Aldan Shield (russian: Алданский щит) is a

shield A shield is a piece of personal armour held in the hand, which may or may not be strapped to the wrist or forearm. Shields are used to intercept specific attacks, whether from close-ranged weaponry or projectiles such as arrows, by means of a ...

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

. It is an exposed

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

of the

Siberian Craton Siberia, also known as Angaraland (or simply Angara) and Angarida, is an ancient craton in the heart of Siberia. Today forming the Central Siberian Plateau, it was an independent continent before the Permian period. The Verkhoyansk Sea, a passive ...

. Together with the

Anabar Shield Anabar Shield (russian: Анабарский щит) is a shield in Siberia. It is an exposed basement of the Siberian Craton. Together with the Aldan Shield to the southeast, the Anabar Shield is one of the main features of the craton. On the su ...

further to the northwest, the Aldan Shield is one of the main features of the

craton A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and ...

. The Aldan Shield geological region coincides geographically with parts of the

Aldan Highlands The Aldan Highlands, or Aldan Plateau ( rus, Алданское нагорье, r=Aldanskoye Nagorye; sah, Алдан үрдэлэ) are a mountainous area in the Sakha Republic, Far Eastern Federal District, Russia. Aldan town and Tommot are loc ...

and

Olyokma-Chara Plateau The Olyokma-Chara Plateau ( rus, Олёкмо-Чарское плоскогорье; sah, Өлүөхүмэ-Чаара хаптал хайалаах сир) is a mountainous area in the Sakha Republic and Irkutsk Oblast, Far Eastern Federal Di ...

, located at the southern end of the

Sakha Republic Sakha, officially the Republic of Sakha (Yakutia),, is the largest republic of Russia, located in the Russian Far East, along the Arctic Ocean, with a population of roughly 1 million. Sakha comprises half of the area of its governing Far Eas ...

and the eastern end of

Irkutsk Oblast Irkutsk Oblast (russian: Ирку́тская о́бласть, Irkutskaya oblast; bua, Эрхүү можо, Erkhüü mojo) is a federal subject of Russia (an oblast), located in southeastern Siberia in the basins of the Angara, Lena, and Nizh ...

Google Earth Google Earth is a computer program that renders a 3D computer graphics, 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposition, superimposing satellite images, aerial photography, and geog ...

The exposed crust parts of the shield date back to the

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 ...

and reflect the first phases of accretion of the crust. They only emerge in a few areas, the eastern and northern sectors of the shield being largely covered by sediments accumulated between the end of the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) 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 ...

and the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

, while in the western and southern regions they have undergone processes of tectonic rejuvenation that have brought about the formation of new structures above and below.Siberian craton - a fragment of a Paleoproterozoic supercontinent
/ref> On the Aldan Shield there is the only

charoite Charoite is a rare silicate mineral, first described in 1978. It was believed to be named after the Chara River, but due to the river being 70 km away from its discovery place, now it is believed to be named after the Russian word ''chary'', ...

deposit known in the world - the Sirenevyi Kamen (Lilac Stone) of the

Murun Massif Murun (russian: Мурун) is a mountain in the Olyokma-Chara Plateau, at the border of Irkutsk Oblast and Yakutia, Russian Federation. Geography A high summit is the highest point of the Murun Massif in the Olyokma-Chara Plateau, part of the ...

. Many other rare and unusual minerals occur in the area of the shield, such as

brookite Brookite is the orthorhombic variant of titanium dioxide (TiO2), which occurs in four known natural polymorphic forms (minerals with the same composition but different structure). The other three of these forms are akaogiite (monoclinic), anatas ...

frankamenite Frankamenite is the fluorine-dominate variation of the rare mineral canasite with a general formula of K3Na3Ca5(Si12O30) ,(OH)sub>4·(H2O). Frankamenite belongs to the triclinic crystal system, with the bases of its structure containing Ca-Na mi ...

tausonite Tausonite is the rare naturally occurring mineral form of strontium titanate: chemical formula: SrTiO3. It occurs as red to orange brown Cubic crystal system, cubic crystals and crystal masses. It is a member of the perovskite group. It was first ...

and

yuksporite Yuksporite is a rare inosilicate mineral with double width, unbranched chains, and the complicated chemical formula . It contains the relatively rare elements strontium, titanium and niobium, as well as the commoner metallic elements potassium, ...

.The Sirenevyi Kamen' deposit location map
/ref>
/ref>

References

External links

Early precambrian A-granitoids in the Aldan Shield and adjacent mobile belts: Sources and geodynamic environmentsArchean crustal evolution of the Aldan Shield, Siberia: Geochemical and Isotopic ConstraintsTrace Element and Sr–Pb–Nd–Hf Isotope Evidence for Ancient, Fluid-Dominated Enrichment of the Source of Aldan Shield Lamproites
{{Coord, 58, 30, N, 125, 30, E, source:ruwiki_region:RU_type:geology, format=dms, display=title Geology of the Sakha Republic Proterozoic Archean

See also

References

External links