V.E. GUZEV (VSEGEI, SPMU), G.A. KOZLOV, А.V. TEREKHOV, А.V. MOLCHANOV, I.O. LEBEDEV, YU.L. SVETLOVA (VSEGEI)

Chara-Sinsk dike swarm (middle reach of the Lena River): local U-Pb age of zircon and petrological and geochemical features of rocks

The research focuses on the comprehensive analysis of petrological, geochemical, and isotopic-geochronological characteristics of the Chara-Sinsk dike swarm, which is mapped in the middle reaches of the Lena River. Intrusions of the Chara-Sinsk dike swarm frame the Vilyui rift from the southeast. The intrusions are dikes, small sills, stocks, and chonoliths. Their petrological composition varies from dolerite and gabbro-dolerite to syenite. In general, in terms of the distribution of petrogenic, trace elements and REE, the studied rocks have a significant similarity with Middle Paleozoic intrusions of the Vilyui rift, in particular, with the Vilyui-Markha dike swarm. The results of isotopic dating of the zircon by the U-Pb method showed that the formation of the Chara-Sinsk dike swarm occurred during a relatively short time interval of 364–374 Ma. The obtained isotope dating results fully correspond to the time interval (357–379 Ma) of Devonian dike magmatism in the large Yakutsk­Vilyui igneous province.
Keywords: U-Pb dating, zircon, Chara-Sinsk dike swarm, large Yakutsk-Vilyui igneous province, Vilyui rift.