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

Ayaka Murofushi, Tsubasa Otake, Kenzo Sanematsu, Kyaw Zay Ya, Akane Ito, Ryosuke Kikuchi, Tsutomu Sato

研究成果: ジャーナルへの寄稿学術誌査読

5 被引用数 (Scopus)

抄録

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

本文言語英語
ページ(範囲)1107-1122
ページ数16
ジャーナルMineralium Deposita
57
7
DOI
出版ステータス出版済み - 10月 2022
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 地球物理学
  • 地球化学および岩石学
  • 経済地質学

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