The territory of Ukraine is characterized by the diversity of geological structures the composition of which is a reflection and consequence of the complex and long (over 3.8 bln years) history of the geological development. Belonging to two major geostructural types of the continental earth crust, they correspond with platform and folded regions.The crystalline basement of the platform region consists of highly dislocated metamorphic complexes and complexes of intrusive formations of the Archaean-Mesoproterozoic (structures of the East European platform), Neoproterozoic-Early Palaeozoic (parts of the West European platform and Carpathian foredeep), and Neoproterozoic-Early Triassic (Scythian plate) ages. The sedimentary cover consists of sedimentary and volcanogenic strata about 300 m thick on the Ukrainian Shield and 10–15 km in the Dnipro-Donets’ and L’viv depressions and Dobruja and Indol-Kuban’ foredeeps.

Tectonics. Within the boundaries of the East European platform (EEP), such main structures are distinguished: the Ukrainian Shield (US), the Volyn’-Podillia plate (VPP), the Dnipro-Donets’ depression (DDD), the South Ukrainian monocline (the Black Sea coastal depression), and the southwestern slope of the Voronezh massif.

The US is a con formation of the Preriphean cratonization, though as a structure it formed in the Early Palaeozoic, simultaneously with the formation of the DDD and the Black Sea depression. It extends over more than 1 000 km from the southeast to the northwest, with the maximum width of 250 km and the minimum width of 50 km. The US is inhomogeneous in its deep structure and compositional substance complexes and consists of the Podillia granulitic, Buh-Ros’ granulito-amphibolic, Dnipro granite-greenstone, Volyn’ and Kirovohrad granite-gneiss-schistose, and Azov granulite-diaphtorite megablocks, the Volyn’-Polissia volcanic-plutonic belt, and interblock suture zones.

The VPP is a platform megastructure with the crystalline Preriphean basement and folded Early Palaeozoic foundation (in the outermost west) and the multilayered sedimentary cover of Phanerozoic formations. In its composition the Polissia saddle, the North Ukrainian horst zone, the Volyn’-Polissia foredeep, the Kovel’ bench, the L’viv depression, and the Volyn’-Podillia monocline are distinguished.

The DDD is based on the 270-km wide aulacogene of the Devonian formation that stretches for 800 km. In the aulacogene basement lie Precambrian complexes divided by regional submeridional faults into blocks that plunge in the direction of the Donets’ folded structure (DFS). In its central part, the aulacogene is filled with Devonian sediments and partly with coal measures that are transgressively overlapped by upper-Visean and more recent formations.

In the utmost southernmost west of Ukraine and Moldova is the Palaeozoic foredeep, whose deposit edges are made by faults with an amplitude of 1 000–2 000 m, which gives grounds to regard it as a graben.

The South Ukrainian monocline, more known as the Black Sea coastal depression, is also inhomogeneous in its structure. In the western part of its basement lie Vendian-Palaeozoic deposits and in the central, mostly post-Jurassic. The depression of the Cretaceous-Palaeogene age formed as a structure that inherited strikes of the Mesozoic grabens of dobruja and Fore-Syvash regions. Its northern edge is confined to the US southern slope and the southern borders upon the Central Crimean uplift zone and the Scythian plate.

Folded regions that surround the EEP and epi-Palaeozoic platform structures from the southwest, south, and southeast formed over a long period of time. the DFS (the main phase of folding is Saalian) and the Prut bench of Northern Dobruja, the formations of which underwent metamorphism and folding in the Bretonian phase and fold-fault redeformations in the time of the late Cimmerian tectogenesis, belong to the palaeozoids (Hercynides).

The DFS is a Hercynian structure, unique in Europe, with the extremely deep (to 20 km) bedding of the basement. It is represented by linear folds with the Main anticline in the centre. The distinguishing feature of the structure is its northeastward thrust with the retrothrust in the opposite direction.
Another region of the folded Hercynides is a part of Northern Dobruja known as the Prut bench. The inner composition of its greenschists, metamorphism and folds of which are associated with the Bretonian phase, is complex, with highly developed overthrust fold deformations of the late Cimmerian tectogenesis. The Marmarosh massif structures also belong to the Variscides. In them, the Riphean-Early Palaeozoic metamorphic formations underwent folding in the Early Carboniferous.

The Mountainous Crimea (the main tectonic phase is Late Cimmerian) and its eastern buried continuation on the Kerch Peninsula (main folding phases are Laramian and Styrian) belong to the region of the Cimmerian-Alpine folding. To the Alpides belong the fold-nappe structure of the Ukrainian Carpathians with inner and outer flysch nappe and the Marmarosh crystalline massif, which acquired their contemporary aspect in the Middle Miocene (Carpathian phase), as well as the Precarpattia (Forecarpathians) foredeep and the Zakarpattia (Transcarpathian) inner Miocene trough.

Linear and ring structures of different type and age play a great role in the tectonic framework of the Ukrainian territory.

