The Lapland Granulite Belt is an elongate and arcuate zone of granulite rock in the

Cap of the North The Cap of the North (''Nordkalotten'' in Norwegian and Swedish, or ''Pohjoiskalotti'' in Finnish) is the regions Norway, Sweden, and Finland located north of the arctic circle. It usually consists of the counties Troms og Finnmark and Nordland in ...

spanning areas within

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

and

Murmansk Oblast Murmansk Oblast (russian: Му́рманская о́бласть, p=ˈmurmənskəjə ˈobləsʲtʲ, r=Murmanskaya oblast, ''Murmanskaya oblast''; Kildin Sami: Мурман е̄ммьне, ''Murman jemm'ne'') is a federal subject (an oblast) of ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. At most the belt is 80 km broad. The main rocks of the belt are migmatized

greywacke Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lit ...

and

argillites :''"Argillite" may also refer to Argillite, Kentucky.'' Argillite () is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes. They contain variable amounts ...

. Studies of

detrital Detritus (; adj. ''detrital'' ) is particles of rock derived from pre-existing rock through weathering and erosion.Essentials of Geology, 3rd Ed, Stephen Marshak, p G-7 A fragment of detritus is called a clast.Essentials of Geology, 3rd Ed, Stephen ...

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the r ...

show that the sedimentary

protolith A protolith () is the original, unmetamorphosed rock from which a given metamorphic rock is formed. For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other kind of non-metamorphic rock and thu ...

of the metamorphic rocks of the belt could not be older than 2900–1940 million years. The belt has

norite Norite is a mafic intrusive igneous rock composed largely of the calcium-rich plagioclase labradorite, orthopyroxene, and olivine. The name ''norite'' is derived from ''Norge'', the Norwegian name for Norway. Norite also known as orthopyroxen ...

and enderbite

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s of calc-alkaline chemistry. It is believed that the belt formed by the closure of an ancient Lapland-Kola Ocean and the

continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains prod ...

of two continents of

Archean The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth Earth ...

age. The granulite belt with its arcuate shape is part of the larger Inari

orocline An orocline — from the Greek words for "mountain" and "to bend" — is a bend or curvature of an orogenic (mountain building) belt imposed after it was formed. The term was introduced by S. Warren Carey in 1955 in a paper setting forth how compl ...

. This orocline include also the Tana and Karasjok belts. Two ideas on origin of the orocline have been proposed; that it originated at the same time as the southwest directed

thrusting Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that sys ...

of the Lapland Granulite Belt or that it former by lateral compression after the thrusting event.

References

{{reflist Archean Geology of European Russia Geology of Finland Geology of Norway