PALEOMAGNETISM OF THE LATE CRETACEOUS INTRUSIONS FROM THE MINUSA TROUGH ( SOUTHERN SIBERIA )
D.V. Metelkina, A.Yu. Kazanskya, V.Yu. Bragina, V.A. Tsel'movichb, A.V. Lavrenchuka, L.V. Kungurtseva
a Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
b Borok Geophysical Observatory of the Institute of Earth's Physics of the RAS,
Borok Village, Yaroslavl' Region, 152742, Russia
Keywords: Paleomagnetism; titanomagnetite; Late Cretaceous; explosion pipes; Minusa trough; intraplate strike-slip motions
Pages: 185-198
Abstract
The paper summarizes paleomagnetic and rock-magnetic data on the Late Cretaceous diatremes and associated dikes from the Minusa trough located within the southwestern Siberian Platform. It is shown that the stable characteristic component of magnetization is superimposed magnetization (in physical sense). It is linked to Fe-rich titanomagnetite produced by the decay and oxidation of Ti-rich titanomagnetite derived from a primary magma. This process, however, coincides in time with the intrusion cooling, which is supported by paleomagnetic tests. Correlation of magnetic polarity with 39Ar/40Ar ages suggests that the acquired stable characteristic component of magnetization corresponds to magnetic Chrons C33-C32 and characterizes the Middle Campanian magnetic field (74-82 Ma). The mean paleomagnetic pole for this span is located at 82.8
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