Conditions of the formation of hypabyssal granitoid intrusions using the example of the Sizindzha Massif, the Okhotsk-Chukotka volcanic belt

The Sizindzha hypabyssal intrusive massif located in the Kuidusun volcanic zone of the Okhotsk-Chukotka volcanic belt has been mapped and studied in detail. The complex of textural-petrographic features indicates the in situ formation of granitoids by the successive replacement of the host sedimentary rocks of the Verkhoyansk Complex and the medium-grained diorites (more rarely, gabbro) by later granites. It was established that the oldest fine-grained intermediate rocks observed as xenoliths in all the granitoids are in situ relicts of the molten substrate.