O. V. Pilipenko

Petro-and paleomagnetic investigations of Tuzla section sediments (krasnodarsk territory)

Petro-and paleomagnetic methods are applied to the study of the upper part of the Late Pleistocene Tuzla section (Azov coast of the Taman Peninsula) composed of continental sediments and dated at 50–10 ka. The detailed curves of the angular components of the geomagnetic field obtained in this study display an anomalous direction coinciding in time (∼25–35 ka) with an anomalous horizon discovered in rocks of the Roxolany section (Ukraine). According to the world time scale of geomagnetic excursions, the anomalous direction correlates with the Mono Lake excursion. A significant correlation between the time series NRM0.015/SIRM (Tuzla section) and NRM250/KB (Roxolany section) in the interval 50–10 ka and the world composite curves VADM-21 and Sint-800 implies that, in this time interval, the curve NRM0.015/SIRM reflects the variation in the relative paleointensity of the geomagnetic field.

Direction and relative paleointensity of the geomagnetic field in the middle and later pleistocene from paleomagnetic data of the Roxolany section (Ukraine)

The lower part of the Roxolany section (Ukraine) is studied, and paleomagnetic and petromagnetic characteristics of rock samples are obtained for the time interval 300-75 ka. Detailed curves of variations in angular parameters of the geomagnetic field are constructed in the entire time interval, and curves of variations in the relative paleointensity are obtained for the interval 300-180 ka. Using the values of the angular parameters and the deviations of the virtual geomagnetic pole from the position of the stationary field, anomalous directions compatible with the Jamaica excursion are identified in the intervals 250-249 and 221-220 ka. The geomagnetic field evolution is studied by methods of wavelet analysis, and the field generation process is shown to vary in the interval 300-180 ka.

Variations in geomagnetic field and temperature in Spain during the past millennium

The archaeomagnetic studies are conducted for the collection of coated ceramic samples from the Albarracin archaeological monument in Spain dated to the 10–20th centuries A.D. The pattern of variations in geomagnetic field intensity during this time interval is identified. The behavior of geomagnetic intensity is dominated by a decreasing trend (from ∼80 to 40 μT). The variation with a characteristic time of a few hundred years is the most striking one. Investigation of the material from this collection by the method of rehydroxylation provided the temperature estimates for this region of Spain for the time interval of pottery production. The temperature variations generally tend to increase, while the main trend in the variations of geomagnetic intensity is decreasing. The time series of temperature and intensity of the main magnetic field contain variations with close characteristic times shifted in time so that the changes in temperature go somewhat ahead of the changes in the geomagnetic field. It was previously suggested to improve the accuracy and resolution of the obtained variations in the past magnetic field using the method of archaeomagnetic dating of the material from archaeological monuments. The method was tested by dating the pottery kiln material from the El Molon monument, Spain, with the use of the virtual geomagnetic pole curve based on the past magnetic field in the East Europe. The method proved to be quite efficient and promising for dating the archaeological material from all over Europe.

Variations in the Intensity of the Geomagnetic Field in Siberia during the Last 13000 Years

The thermal magnetization of the samples from the archaeological sites in Siberia is studied. The magnetization of the collected samples was studied using the authors’ modification of the Thellier method amended by the magnetic anisotropy and chemical alterations. Resulting from the study of the burned material from the Kazachka site, the time series of the geomagnetic field intensity in Siberia spanning the time interval from 10000 to 1000 B.C. is obtained. These data are unique in terms of the duration and representativeness. For the first time, the main variation in the intensity of the geomagnetic field is traced by studying the magnetization of the samples from a single archeological site. The pattern of the variations in the intensity of the geomagnetic field in Siberia from 11000 B.C. to 2000 A.D., which is reconstructed from the data of the Kazachka, Ust-Karenga, and some other sites of Cis-Baikalia, indicates that the characteristics time of the long-period oscillation in the intensity of the geomagnetic field is about 8000 years. It also suggests the existence of rapid variations superimposed on the main oscillation.

Rock magnetism and paleomagnetism of Maeotian deposits of the Popov Kamen reference section (Taman Peninsula)

One of the reference sections of Maeotian deposits in the south of Russia (the Popov Kamen section) is studied in terms of rock magnetism and paleomagnetism within the framework of the project “Study of Reference Sections of the Taman Downwarp as a Basis for Developing a Detailed Event Scale of the Neogene of the Eastern Paratethys.” The section is located in the southwestern part of the Taman Peninsula, to the south of the Taman Cape. It has been established that the lower-Maeotian deposits carry the magnetization of mainly reversed polarity, whereas the upper-Maeotian deposits are characterized by normal polarity. Two horizons of normally magnetized rocks are recognizable against the background of reversely magnetized lower-Maeotian deposits. A horizon of reversely magnetized rocks is outlined in the upper part of the upper Maeotian. If the paleomagnetic interpretation of the section is true, it can be concluded that the upper part of the upper Maeotian is absent in this section. Comparison with the magnetochronological scale shows that the lower Maeotian probably corresponds to the C3Br, C3Bn, and C3Ar Chrons, and the part of the upper Maeotian studied in this section corresponds to the lower part of the C3An Chron.

