Formation Conditions of Devonian Basites of the Vilyui–Markha Dike Swarm in the Vilyui Paleorift (Siberian Platform)

Melt inclusions in the minerals from a dolerite dike of the Vilyui–Markha dike swarm, located on the northwestern shoulder of the Vilyui paleorift, have been studied. Data on the composition of homogeneous glasses of melt inclusions in minerals made it possible to establish the PT parameters of mantle sources of primary deep melts responsible for the formation of gabbro-dolerites of the Vilyui paleorift. Two levels of generation of the initial melts have been established for dolerites: in the intervals of 95–65 km at 1480–1400°C and 55–45 km at 1360–1320°C. The presence of two intermediate chambers in the crust, where melts crystallized, was identified at depths of about 12 and 9–4 km with a decrease in temperature to 1175–1125°С. The two-level arrangement of centers of magma generation, as well as the heterogeneity of the chemical composition of the minerals studied, makes it possible to explain the presence of two pulses of Devonian basic magmatism.