Geology, Geography and Geoecology

. Well 11 is located near the village of Velika Lanna, Krasnograd District, Kharkiv Region, and at the current stage of research is the most representative section of the continental Upper Cenozoic deposits of the Dnieper-Donets depression. For the first time, a comprehen - sive description of the Upper Miocene, Pliocene, and Pleistocene deposits obtained from the results of paleopedological, palynological, and paleomagnetic studies is presented for the research region. Characteristic features of 13 climatolites (pedocomplexes and intersoil clays) including five upper Miocene, three lower Pliocene, two upper Pliocene and two climatolites correlated with the Gelasian of the International Stratigraphic Scale were determined. According to the results of miner - alogical studies, three mineralogical strata such as montmorillonite-kaolinite, hydromica-montmorillonite, and hydromica were traced for the deposits of the section. The mineralogical boundaries are confined to the levels of the Salgir–Liubymivka and Siversk–Beregove climatolites. The spore-pollen complexes of all studied deposits are described. It was established that the complexes characterizing each studied climatolite differ in taxonomic composition, the ratio of the pollen of the main groups of plants, and the presence of characteristic taxa. Changes in the composition of spore-pollen spectra characterizing all soils of pedocomplexes as well as intersoil clays and embryonic soils formed during short-term warming at the time of the cool stages of the Miocene, Pliocene, and Gelasian periods were traced. The described spore-pollen complexes and spectra were compared with those from the deposits of the same age in adjacent regions, which allowed identifying the general and regional features of the compared complexes. A detailed record of changes in the geomagnetic field during the formation of the Upper Miocene-Pleistocene deposits was obtained, which enables to construct a paleomagnetic section reflecting the areas with normal , reverse and anomalous polarity. According to the nature of distribution of such areas, the section is tied to the Cox scale. All these materials allowed carrying out the stratigraphic dissection of the Miocene-Gelasian deposits of the studied section, as well as to substantiate the feasibility of defining it as a reference for the Miocene-Pleistocene deposits of the Dnieper-Donetsk depression.


Introduction
The continental regime existed within the Dnieper-Donetsk depression in the Late Miocene-Pleistocene. The feature of the formation of the Upper Miocene-Pleistocene deposits of this region is the wide development of subaerial facies represented in sections by alternating brown-red, red-brown, dark-brown fossil soils and gray-brown clays and loess. Fossil soils were formed during the warm phases of climatic rhythms. Each pedocomplex includes several soils. The middle soils of the pedocomplexes are the most thick and correspond to the climatic optimum of this phase, while the lower and upper soils are poorly developed, differ in small thicknesses, and were formed under drier and less warm climatic conditions (Veklich et al., 1979). Brown-colored clays were formed during cool climatic rhythms. During short-term warmings, underdeveloped «embryonic» thin fossil soils were formed in the strata of brown-colored clays. Brown-colored clays differ in thickness, granulometric composition, and the presence of embryonic soils.
The basis of any stratigraphic constructions is a detailed comprehensive study of the reference sections of deposits with a clear sequence of stratifications. One of such sections for the Upper Cenozoic deposits of the Dnieper-Donetsk depression is the section of well 11, drilled in the northeastern outskirts of the village of Velika Lanna, Krasnograd District, Kharkiv Region ( Fig.  1). In geomorphological terms, the territory is the interfluve of the Velica and Mala Lanna rivers. The absolute elevation of the well mouth is +160 m. The well penetrated the Upper Miocene, Pliocene and Pleistocene deposits. This is the most complete and representative section of the Upper Cenozoic deposits in the study region. Taking into consideration these points, this section was selected as a reference for the region.
The purpose of this study was to obtain a comprehensive characterization of the Upper Miocene-Pliocene and Gelasian deposits of the section.

Materials and research methods
The deposits were studied by paleopedological, palynological and paleomagnetic methods. Note that such research for the studied region was conducted for the first time. A set of analytical works was also carried out to determine the chemical, granulometric and mineralogical composition of rocks. This article presents the main results of the studies of the Upper Miocene-Gelasian deposits. Paleopedological description and primary stratigraphic subdivision of the section was made by Doctor of Geographical Sciences N.A. Sirenko and B.D. Vozgrin. Later, according to palynological data, the boundaries of certain climatolitеs were refined. The stratigraphic subdivision of the deposits was carried out according to the Correlation Stratigraphic Scheme of the Continental Deposits of Ukraine (Stratigraficheskie shemy,1993) with specification proposed by the author (Sirenko, 2017). We consider it justified to call the stratons of the subaerial section of the Upper Miocene-Pliocene not horizons, as accepted in the Stratigraphic scheme (1993), but climatolitеs. Since these stratons are more climatostratigraphic than lithostratigraphic units, their formation is associated with warm and cold phases of climatic rhythms. According to the Modern International Stratigraphic Scale, the two-term structure of the Pliocene is accepted, and the Siversk and Beregove climatolitеs are assigned to Gelasian.
Palynological studies were carried out at the Institute of Geological Sciences of the National Academy of Sciences of Ukraine. This paper presents the results of studies of the Upper Miocene, Pliocene, and Gelasian deposits of the section.
In general, 94 samples from the Upper Miocene, Pliocene and Gelasian deposits of the well were studied by spore-pollen analysis. Maceration was carried out according to the standard method used at the Institute of Geological Sciences for Upper Cenozoic deposits, which includes the following operations: rock treatment with 10% (HCL) 100˚ for 7-10 minutes, decantation with distilled H 2 O, treatment with 10% Na 2 P 4 O 7 100˚, decantation with distilled H 2 O, treatment with 10% KOH for 7 minutes, decantation of distilled H 2 O, treatment with 10% HCL without boiling -decantation with distilled H 2 O, and two-fold separation into potassium cadmium (KJ + CdJ2) heavy liquid with a specific gravity of 2.3 and 2.2 . The intervals between decantations were three hours (for beakers of 1 L). When isolating pollen from rocks of individual climatolites of the Upper Miocene and Lower Pliocene, HF was additionally used. 200 g of rocks were used for each sample.
