Crystallographic controlled exsolution and metal partitioning in magmatic sulfide deposits

Smith, Jennifer; Graziani, Riccardo; Petts, Duane C.; Regis, Daniele

doi:10.1016/j.chemer.2023.125954

Cited by 5 publications

(3 citation statements)

References 49 publications

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“…The first hypothesis is supported by recent nanoscale experimental studies in the Cu-Ni-Fe system of Helmy et al (2021), where pentlandite directly exsolved from the ISS at temperature as low as 250ºC. The second hypothesis is sustained by several other experimental data (Kullerud et al 1969;Naldrett et al 1967;Kelly and Vaughan 1983;Etschmann et al 2004) along with the study of natural samples (Smith et al 2023). These works showed that Ni-rich MSS is the first sulfide to crystallize from melt in the Fe-Ni-S in equilibrium with a coexisting Cu-Fe rich melt parental to ISS.…”

Section: Origin Of Cu-fe-ni Sulfide Inclusions In Laurite: Solidstate...mentioning

confidence: 75%

Micron-to-nanoscale investigation of Cu-Fe-Ni sulfide inclusions within laurite (Ru, Os)S2 from chromitites

González-Jiménez,

González-Pérez,

Plissart

et al. 2024

Miner Deposita

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This paper provides a top-down nanoscale analysis of Cu-Ni-Fe sulfide inclusions in laurite from the Taitao ophiolite (Chile) and the Kevitsa mafic-ultramafic igneous intrusion (Finland). High-resolution transmission electron microscopy (HRTEM) reveal that Cu-Ni-Fe sulfide inclusions are euhedral to (sub)-anhedral (i.e., droplet-like) and form single, biphasic or polyphasic grains, made up of different polymorphs, polytypes and polysomes even within a single sulfide crystal. Tetragonal (I4$$\stackrel{-}{2}$$d) and cubic (F$$\stackrel{-}{4}$$3m) chalcopyrite (CuFeS2) host frequent fringes of bornite (Cu5FeS4; cubic F$$\stackrel{-}{4}$$3m and/or orthorhombic Pbca) ± talnakhite (Cu9(Fe, Ni)8S16; cubic I$$\stackrel{-}{4}$$3m) ± pyrrhotite (Fe1 − xS; monoclinic C2/c polytype 4C and orthorhombic Cmca polytype 11C) ± pentlandite ((Ni, Fe)9S8; cubic Fm3m). Pentlandite hosts fringes of pyrrhotite, bornite and/or talnakhite. Laurite and Cu-Fe-Ni sulfide inclusions display coherent, semi-coherent and incoherent crystallographic orientation relationships (COR), defined by perfect edge-to-edge matching, as well as slight (2–4º) to significant (45º) lattice misfit. These COR suggest diverse mechanisms of crystal growth of Cu-Fe-Ni sulfide melt mechanically trapped by growing laurite. Meanwhile, the mutual COR within the sulfide inclusions discloses: (1) Fe-Ni-S melt solidified into MSS re-equilibrated after cooling into pyrrhotite ± pentlandite, (2) Cu-Ni-Fe-S melts crystallized into the quaternary solid solution spanning the compositional range between heazlewoodite [(Ni, Fe)3±xS2] (Hzss) and ISS [(Cu1±x, Fe1±y)S2]. Additionally, nanocrystallites (50–100 nm) of Pt-S and iridarsenite (IrAsS) accompanying the sulfide inclusions spotlight the segregation of PGE-rich sulfide and arsenide melt earlier and/or contemporarily to laurite crystallization from the silicate magmas. Cobaltite (CoAsS)-gersdorffite (NiAsS) epitaxially overgrown on laurite further supports the segregation of arsenide melts at early stages of chromitite formation.

