@article{fdi:010074152,
  title = {{P}latinum-group element and gold enrichment in soils monitored by chromium stable isotopes during weathering of ultramafic rocks},
  author = {{R}ivera, {J}. and {R}eich, {M}. and {S}choenberg, {R}. and {G}onzalez-{J}imenez, {J}. {M}. and {B}arra, {F}. and {A}iglsperger, {T}. and {P}roenza, {J}. {A}. and {C}arretier, {S}{\'e}bastien},
  editor = {},
  language = {{ENG}},
  abstract = {{W}eathering of ultramafic rocks can lead to the formation of soil profiles with high contents of {F}e, {N}i, {C}o, platinum-group elements ({PGE}) and gold. {T}raditionally, these metal-rich soils are known as "laterites" and are formed under tropical climates and stable tectonic conditions. {H}owever, little is known about their possible development in cold/humid regions, and the factors governing {PGE} and gold mobility and enrichment under these weathering conditions are poorly constrained. {I}n this study, five soil profiles developed on serpentinized, chromite-bearing ultramafic rocks at {L}a {C}abana, located in the {C}oastal {R}ange of south-central {C}hile (38 degrees {S}) were studied by combining major and trace element geochemistry with chromium stable isotope data. {T}he results show that the soils developed at {L}a {C}abana have higher {PGE} and {A}u contents than the parent serpentinite rock, with {S}igma {PGE} and {A}u reaching up to 160 ppb and 29 ppb in a limonitic soil horizon and clay saprolite, respectively. {M}ost soil samples have slightly negative delta {C}r-53/52({SRM}979) values, within a range of -0.089 +/- 0.012 parts per thousand to -0.320 +/- 0.013 parts per thousand (average of -0.178 parts per thousand), and are in agreement with previous data reported for modern soils. {A} noteworthy relation between delta {C}r-53/52 data and {PGE} + {A}u contents is observed in the studied soil horizons, where isotopically lighter values of delta {C}r-53/52 match the higher contents of {PGE} and gold. {T}hese results show that pedogenetic processes operating at the cold and humid {L}a {C}abana area are capable of increasing the total {PGE} and {A}u contents of certain soil horizons. {S}uch processes are complex and multivariate but are primarily modulated by chromite dissolution and the formation of secondary phases such as clay minerals and oxy-hydroxide phases in the soil. {T}hese findings provide evidence that important weathering and {PGE} + {A}u supergene accumulation are not only restricted to tropical latitudes, and that the chromium isotope system is a useful proxy to track surface redox process and noble metal enrichment during pedogenesis.},
  keywords = {{S}upergene ; {N}oble metals ; {C}hromium isotopes ; {W}eathering ; {U}ltramafic rocks ; {S}oil formation ; {CHILI}},
  booktitle = {},
  journal = {{C}hemical {G}eology},
  volume = {499},
  numero = {},
  pages = {84--99},
  ISSN = {0009-2541},
  year = {2018},
  DOI = {10.1016/j.chemgeo.2018.09.008},
  URL = {https://www.documentation.ird.fr/hor/fdi:010074152},
}