Paleomagnetic data from Siberian Ediacaran rocks (Yenisei Ridge and Olenek Uplift)

Paleomagnetic results obtained from rocks of Ediacaran age in several localities in Siberia display co-existence of two magnetization components, one shallowly component and the other one is steeply inclined. Both components pass criteria for a primary magnetization. The conventional interpretation of paleomagnetic results in such cases have been rejected as dynamically implausible. In search of the reasons for the irregular behavior of the geomagnetic field in the Ediacaran, the study compares the key Ediacaran sections of the Yenisei Ridge and the Olenek Uplift, which are close in age.

The first paleomagnetic data for the Vorogovka Group were obtained in the northwest of the Yenisei Ridge. Age of deposits, according to different authors, from Cryogenian to Ediacaran. However, recent data indicate that the age of sedimentation within the Vorogovka basin is less than 585 million years. In the southwestern margin of the Siberian platform, the Taseeva Group is of considerable interest for paleomagnetic studies. New data on the age make it possible to significantly narrow the formation interval of the series to the Late Ediacaran, and also to refine the paleomagnetic pole calculated for the upper and lower formations of the Taseeva Group. In the Vorogovka and Taseeva groups, the shallowly inclined component of magnetization is more often present, while the steeply inclined component is less common.

Over the past several years, we have carried out paleomagnetic studies of the Precambrian rocks of the Olenek Uplift, including the Late Ediacaran Maastakh and Khatyspyt formations, as well as intrusions of the Tas-Yuryakh volcanic complex that break through them. In both sedimentary and igneous rocks of the Olenek Uplift, only a steeply inclined component of magnetization is present.

The results of the studies of paleointensity in basalts of the Tas-Yuryakh volcanic complex indicate an ultra-low intensity of the Earth's magnetic field at the end of the Ediacaran. These results confirm that the explanation for the disparate paleomagnetic data for the Ediacaran period must be sought in the behavior of the geomagnetic field, and not in tectonic reasons.

This work was financially supported by the Russian Science Foundation grant no. 21-17-00052.