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Section: Origin Of Cu-fe-ni Sulfide Inclusions In Laurite: Solidstate...mentioning

confidence: 75%

Micron-to-nanoscale investigation of Cu-Fe-Ni sulfide inclusions within laurite (Ru, Os)S2 from chromitites

González-Jiménez,

González-Pérez,

Plissart

et al. 2024

Miner Deposita

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“…Fully quantitative elemental maps on two garnet crystals (Table S2, Supporting Information) were acquired over two analytical sessions, using a Teledyne Analyte G2 and Applied Spectra RESOlution‐SE coupled to an Agilent 7700x ICP‐MS. Analytical protocols follow the methodology outlined in Lawley et al (2020) and Smith et al (2023) but were optimized for mapping garnet (Gaidies et al, 2021) and are outlined in Table S2 (Supporting Information).…”

Section: Methodsmentioning

confidence: 99%

“…Following electron beam analyses, major and trace element maps of the FICH3A sample were acquired by LA-ICP-MS at the Geological Survey of Canada on 30 μm polished thin sections. Fully quantitative elemental maps on two garnet crystals (Table S2, Supporting Information) were acquired over two analytical sessions, using a Teledyne Analyte G2 and Applied Spectra RESOlution-SE coupled to an Agilent 7700x ICP-MS. Analytical protocols follow the methodology outlined in Lawley et al (2020) and Smith et al (2023) but were optimized for mapping garnet and are outlined in Table S2 (Supporting Information).…”

Section: Chemical Analysis and Mappingmentioning

confidence: 99%

Formation of multistage garnet grains by fragmentation and overgrowth constrained by microchemical and microstructural mapping

Manzotti,

Regis,

Petts

et al. 2024

Journal Metamorphic Geology

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Garnet is an exceptionally useful mineral for reconstructing the evolution of metamorphic rocks that have experienced multiple tectonic or thermal events. Understanding how garnet crystallizes and its mechanical behaviour is important for establishing a petrological and temporal record of metamorphism and deformation and for recognizing multiple geologic stages within the growth history of an individual crystal. Here, we integrate fine‐scale microstructural (electron backscatter diffraction [EBSD]) and microchemical (Laser Ablation Inductively Coupled Plasma Mass Spectrometry [LA‐ICP‐MS] mapping) data obtained on a polycyclic garnet‐bearing micaschist from the Alpine belt. Results suggest that fragmentation of pre‐Alpine garnet porphyroblasts occurred during the late pre‐Alpine exhumation and/or the onset of the Alpine burial, such that the older pre‐Alpine garnet fragments were transported/redistributed during Alpine deformation and acted as nucleation sites for Alpine garnet growth. These processes produced a bimodal garnet size distribution (millimetre‐ and micrometre‐sized grains). Thermodynamic modelling indicates that Alpine garnet grew during the final stage of burial (from 1.9 GPa 480°C to 2.0 GPa 520°C) and early exhumation (down to 1.6 GPa 540°C) forming continuous idioblastic rims on and sealing fractures in pre‐Alpine garnet grains. We propose that fragmentation–overgrowth processes in polycyclic rocks, coupled with ductile deformation, may produce a bimodal garnet size distribution in response to fragmentation and re‐distribution of pre‐existing grains; these clasts can act as new nucleation sites during a subsequent orogenic cycle.

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How Pt and Pd are hosted in magmatic sulfides, substitutions and/or inclusions?

Helmy

Botcharnikov

Ballhaus

et al. 2023

Contrib Mineral Petrol

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Crystallographic controlled exsolution and metal partitioning in magmatic sulfide deposits

Cited by 5 publications

References 49 publications

Micron-to-nanoscale investigation of Cu-Fe-Ni sulfide inclusions within laurite (Ru, Os)S2 from chromitites

Micron-to-nanoscale investigation of Cu-Fe-Ni sulfide inclusions within laurite (Ru, Os)S2 from chromitites

Formation of multistage garnet grains by fragmentation and overgrowth constrained by microchemical and microstructural mapping

How Pt and Pd are hosted in magmatic sulfides, substitutions and/or inclusions?

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