Response of the paleomagnetic record to environmental changes in the late Pleistocene

During revisiting the Upper Pleistocene Pekla loess-soil section located on the Sea of Azov coast of the Taman Peninsula, its lower 6 m were continuously sampled, which led to an increase in the age range from ∼50 to 400 ka. The detailed rock magnetic study of the structure, grain-size, and concentrations of magnetic mineral (natural remanent magnetization (NRM) carrier) in the collected rock samples revealed regular changes in rock magnetic characteristics along the section and their correlation with climatic fluctuations. Magnetite and hematite both deposited during the transport of sedimentary material and formed during pedogenesis, which involved the entire section to a varying extent, represent the main magnetic minerals in the examined rocks. Automorphic paleosoils that were formed during warm and humid periods corresponding to odd stages of the MIS scale are characterized by elevated concentrations of magnetic mineral (NRM, magnetic susceptibility (Klf), saturation isothermal remanent magnetization (SIRM), and anhysteresis (ideal) remanent magnetization (ARM)) parameters and share of superparamagnetic particles (up to 80%, according to elevated values of the frequency-dependent magnetic susceptibility Ktd) as well as by lowered rigidity parameter (Bcr) and grain size (ARM/K parameter). Such changes in the paleosoils may be explained by the occurrence of newly formed fine-grained magnetite particles close in size to its superparamagnetic and single-domain varieties due to the activation of bio/geochemical processes during warm stages. The growth of the above-mentioned rock magnetic parameters in automorphic soils may be considered as serving a quantitative criterion for defining the boundary between warm and cold periods even in poorly developed soils.

Study of Changes in the Rock Formation Medium of the Karadzha Section (Azerbaijan) from the Results of Petromagnetic Investigations

The petromagnetic characteristics of marine and subaqueous deposits on the upper marine terrace of the Karadzha section (Azerbaijan) are investigated. These deposits correspond to the great Khvalynsk transgression of the Paleocaspian. Thirteen meters of the section encompassing an age interval of ∼45–20 ka are sampled continuously. Regular along-section changes are revealed, and their relation to environmental changes is established. Magnetite, maghemite, and hematite that were formed in the process of alteration of the maternal rocks in the Paleocaspian wash-down basin are the main ore minerals of the studied rocks. The ratios of these minerals in the deposits depend on the degree of alteration of the maternal rocks. Both the total amount of ore mineral (K and SIRM parameters) and the rigidity parameter Bcr regularly increase in the basal part of the section and in the sediments reflecting finer variations in the basin level. An increased magnetic rigidity and the sensitivity of petromagnetic parameters to weak variations in the sea level are characteristic features of sediments in this part of the Paleocaspian compared with normal marine sediments.

The geomagnetic field recorded in sediments of the Tuzla section (the Krasnodar Territory, Russia) over the time interval 120–70 ka

Petro-and paleomagnetic methods are applied to the study of the lower part of the Early Pleistocene Tuzla section on the Black Sea coast of the Taman Peninsula, This part of the section is composed of marine and lagoonal sediments deposited over the time interval 120–70 ka. The measured curves of the variation in the geomagnetic field inclination reveal an anomalous direction dated at ∼110 ka that coincides with a similar anomalous direction in the Eltigen section (Ukraine) correlating with the Blake paleomagnetic event. The significant correlation between the time series NRM0.015/SIRM0.015 (Tuzla section) and the world composite Sint-800 curve indicates that the curve NRM0.015/SIRM0.015 in the interval 110–70 ka actually reflects the variation in the relative paleointensity of the geomagnetic field.

Rock magnetic and petrographical–mineralogical studies of the dredged rocks from the submarine volcanoes of the Sea-of-Okhotsk slope within the northern part of the Kuril Island Arc

The rock magnetic properties of the samples of dredged rocks composing the submarine volcanic edifices within the Sea-of-Okhotsk slope of the northern part of the Kuril Island Arc are studied. The measurements of the standard rock magnetic parameters, thermomagnetic analysis, petrographical studies, and microprobe investigations have been carried out. The magnetization of the studied rocks is mainly carried by the pseudo-single domain and multidomain titanomagnetite and low-Ti titanomagnetite grains. The high values of the natural remanent magnetization are due to the pseudo-single-domain structure of the titanomagnetite grains, whereas the high values of magnetic susceptibility are associated with the high concentration of ferrimagnetic grains. The highest Curie points are observed in the titanomagnetite grains of the igneous rocks composing the edifices of the Smirnov, Edelshtein, and 1.4 submarine volcanoes.

Paleomagnetic studies of late pleistocene rocks from the Malyi Kut section (Taman Peninsula, Krasnodar krai)

Paleomagnetic studies of Quaternary deposits from the Malyi Kut rock sequence (Krasnodar krai, western part of the Taman Peninsula) in two time intervals of Late Pleistocene are carried out. The Malyi Kut sequence is a marine terrace of the Baku age, which is embedded in the disturbed marine Sarmatian deposits. The terrace of the Bakinian age nests the Karangat marine terrace. The presence of the marine molluscan fauna in the both terraces enables reliable dating of the studied deposits. The composition, grain size, and concentration of ferromagnetic fraction present in the studied rocks are investigated by a set of rock magnetic methods. The directions of natural remanent magnetization (NRM) are studied, and the reliability of their isolation is estimated. The results are compared with the paleomagnetic records of NRM in the rocks of the parallel coeval sections of the Tuzla (Taman Peninsula) and Roxolany (Ukraine). This correlation suggests that the studied rock sequences recorded the Mono Lake geomagnetic excursion.