Low-sulfide PGE mineralization type in the Dukaly mafic-ultramafic massif (Khabarovsk territory): minerals associated with PGE and their petrogenetic significance

Relevance. The unique genesis of low-sulfide platinum-group element mineralization in basalt-ultrabasic massifs, such as the Dukali massif, which combines magmatic and post-magmatic processes, and its significant economic potential for expanding the mineral resource base of platinum-group element in Russia. Aim. To identify the features of the formation of this type of mineralization based on the study of accessory minerals and assessment of the role of the fluid factor. Methods. Integrated approach, including field observations, ICP-MS analysis, SEM-EDS, and XRD. Results and conclusions. The comprehensive research led to the first identification of low-sulfide platinum-group element mineralization in the Dukali massif, associated with rocks that combine geochemical features of both chromite and sulfide ore genesis. It was established that the host rocks are characterized by geochemical paradoxes, combining high contents of both chalcophile (Cr, Ni, Co, Cu) and lithophile (K, Ba, Sr) elements. The mineralization is represented by native metals (Pt), intermetallic compounds, and compounds of Pt, Pd, Ir with Hg, Cu, Sn, Bi, As. A critical factor in ore formation is the interaction of magmatic rocks with chlorine-bearing fluids, confirmed by the development of reaction rims, the presence of Cl-apatite and phlogopite, and the association of platinum-group element minerals with low-temperature hydrosilicates (chlorite, serpentine, cronstedtite). The composition of chromspinels (Cr# ~0.57, Al₂O₃ 14–24 wt %, TiO₂ up to ~3 wt %) and the abundance of polymineralic silicate and sulfide inclusions within them indicate their crystallization from a fluid-saturated melt. It was determined that the formation of the low-sulfide platinum-group element mineralization in the Dukali massif is the result of the combined action of magmatic and subsequent pneumatolytic-hydrothermal processes. The obtained data can serve as a basis for developing exploration criteria for similar objects both within the Khabarovsk Territory and beyond.