Geomagnetic field variations before and after the Matuyama-Jaramillo reversal in western Turkmenistan

Based on the maximum entropy and integral wavelet methods, processing of th e stationary geomagnetic field of the Matuyama chron prior to the Matuyama- Jaramillo reversal and of the Jaramillo subchron provided the field variati on spectrum similar to that derived from archaeomagnetic investigations. Ho wever, the time stability analysis of these spectra using their wavelet dia grams rejected some of the inferred periodicities which may reflect singula r features and quasi-periodic behavior of the series under study. The spect ra that were reliably inferred are discrete and often dissimilar for differ ent field components and time intervals, which may be evidence of a change in the geodynamo operation mode during the reversal.