Baltic Shield

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Baltic Shield,

the continental core of Europe, composed of Precambrian crystalline rock, the oldest of Europe. The tectonically stable region was not affected by the Caledonian, Hercynian, and Alpine mountain-building periods of Europe, although mountains did rise along the edges. The exposed portion of the Baltic Shield is found in Finland, Sweden, and Norway. During the Pleistocene epoch, great continental ice sheets scoured and depressed the shield's surface, leaving a thin covering of glacial material and innumerable lakes and streams. The ancient rocks have yielded a rich variety of minerals, especially iron and copper. In W former USSR the Russian Platform is that portion of the Baltic Shield buried beneath a great thickness of sedimentary rock.

Baltic Shield

 

a major structural uplift in the northwestern part of the Eastern European Platform, where its Pre-cambrian folded basement emerges on the surface, while the rock of the younger sedimentary mantle is almost completely absent. The Baltic Shield occupies the Karelian ASSR, Murmansk Oblast, and part of Leningrad Oblast in the USSR and Finland and Sweden. The highly metamorphosed and complexly dislocated Precambrian rock of the basement, which has been pierced by intrusions of an acid and basic composition, can be divided into a number of variously aged complexes which form the Precambrian folded systems. The Archean gneisses, the crystalline schists and intrusions (White Sea, Kola, and other complexes) have an absolute age of from 3.5 billion to 2.7–2.5 billion years. The younger Karelian and Svecofennian complexes of the Proteiozoic are widely developed; they were formed 1.85–1.75 billion years ago. Rapakivi granites also developed 1.64–1.62 billion years ago. On small areas, Upper Protero-zoic rock of the Jotnian age (1.4–1.3 billion years ago) has remained, and this occurs as the platform mantle.

On the Baltic Shield there are iron ore deposits (Kiruna and the Grangesberg region in Sweden, the Olenegorsk and Kovdor regions in the USSR), as well as copper-nickel ores (Monchetundra, the Pechenga region of the USSR); apatite deposits are associated with the Paleozoic alkali intrusions (Khibiny in the USSR).

REFERENCES

Kratts, K. O., N. Mangusson, A. Simonen, and O. Khol’tedal’. “Baltiiskii shchit.” Tektonika Evropy. Moscow, 1964.
Kratts, K. O., E. K. Gerling, and S. B. Lobach-Zhuchenko. “Geokhronologiia dokembriia. Baltiiskogo shchita.” Geologiia dokembriia. Leningrad, 1968. (Mezhdunarodnyi geologicheskii kongress. XXIII sessiia. Doklady sovetskikh geologov. Problema 4.)

M. F. MIKUNOV

References in periodicals archive ?
Sovremennye i pozdnegolotsenovye vertikal'nye dvizheniya zemnoj kory v Yugo-Vostochnoj Baltike--perehodnoj zone ot Fennoskandinavskogo shchita k Russkoj plite [Modern and late Holocene vertical earth crust movements in the South-Eastern Baltic as a transitional zone between the Fennoscandian shield and the Russian plate].
Rasmus has tremendous experience across the Fennoscandian shield and is an excellent fit with Beowulf, as we advance mineral projects up the value curve and continue to evaluate opportunities across the Nordic region.
Current results from the Hattu belt and analogous, geochemical anomaly zones and gold discoveries, recently identified through out the 150-km-long Kuhmo-Suomussalmi belt, demonstrate that Archean greenstone belts in the Fennoscandian Shield are not devoid of gold, as previously thought, but, actually appear to have good potential for mineable deposits.
Sundblad, "Metallogeny of Gold in the Fennoscandian Shield," Mineralium Deposita, Vol.
Hietanen (1975) proposed a model, which explains rock variations in the Fennoscandian Shield by the opening of an oceanic basin, subduction, and island arc magmatism.
The Precambrian Bedrock of Finland--Key to the Evolution of the Fennoscandian Shield. Elsevier, Amsterdam, 736 pp.
in the Fennoscandian Shield, combined 2.5D and 3D gravity and magnetic modelling along DSS lines has been successfully used for the interpretation of the crustal and upper mantle structure since the late 1980s (Elo et al.
These results can be compared with the results from the Fennoscandian Shield area.
The primary model of the historically uniform, 1.93-1.8 Ga Svecofennian Domain of the Fennoscandian Shield and NW Russian Platform basement (Gaal & Gorbatschev 1987; Gorbatschev & Bogdanova 1993) has been divided into a series of slightly temporally different orogenic belts.
Precambrian Geology of Finland: Key to the Evolution of the Fennoscandian Shield. Developments in Precambrian Geology, 14.