Protracted mafic magmatism and two-stage mineralization of the Kalatongke Cu-Ni sulfide deposit in the Central Asian Orogenic Belt

The Kalatongke Cu-Ni sulfide deposit in the Central Asian Orogenic Belt (CAOB) is hosted by the early Permian mafic intrusions. After conducting a detailed field survey, we found that the massive sulfide ores and network olivine gabbro were emplaced separately into the dominant sulfide-barren mafic suite. Secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were performed for zircon U-Pb dating to determine the ages of rocks derived from the sulfide-rich suites and adjacent sulfide-barren suites. The results revealed that the U-Pb ages of olivine gabbro with network ore, gabbro with globular ore and breccia ore are 276.0 +/- 1.1, 272.4 +/- 0.9 and 271.9 +/- 1.3 Ma, respectively. Biotite diorite in the Y1 intrusion, biotite gabbro and biotite norite in the Y2 intrusion presented with ages of 287.4 +/- 1.1, 281.7 +/- 3.0 and 286.7 +/- 1.1 Ma, respectively. Combined with the published data, our findings demonstrated that the Kalatongke sulfide deposit experienced two stages of magma replenishment, lasting at least 16 Myr (287-271 Ma). The sulfide-rich magmas were most likely transported upward from the staging chamber via magma overpressure attributable to considerable tectonic compressive stresses. It could be proposed that the sulfide-rich magmas were derived from a strongly evolved magma chamber, whereas the sulfide-barren mafic suite was related to the emplacement of a weakly evolved magma in the same or a related plumbing system.