STUDY OF THE GEOMAGNETIC FIELD STRUCTURE IN TERTIARY IN THE CONTEXT OF MAGNETOSTRATIGRAPHIC SCALE ELABORATION. III - THE MIOCENE

摘要

The results succeed to the previous data published in the first two parts of a three paper series fo-cussed on the palaeofield directional variability, with particular view on the polarity of the Earth's magnetic field over geological time. The palaeogeomagnetic record was detected in Mio-cene/Sarmatian sedimentary deposits located in the Comanesti Basin (East Carpathians, Romania). The calibration of the achieved resultant magnetic polarity sequence to the GPTS (CK95) indicates that a temporal interval between ~ 12.75 - 11.95 Ma has been spanned. The lithostratigraphic unit called the "Supanu Formation", composing the investigated section, has recorded five changes of the geomagnetic palaeofield polarity, produced during the fore-mentioned time period. These changes support six magnetic polarity zones, defining 3 reverse polarity intervals (C5Ar.2r, C5Ar.lr and C5An.lr) and 3 normal polarity intervals (C5Ar.1n, C5An.2n and C5An.ln). The magnetostrati-graphic model under attention in the article is equally of interest for the chronostratigraphic calibration of the Sarmatian deposits sampled from natural exposures in the Scaricica Valley. Consequently, the results stand for arguments for direct and indirect applications of the Palaeomagnetology, expressing its two facets.