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Distribution and Mobility of Platinum-Group Elements in the Late Cretaceous Ni-laterite Soil in the Northern Oman Mountains
  • Salah A. Al-Khirbash,
  • Ahmed H. Ahmed
Salah A. Al-Khirbash
Sultan Qaboos University

Corresponding Author:khirbash@squ.edu.om

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Ahmed H. Ahmed
Faculty of Earth Sciences, KAU
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Low-grade Ni-laterite deposits are well-developed over the mafic/ultramafic protoliths in the northern Oman Mountains. Concentrations, distribution patterns and mobility of platinum-group element (PGE) are investigated in some Ni-laterite profiles of the Oman ophiolite as a possible unconventional PGE resource. The highest PGE contents (up to 253 ppb) in the Oman Ni-laterites are mainly concentrated in the oxide/clay-rich zone of the laterite profiles. The PGE contents are substantially decreased toward the saprolite and underlying protoliths (average total PGE = 35 ppb). The highest PGE content in the oxide zone is mostly corresponding to Pt > Ru > Pd, while the lowest PGE content is mostly corresponding to Os < Rh < Ir, which shows a general positive trend of PGE distribution patterns. There is a general positive correlation between PGE contents and both Cr2O3 and Fe2O3 contents in the Ni-laterite profiles. This may reflect the formation of PGE-Fe nanoparticle alloys that are hosted by Fe-rich oxyhydroxides or due to the residual accumulation of chromite in the oxide/clay-rich zone during the lateritization process. The PGE distribution patterns and positive correlation with the ultramafic index of alteration (UMIA) indicate that PGE can be mobilized in different proportions in the surficial environment upon progressive lateritization processes. The high concentration of total PGE in the Oman Ni-laterite is in good agreement with the PGE-rich laterite deposits worldwide, which can be considered as an unconventional PGE resource if adequate extraction and refining processes can be applied for their recovery from the possible upcoming Ni production.
Oct 2021Published in Journal of Geophysical Research: Solid Earth volume 126 issue 10. 10.1029/2021JB022363