Indonesia is one of the largest Ni ore producers in the world and is also expected to be an important potential source of some critical metals (e.g., Co, Sc, rare-earth elements, and platinum-group elements). However, few studies have examined Ni laterite deposits in this country. In this study, we investigate Ni enrichment and the potential accumulation of critical metals in four laterite profiles with varying degrees of serpentinization and weathering intensity in the Soroako and Pomalaa mining areas of Sulawesi, Indonesia. We integrate geochemical evaluation with a mass-balance approach and mineralogical analysis to better constrain the geochemical factors influencing the mobilization of Ni during lateritization. Nickel contents in the saprolite horizon of the profiles that are strongly weathered and developed over serpentinized peridotite are higher than those that are weakly weathered and developed over unserpentinized harzburgite. The bulk Ni contents of saprolite horizons are related to Ni contents of Ni-bearing Mg-phyllosilicates, which suggests that Ni remobilization is the main control on Ni enrichment in the profiles. Mass-balance calculations reveal that the amounts of gained Fe and Ni in the profiles are positively correlated. This relationship indicates that the redistribution of Ni is likely controlled by the aging of Ni-bearing goethite (dissolution/recrystallization) involving ligand-promoted dissolution by organic matter and/or reductive dissolution by microbial activity near the surface. Critical metals show enrichment in specific horizons. Enrichments in Co and rare-earth elements are strongly influenced by the formation of Mn-oxyhydroxides in the oxide zone of the profiles. In contrast, Sc, Pt, and Pd show residual enrichment patterns, with grades influenced mainly by their initial contents in bedrock. The profiles show a positive correlation between Sc and Fe, as reported for other Ni laterite deposits. Among the critical metals, Sc, Pt, and Pd contents in the studied profiles are comparable with values reported from other Ni laterite deposits worldwide.

中文翻译：

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印度尼西亚苏拉威西红土矿床中镍和关键金属流动的地球化学限制：质量平衡方法

印度尼西亚是世界上最大的镍矿生产国之一，也有望成为一些关键金属（例如，钴、钪、稀土元素和铂族元素）的重要潜在来源。然而，很少有研究调查该国的镍红土矿床。在这项研究中，我们调查了印度尼西亚苏拉威西岛 Soroako 和 Pomalaa 矿区具有不同程度蛇纹石化和风化强度的四个红土剖面中的 Ni 富集和关键金属的潜在积累。我们将地球化学评价与质量平衡方法和矿物学分析相结合，以更好地限制影响红土化过程中镍迁移的地球化学因素。在蛇纹石化橄榄岩上强烈风化和发育的剖面腐泥土层中镍含量高于弱风化和在非蛇纹石化方辉石上发育的剖面的镍含量。腐泥土层位的本体 Ni 含量与含 Ni 的镁页硅酸盐的 Ni 含量有关，这表明 Ni 再迁移是剖面中 Ni 富集的主要控制因素。质量平衡计算表明，分布中获得的 Fe 和 Ni 的量呈正相关。这种关系表明镍的重新分布可能受含镍针铁矿的老化（溶解/重结晶）控制，包括有机物促进配体溶解和/或表面附近微生物活动的还原溶解。关键金属在特定范围内显示出富集。Co 和稀土元素的富集受到轮廓氧化区中 Mn-羟基氧化物的形成的强烈影响。相比之下，Sc、Pt 和 Pd 显示出残余富集模式，其品位主要受其在基岩中的初始含量影响。剖面图显示 Sc 和 Fe 之间呈正相关，正如其他镍红土矿床所报道的那样。在关键金属中，研究剖面中的 Sc、Pt 和 Pd 含量与全球其他镍红土矿床报告的值相当。正如其他镍红土矿床所报告的那样。在关键金属中，研究剖面中的 Sc、Pt 和 Pd 含量与全球其他镍红土矿床报告的值相当。正如其他镍红土矿床所报告的那样。在关键金属中，研究剖面中的 Sc、Pt 和 Pd 含量与全球其他镍红土矿床报告的值相当。