The pollen and spores were determined according to the Engler classification system. When counting palynomorphs, the sum of all established pollen grains and spores, except for algae, was taken as 100%. The percentage composition of pollen and spores of each taxon was calculated from the indicated amount.
Thermal analysis of fine fractions (0.006 mm) from the Upper Miocene-Pliocene and Pleistocene deposits of well 11 was performed in the laboratory of the Kharkiv geological party of the Dnieper Geological Exploration Expedition of the State Enterprise UGK (former Kharkiv Geological Exploration Expedition) by the DTA method.
Paleomagnetic studies were carried out by Dr. A.N. Tretiak and Phd. L.I. Vigilyanska at the Institute of Geophysics of the National Academy of Sciences of Ukraine. The results of paleomagnetic studies are given for the deposits of the entire studied section.
For paleomagnetic studies, 340 cube-shaped samples were selected from 154 core samples with a rib size of 4.5 cm in most cases.
The core material of 30 cm length was taken out by pipes with a diameter that made it possible to produce two cubic samples side by side horizontally: one with an edge of 4.5 cm and another with an edge of 2.5 cm.
The sampling interval was mainly 15-20 cm. From each piece, two cubes were made vertically directly below each other, with an edge equal to 4.5 cm, sometimes 1-2 additional cubes with an edge of 2.5 cm were cut horizontally next to the main one. These samples were taken from the central part of the core, where the disturbance of the rock structure during the entry of drilling equipment into the rock was minimal. The cubes were pasted over with paper immediately after production to store their form and marked with the direction «top-bottom» of the sample.
It is important to note that a common serious shortcoming of paleomagnetic studies of samples from wells is the lack of core orientation in relation to the countries of the world. This fact prevents the possibility of including such an important component as magnetic declination (D) in the analysis of the patterns of changes in the earth's magnetic field along the section.
In determining the polarity of the geomagnetic field in this case, the main criterion is the change in the inclination of the characteristic component of remanent magnetization of the samples.
All laboratory work and processing of the obtained data were carried out in accordance with the generally accepted methodology of paleomagnetic studies. Rock characteristics were determined using MA-21 magnetometer and Kappabridge.
The paleomagnetic stability of natural remnant magnetization I n of sediments was tested by changing magnetic fields from 25 to 600 oersted (37 samples) on rock samples and heating in zero field to the temperatures of 150º, 200º, and 250ºC, -for one hour and subsequent cooling of samples to the room temperature (286).
The studied section is represented by 27 units of the Miocene-Pleistocene deposits. Depending on a thickness, each unit was sampled at 1-13 levels represented by 1-30 samples, respectively, selected for paleomagnetic studies.

Main results and discussion
Рaleopedological description 45.4-43.8 m of gray clay kaolinized sands and sandstones 43.8-43.1 m complex of hydromorphic Efremivka soils of ocher-orange color composed of heavy sandy loam. These soils are dense, with manganese dendrites on the surface of shallow units, without visible forms of carbonates, kaolinized.
43.1-38.4 m. Belbek climatolite is represented by sandy clay, bluish-greenish-gray with ocher spots, dense with manganese dendrite on the surface of shallow units. Embryonic soils of reddish and brownish-brown color are traced in the middle part of the stratum. The Belbek deposits are overlain by carbonates.
38.4-36.2 m Ivankiv climatolite is represented by a pedocomplex of three soils separated by weak layers of reddish-brown clays. The soils are intensively colored, red and orange-red in color, heavy clay, pseudosandy, dense. The intensity of soil coloring increases from the top to the bottom of the pedocomplex. Soils are leached from carbonates. Only low-strength clay layers between soils are sandblasted.
36.2-33.9 m Salgir climatolite is represented by clay of olive-yellow color, very dense, fused, without visible forms of carbonates, with films of manganese. In the middle part of the layer, a low-strength embryonic soil with a thickness of 0.5 m is traced.
33.9-31.2 m Liubymivka climatolite is represented by a pedocomplex of three hydromorphic soils. The soils are composed of fine-sandy dense clay and characterized by a non-uniform color, with bluish ocher spots, with vaguely defined lumpy-deep separates, the surfaces of which are covered with black films of manganese oxides. The soils of the pedocomplex are separated by vaguely defined carbonate horizons with flour-like carbonates nests, although visible forms of carbonates are not visible in the soil layer. 31.2-30.9 m Oskil climatolite is represented by unevenly colored clay, with olive and red-brown spots, strongly transformed by the processes of Sevastopol pedogenesis.
30.9-28.2 m Sevastopol climatolite is represented by a pedocomplex consisting of three soils. Soils are brownish-red in color. The bottom soil of the pedocomplex, st 1 is unevenly colored, red, with olive spots of Oskil material. The medium soil st 2 is the most intensively colored, brown-red color. The upper soil st 3 is red with bluish-olive spots, which is evidence of hydromorphism. All soils of the pedocomplex have a heavy clay composition, a nutty-prismatic structure with shiny faces, without visible forms of carbonates.
28.2-25.9 m Aydar climatolite is represented by unevenly colored clay. Ocher-olive layers of heavy clays alternate with reddish-brown layers of embryonic soils, iron-rich. The entire indicated thickness is without visible forms of carbonates.
25.9-24.8 m Jarkiv climatolite is represented by a pedocomplex of two red-brown soils. The lower soil is darker in color, fine-dusty, well-structured, with a clear carbonate horizon. The top soil is also red, but unevenly colored, due to inflows of gray-colored Kyzyljar clay. The soils are clayey, sandy, with a large number of floury carbonates. jr 2 25.9-25.0 m; jr 3 25.0-24.8-m.
24.8-24.4 m Kyzyljar climatolite is represented by unevenly colored clays with brown, red, and olive spots, significantly sanded, dense, cemented, reworked by soil formation processes.
