Paleomagnetism of terrigenous rocks of the Volynian series (Ediacaran) from Podolia (Ukraine)

Abstract

We present the results of palaeomagnetic study of Ediacaran terrigenous rocks from the SW part of East European Craton (EEC), Podolia (Ukraine). Samples are represented by red tufits of Grushkinska suite by Volhynian series, which is comparable to the upper part of the Ediacaran age by the international stratigraphic scale. Samples for paleomagnetic studies were taken at the reference section of the Grushkinsky suite of the Volhynia series in the village of Grushka (48.45°N 28°E). A total of 50 oriented core samples were selected. For the entire collection of samples, the standard procedure for paleomagnetic studies was applied. The samples underwent stepwise temperature demagnetization. Demagnetization showed that all samples are completely demagnetized at a temperature close to 700°C. The results of demagnetization showed that additionally to the viscous components of the magnetization released up to 200°C, four more stable components of NRM are released: CLM-1–component, relatively low temperature, in the range of deblocking temperatures of 200–360°C. It is characterized by south-south-west declination and negative inclination (D/I = 197.9/-28.6); CLM-2–component, is allocated in the same temperature range as component CLM-1 (200-360°С), is characterized by south-south-west declination and positive inclination (D/I = 202.4/31); CMH–component, is strictly allocated in the range of unlocking temperatures of 590–630°C. It is characterized by northwestern declination and positive inclination (D/I = 311/18.9); CH –component, a bipolar high-temperature component, is released in the temperature range of 650–700°C. The middle direction of the forward and reverse polarity is characterized by north-north-west declination and positive inclination (D/I = 296.4/71.2). The directions of normal and reverse polarity of this component are closely antipodal and successfully pass the reversal test (γ/γ c = 7.85/8.82), class “B” in accordance with [McFadden & McElhinny, 1990].