Mineralogical evolution of a weathering profile in the Tagaung Taung Ni laterite deposit: significance of smectite in the formation of high-grade Ni ore in Myanmar

Myanmar has a drier sub-tropical climate than countries that typically contain Ni laterite deposits, but hosts deposit at Tagaung Taung. Given enrichment processes in the Taung are poorly understood, we investigated geochemical and mineralogical evolution of two weathering profiles developed on different bedrocks central part Myanmar: partly serpentinized harzburgite an almost completely peridotite Budaung. The whole-rock data indicate Si was retained relative to Fe Al profiles. Nickel been enriched contents as high 4.89 wt.% NiO saprolite layers Tagaung, whereas Budaung ≤ 1.55 NiO. Smectite is main mineral formed secondary serpentine dominates Microscopic observations Ni-smectite (> 10 NiO), which only observed replacement product orthopyroxene. In addition fixation capacity smectite serpentine, Ni-rich pore water derived from dissolution olivine likely contributed smectite. Our results imply high-grade deposits may develop unaltered or under climatic conditions typical Myanmar.