Synchronism of Rift and Platform Magmatism in Eastern Siberia at the Permian–Triassic Boundary

The Siberian igneous province is made up of two types of volcanic rocks that formed under different geodynamic conditions: platform and rift ones, which were previously thought to have formed sequentially. The paper presents the first data indicating that rift and platform magmatism occurred simultaneously in this LIP, as follows from the presence of contrastingly different rocks in the same geological sections, including basalts, picrites, and tuffs. The most interesting rocks are picrite basalts and picrites, which provide evidence for the successive intrusion of mantle magmas from west to east along the southern boundary of the Yenisei–Khatanga trough. This indicates that a large paleorift developed in this direction. Variations in the contents and ratios of trace elements in the mantle rocks demonstrate their formation at greater depths during the evolution of magmatism. None of the current genetic models of the province takes into account these structural features, which call for further adequate explanations.