24.4-21.0 m Bogdanivka climatolite is represented by a pedocomplex consisting of four soils separated by low-strength intersoil layers of brown-colored clays. The soils are dark brown with a red tint, clayey, sandy, dense, cemented, with a deep structure, with manganese dendrites on the surface of individual parts. The soils are distinguished mainly by the intensity of color and well-formed carbonate horizons with abundant floury concretionary forms in the bottom of each soil. The most intense color is typical for the lower soil of the pedocomplex, the intensity of the red color decreases towards the upper part of the pedocomplex, the upper soil has a dark brown color with brown-red spots. bd 1 -bd 2 23.7-23.5 m; bd 2 23.5-23.0 m; bd 2 -bd 3 23.0-22.8 m; bd 3 22.8-22.0 m; bd 3 -bd 4 22.0-21.8 m; bd 4 21.8-21.0 m. 21,0-19.9 m In complete sections of the Gelasian deposits of Ukraine, the Sіversk climatolite is represented by clays in the lower and upper parts, and lowstrength fossil soils in the middle part. In the studied section, the lower layer of clay is reduced and the middle part of climatolite is represented by three lowstrength soils separated by carbonate horizons. Soils are brownish-light brown and brown, clay composition. The upper part of the climatolite is composed of unevenly colored grayish-brownish-brown clay.
19.9.-17.8 Beregove climatolite is represented by a pedocomplex of three soils. A characteristic feature of the soils is a grayish shade. The bottom soil bv 1 (19.9-19.0 m) is brown, the most intensively colored, clay composition with signs of coalescence. Medium soil bv 2 (19.0-18.0 m) is brown, with a grayish tint, a prism-shaped coarse-grained structure, with numerous manganese dendrites on the surface of parts, without a clear carbonate horizon. The upper soil bv c (18.0-17.8 m) is lite-brownish-brown with a grayish tint, clayey, carbonate, but there is no carbonate illuvium.

Clay mineral composition
The mineralogical characteristics of sediments, especially the composition of clay minerals, are important for climate-stratigraphic constructions; they are indicators of the hypergenic processes and hydrothermal conditions under which the rocks were formed. Among the clay minerals, the quantitative ratios between the hydromica group minerals, montmorillonite on the one hand, and kaolinite on the other, are particularly indicative. The formation of hydromica and chloride is typical of colder climates. In warm and temperate zones montmorillonite and hydromica are formed, in subtropical and tropical zones kaolinite is formed (Yasamanov, 1986). The results of thermal analysis of fine fractions (0.006 mm) from upper Miocene, Pliocene and Pleistocene deposits in the well showed that the sediments of different age were characterised by different compositions of clay minerals. The Upper Miocene sediments are heterogeneous in terms of quantitative clay mineral content. In particular, the deposits of the Efremivka, Belbek, Ivankiv and Salgir climatolites are dominated by montmorillonite and kaolinite minerals in almost equal proportions; hydromica is recorded in insignificant amounts (Fig. 2). The deposits of the Liubymivka pedocomplex and the Oskil climatolite, as well as the Pliocene rocks, are characterised by an increased content of minerals of the montmorillonite group, which are close to such hydromica groups in quantitative content. The mineralogical composition of the Lower Pliocene soils of Sevastopol and Jarkiv climatolites contains kaolinite in small amounts. Hydromica predominates in the mineralogical composition of the Beregove climatolite soils, and montmorillonite is of minor importance (Fig. 2). Hydromica also predominates in the Eopleistocene and Neopleistocene sediments. Thus, three mineralogical layers such as montmorillonite-caolinite, hydrosludite-montmorillonite and hydrosludite are clearly traceable in the section. The mineralogical boundaries are confined to the Salgir-Liubymivka and Siversk-Beregove levels.
The spectra of samples from the interval (43.8-43.1 m), which characterize Efremivka hydromorphic soils (ef), are also dominated by coniferous pollen (mainly Pinus spp. subg. Diploxylon). The content of Picea spp. pollen, compared to the spectra of the first type, decreased to 5.6%. Tsuga pollen was not noted. The amount of the Betulaceae family pollen decreased to 4.7%, single pollen grains of Quercus sp. are fixed.
In contrast to the spectra described above, the role of herbaceous plant pollen increased somewhat (up to 17.2%). Spores (Polypodiaceae) do not exceed 1.9% of the spectra. The Ephraim soils were studied by us at later stages of research, so they are not represented on the diagram.
The distinctive feature of the spectra, which characterize the clay layer (37.2-36.7 m) between the second (iv 2 ) and the third (iv 3 ) soils from the bottom, is the leading role of herbaceous pollen (58.7-60.7%), mainly due to the representatives of the Asteraceae family (36.0-38.6%). The pollen of Chenopodiaceae is 10.6-11.5%, Poaceae is 5.0-5.3%. Pollen grains of Polygonaceae, Ranunculaceae, Plantaginaceae, Apiaceae are rare. The group of tree species (35.2-36.1%) is dominated by Pinus pollen (16.0-21.5%). Picea spp. pollen is 4.9-6.1%. Compared to the previous spectra, the role of broad-leaved species pollen has decreased, and its taxonomic composition has significantly decreased. Among this group, only the pollen of Quercus sp. (1.6-2.6%) and Tilia cf. сordata Mill (0.8-1.8 %) are noted. Thermophilic species are represented only by the pollen of the Moraceae family plants (0.8-1.8%). A number of spores also decreased (1.6-2.6%).
It was not possible to obtain a spore-pollen spectra from the uppermost soil (iv 3 ) of the Ivankiv pedocomplex (36.7-36.2 m) but the number and the taxonomic composition of the determined pollen provide the ability to state that these deposits contain more pollen of broad-leaved and thermophilic plants compared to the clay layer A distinctive feature of the spore-pollen spectra, which characterize the Salgir (sg) climatolite (36.2-33.9 m), is the dominance of herbaceous plant pollen (up to 76.2%) as well as its notable taxonomic diver-sity (Fig 3). This group is dominated by the pollen of the Asteraceae family (24.4-39.2%). Compared to the spectra from the Ivankiv pedocomplex, the role of Chenopodiaceae (12.7-16.8%) and Poaceae (5.7-6.8%) pollen increased. Cyperaceae, Lamiaceae, Plantaginaceae, Ranunculaceae, Apiaceae, and Rubiaceae pollen is constantly present in all spectra. Single pollen grains of Cannabaceae, Solanaceae, Brassicaceae, and Urticaceae were also noted. The pollen of coastal aquatic plants (Typha sp. and Sparganium sp.) does not exceed 1.8%. Compared to the Ivankiv spectra, the role of spores decreased by 0.8-1.9%. Most often, these are leguminous forms of the Polypodiaceae family, but single Sphagnum sp. and Bryales.
