Abstract Sulfides are the main host of platinum-group elements (PGE) in the mantle and the stability of sulfide controls PGE mobilization and enrichment. The enrichment of PGE in mantle melts is generally interpreted as the result of complete dissolution of sulfide during the high-degree melting. However, the mechanism by which PGE are transferred from sulfides to the melt is not well known. Here we show that in areas where sedimentary carbonate is recycled, PGE mobility in the mantle could be greatly increased by the transformation of sulfide into sulfate. Carbonatitic xenoliths from the Neogene Dalihu basalt in Inner Mongolia represent sedimentary carbonates recycled into the mantle, documented by limestone-like trace element patterns and high 87Sr/86Sr ratios. They also contain micro-diamonds and silicate minerals with chemical features of mantle peridotite, showing that they must have resided in the mantle. However, the carbonatitic xenoliths contain 1000 times more PGE than sedimentary carbonate, indicating the incorporation of mantle sulfide. Moreover, δ 34 Ssulfate values (9.6-10.2‰) are much lower than in the original limestone source (25-35‰), and higher Ni, Cu contents in the carbonate groundmass than in sedimentary carbonates suggest that sulfide had been transformed into sulfate. With the destruction of sulfide, PGE contained in sulfide was released into the carbonate melt, thus promoting their mobility in the mantle.

中文翻译：

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再循环沉积碳酸盐增强地幔中铂族元素的迁移

摘要 硫化物是地幔中铂族元素（PGE）的主要宿主，硫化物的稳定性控制着铂族元素的迁移和富集。PGE在地幔熔体中的富集通常被解释为硫化物在高度熔融过程中完全溶解的结果。然而，PGE 从硫化物转移到熔体的机制尚不清楚。在这里，我们表明，在沉积碳酸盐再循环的地区，地幔中 PGE 的迁移率可以通过硫化物转化为硫酸盐而大大增加。来自内蒙古新近纪大理湖玄武岩的碳酸岩捕虏体代表了再循环到地幔中的沉积碳酸盐，由类似石灰岩的微量元素模式和高 87Sr/86Sr 比率记录。它们还含有具有地幔橄榄岩化学特征的微金刚石和硅酸盐矿物，表明它们一定存在于地幔中。然而，碳酸岩捕虏体含有比沉积碳酸盐多 1000 倍的 PGE，表明地幔硫化物的掺入。此外，δ 34 Ssulfate 值（9.6-10.2‰）远低于原始石灰岩源（25-35‰），碳酸盐地块中的 Ni、Cu 含量高于沉积碳酸盐，表明硫化物已转化为硫酸盐. 随着硫化物的破坏，硫化物中所含的 PGE 被释放到碳酸盐熔体中，从而促进了它们在地幔中的迁移。表明地幔硫化物的掺入。此外，δ 34 Ssulfate 值（9.6-10.2‰）远低于原始石灰岩源（25-35‰），碳酸盐地块中的 Ni、Cu 含量高于沉积碳酸盐，表明硫化物已转化为硫酸盐. 随着硫化物的破坏，硫化物中所含的 PGE 被释放到碳酸盐熔体中，从而促进了它们在地幔中的迁移。表明地幔硫化物的掺入。此外，δ 34 Ssulfate 值（9.6-10.2‰）远低于原始石灰岩源（25-35‰），碳酸盐地块中的 Ni、Cu 含量高于沉积碳酸盐，表明硫化物已转化为硫酸盐. 随着硫化物的破坏，硫化物中所含的 PGE 被释放到碳酸盐熔体中，从而促进了它们在地幔中的迁移。