Granitoids of the Gamov intrusion (southern Primorye), its peculiarities and indicative and geodynamic role

We studied the geologic position, mineralogy, petrography, chemical composition, and age of granitoids of the Gamov batholith located in the Heilongjiang-Grodekovo terrane, southern Primorye (Russia). The studies have revealed four intrusive rock phases, from gabbro to leucogranites, in the massif. U-Pb zircon dating of tonalites of phase II and leucogranites of phase IV (254 ± 4 and 259 ± 2 Ma, respectively) shows that the intrusion of granitoids took place in the Late Permian without a significant gap in time. Structural investigations gave evidence for the intrusion in the E-W compression setting. Geochemical studies have revealed granitoids of strongly different compositional types in the intrusive massif: gabbroids, quartz diorites and tonalites with characteristics of low-alumina TTG, calc-alkalic granodiorites and I-type granites, and moderately alkaline leucogranites. The obtained data, together with the results of previous research into the Permo-Triassic granitoids of southern Primorye, reject their formation as a result of the evolution of the Solonker oceanic structures and suggest a more intricate tectonic scenario, which calls for additional study.