Despite the general features of the Salgir spectra described above, there are some differences regarding the spectra from Salgir clay samples directly and the spectra corresponding to the embryonal soil in the middle part of the Salgir climatolite. In particular, in the spectra obtained from Salgir clay, the pollen of woody tree species is 21.4-29.5%. Pinus spp. pollen does not exceed 16.5%. Pollen grains of Picea spp.
Characteristic features of the spore-pollen spectra from the bottom soil (lm 1 ) of the Liubymivka pedocomplex (33.9 -33.6 m) are a slight predominance of the pollen of woody tree species (up to 51.9%) and, at the same time, a variety of forbs, an increase in the amount of the pollen of deciduous plants of the temperate zone. Conifers dominate among tree pollen. In this group besides Pinus sp. sect. Eupitys Spach., pollen grains of Pinus minutus Zakl., Pinus sp. sect. Cembrae Spach., P. sp. sect. Strobus Shaw were also noted. However, such a species diversity of pine pollen as in the spectra of the Ivankiv complex was not recorded. Picea sp. sect. Eupicea Willkm. and Picea sp. pollen grains does not exceed 4.8%. Alnus cf glutinosa (L.) Gaertn., Alnus cf. incana (L) Willd, Betula cf. pubescens Ehrh, Betula sp., Quercus cf. robur L., Quercus sp. pollen dominate among deciduous plants. Pollen grains of Alnaster sp., Ulmus cf. laevis Pall. Salix cf. caprea L. were also determined. Moraceae pollen is singly noted. The group of herbs is represented variously: Chenopodiaceae, Asteraceae, Poaceae, Polygonaceae (predominant) as well as Cyperaceae, Apiaceae, Brassicaceae, Rosaceae, Sparganiaceae. Spores belong to Lycopodium sp., Polypodiaceae and Sphagnum sp.
The spore-pollen spectra from the second lower (lm 2 ) (33.4-32.6 m) and upper (lm 3 ) (32.6-31.2 m) soils of the pedocomplex are quite similar. Among the features of these spectra, the following can be included: a slight predominance of herbaceous pollen (57.3-64.2%), which belongs to mainly plants of the Chenopodiaceae, Asteraceae, and Poaceae families; the constant presence of pollen grains of coastal aquatic plants (Typha sp., Sparganium sp., Potamogeton sp.) as well as the belonging of Pinus pollen mainly to the Diploxylon subgenus. Finds of Pinus sp. sect. Cembrae Spach. and P. sp. sect. Strobus Shaw pollen are rare. It is also necessary to note the presence of Sphagnum sp. in the composition of the spectra. The deciduous pollen group is dominated by the representatives of plants of the temperate zone: Alnus spp. (0.0-2.8%), Betula spp. (1.9-2.9%) and Alnaster sp. Single pollen grains of Quercus spp., Tilia cf. cordata and shrubs of the Rosaceae family were not noted in all spectra.
In the investigated well, the Oskil (os) clays (31.2-30.9 m) were significantly reworked by the processes of Sevastopol pedogenesis. According to the palynological data, the Oskil deposits can probably be characterized only by the spectrum of the sample from the depth of 31.1 m. In its composition, compared to the spectra of the Liubymivka complex, the role of tree pollen increases (up to 41%), mainly at the expense of conifers. Its composition has the lowest content of grass pollen, the highest amount of pollen from the Asteraceae family, Chenopodiaceae, and Artemisia genus, as well as the lowest amount of tree pollen.
In the composition of the spore-pollen spectra, which characterizes the clay layer between the lowest (st 1 ) and middle (st 2 ) soils of the Sevastopol pedocomplex (a depth of 30.2-30.0 m), herbaceous plant pollen prevails (67.7%). Compared to the spectra described above, the role of Chenopodiaceae pollen increased to 23.4% (on the other hand, in the spectra from the bottom soil, the pollen of plants of this family was in the range of 8.5-11.0%). Asteraceae pollen is 26.4%, Poaceae is 7.5%, Polygonaceae is 5.3%. Apiacee and Ranunculaceae pollen grains were also noted. Spores were not found. Tree pollen (31.6%) is not very diverse: Pinus spp. (18.8 %), Picea spp. (6.8 %), as well as single pollen grains of Abies, Alnus spp. (2.3%), Betula sp., Tilia cf. cordata Mill., and Moraceae.
Spore-pollen spectra characterizing the second soil (st 2 ) from the bottom of the pedocomplex (30.0-29.0 m) are of the forest-steppe type. A significant diversity of Pinus pollen types (29.4-28.8 %) was noted in the spectra composition, while spruce pollen is absent. The pollen of broad-leaved species such as Quercus cf. petraea Liebl., Q. cf. robur L., Q. cf. pubescens Willd., Quercus sp., Fagus sp., Carpinus cf. betulus L., Tilia cf. platyhyllos Scop., Juglans sp., Moraceae, Corylus cf. americana L., and Elaeagnus sp. plays a significant role in the spectra composition. Compared to the spectra from the lower part of the pedocomplex, the group of forbs is more diverse. At the same time, spores of Sphagnum sp. and Polypodiaceae do not exceed 1.4%.
From the upper soil (st 3 ) of the Sevastopol pedocomplex (29.0-28.2 m), only one spore-pollen spectra was obtained, in which the pollen of tree species is 49.4%. Compared to the spectra from the previous soil, the amount of Alnus spp. and Betula spp. pollen increases, while the amount of the pollen of broadleaved species decreases. Only single pollen grains of Quercus spp. and Carpinus cf. betulus L were noted in this group. Among the pollen of herbaceous plants, the participation of forbs decreases.
