Possible causes of quasiperiodic variations in geomagnetic reversal frequency and 87Sr/86Sr ratios in marine carbonates through the Phanerozoic

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, (i) both time series have five local minimums spaced at similar intervals (period lengths); (ii) the minimums 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; (iii) 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.