Carregant...
Fitxers
Tipus de document
ArticleVersió
Versió publicadaData de publicació
Llicència de publicació
Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/109002
Chromite and platinum-group-elements mineralization in the Santa Elena ophiolitic ultramafic nappe (Costa Rica): geodynamic implications
Títol de la revista
Director/Tutor
ISSN de la revista
Títol del volum
Recurs relacionat
Resum
Chromitites associated with strongly altered peridotite from six distinct localities in the Santa Elena ultramafic nappe (Costa Rica) have been investigated for the first time. Santa Elena chromitites commonly display a compositional variation from extremely chromiferous (Cr/(Cr+Al)=0.81) to intermediate and aluminous (Cr/(Cr+Al)=0.54). This composition varies along a continuous trend, corresponding to calculated parental liquids which may have been derived from the differentiation of a single batch of boninitic magma with Cr-rich and (Al, Ti)-poor initial composition. Fractional precipitation of chromite probably occurred during differentiation of the boninitic melt and progressive metasomatic reaction with mantle peridotite. The distribution of platinum group elements (PGE) displays the high (Os+Ir+Ru)/(Rh+Pt+Pd) ratio typical of ophiolitic chromitites and, consistently, the platinum group minerals (PGM) encountered are mainly Ru-Os-Ir sulfides and arsenides. Textural relations of most of the platinum group elements suggest crystallization at magmatic temperatures, possibly under relatively high sulfur fugacity as indicated by the apparent lack of primary Os-Ir-Ru alloys. The chemical and mineralogical characteristics of chromitites from the Santa Elena ultramafic nappe have a strong affinity to podiform chromitites in the mantle section of supra-subduction-zone ophiolites. Calculated parental melts of the chromitites are consistent with the differentiation of arc-related magmas, and do not support the oceanic spreading center geodynamic setting previously proposed by some authors
Matèries
Matèries (anglès)
Citació
Citació
ZACCARINI, Federica, GARUTI, G., PROENZA FERNÁNDEZ, Joaquín antonio, CAMPOS, L., THALHAMMER, Oskar a.r., AIGLSPERGER, Thomas hans, LEWIS, J. f.. Chromite and platinum-group-elements mineralization in the Santa Elena ophiolitic ultramafic nappe (Costa Rica): geodynamic implications. _Geologica Acta_. 2011. Vol. 9, núm. 3-4, pàgs. 407-423. [consulta: 20 de gener de 2026]. ISSN: 1695-6133. [Disponible a: https://hdl.handle.net/2445/109002]