The Jarkiv (jr) pedocomplex (25.9-24.8 m) is characterized by only two spore-pollen spectra. Usu-ally, the Jarkiv deposits remain the least characterized palynologically compared to other Pliocene rosks. This may be related to the lithological features of the Jarkiv rocks. Strong fertilization and a high degree of carbonation, on the one hand, do not contribute to the good preservation of pollen, and, on the other hand, significantly complicate the extraction of pollen and spores from the rocks. In addition, according to paleopedological data, the Jarkiv rocks were formed in conditions of alternating moistening and aridization, which also had a negative effect on the preservation of palynomorphs. The tree pollen in the composition of the established spectra is 21.9-23.2%. Pollen grains of Pinus do not exceed 16.7%. Among the group of deciduous species, pollen grains of Quercus sp. (1.8-2.6%) and Juglans sp. (1.8 %) predominates. The single pollen of Betula sp., Fagus sp., Tilia cf. cordata Mill., Moraceae, and Corylus sp. is also noted. Among the group of herbaceous pollen (73.1-74.5 %), pollen grains of Asteraceae, Chenopodiaceae, and Polygonaceae dominate. Poaceae pollen is 2.6-3.6%, and single pollen grains of Apiacee, Lamiaceae, Plantaginaceae also occur. In comparison to the spectra of the Aydar climatolite, the spores of Polypodiaceae and Lycopodium sp. (1.8-2.7%) were noted.
The spore-pollen complex of the Kyzyljr (kz) climatolite (24.8-24.4 m) is of the forest-steppe type (Fig 3). A characteristic feature of the spore-pollen spectra from the bottom soil of the Bogdanivka pedocomplex (bd 1 ), the interval of 24.4-23.7 m, is the leading role of woody tree pollen (53.5-64.9%) and a significant increase in the number of spores (up to 12 ,3 %) represented in quite a variety: Polypodiaceae, Sphagnum sp., Bryales. Pinus spp. predominates among tree pollen but the pollen grains of Pinus minutus Zakl. and P. sp. sect. Taeda Spach. are not already marked. The content of Pinus sp. sect. Strobus Shaw. and P. sp. sect. Cembrae Spach. pollen does not exceed 4.0%. Picea sp. sect Eupicea Willkm pollen is 0.8-1.8% in the spectra. The pollen of broad-leaved species does not exceed 2.5% and refers mainly to Quercus sp. and Tilia cf. cordata Mill. In some spectra single pollen grains of Alnus sp., Corylus cf. avellana L. Moraceae are noted. Betula spp. pollen is 3.3-5.1%. No significant taxonomic diversity was recorded among the pollen of herbaceous plants (25.4-34.9%). The representatives of the Asteraceae (8.2-11.7%), Chenopodiaceae (15.0-11.1%) and Polygonaceae (up to 5.8%) families predominate. The pollen of Poaceae, Ranunculaceae, Brassicaceae, and Typhaceae was also noted.
The spore-pollen spectrа, which characterizes the clayey layer between the lowest (bd 1 ) and the second from the bottom (bd 2 ) Bogdanivka soils (23.7-23.5 m), according to the pollen ratios of the main groups of plants, is near to the spectra described above from the lower soils (bd 1 ). However, compared to the spectra that characterize the bd 1 soil, the amount of Betula spp. pollen increased (up to 5.1%), Poaceae -up to 4.3%, the count pollen grains of broad-leaved species decreased. Only one spore of Sphagnum sp. was noted.
The spore-pollen spectra from the second soil from the bottom (bd 2 ) of the Bogdanivka pedocomplex (23.5-23.0 m) are of the forest-steppe type. They are distinguished from the spectra described above by the increased percentage content of herbaceous plant pollen (49.9-53.8%), and also its taxonomic diversity is noticeable. In addition to the dominant pollen of the families Chenopodiaceae (18.3-20.5%) and Asteraceae (16.7-15.6%), the role of Poaceae increased to 7.8%. Forbs are represented by the pollen of Cichoriaceae, Apiaceae, Polygonaceae, and Ranunculaceae. The content of spores (Polypodiaceae and Sphagnum sp.) decreased to 1.9% compared to the spectra from the lower part of the section. Wood tree pollen is represented by Pinus spp. (35.4-41.7%), Picea sp. sect Eupicea Willkm, P. sp. sect. Omorica Willkm in small quantities (0.7-1.7%), Alnus spp., Betula spp., Tilia cf. cordata Mill., and Moraceae.
The spore-pollen spectra from the intrasoil layer (23.0-22.7 m) has transitional features between the spectra of bd 2 and bd 3 soils. In particular, in the described spectra, the role of tree pollen increased to 69.0% compared to bd 2 soil while the taxonomic composition of the pollen of this group as well as the pollen of herbaceous plants did not change.
At the same time, the spectra from the third Bogdanivka soil from the bottom (bd 3 ) (22.7-21.9 m) are characterized by the impoverishment of the taxonomic composition of pollen. The pollen group of woody species makes up 78.9-84.9% of the spectra and is mainly represented by Pinus spp. and sometimes also by Picea sp. sect Eupicea Willkm. One pollen grain of Tilia cf cordata Mill. was noted only in the spectra from a depth of 22.1 m. and Betula sp. in the spectra from a depth of 22.5 m. The pollen of herbaceous plants also does not differ in significant diversity and mainly belongs to the Chenopodiaceae and Asteraceae families. Spores (Polypodiaceae and Sphagnum sp.) do not exceed 1.8%.
In the spore-pollen spectra that characterizes the clay layer (see 21.9-21.7 m) between bd 3 and the uppermost soil (bd 4 ,) of the pedocomplex, herbaceous plant pollen, which mainly belongs to plants of the Chenopodiaceae and Asteraceae families, dominates (68%), and the content of forbs pollen does not exceed 3%. Wood pollen belongs mainly to Pinus sp. subg. Dipoxylon Koehne. Deciduous plants are represented by the pollen of Alnus sp. and Betula sp. (a total of 3.6%).
