Boron in late precambrian igneous formations of the Northwestern Pay-Khoy

The first results of the determination of boron content in igneous rocks of the Morozov (RF3 mr ) and Sokolninsk (RF3-V sk ) Formation and the Morozov (bRF3 mr ) subvolcanic bodies of the northwestern Pay-Khoy are reported. Elevated boron concentrations may indicate the presence of sedimentary material in the magma source, where boron can be introduced during the dehydration of oceanic sediments that enter the subduction zone along with the slab material. Transverse geochemical zoning in the island arc system of the Morozov paleoarc is expressed by increasing concentration of boron in magmatites from the frontal zone (boron content 12-18 ppm) to the rear (boron content 19-45 ppm), which is due to the ingress of a larger volume of sedimentary material by the time of the formation of melts in the rear part of the arc. The boron concentration in the basalts of the Sokolninsk Formation varies from 17 to 22 ppm, which indicates the entry of a smaller volume of sedimentary material into the magma generation area during the formation of the Sokolninsk paleoarc.