The First Paleomagnetic Data on Lower Carboniferous Volcanics of the Central Magnitogorsk Zone in the South Urals

Abstract

This paper gives new paleomagnetic research results concerning Lower Carboniferous volcanics of the Central Magnitogorsk Zone in the South Urals, with the aim to independently assess geological ideas about the development history of the Magnitogorsk island arc. We studied 9 sections of effusive rocks with primarily basic composition in the Grekhovka and Berezovka Formations located in the meridional flow of the Ural River from the village of Kizilskoe on the north to the village of Ershovka on the south. Laboratory paleomagnetic investigations were conducted according to currently accepted methods, including thermal demagnetization and component analysis of the isolated magnetization directions. The mean direction of the high-temperature magnetization component obtained on 28 sites and the paleolatitude calculated therefrom virtually coincide with global data on the eastern margin of the paleocontinent Baltica. Consequently, according to paleomagnetic data the Central Magnitogorsk Zone was a part of the continent in the Early Carboniferous. A combined analysis of the new results on Lower Carboniferous rocks and our previous data on Devonian rocks suggest that paleomagnetic data and modern ideas about the evolution of the Uralian Orogen associated with the collision between the Magnitogorsk island arc and the passive continental margin do not contradict each other.