The spore-pollen spectra from the uppermost soil (bd 4 ) of the pedocomplex (21.7-21.0 m) are characterized by almost equal ratios of pollen of woody tree species (49.5-50.8%) and herbaceous plants (47.0-48.8%). Single pollen grains of Celtis sp. and Juglans sp. were noted in the group of thermophilic plants as part of the spectra. The Betulaceae family is represented by birch and alder pollen. Asteraceae (18.3-21.2%) and Chenopodiaceae (13.2-14.2%) pollen prevails in the group of herbaceous plants. Pollen content of Artemisia sp. is reaches 6.1%, Poaceae is 7.0%, and Polygonaceae is 4.1%. Single pollen grains of Cyperaceae, Apiaceae. Typhaceae, and Alismataceae are noted. The described spectra have a certain similarity with the spectra of the lowest soil of the pedocomplex (bd 1 ), with the exception of the insignificant content of spores (0.8%), while their amount reaches 12% in the spectra of bd 1 soil.
In addition to the specified differences in the composition of the described spectra from different soils of the Bogdanivka climatolite, the composition of the spore-pollen complex clearly shows general features of the complex as a whole. First of all, this is a small amount of pollen from thermophilic and broad-leaved species in the spectra. The group of deciduous species is mainly represented by the pollen of Alnus, Betula, and Quercus with the participation of single pollen grains of Tilia cf. cordata, Corylus sp., and Moraceae. A peculiarity of the complex is also the low content of forbs pollen, which reaches only 6% in one spectra, and usually 2.4-3.6%. Thus, the described complex is characterized by a relative impoverishment of taxonomic composition compared to the complexes of other Pliocene climatolites, as well as a small content of the pollen of thermophilic and broad-leaved plants.
The spore-pollen spectra characterizing the lowest intra-Siversk soil (21.0-20.8 m) is significantly different from the spectra of the upper Bogdanivka soil, primarily, by the ratio of the pollen of woody species (76.6%) and herbaceous plants (21.8%). Compared to the spectra of the upper Bogdanivka soil, the content of Chenopodiaceae pollen decreased by more than two times (5.9%), the content of Asteraceae pollen also decreased up to 14.3%, and only one Poaceae pollen grain was noted. Pinus spp. dominates among tree pollen (65.8%). Compared to the upper Bogdanivka spectra, the amount of Picea sp. pollen increased up to 5% and Betula sp. up to 3.4%. Pollen grains of Alnus sp., Quercus cf. robur L., and Corylus cf. avellana L are noted.
The spore-pollen spectra that characterize the second intra-Siversk soil from bottom (20.8-20.4 m) are similar in taxonomic composition to the spectra corresponding to the first soil from the bottom. They differ only by a slight reduction in the pollen of woody tree species (60.8-67.4%) and, accordingly, by some growth in the pollen of herbaceous plants (29.8-38.6%).
In the spore-pollen spectra, which characterize the uppermost intra-Siversk soil (20.4-20.2 m), a slight predominance of herbaceous plant pollen (51.3%) was noted. Asteraceae pollen is 19.5%, Poaceae is 3.4%. Pollen grains of Liliaceae, Apiaceae, and Sparganiaceae were noted. Among the group of woody tree pollen (45.4%), some changes were also observed. In particular, the content of Betula sp. pollen, compared to the spectra described above, decreased to 1.7%, and at the same time, the amount of pollen of broad-leaved and thermophilic plants such as Quercus sp., Tilia cf. cordata Mill., Ostrya cf. carpinifolia Scop increased (3.3%). Pollen of Pinus spp.and Picea sp. sect. Eupicea Willkm is 38.7% and 1.7%, respectively.
In the spore-pollen spectra, which characterize the bottom soil (bv 1 ) of the Beregove pedocomplex (19.9-19.0 m), the pollen of tree species prevails. Compared to the spectra from the Bogdanivka and Siversk sediments, the role of pollen from deciduous plants increases (up to 7.4%), especially due to the pollen of broad-leaved species, which makes up 4.5-5.0% in the spectra. In this group, the pollen of Tilia cf. cordata Mill., Quercus sp., Ulmus cf. laevis Pall., and Fagus sp. was noted. Shrub pollen belongs to Corylus sp. The content of pollen of the Betulaceae family plants does not exceed 2.2%. The pollen of herbaceous plants (36.8-40.3%) is represented by Chenopodiaceae, Asteraceae, Poaceae, Ranunculaceae, Plantaginaceae, Sparganuaceae, and Potamogetonaceae. Spores (8.6-9.5%) mainly belong to the Polypodiacea family and less often to Lycopodiaceae.
The spore-pollen spectra, which characterize the second soil (bv 2 ) from the bottom of the pedocomplex (19.0-18.0 m), are also of the forest-steppe type, but the amount of herbaceous plant pollen increases in its composition mainly due to the forbs of rich taxonomic composition. In addition to the pollen of Chenopodiaceae (18.5%), Asteraceae (15.7%) and Poaceae (2.7%), the pollen of the families Cyperaceae, Polygonaceae, Cichoriaceae, Liliaceae, Lamiaceae, Ranunculaceae, Fabaceae, Apiaceae are constant components of the spectra. Aquatic and coastal aquatic plants are represented by the pollen of Typha sp. and Sparganium sp. Among the spores, Polypodiacea dominates (up to 6.8%) and less often Sphagnum sp. The group of tree pollen (44.0-44.7%) is also diverse. Coniferous pollen belongs mainly to Pinus sp. sect. Eupitys Spach., and pollen grains of Pinus longifoliaformis Zakl., Pinus sp. sect. Cembrae Spach., P. sp. sect. Strobus Schaw are noted in a small amount (up to 1%). Picea pollen grains belong mainly to the subgenus Eupicea. In addition to the pollen of conifers and small-leaved species, the spectra include the pollen of broad-leaved species and shrubs of a rather diverse taxonomic composition: Quercus cf. robur L., Quercus sp., Carpinus cf. betulus L., Tilia cf. cordata Mill., Tilia cf. platyphyllos Scop., Hedera sp. and Corylus cf. avellana L.
