Geological structure


The geological structure of the territory of Mordovia is attended by the rocks of the basement and sedimentary cover.

The Archean and Lower Proterozoic rocks of the crystalline basement on the territory of Mordovia are represented by biotite-plagioclase gneisses, shales, and magmatic rocks-granodiorites.

The Upper Proterozoic formations have been opened by supporting wells in the region of the river. Zubov Polyana village. The rocks are found on the foundation weathering crust. The lower part of the section is composed of conglomerate breccias of weathered gneisses, the upper part - sandstones. The lithological composition of the rocks indicates the continental conditions for their formation.

The Paleozoic group includes the Devonian, Carboniferous and Permian sediments.

The Devonian system is represented by the middle and upper divisions. The total thickness of sediments is up to 600 m. The interlayering of siltstones, clay sandstones, anhydrite, dolomite, marl and rarely clay is characteristic. The upper part is characterized by a rather monotonous stratum of limestones, in varying degrees dolomitized.

The coal system includes the lower, middle and upper divisions. The formations of the lower and middle sections include clays, sandstones, siltstones, limestones, marls. Deposits of the upper part of the coal system extend to the surface in the northwestern regions of the republic (along the rivers Satis, Moksha, Urkat, Si Vinh). Characteristic intercalation of limestones, dolomites and dolomitized limestones. The total thickness of Carboniferous deposits varies from 125 to 400 m.

The Perm system is represented by the lower department. Deposits have limited access to the surface only in the north-west of the republic in the valley of the middle reaches of the river. Satis and in the right bank of the middle reaches of the river. Urquat. They are represented by dolomites with interbeds of dolomitized and organogenic-detrital limestones with interlayers of gypsum, anhydrite and flint. The thickness of sediments is up to 60 m.

The Mesozoic group is represented by Jurassic and Cretaceous sediments.

Deposits of the Jurassic system are quite widely developed on the territory of the republic. On the valleys of the rivers Moksha, Sivin, Insar, as well as along the middle course of the river. Wad (in the west of the republic) they are exposed on the day surface. Faunistically characterized sediments of the middle and upper sections are distinguished, represented by a thick stratum of sandy-argillaceous formations; in the upper part, at the contact of the Jurassic and Lower Cretaceous deposits, a glauconite sand interlayer with the inclusion of phosphorite nodules is almost everywhere observed.

The chalk system includes the lower and upper divisions. The Lower Cretaceous section is composed mainly of clay sediments with thin interlayers of glauconite-quartz sands, marls, sandstones with inclusions of phosphorite nodules. Their total thickness reaches 175 m. Upper Cretaceous deposits occur in the eastern, south-eastern and southern regions of the republic. They are represented in the lower part by sands with interbeds of marls and oporny clays. The upper part of the section is composed of grayish-white chalk with interbeds of chalk-like marl. The total thickness of Upper Cretaceous sediments is up to 90 m.

The Cenozoic group is represented by Paleogene, Neogene and Quaternary sediments.

Deposits of the Paleogene system are widespread in the southern and southeastern regions of the republic. They are represented by flasks with rare diatomite lenses and interlayers of glauconite-quartz sand, interbedded with sandstones of the same composition. The thickness of sediments is up to 90 m.

Deposits of the Neogene system are found in the western and central regions of Mordovia, where the Miocene and Pliocene rocks are represented by quartz, coarse-grained, clayey and clay sands, oily, unclarified with aleurite sandstones. The thickness of the sediments ranges from 2 to 155 m.


According to geotectonic zoning, most of the territory of Mordovia belongs to the western edge of the Volga-Kama anteclise, limited in the south-west of the republic by the Ryazan-Saratov trough.

The formation of the Volga-Kama anteclise refers to the beginning of the Proterozoic. The entire period prior to the beginning of the Middle Devonian transgression, it was mainly an uplifted shield, i. the area of ​​demolition of the products of the destruction of rocks in the surrounding extensive lower parts of the platform and partly into internal cavities. Volgo-Kamskaya antekliza in the territory of Mordovia is represented by the Tokmov arch, which enters the republic with its southern end and the central part of the Sura trough.

The Tokmov arch is differentiated by a system of regional faults into a series of composite elevations, depressions and deflections. In its limits in the territory of Mordovia are three most elevated sections of the foundation, separated by shallow depressions - Tokmov and Temnikovski peaks, the Penza block. The surface of the foundation is located at absolute elevations from minus 800 m to minus 1,200 m. To the zone of the Insara valley, the foundation surface gradually sinks in the eastern and south-eastern directions from absolute marks minus 1,600 m to the Ulyanovsk-Saratov trough area.

