Recent tectonomagmatic reactivation of the Kolyuchino-Mechigmen zone of the Chukchi Peninsula from data on the composition of gases in hydrothermal springs

Thirty-three groups of thermal mineral springs in the Chukchi Peninsula are studied. The thermal fluids of the Kolyuchino-Mechigmen Zone (KMZ) show specific characteristics. The zone corresponds to recent depression with occurrences of basic volcanism and high seismicity. Characteristic features of the gases in the springs of the KMZ include the predominance of carbon dioxide, high percentage of mantle-derived helium, enrichment of CO2 in 13C, admixture of nonatmospheric nitrogen, excess in 40Ar and 15N relative to the atmosphere, maximal depletion of thermal water in deuterium and heavy oxygen isotope, and the highest estimates of deep temperature in reservoirs of hydrothermal fluid. All these features indicate the contemporary ascent of a mantle diapir that supplied helium enriched in 3He and thermal energy to the crust, thus provoking thermal metamorphism of rocks and degradation of permafrost.