Аннотация:A detailed rock magnetic study of marine deposits of the Cop-Takyl section was carried out with the goal to check the reliability of the previously obtained magnetostratigraphic data. The Cop-Takyl section is located on the Black sea coast of Kerch peninsula, Crimea. The section has a total thickness of ~ 53 m and composed mainly of clays. The Cop-Takyl section covered the Tarhanian stratigraphic interval of the Miocene. Paleomagnetic studies have shown that the interval of the Kuvinian beds of the Tarkhanian in the lower parts is composed of sediments of normal polyrity magnetization, and rocks in its upper part are reversed magnetized. The rocks of the Terskian and Argunian beds are characterized by normal polarity magnetization. NRM, magnetic susceptibility K, SIRM, ARM increase with depth, reflecting the growth of magnetic minerals within the sediment as a consequence of organic activity. Bcr, determined from backfield demagnetization measurements, range between ~35 and 58 mT. The thermomagnetic analyzes K(T) and Ms(T) showed that 320°C is the temperature of chemical changes on the air. The rapid and big growth of the magnetic susceptibility and saturation magnetic moment means that the new grains of magnetite are formed. The thermomagnetic analysis Mrs(T) showed that the blocking temperature is about 575°C and magnetite is the main carrier of NRM in the whole section. The iron sulfide have been detected in the lower part of the section from ~26 m up to 53 m in depth as well as magnetite. The biplot of IRM(-100 mT) / SIRM versus ARM(40mT) /SARM showed that the ratios fall down into the field around the greigite area. Magnetic minerals are found in fairly low concentrations, the mean value of K is ~1.5 *10-4 un. SI . The pseudosingle domain state of magnetite and greigite was determined from their Mrs/Ms and Bcr/Bc ratios by Day-plot. Frequency dependent susceptibility Kfd is low then 2% reflecting the absence of the superparamagnetic grains. So, one can conclude that detrital grains of greigite took place in the section. Greigite being a chemically metastable mineral reformed into magnetite releasing sulphuric acid. These grains of magnetite mimic the detrital fabrics of greigite. Although the magnetic fabric has primary depositional fabrics, the magnetization of magnetite may well be secondary.
