| Abstract: | The geochemical characteristics and behaviors of highly siderophile elements (HSEs) in forearc peridotites remain poorly constrained due to the scarcity of data. Here, we report HSE abundances of mantle peridotites from the New Caledonia ophiolites, a classical ophiolite generated in a forearc setting. Those peridotites show non‐chondritic, strongly fractionated HSE patterns and can be classified into two distinct types (namely Group I and Group II). Group I peridotites have higher HSE contents than Group II peridotites, which might be because intergranular sulfides were completely removed but sulfide inclusions were retained during partial melting of peridotites in a forearc environment, and meanwhile the distribution of sulfide inclusions are not uniform in mantle. Moreover, Group I peridotites display flat patterns from Os to Pt but strongly depleted in Pd, which resemble those patterns of some mantle wedge xenoliths. The Pt–Pd decoupling can be attributed to high degrees of partial melting. However, Group II peridotites are characterized by strongly positive Ru anomaly with highly super‐chondritic Ru/Os and Ru/Ir ratios. Such characteristics are the first reported cases for forearc peridotites. The fractionation of Ru from other HSEs might reflect the stability of refractory Ru‐rich phases in mantle wedge peridotites during different processes, e.g., partial melting and melt/fluid‐rock reactions. |
