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Thegeology of Belarus began to form more than 2.5billion years ago in thePrecambrian, although many overlying sedimentary units deposited during thePaleozoic and the currentQuaternary.Belarus is located in the eastern European plain. From east to west it covers about 650 kilometers while from north to south it covers about 560 kilometers, and the total area is about 207,600 square kilometers. It borders Poland in the north, Lithuania in the northwest, Latvia and Russia in the north, and Ukraine in the south. Belarus has a planar topography with a height of about 160 m above sea level. The highest elevation at 346 meters above sea level isMt. Dzerzhinskaya, and the lowest point at the height of 80 m is in theNeman River valley.
The soils are soddypodzols andpeat bogs are common. Belarus is situated onCratons basement is made ofArchean and earlyProterozoic crystalline basement rocks and covered by terrigenous,volcanogenic, andcarbonate rocks that date to theRiphean (a stratigraphic division of the Proterozoic in Russia and Scandinavia) through the last 2.5 million years of theQuaternary.[1]
The land surface in Belarus is mostly covered withQuaternary deposits.[2] In the quarries inMikashevichy,Precambrian basement rocks is uncovered, whileJurassic,Devonian,Cretaceous,Neogene, andPaleocene deposits are exposed throughout most of the rest of the country. Data about the different stratigraphic subsections was collected from numerous boreholes in Belarus during the Soviet period.[3]
The internal structure of the crystalline basement resulted from the long-term transformation of the primary proto-oceanic crust to well-defined continental crust. This took place when the early Archean basalt proto-oceanic crust formed. The rocks formed and metamorphosed intogranulite basite, andgneiss.
The accumulation offlysch and volcanogenic-silica-iron, andgreywacke took place in the late Archean and at the beginning of theProterozoic age. They were later transformed intoschist andamphibolitegneiss complexes through regional metamorphism, and then deposited in the granulite gneissic basement as the structure evolved.[4]
West Belarus is dominated by rocks of the EarlyArcheanShchuchin series, which is composed ofamphibolite, crystallineschists, andgneisses that are metamorphosed under moderate pressure togranulite grade on the sequence of metamorphicfacies. This series is about 5 to 7 kilometers thick. In the east of the region, most of the rocks found there are Early ArcheanKulazhin Series. These rocks are represented bybiotite gneisses andgarnet-biotitic gneiss about 5 kilometers thick. Most of the upper Archean rocks include theOkolovo Series and theOzery Series. The Okolovo rocks are plagiogneisses, amphibolites, and schists embedded with ferruginousquartzite. The Ozery Series is made up of an amphibolite gneiss complex. The total thickness of both the Okolovo and the Ozery is about 10 kilometers. These rocks are mostly present in central Belarus.
In the south, the series is made up ofchlorite-sericite schists,rhyolites,quartzite,andesite, anddacites. In this part of the country, the series has a thickness of about 500 meters, and reachesgreenschist metamorphicfacies. Some of the rocks that can be found in abundance are ultrametamorphic, intrusive, andmetasomatic complexes—that include lower Archean metagabbro,granites,diabase,granitoids,granodiorites,enderbite-charnockite, and Late Archean metagabbros.
LateProterozoic deposits include theVendian and theRiphean rocks. Riphean rocks are found in large paleotroughs and small depressions. Vendian rocks cover most of the country—about 85%. The Riphean rocks are mostly made up of volcanogenic-sedimentary strata includingtrachandesites,quartz- rhyolites,quartzites,schists,sandstones, andconglomerates. These rocks are encountered in isolated local boreholes—usually at around 140 meters deep.
The middle Riphean series is composed of theSherovichy Series. These rocks can be seen as apolymicticarkose sandstone strata with gravestone underlining it and quartzitic sandstone on top. On the other hand, the upper Riphean fills theVolyn-Orsha paleotrough that extends from northeast to southwest across the Belarus regions. These series form the Belarus Series
Vendian deposits are divided into three subseries from bottom to top, including theVilcha Series,Volyn Series andValdai Series. The Vilcha series is made up oftillite,clay andsandstones that originated during theNeoproterozoic glaciations.. They form a sheet 310 meter thick on the surface. This layer is mostly composed of andesite,dacites,basalts,tuff, trachyliparites withtuff, and tuff-siltstone intercalations with thicknesses of about 550 meters. The Valdai series can be seen as a layer of alternating clays, siltstones, sandstones, and some gravels. In most cases, this layer is about 300 meters thick.
This layer is represented by all the systems discoursed above, and it is widely spread in the region of Belarus. TheOrdovician,Cambrian, andSilurian deposits are mostly found in the SW and NW of Belarus. In most of the other parts of the country, thePhanerozoic begins with middleDevonian deposits. However, in uplifted areas it starts with theCenozoic andMesozoic sediments.
TheCambrian has two stages: lower and middle stages. The lower consists of theBaltic Series andVysokovsk Series. The Baltic series is composed of clays, sandstones, and siltstones up to 180 meter thick. The Vysokovsk Series consists of the same components as the Baltic Series but is a little thicker (about 250 meter thick). The middle stage consists of layers of siltstones, sandstones and rarely clays of about 115 meters thick.
TheOrdovician has the same components as the Cambrian with additional limestone, sandstone and clay intercalations at the bottom. This layer is about 153 meters thick in the northwest and 53 meter thick in the southwest. TheSilurian is about 640 meters thick in the southwest and 60 meter thick in the northwest. This layer consist of limestone,marls, anddolomites. TheDevonian includes all the stages, with the early Devonian predominantly found in central Belarus.[5]
TheBelarusian Baltic Granulite Belt extends from north southwards for a distance of about 1000 kilometers and is approximately 100–200 kilometers wide. This belt is made-up of metabasic rocks that are products of ultra-metamorphic transformation. It includes granulite blocks that are separated byblastomylonite zones andnappe-thrust structures and linear folding.. Magnetic field research has revealed a series of intense magnetic band anomalies. In the southeast of Belarus is theBraguin Granulite Massif that measures about 150 to 70 kilometers wide, and shows magnetic anomalies of low intensity. Another granulite massif is the triangularVitebsk Massif which has a composition is similar to that of the Braguin Massif. In northernmost Belarus, the Latvian Saddle is about 200 by 150 kilometers wide, separating the Baltic and the Moscow Synclines. The depth of the ridge is about 0.6 kilometers.
There are large iron deposits in the basement rocks. For example, in theNovoselki deposits there are about 26% iron deposits at a depth of about 150 m. TheOkolova has iron deposits of about 35% at a depth of about 260 meters. High volume iron ore reserves are found at a depth of about 700 meters, and they are estimated to hold about t 700 million tons of reserves. Some estimates suggest as much as 1.5 billion tons. The ore contains cobalt, vanadium, titanium, silver and gold. At theGlushkovichy area andMikashevichy area, are large deposits of gneisses and granites.[6]
