The Influence of the Permian-Triassic Magmatism in the Tunguska Basin, Siberia on the Regional Floristic Biota of the Permian-Triassic Transition in the Region

V I Davydov,E V Karasev

doi:10.3389/feart.2021.635179

Abstract

The end-Permian extinction event (EPEE) considered to have been caused by the eruption of the Siberian Large Igneous Province (SLIP), the age of which is critical for extinction-SLIP model evaluation. The Tunguska Basin flora during this time, in accordance with the EPEE model, supposed to have been killed by the massive injection into the atmosphere of poisonous substances such as methane, sulfates, mercury and massive combastion of coals. In addition, supposed numerous fires presumably devastated the regional flora. However, the diversity of the Tunguska Basin flora drasticly increased at the beginning of Induan or slightly earlier and become diverse at the species level in the Olenekian and Anisian, when the main phase of basalt eruption and associated intrusive activity occurred. The overall magmatic activity during the latest Permian and Early Triassic did not kill the flora, but rather stimulate their diversity. The geomagnetic secular variations from the intrusions revealed the similarity of paleomagnetic directions of the Norilsk group layered intrusions with those of the upper Olenekian and lower Anisian Mokulaev and Kharaelakh volcanic formations and intrusions of the Talnakh group with the Olenekian Moronga-Mokulaev formations. The U-Pb dates and the geomagnetic secular variations data expose the obvious discrepancy between these two datasets. The paleomagnetic data suggest that the Norilsk-1 intrusion is younger than the Talnakn and Kharaelakh intrusions, but the U-Pb dates indicate the opposite. The data from layered intrusions in Norilsk and the other regions suggest their prolonged duration and multi-stadial formation. The U-Pb dates from the intrusions of the Norilsk region roughly constrain the onset of the SLIP and generally postdate the end-Permian extinction.

Highlights

Recent advances in zircon CA-IDTIMS dating resolve many important geological problems especially those dealing with the rates of different geological and biological processes
These dates suggested to confirm the coincidence of the Siberian Large Igneous Province (SLIP) magmatism in the Tunguska Basin with the onset of the marine extinction in South China (Burgess and Bowring, 2015)
The time frame of the SLIP intrusive magmatism relative to the age of the end-Permian extinction event (EPEE) is very critical for this model evaluation

Summary

INTRODUCTION

Recent advances in zircon CA-IDTIMS dating resolve many important geological problems especially those dealing with the rates of different geological and biological processes. The latest PermianEarly Triassic magmatism that created the Siberian traps, including the products of the explosion and interaction of the magmas with regional volcanic and sedimentary rocks (coal, evaporite and sulfates), is considered by many authors to be the main driving force of the EPEE (Hoenisch et al, 2012; Bond and Wignall, 2014; Sobolev et al, 2015; Bond and Grasby, 2017; Burgess et al, 2017; Rothman 2017; Ernst et al, 2021, in press) This extinction model suggests that the large scale of the SLIP volcanic explosions and intrusive/sill emplacement within the Tunguska Basin released large volumes of CO2, and induced metamorphism of the sedimentary succession surrounding the intrusive and sills, that released sedimentderived hazardous volatiles into the atmosphere through the numerous pipe and vent structures throughout the basin (Svensen et al, 2009; Black et al, 2021, in press). The recent secular variation of paleomagnetic data from the Permian and Triassic for the first time suggested the direct correlation of intrusive and extrusive rocks in the Tunguska Basin (Latyshev et al, 2020)

DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT