The paper presentsthe results of geochemical, Sm-Nd isotope-geochemicalstudies of metavolcanic rocks of the western Tukuringra terrain, one of the largest terrains of the Mongol-Okhotsk fold belt. . It is shown that among the metavolcanics of the Teplyi Kluch, Garmakan and Algain suites are present differences similar to OIB and N-MORB but metavolcanics characteristics of the subduction origin are not found. Taking into account the Early Mesozoic age of these suites, the studied metabasalts are the youngest in the structure of the Mongol-Okhotsk belt. It is not excluded that Lower Mesozoic deposits of the western Tukuringra terrane, including the volcanics of OIB and N-MORB types are the relics of the residual ocean basin. The data obtained may indicate the absence ofsubduction processes in the Late Triassic – Middle Jurassic at the nal stages of the formation of the MongolOkhotsk fold belt. The closure of the Early Mesozoic basin was probably due to large-scale displacement.