Paleomagnetism and magnetostratigraphy of Tarkhanian sediments of the Eastern Paratethus (Skelya section, Kerch peninsula, Crimea)

A detailed paleomagnetic study of Tarkhanian sediments of Skelya section was carried out with the goal to obtained magnetostratigraphy data. The Skelya section is located on the Azov sea side of Kerch peninsula, Crimea (45^o42′N, 36^o53′E). The Tarkhanian sediments of Skelya section are represented mainly of clays and have a total thickness of ~ 100 m. According to GTS (2012), the Tarkhanian stage of Miocene is related to the lower part of the Langhian of the General Stratigraphic Scale. Standard paleomagnetic measurements have been carried out to investigate magnetic parameters: natural remenent magnetization, magnetic susceptibility, saturation remanent magnetization, anhysteretic   remanent magnetization varied through out the section. The remanent coercitivity force, determined from backfield demagnetization measurements, range between ~34 and 67 mT.   The composition of the ferromagnetic fraction was examined using temperature dependences of saturation remanent magnetic moment. The thermomagnetic analysis showed that the blocking temperatures are  about 320 ^oC and 410-470 ^oC and  greigite and titanomagnetite  are the main carriers of NRM in the section.  The biplot of  IRM_{-100 mT} / SIRM versus  ARM_40mT /SARM showed that the ratios fall down into the field around the titanomagnetite and greigite areas. The pseudo-single domain  state of titanomagnetite and greigite was determined from their Mrs/Ms and Bcr/Bc ratios by Day-plot. Paleomagnetic studies have shown that the interval of the Kuvinian beds in its upper part is composed of sediments of reversal polarity magnetization. The rocks of the Terskian and Argunian beds are characterized by intervals of normal and reversed polarity magnetization. This work was supported by Russian Science Foundation, project № 19-77-10075.