Home – Home – Jornals – Russian Geology and Geophysics 2020 number 9

Magnetostratigraphic data from wells in southern West Siberia that strip the Upper Cretaceous and Cretaceous-Paleogene boundary strata in three areas (three wells in the Omsk Basin, two wells in the Bakchar Iron Basin, and two wells in the southern Kulunda Basin) are used to compile the respective regional magnetic-polarity scale. According to the available biostratigraphic constraints, the deposition spanned the period from Albian to Bartonian. The reported regional polarity scale is based on integrated paleomagnetic and biostratigraphic data from the seven wells and comprises four Upper Cretaceous zones of normal (NK_1-2(al-st) and NK₂mt) and reverse (RK₂km and RK₂mt) polarity corresponding to the C34, C33r, C31r, and C30n Chrons of the global magnetic polarity scale and four Paleogene zones of reverse polarity: R₁E₁zl, R₂E₁t, R ₁E₂t-i(?), and R ₁E₂l-b, with the first two correlating with the C26r and C25r Chrons. Some of the Upper Cretaceous magnetozones enclose thin intervals (microzones) of the opposite polarity. The regional Cretaceous-Paleogene magnetic polarity scale of southern West Siberia reveals several deposition gaps from 6 to 28 Myr long. The magnetostratigraphic data can be used to determine deposition rates and can make reference for local, regional, and global correlations of geologic events given that polarity reversals are of global extent.