The spore-pollen spectra from the upper soil (bv 3 ) of the pedocomplex (18.0-17.8 m) contains approximately an equal amount of the pollen of woody species (46.8%) and herbaceous plants (48.3%), but compared to the spectra described above, a decrease in the pollen of broad-leaved species can be traced to 2.8%. In this group, only the pollen of Quercus cf. robur L. and Tilia cf. cordata Mill. was noted. Among conifers, as in the previous spectra, the pollen of Pinus spp. prevails (38.9%), and pollen grains of Picea spp. make up 2.9%. Small-leaved species are represented by the pollen of Betula sp. (1.4%) and Alnus sp. (0.8%). Certain changes were also observed among the pollen of herbaceous plants. In particular, the amount of the pollen of forbs decreased to 3.6. In addition to the dominant pollen of Chenopodiaceae (21.4%), Asteraceae (17.1%) and Poaceae (4.3%), single pollen grains of Cyperaceae, Liliaceae, Ranunculaceae, Sparganiaceae, and Potamogetonaceae were noted. Spores (Polypodiacea and Sphagnum sp.) make up 5%.
It was established (Sirenko, 2017) that the palynological characteristics of the subaerial Upper Cenozoic deposits of each studied section have their individual features associated with the geographical and geomorphological conditions of their location. Individual features of the spore-pollen complexes of the Miocene-Pleistocene deposits of the studied section are the constant presence (in various amounts) of spruce pollen in most spectra and an increased number of spores. These features are probably associated with the relatively low hypsometric location of the studied well. All the established and described spectra of the Miocene-Pleistocene deposits of the investigated well are characterized by a more impoverished composition and lower content of broad-leaved and thermophilic plants compared to the complexes and spectra characterizing rocks of the same age in the Donetsk folded structure and the southern part of the Ukrainian Shield (Sirenko,2017, Vozgrin, Sirenko, 1990, which is probably related to plant zonation as well as the fact that the studied section is located on the northern slope of the watershed.
All the Upper Miocene-Gelasian deposits uncovered by the well were characterized in detail by palynological results.
The spore-pollen spectra from the Efremivka soils are similar in composition to those that characterize the Efremivka soils of well 86 near the village of Efremivka in Kharkiv Region (Vozgrin Sirenko,1989).
The spectra from the Belbek deposits are closest to the spectra from the coeval deposits of well 86 (Vozgrin Sirenko, 1989). The described spectra differ from the spectra from the Belbek deposits of the Donetsk folded structure (Vozgrin Sirenko, 1990) by a lower content of pollen from thermophilic and broadleaved species. In general, the Belbek deposits are not yet sufficiently characterized palynologically in all the studied sections. This is probably related to their lithological composition. Usually, rocks in which a large percentage of kaolin is determined in the mineralogical composition contain an insignificant amount of pollen and spores. Due to the insufficient palynological study of the marine Maeotian and the lower part of the section of the Pontian deposits of Ukraine, it is still difficult to compare the Efremivka and Belbek climatolites with their age analogues of the Miocene marine section of Ukraine (Sirenko, 2016).
According to the dominance of pine pollen as well as their species diversity, taxonomic composition of the pollen of deciduous plants, and the ratio of pollen grains of woody and herbaceous plants, the spore-pollen complex of the Ivankiv climolite of the studied section is similar to the complex from the Ivankiv deposits of the Artemivsk (Bakhmut) section (Vozgrin, Sirenko, 1990), as well as rocks of the same age from well 86 (Vozgrin, Sirenko, 1989).
The Salgir spore-pollen complex of the studied section is similar to the one from the Salgir deposits of well 86 in terms of the ratio of tree and herbaceous plant pollen, taxonomic composition, and the features of spore-pollen spectra from the intra-Salgir embryonic soil (Vozgrin, Sirenko 1989).
According to the decrease in the role of pine pollen, the increase in the amount of the pollen of deciduous plants, mainly due to the pollen grains of Quercus, Alnus, Betula, Salix, as well as grasses, the Liubymivka spore-pollen complex correlates clearly with the complexes from the Liubymivka deposits of both the Dnieper-Donetsk depression (well 86) and the Donetsk folded structure (Artemivsk (Bakhmut) section). (Vozgrin, Sirenko, 1989, 1990. In terms of the depleted taxonomic composition, the spore-pollen spectra of the Oskil climatolite is close to the complex from the Oskil sediments of the Donetsk folded structure (Vozgrin Sirenko, 1990). According to palynological data, the Ivankiv, Salgir, Liubymivka, and Oskil climatolites are correlated with the Pontian deposits of the marine Miocene section of Ukraine (Sirenko, 2016).
The second optimal soil of the Sevastopol pedocomplex is represented and palynologically characterized most completely in the studied section. According to the forest-steppe type, the taxonomic diversity of the pollen of both woody and herbaceous plants, a high percentage of the pollen of plants of the moderate-warm zone and thermophilic species, the spore-pollen spectra characterizing it correlate with the spectra from the middle Sevastopol deposits of well 86 and Artemivsk (Bakhmut) section). (Vozgrin Sirenko, 1989, 1990. With respect to the depleted, relative to the Sevastopol complex, composition of the pollen of plants of the moderate-warm zone, the reduced number and taxonomic diversity of grasses, the spore-pollen spectra from the Jarkiv pedocomplex correlate with the Jarkiv spore-pollen complex of the section near Artemivsk (Bakhmut) (Vozgrin, Sirenko, 1990). According to palynological data, the Sevastopol, Aydar and Jarkiv climatolites are compared with the Kimmerian deposits of the Pliocene marine section of Ukraine (Sirenko, 2016).
The spore-pollen spectra characterizing the Kyzyljar climatolite are distinguished by the depleted taxonomic composition of both tree and grass pollen, and the dominance of pollen from Pinus spp. subg. Diploxylon Koehne. among the pollen of tree species, correlate clearly with the spectra from the Kyzyljar deposits of the Donetsk folded structure (Sirenko, 2017). Depending on the geomorphological location of the sections, the pollen of pines or herbaceous plants may predominate in the spectra, but the mentioned common features of the Kyzyljar complex are always determined.
Two rhythms reflecting the conditions of the formation of the Bogdanivka pedocomplex are clearly traceable by the palynological data (Sirenko, 2017).