Geodynamics. The formation of major tectonic structures took place under different geodynamic conditions. In the Archaean period, in the boundaries of the US the geodynamic conditions of island arcs, ocean, and active continental edges were considerably developed; in the Proterozoic – the conditions of active continental edges, collisional, and of volcanic arcs. During the Phanerozoic, the formation of tectonic structures contiguous to the US took place in the geodynamic conditions of inner parts of the plates, whose edges embody continental valleys, continental rifts, the aulacogene, and intercontinental depressions.

During the neotectonic stage (Late Cenozoic-Anthropogene) the geodynamic conditions of inner parts of plates are dominating, associated with the formation of continental valleys, epicontinental sea basins, as well as epigeocynclinal orogenes that correspond with collisional zones of interplate mobile belts. In the platform part of the territory of Ukraine the total amplitudes of neotectonic movements of the earth’s crust vary from +350 m to –700 m, being complexly differentiated within the zones of predominantly unidirectional (ascending or descending) and oscillatory movements of the earth’s crust, as well as tectonic structures of different types and ranks. The block movements are predominating.

In the orogenic belt of Ukraine represented by the vaulted-folded-block-napped structure of the Ukrainian Carpathians and the vaulted-block-monoclinal structure of the Mountainous Crimea, the total amplitudes of elevation make 400–2 000 m, and of subsidence in the adjacent troughs, 0 to -7 000 m.

Recent slow and rapid tectonic movements of the earth’s crust have been quantitatively estimated by instrumental measurements over the past 100–150 years. The velocities of slow movements are differentiated in the zones of inherited tectonic rising and subsidence and appearance of oscillatory movements, as well as within some tectonic structures, in particular in the zones of active faults with anomalous risings of velocity gradients. Recent rapid tectonic movements (seismic) are most pronounced in the orogenic belt and adjacent platform structures of various types. Characteristic peculiarities of the neotectonic and recent tectonic stages are: migration between zones with different types of crustal movements (unidirectional, oscillatory); quasi-periodicity of movements of the earth’s crust fixed in phases, stages, and substages that differ in the movement intensity, deformation style, etc.; manifestation of vertical and horizontal movements, as well as complication of the tectonic component of movements of the earth’s crust through halogenic, glacioisostatic, and technogenic components.

Stratigraphy. The oldest rocks in the territory of Ukraine comprise the US crystalline basement. They are represented by differently-aged complexes of sedimentary, sedimentary-volcanogenic, and volcanogenic metamorphosed formations, intrusive granitoids, and metasomatic formations. The oldest rocks belong to the Archaean acrothem that divides into eonothems: Palaeoarchaean – >3 400 mln years, Mesoarchaean – 3 400–3 150 mln years, and Neoarchaean – 3 150–2 600 mln years. The Palaeoarchaean is represented by the granulite-basite complex practically on the entire US territory, the Mesoarchaean by the gneiss-granulite complex, the Neoarchaean by the greenstone complex and sedimentary-volcanogenic formations metamorphosed in the greenschist facies of the metamorphism.

The Proterozoic acrothem also divides into three eonothems: Palaeoproterozoic – 2 600–2 000 mln years, Mesoproterozoic – 2 000–1 700 mln years, and Neoproterozoic – 1 700–570 mln years. The Palaeoproterozoic is characterized by the wide manifestation of granitization, rheomorphism, metasomatism, and basalt and granitoid plutonism processes. In the Mesoproterozoic, the tectonomagmatic activation of geoblocks consolidated in the Palaeoproterozoic occurred. At that time the Polissia volcano-plutonic belt and complex gabbro-anorthosite-rapakivigranite Korosten’ and Korsun’-Novomyrhorod plutons formed. In the Neoproterozoic, the platform regime set in throughout all the US territory with separate manifestations of volcanism and appearance of belts and some swarms of dikes. In the Neoproterozoic, between 1 000 and 650 mln years the Riphean became distinguished, and between 650 and 542 mln years – the Vendian system that divides into the Volyn’, Mohyliv-Podil’s’kyi, and Kanyliv series. Faunistic remains are already present in the Vendian sediments.

Stratigraphically, above the deposits of the Proterozoic acrothem are mainly sedimentary deposits of the Phanerozoic eonothem, the stratigraphic division of which is based primarily on studies of the stage development of different groups of the organic world. The Phanerozoic eonothem divides into the Palaeozoic, Mesozoic, and Cenozoic erathems.

The oldest system of the Palaeozoic erathem is the Cambrian one (542–488 mln years). Its deposits are prevalent on the larger part of the US eastern slope, the Volyn’-Podillia plate, and the carpathian foredeep. The Lower Cambrian is represented mainly by glauconitic sands and clays; the Middle, by sandstones; and the Upper, by aleurolites and clays. The overall thickness varies in different regions from 130–150 m to 250 m.
Deposits of the Ordovician system (488–443 mln years) are spread in general in the same regions where the Cambrian are. Limestones and carbonate sandstones 60–80 m thick predominate in their composition.

