiolitic complexes. The chromitites occur as veins hosted by orthopyroxenite bands within mantle peridotites. The peridotites are mostly harzburgites and their accessory chromite shows high-Al compositions (Cr# [Cr/(Cr+Al), atomic ratio] = 0.39-0.50), which are typical of spinels in abyssal peridotites. Conversely, chromite from the chromitite veins and their host orthopyroxenite are high-Cr (Cr# = 0.72-0.73 and 0.62-0.69, respectively), with lower Mg# [Mg/(Mg+Fe2+), atomic ratio]. This suggests that both the chromitite and the orthopyroxenite formed from melts with boninitic affinity. The abundant PGM inclusions found in the chromitites are mainly Os-rich laurite grains, which is also characteristic of chromitites formed from magmas with boninitic affinity. Therefore, we propose that the chromitite veins and the orthopyroxenite bands probably formed contemporaneously in the fore-arc setting of an intra-oceanic arc during subduction. The chromitite-orthopyroxenite pair of the Havana-Matanzas Ophiolite could form after the reaction of a Si-rich melt with boninitic affinity and mantle harzburgite, with the orthopyroxenite bands preserving fingerprints of the infiltration of boninitic-affinity melts within the mantle. The small volume of forming chromitite could maximize the efficiency for the mechanical collection of the PGM forming in the parental melt of these rocks, resulting in the anomalous enrichment of primary PGM in the chromitites.
Subjects:Aluminum; Andesites; Basins; Boninite; Cenozoic; Chromite; Chromitite; Cretaceous; Dunite; Electron microscopy data; Enrichment; Eocene; Fluid inclusions; Foliation; Fore-arc basins; Genesis; Harzburgite; Igneous rocks; Inclusions; Infiltration; Laurite; Lithosphere; Mantle; Melt inclusions; Melts; Mesozoic; Metals; Metasomatism; Middle Eocene; Mohorovicic discontinuity; Obduction; Oceanic lithosphere; Ophiolite; Orthopyroxenite; Oxides; Paleogene; Peridotites; Plate tectonics; Platinum group; Plutonic rocks; Pyroxenite; Reconstruction; SEM data; Serpentinization; Subduction; Sulfides; Tertiary; Ultramafics; Upper Cretaceous; Upper mantle; Veins; Volcanic rocks; Antilles; Caribbean region; Cuba; Greater Antilles; West Indies; Havana Matanzas Ophiolite
Coordinates:N220000 N231500 W0800000 W0830000
Record ID:897043-3
Copyright Information:GeoRef, Copyright 2021 American Geosciences Institute.
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