The first rhythm is the time of formation of the lower and the second lower soil of the Bogdanivka pedocomplex. The spore-pollen spectra characterizing these deposits are predominantly of the forest-steppe type, sometimes with a predominance of tree species pollen. Apart from pine pollen, the spectra usually include a small amount of the pollen of broad-leaved and thermophilic species. The second rhythm is the time of formation of the upper soils of the pedocomplex. The spore-pollen spectra from these deposits have very poor taxonomic composition with domination of either pine pollen or the representatives of the Asteraceae and Chenopodiaceae families depending on the geomorphological and geographical location of the sections. A similar pattern is traceable both for the Bogdanivka spore-pollen complex of the studied section and for the complexes of the Bogdanivka deposits from other regions of Ukraine (Sirenko, 2017).
Thus, the Bogdanivka spore-pollen complexes can be a benchmark for the stratification of the continental Pliocene sections by palynological data.
The palynological data provide a good correlation between the Siversk and Beregove climatolite deposits, which correlate with the ISS Gelasian. In particular, the palynological data substantiate that the Siversk climatolite in the studied section is represented by three soils and a clay interbed separating the Siversk and Beregove deposits. It was established (Sirenko, 2017) that the Siversk climatolite has a complex structure, which we traced in the study of the Siversk de-posits of the Donetsk folded structure. The distinctive features of the spore-pollen spectra characterizing the Siversk clays and fossil soils were also characterized (Sirenko, 2017). In the studied section, we also traced the pattern established in the previous stages of the research for Siversk deposits from other regions concerning the fact that spore-pollen spectra from the intra-Siversk soils contain more pollen of broad-leaved and thermophilic species compared with the spectra of the Bogdanivka soils. The spectra characterizing the intra-Siversk soils differ from such Siversk clays by an increase in the number and taxonomic diversity of tree species pollen and, among this group, pollen grains of plants of the moderate-warm zone and thermophilic species.
The spore-pollen complex from the Beregove deposits of the studied section is well correlated with the same-age complexes of the Donetsk folded structure by the peculiarities of changes in the spectra characterizing the early and the late optimum soils, as well as the final stage of soil formation (Sirenko, 2017).
In particular, the common features of the compared complexes are the following: the predominance of the pollen of woody moisture-loving species in the spectra characterizing the early optimum soil, the forest-steppe type of spectra characterizing the late optimum soil, in which a significant percentage belongs to the pollen of forbs of various taxonomic composition and pollen grains of deciduous plants, in particular, heat-loving; the lunch taxonomic composition of the spectra from the soil of the final stage of pedogenesis. According to palynological data, the Kyzyljr and Bogdanivka climatoliths are correlated with the lower Kuyalnitk deposits of the Pliocene marine section of Ukraine, the Siversk and Beregove climatolites are compared with the upper Kuyalnik deposits (Sirenko, 2016).

The main results of paleomagnetic studies
The analysis of the results of the magnetic cleaning of the samples made it possible to establish layers with normal, reversed, and indeterminate magnetization of the deposits. The nature of the geomagnetic field during the formation of each climatolite (from top to bottom) can be represented as follows. The upper part of the section is composed of normal polarity rocks, represented by layers of fossil soils, loess loams and loess of the Holocene, Prychornomorya, Dofinivka, Vytachiv, Uday, Pryluky, and upper part of the Dnipro climatolites. Starting from the middle part of the Dnipro climatolite to the upper part of the Zavadivka climatolite, the rocks are characterized by negative inclination (Fig. 4). The rocks of the Tyligul, Lubny, Martonosha, and most part of the Shyrokyne climatolithes are normally magnetized, with inclination values ranging from 40º to 50º in most cases. The lower part of the Shyrokyne climatolite is negatively magnetized.
The layer of rocks that lies below and represented by the Illichivsk, Kryzhanivka, Beregove, and Siversk climatolites is characterized by alternating reversed and indeterminate polarity rock layers with a predominance of reversed magnetized areas in terms of total strength.
Below, in the depth of 21.0-24.6 m, a layer of predominantly normal magnetized rocks of the Bogdanivka and the uppermost part of the Kyzyljar climatolites can be traced. In the lower part of the Bogdanivka pedocomplex, areas of reversed polarity rocks were recorded at two levels of sampling: one in fossil soils, the other in loess loams.
In the depth of 24.6-36.2 m, the section is represented by the layering of clays and fossil soils of different strengths: the lower part of the Kyzyljar climatolite, the Jarkiv, Aydar, Sevastopol, Oskil, Liubymivka, and Salgir climatolites, which is characterized by the alternation of reverse, normal, and indeterminate magnetized areas with a predominance of the total by the power of indeterminate magnetized rocks.
The layer of fossil soils and clays of the Ivankiv, Belbek, and Efremivka climatolites, located in the depth range of 36.2-43.8 m, are characterized mainly by normal magnetization. Only in the middle part of the Belbek climatolite a 1 m thick area of reversed polarity fossil soils and clays was recorded. The section ends with clayey sands and sandstones of reversed polarity that lie below the clayey sands of the Efremivka climatolite.
Thus, based on the results of the research, a detailed record of the change in the geomagnetic field during the formation of the studied deposits was obtained, which made it possible to construct a paleomagnetic section, which reflected the area with normal, reversed and indeterminate polarity of the rocks (Fig. 4). According to the nature of their distribution, this section can be tied to the Cox scale, which presents the levels of changes in geomagnetic polarity for the last 5 million years. In the upper part of the Ivankiv сlimatolite, at a depth of 36.2 m, there is a boundary between the Gilbert and the Epoch 5. The time of formation of normal polarity fossil soils and clays traced in the interval 36.0 -43.8 m is compared with the Epoch 5.
Below the section, deposits are traced, the time of their formation is correlated with the Epoch 6 of polarity. The boundary between the 5 th and 6 th epochs of the geomagnetic field is fixed by the reversed polarity of clayey sands N 1 3 . Summarizing the obtained results, it is worth noting that at the current stage of research there is no generally accepted idea about the position of the strata of marine and continental sections of the upper Miocene and Pliocene in the magnetochronological scale. Such discrepancies are well illustrated in the publication (Pevzner, Semenenko, Vangengejm, 2003) (Fig. 5).  Pevzner, Semenenko, Vangengejm, 2003)