The Silurian system (443–416 mln years) is represented by limestones, marls, argillites, and clays with the overall thickness of 600–700 m. They are spread mainly on the Volyn’-Podillia plate.

Deposits of the Devonian system (416–359 mln years) are spread in the northwestern Black Sea coastal Maritime Region, the Predobrogean foredeep, the Black Sea depression, the DDD, and the Donets’ folded region. In the Lower Devonian predominate red-brown sandy-argillaceous deposits up to 450 m thick; in the Middle, dolomitic limestones, shales, and marls, 100–150 m thick; and in the Upper, limestones, saliferous and marl-anhydrite deposits with the thickness of 300–400 m on the Volyn’-Podillia plate, 1 500–2 000 m in the DDD, and over 2 500 m in the Dobruja foredeep.

The Carboniferous system (359–299 mln years) is represented by limestones, argillites, sandstones, and clays with numerous coal measures. The scheme of the system differentiation that obtained the international recognition is based on the cyclic recurrence. The system deposits are widespread in the Donets’ folded structure where their thickness reaches 10–12 km, in the Plain Crimea, the DDD, the Volyn’-Polissia and L’viv depressions, and the Predobrogean foredeep.

Deposits of the Permian system (299–251 mln years) are present in the eastern part of the Donets’ folded structure and the DDD and are represented by the limestones, dolomites, cupriferous sandstones, gypsums, and rock salt often of reddish colour, with the overall thickness to 2.5 km.

The Mesozoic erathem is represented by the Triassic, Jurassic, and Cretaceous systems. Deposits of the Triassic system (251–200 mln years) are spread in the DDD, in the northwestern Black Sea Maritime Region, the Predobrogean foredeep, the Donets’ folded structure, the Ukrainian Carpathians, and the Mountainous Crimea. They are represented by sands, sandstones, clays, siliceous schists, rarely by jasper (in the Carpathians), and marls. Their thickness in the DDD does not exceed 350 m, in the Carpathians 250 m, while in the Predobrujean foredeep is over 2 000 m. The maximum thickness is fixed in the Plain Crimea – 4 700 m.

Deposits of the Jurassic system (200–145 mln years) are widespread in the Donets’ folded structure, the Mountainous Crimea, the Predobrogean foredeep, the Ukrainian Carpathians, and Northern Dobruja. They are represented by clays, sands (often glauconite sands), marls, and limestones. Most fully they are represented in the Predobrujean foredeep, in the DDD central part and in the Crimea, where their thickness exceeds 2 000–2 500 m.

Deposits of the Cretaceous system (145–65 mln years) has the maximum thickness (2 000–3 000 m) in the DDD, the Black Sea depression, the Crimea, and the Carpathians. The Lower Cretaceous deposits are represented by sandy-argillaceous facies (flysch facies in the Carpathians), and the Upper Cretaceous, mostly by carbonate facies (except for the Carpathians) among which special place belongs to white chalk with flints, marls, and limestones with the thickness of several dozen metres in the US to 3 000 m in the Plain Crimea.

The Cainozoic erathem consists of the Palaeogene, Neogene, and Anthropogene systems. Deposits of the Palaeogene system (65–23.3 mln years) are found in the considerable part of the territory of Ukraine: the Palaeocene occur only in the DDD, the Crimea and the Carpathians, where they are represented by sands, sandstones, and conglomerations; the Eocene (sands, sandy-argillaceous layers with lignite bands, marls, clays) are abundant in the considerable part of the US; the Oligocene are abundant in the entire territory of Ukraine except the VPP. In the DDD the thickness of the Palaeogene deposits in the DDD is near 400 m, in the Carpathians (flysch layer) – to 2 000 m.

Deposits of the Neogene system (23.3–1.8 mln years) occur almost everywhere. Marine sediments (clays, limestones) take up large areas in the west and south, continental (sandy-argillaceous rocks) occur in the DDD and the US. In the Carpathians, magmatic rocks can be found. The thickness of the Neogene deposits varies from dozens to 100–150 m and over.

Deposits of the Anthropogene system (1.8 mln years – to present) are spread throughout the entire territory of Ukraine and are represented by marine (coasts of the Black Sea and the Sea of Azov), glacial (northern part of Ukraine, and along the Dnipro valley to Dniprodzerzhyns’k), alluvial (floodplain and terrace deposits), and subaerial (loesses with buried grounds) deposits. Other genetic types are spread fragmentally. Glacial deposits are represented by moraines, glacial and lacustrine-glacial sediments of two glaciations – Oka and Dnipro. Loesses cover capelike the older rocks. Their thickness varies from 5–6 to 40 and over metres.

The information on the geological structure is of great practical importance, in particular in defining the areas of formation of various mineral resources and argumentation of criteria of their search, the analysis of engineering-geological conditions and grounds and guidelines for the development of the engineering-geological environment, with relation to the estimation of its geodynamic state, developments of dangerous processes, as well as solutions of a number of geoecological problems.