@misc{10481/105770,
year = {2025},
month = {6},
url = {https://hdl.handle.net/10481/105770},
abstract = {Oxygen-bearing platinum group minerals (O-bearing PGMs) are intergrown with
base metal sulfides (BMS, e.g., pentlandite–[NiFe]9S8) within fractures in chromite grains
from chromitite bodies on Ouen Island, New Caledonia. These PGMs are hosted in chlorite
and serpentine, which formed during serpentinization of olivine and pyroxene. The Obearing PGM grains are polygonal, show microfracturing (indicating volume loss), and
contain Pt-Pd-rich sulfide remnants, suggesting pseudomorphic replacement of primary
(magmatic) sulfides. They display chemical zonation, with Pt(-Pd-Ni-Fe) relict sulfide cores
replaced by Pt-Fe-Ni oxidized alloy mantles and Pt-Cu-Fe(-Pd) alloy rims (tulameenite),
indicating desulfurization. The core and mantle show a nanoporous structure, interpreted
as the result of coupled dissolution–reprecipitation reactions between magmatic sulfides
and low fO2–f S2 serpentinite-related fluids, probably formed during olivine transformation
to serpentine + magnetite (early stages of serpentinization). This fluid infiltrated magmatic
sulfides (PGE-rich and BMS), degrading them to secondary products and releasing S and
metals that were accommodated in the mantle and rim of O-bearing PGMs. Upon olivine
exhaustion, an increase in fO2 might have stabilized Pt-Fe-O compounds (likely Pt0/PtFe + Fe oxyhydroxides) alongside Ni-Fe alloys. Our results show that post-magmatic
desulfurization of primary sulfides produces complex nano-scale intergrowths, mainly
driven by changes in the fluid’s physicochemical properties during serpentinization.},
organization = {MCIN/AEI/10.13039/50110001133 - ERDF,  EU  (NANOMET PID2022-138768OB-I00)},
organization = {Geological Society of America (grant 14012-24)},
publisher = {MDPI},
keywords = {Pt group minerals (PGMs)},
keywords = {PGE oxides},
keywords = {PGE alloys},
keywords = {chromitite},
keywords = {tulameenite},
keywords = {nanotexture},
keywords = {focused-ion beam (FIB)},
title = {HRTEM Study of Desulfurization of Pt- and Pd-Rich Sulfides from New Caledonia Ophiolite},
doi = {10.3390/min15010066},
author = {Cano, Néstor and González Jiménez, José María and Gervilla Linares, Fernando and Kerestedjian, Thomas},
}