In the watershed zone of the Vada and Moksha, the foundation surface drastically sinks to the southwest in the direction of the Ryazan-Saratov trough to minus 2 400 m. The boundary is complicated by faults laid parallel to each other.

In the rocks of the sedimentary complex, the Oka-Tsninsky, Alatyrsky and Sursko-Mokshinskiy shafts are distinguished. The Oksko-Tsninsky shaft enters the western part of the republic with its eastern wing. The Alatyr shaft covers the interfluve of Moksha and Alatyr, the Sursko-Mokshinsky Val - the interfluve of Issa, Insara and Sivini. In the nuclei of these uplifts, rocks of the Upper Carboniferous and Lower Permian often reach the surface of the day.

The eastern part of the territory of the republic is located in the area of ​​the western wing of the Ulyanovsk-Saratov syneclise. Here, powerful sequences of Paleogene and Cretaceous deposits are distributed, along which this tectonic structure is distinguished. Its origin refers to the second half of the Mesozoic, that is, to the initial phase of the Alpine folding.

The occurrence of rocks in the sedimentary cover is complicated by a multitude of breaking dislocations and zones of fragmentation. They often define a drawing of the hydrographic network.


Quaternary deposits are absent only in the most elevated areas of the Volga Upland, where the indigenous Cretaceous and Paleogene rocks form the day surface. The total increase in the thickness of the Quaternary sediments occurs as we approach the Oka-Don lowland.

The quaternary period includes the Eopleistocene (1.8-0.8 Ma), the Neo-Pleistocene (800-10 thousand years ago), and the Holocene (10,000 years ago, the present time), due to the peculiarities of the rhythm of climatic changes and the formation of surface sediments.

The Eopleistocene deposits in Mordovia are represented by alluvial sediments.

Neo-Pleistocene is divided into lower, middle and upper links.

Lower neopleistocene (800-400 thousand years ago) is characterized by alternation of interglacial and glacial epochs. Petropavlovsk, Pokrovsky, Ilyinsky, Don, Muchkap and Oksky horizons stand out. The most significant impact on the nature of the region was provided by the Don glaciation. The moraine deposits of the Don horizon are of a coarse composition, sufficiently compacted, poorly sorted, represented by boulder loam or sandy loam with the inclusion of boulder-pebble material of magmatic and metamorphic rocks, as well as fragments of local sedimentary rocks. Water-glacial deposits of the maximum glacier spread are represented by sands of gray, quartz, heterogeneous grains with interbeds of clay, gravel sand, sometimes with pebbles and boulders of eratric and local rocks. Alluvial deposits are represented by sands that are heterogeneous, cross-bedded with interlayers of clays, loam, sandy loam and gravel-pebble material. Lacustrine formations contain gray, dark gray clays with interlayers of quartz sand.

The average neopleistocene (400-130 thousand years ago) includes Likhvin interglacial and Dnieper (Moscow) glaciation. In the Moksha basin at this time alluvial-fluvioglacial and alluvial deposits of the 4th and 3rd above-floodplain terraces are formed. They are represented mainly by different-grained quartz sands with gravel and pebbles of quartz, flint, and petrified limestones.

The upper Neo-Pleistocene (130-10 thousand years ago) is represented by the Mikulino (interglacial) and Kalinin (glacial) horizons composing the second terrace above the floodplain, the Monchalovo (interstadial) and Ostashkov (glacial) horizons of the first terrace in the river valleys. They are represented mainly by sands with a rare pebble of quartzite. Sands contain rare interlayers of clay. In the bottom of the terrace alluvium, a clear layer of gravel and pebbles of various species or a layer of coarser gravel sand is clearly visible.

Holocene is the last interglacial. In the river valleys at this time, alluvium floodplains are formed - sands with subordinate interlayers of loam and clay, pebbles and gravel. In the watershed spaces, eluvial-deluvial formations are accumulated-loams, in southeastern Mordovia-loams with crushed stone. In the valleys of the rivers Moksha, Sura, Alatyr, Vada, Partsy, less often on the slopes and low watersheds of water-glacial and secondary moraine plains, marsh sediments are widespread.

Pre-Quaternary deposits


Tectonic structures of the foundation


Tectonic structures of the sedimentary cover


The thickness of the Neogene-Quaternary sediments


Quaternary sediments


Map of lineaments


Map of ring structures