The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.
The Archean Eon, in older sources sometimes called the Archaeozoic, is the second of four geologic eons of Earth's history and by definition representing the time from 4,000 to 2,500 million years ago. The Archean was preceded by the Hadean Eon and followed by the Proterozoic.
Lapland is the largest and northernmost region of Finland. The 21 municipalities in the region cooperate in a Regional Council. Lapland borders the region of North Ostrobothnia in the south. It also borders the Gulf of Bothnia, Norrbotten County in Sweden, Troms and Finnmark County in Norway, and Murmansk Oblast and the Republic of Karelia in Russia. Topography varies from vast mires and forests of the South to fells in the North. The Arctic Circle crosses Lapland, so polar phenomena such as the midnight sun and polar night can be viewed in Lapland.
The Baltic Shield is a segment of the Earth's crust belonging to the East European Craton, representing a large part of Fennoscandia, northwestern Russia and the northern Baltic Sea. It is composed mostly of Archean and Proterozoic gneisses and greenstone which have undergone numerous deformations through tectonic activity. It contains the oldest rocks of the European continent with a thickness of 250–300 km.
The Ungava Peninsula is the far northwestern part of the Labrador Peninsula of the province of Quebec, Canada. Bounded by Hudson Bay to the west, Hudson Strait to the north, and Ungava Bay to the east, it covers about 252,000 square kilometres (97,000 sq mi). Its northernmost point is Cape Wolstenholme, which is also the northernmost point of Quebec. The peninsula is also part of the Canadian Shield, and consists entirely of treeless tundra dissected by large numbers of rivers and glacial lakes, flowing generally east–west in a parallel fashion. The peninsula was not deglaciated until 6,500 years ago and is believed to have been the prehistoric centre from which the vast Laurentide Ice Sheet spread over most of North America during the last glacial epoch.
Kenorland was one of the earliest known supercontinents on Earth. It is thought to have formed during the Neoarchaean Era c. 2.72 billion years ago by the accretion of Neoarchaean cratons and the formation of new continental crust. It comprised what later became Laurentia, Baltica, Western Australia and Kalaharia.
The Central Lapland Greenstone Belt (CLGB) is a greenstone belt located in the northern part of the Fennoscandian Shield. The region belongs to Lapland, northern Finland. The CLGB is part of a much larger belt of Paleoproterozoic greenstones, a cover of metamorphosed volcanic and sedimentary rocks that cover the Archean basement, the latter which is representative of the Archaean Karelian craton. Deposition of the cover sequence occurred between about 2.5 Ga and 1.8 Ga, thus it preserves information about Earth's history from a period that encompass about 700 Ma.
Lake Bermen is a 103 square kilometres (40 sq mi) lake in the province of Quebec, Canada. The lake is on ancient rocks of the Superior Province where gold mineralization has been found. It is named after Claude de Bermen de la Martinière (1636–1719), a senior official in New France.
The Churchill Craton is the northwest section of the Canadian Shield and stretches from southern Saskatchewan and Alberta to northern Nunavut. It has a very complex geological history punctuated by at least seven distinct regional tectonometamorphic intervals, including many discrete accretionary magmatic events. The Western Churchill province is the part of the Churchill Craton that is exposed north and west of the Hudson Bay. The Archean Western Churchill province contributes to the complicated and protracted tectonic history of the craton and marks a major change in the behaviour of the Churchill Craton with many remnants of Archean supracrustal and granitoid rocks.
The Trans-Hudson orogeny or Trans-Hudsonian orogeny was the major mountain building event (orogeny) that formed the Precambrian Canadian Shield and the North American Craton, forging the initial North American continent. It gave rise to the Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), which is the largest Paleoproterozoic orogenic belt in the world. It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents. The event occurred 2.0–1.8 billion years ago.
The Wyoming Craton is a craton in the west-central United States and western Canada – more specifically, in Montana, Wyoming, southern Alberta, southern Saskatchewan, and parts of northern Utah. Also called the Wyoming Province, it is the initial core of the continental crust of North America.
The Taltson Magmatic Zone (TMZ) is a north-trending belt of Archean to Paleoproterozoic granitic basement gneiss, amphibolite supracrustal gneissic rock and Paleoproterozoic magmatic rocks in the Canadian Shield, extending from Northern Alberta to the southwestern Northwest Territories. The TMZ basement is 3.2–3.0 Ga and the Rutledge River supracrustal gneisses 2.13–2.09 Ga years old and were intruded by magmatic rocks around 1.99–1.92 Ga.
