Paleomagnetism of the Permian-Triassic intrusions from the Norilsk region (the Siberian platform, Russia): Implications for the timing and correlation of magmatic events, and magmatic evolution

Abstract

The Norilsk region is a key area within the Siberian Traps Large Igneous Province, due to the thickest sections of the Permian-Triassic extrusive rocks and high diversity of intrusions and volcanics in composition. The unique Cu-Ni-PGE deposits related to the Siberian Traps intrusions are present here. On the basis of the new representative paleomagnetic and geochemical data, we distinguished three stages of intrusive magmatic activity. At the initial stage, high-Ti trachydolerites of the Yergalakhsky complex were emplaced synchronously with the lower part of the Norilsk volcanic section. The middle stage was manifested by emplacement of ore-bearing intrusions of the Norilsk type, leucogabbro of the Kruglogorsky type, and barren gabbro-dolerites of the Oganer complex, coeval with the Morongovsky and Mokulaevsky volcanic formations (about 251.8–251.6 Ma). At this stage, magmatic activity occurred as a series of brief and powerful events. Finally, the terminal stage is represented by geochemically contrasting dikes of the Avamsky and Daldykan complexes, cutting the entire volcanic section of the Norilsk region. Our new paleomagnetic results together with U-Pb show that the Permian-Triassic boundary in the Norilsk volcanic section should be set at the base of the Morongovsky Formation (the middle part of the Norilsk tuff-lava pile), and the duration of volcanic activity after this boundary can be estimated as ~0.5 Myr.