POSSIBLE CAUSES OF QUASI-PERIODIC VARIATIONS IN GEOMAGNETIC REVERSAL FREQUENCY AND 87Sr/86Sr RATIOS IN MARINE CARBONATES THROUGH THE PHANEROZOIC
A.N. Didenkoa,b
aKosygin Institute of Tectonics and Geophysics, Far East Branch of the Russian Academy of Sciences, ul. Kim Yu Chen 65, Khabarovsk, 680000, Russia
bGeological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, Moscow, 119017, Russia
Keywords: Frequency of geomagnetic reversals, superchron, 87Sr/86Sr in marine carbonates, relationship in time between processes in DВґ Вґ layer and in shallow Earth
Pages: 1530-1538
Abstract
Variations in frequency of geomagnetic reversals through the Phanerozoic have been analyzed jointly with 87Sr/86Sr ratios in marine carbonate sediments. The time series of both parameters contain principal components with periods from 90 to 110 Ma and show a certain correlation. Namely, (1) both time series have five local minima spaced at similar intervals (period lengths); (2) the minima in the Δ87Sr/86Sr curve follow in time those of the reversal frequency, with a lag from 12 Myr in the Ordovician to 38 Myr in the Cretaceous; (3) the rate of heat transfer from processes at the core-mantle boundary (in D´ ´ layer) which control the Earth's geological life was from 7 to 25 cm/yr in the Phanerozoic. This rate approaches the observed velocities of horizontal plate motion and the predicted mantle convection rates.
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