The rift origin of the Vilyui basin (East Siberia), from reconstructions of sedimentation and mechanical mathematical modeling

Abstract

Results of modeling of the formation of the Vilyui sedimentary basin are presented. We combine backstripping reconstructions of sedimentation and thermal regime during the subsidence with a numerical simulation based on the deformable solid mechanics. Lithological data and stratigraphic sections were used to “strip” the sedimentary beds successively and calculate the depth of the stratigraphic units during the sedimentation. It is the first time that the evolution of sedimentation which is nonuniform over the basin area has been analyzed for the Vilyui basin. The rift origin of the basin is proven. We estimate the spatial distribution of the parameters of crustal and mantle-lithosphere extension as well as expansion due to dike intrusion. According to the reconstructions, the type of subsidence curves for the sedimentary rocks of the basin depends on the tectonic regime of sedimentation in individual basins. The backstripping analysis revealed two stages of extension (sediments 4–5 km thick) and a foreland stage (sediments > 2 km thick). With the two-layered lithosphere model, we conclude that the subcrustal layer underwent predominant extension (by a factor of 1.2–2.0 vs. 1.1–1.4 in the crust). The goal of numerical experiments is to demonstrate that deep troughs can form in the continental crust under its finite extension. Unlike the oceanic rifting models, this modeling shows no complete destruction or rupture of the continental crust during the extension. The 2D numerical simulation shows the possibility of considerable basement subsidence near the central axis and explains why mafic dikes are concentrated on the basin periphery.

Density heterogeneity of the cratonic lithosphere: A case study of the Siberian Craton

“…Based on back-striping analysis of borehole data, two major extensional events (the Cambrian and Devonian) caused subsidence of the Viluy Basin (Polyansky et al, 2013). The next phase (at ca.…”

“…250 Ma) of rapid intensive basin subsidence (with a rate of 800-1200 m/My) cannot be explained by rifting, due to the absence of the post-rifting phase of slow subsidence and no indication of temperature increase ca. 90-100 Ma after the main Devonian subsidence (borehole 9, Polyansky et al, 2013). It has long been proposed that phase transitions may have played an important role in the Viluy Basin formation (Artyushkov, 1993).…”

The mechanism of magma ascent through the solid lithosphere and relation between mantle and crustal diapirism: numerical modeling and natural examples

“…This extension zone has a width of 90-100 km and the depth of subsidence of the crustal surface is 7-7.5 km. The calculated parameters of crustal extension/subsidence are typical for rift zones above intrusions of mantle-derived mafic melts into the lower crust (Polyansky et al, 2013Thybo and Artemieva, 2013).…”

“…It is assumed that a superplume rising under the Vilyui rift in the Middle Paleozoic may have transported significant amounts of molten material to the base of the lithosphere, which was in part (320 thousand km 3 ) extruded to the surface or intruded into the sedimentary successions (Kiselev et al, 2014). Indirect evidence of the existence of a mantle diapir beneath the Vilyui province comes from plutons of alkalineultramafic rocks, flood basalt eruptions at 380-350 Ma, formation of rift zones and mafic dike belts (Kuzmin et al, 2010;Polyansky et al, 2013).…”

Tectonic depressions on the East-European and Siberian platforms: numerical modeling of convection beneath the Eurasian continent

“…Полянского с соавторами предлагается рифтовый механизм становления Вилюйского прогиба. Приводятся убедительные доводы, подкрепленные численными экспериментами, указывающие на природу возникновения депрессии в результате растяжения земной коры [Polyansky et al, 2013[Polyansky et al, , 2017[Polyansky et al, , 2018.…”