Exploration and research progress of magmatic copper−nickel−cobalt sulfide deposits in the north−eastern margin of the Qinghai−Xizang Plateau

This paper is the result of mineral exploration engineering.

Objective To improve the supply security of Cu−Ni−Co resources in China, it is necessary to sort out the mineralization regularity and prospecting indicators of the magmatic copper−nickel−cobalt sulfide deposit in the Phanerozoic in the Eastern Kunlun orogenic belt on the northern margin of the Qinghai−Xizang Plateau.

Methods To establish the exploration model, this paper analyzed the geological characteristics and genesis of representative magmatic copper-nickel sulfide deposits, and the geological, geochronology, geochemistry, and geophysical characteristics of five stages mafic−ultramafic complexes including the Late Ordovician−Early Silurian, the Middle Silurian−Middle Devonian, the Early Carboniferous, the Middle Permian−Early Triassic, and the Middle−Late Triassic are summarized.

Results There are two stages of island arc mafic or basic−ultramafic rocks in the East Kunlun during the Phanerozoic: (1) Mafic rocks formed in the Late Ordovician−Early Silurian during the northward subduction of the Proto−Tethys Ocean; (2) Mafic−ultramafic rocks formed due to the subduction of the Paleo−Tethys Ocean in the Middle Permian−Early Triassic. Correspondingly, there are two stages of post−collision extensional mafic−ultramafic rocks: From Middle−Late Silurian to Early−Middle Devonian and Middle−Late Triassic. The pyroxenite mantle may be the source of some magmatic nickel deposits in the East Kunlun, and the plate break−off model can explain the phenomenon that the mineralization age of magmatic copper−nickel−cobalt sulfide deposits is nearly same to the high−pressure−ultrahigh−pressure retrograde metamorphism age. Regarding the sulfide saturation mechanism of mantle−derived magma, the types of favorable crustal contamination and harmful crustal contamination were roughly identified, and the influence of crystal differentiation on sulfide saturation was analyzed. The preferred location of ore bodies was proposed, and the representative differences between ore−forming and non−ore−forming rock bodies in geological structure, rock type, mineralogy, age, alteration type, and surrounding rock types were compared.

Conclusions Finally, this paper established a geological−geochemical−geophysical comprehensive information exploration model for magmatic copper−nickel−cobalt sulfide deposits in the East Kunlun orogenic belt.