The Algoman orogeny, known as the Kenoran orogeny in Canada, was an episode of mountain-building (orogeny) during the Late Archean Eon that involved repeated episodes of continental collisions, compressions and subductions. The Superior province and the Minnesota River Valley terrane collided about 2,700 to 2,500 million years ago. The collision folded the Earth's crust and produced enough heat and pressure to metamorphose the rock. Blocks were added to the Superior province along a 1,200 km (750 mi) boundary that stretches from present-day eastern South Dakota into the Lake Huron area. The Algoman orogeny brought the Archean Eon to a close, about 2,500 million years ago; it lasted less than 100 million years and marks a major change in the development of the Earth's crust.
The Svecofennian orogeny is a series of related orogenies that resulted in the formation of much of the continental crust in what is today Sweden and Finland plus some minor parts of Russia. The orogenies lasted from about 2000 to 1800 million years ago during the Paleoproterozoic Era. The resulting orogen is known as the Svecofennian orogen or Svecofennides. To the west and southwest the Svecofennian orogen limits with the generally younger Transscandinavian Igneous Belt. It is assumed that the westernmost fringes of the Svecofennian orogen have been reworked by the Sveconorwegian orogeny just as the western parts of the Transscandinavian Igneous Belt has. The Svecofennian orogeny involved the accretion of numerous island arcs in such manner that the pre-existing craton grew with this new material from what is today northeast to the southwest. The accretion of the island arcs was also related to two other processes that occurred in the same period; the formation of magma that then cooled to form igneous rocks and the metamorphism of rocks.
The geology of Finland is made up of a mix of geologically very young and very old materials. Common rock types are orthogneiss, granite, metavolcanics and metasedimentary rocks. On top of these lies a widespread thin layer of unconsolidated deposits formed in connection to the Quaternary ice ages, for example eskers, till and marine clay. The topographic relief is rather subdued because mountain massifs were worn down to a peneplain long ago.
The Kola Province is an area of the Fennoscandian Shield spanning an area near the borders of Russia, Finland, and Norway, including the bulk of its namesake Kola Peninsula. The continental crust that makes up the province is a collage of Mesoarchean and Neoarchean age with some lesser amounts being of Paleoproterozoic age.
Archean felsic volcanic rocks are felsic volcanic rocks that were formed in the Archean Eon. The term "felsic" means that the rocks have silica content of 62–78%. Given that the Earth formed at ~4.5 billion year ago, Archean felsic volcanic rocks provide clues on the Earth's first volcanic activities on the Earth's surface started 500 million years after the Earth's formation.
The Superior Craton is a stable crustal block covering Quebec, Ontario, and southeast Manitoba in Canada, and northern Minnesota in the United States. It is the biggest craton among those formed during the Archean period. A craton is a large part of the Earth's crust that has been stable and subjected to very little geological changes over a long time. The size of Superior Craton is about 1,572,000 km2. The craton underwent a series of events from 4.3 to 2.57 Ga. These events included the growth, drifting and deformation of both oceanic and continental crusts.
The Siilinjärvi carbonatite complex is located in central Finland close to the city of Kuopio. It is named after the nearby village of Siilinjärvi, located approximately 5 km west of the southern extension of the complex. Siilinjärvi is the second largest carbonatite complex in Finland after the Sokli formation, and one of the oldest carbonatites on Earth at 2610±4 Ma. The carbonatite complex consists of a roughly 16 km long steeply dipping lenticular body surrounded by granite gneiss. The maximum width of the body is 1.5 km and the surface area is 14.7 km2. The complex was discovered in 1950 by the Geological Survey of Finland with help of local mineral collectors. The exploration drilling began in 1958 by Lohjan Kalkkitehdas Oy. Typpi Oy continued drilling between years 1964 and 1967, and Apatiitti Oy drilled from 1967 to 1968. After the drillings, the laboratory and pilot plant work were made. The mine was opened by Kemira Oyj in 1979 as an open pit. The operation was sold to Yara in 2007.
The Lopian orogeny was a mountain building event that affected the Baltic Shield during the Archean, between 2.9 and 2.6 billion years ago. The Kola-Belomorian gneiss and Karelian granitoid-greenstone terrane both formed during this time.
