Baltic Shield
The Baltic Shield (or Fennoscandian Shield) is a segment of the Earth's
The Baltic Shield is divided into five provinces: the
Thought to be formerly part of an ancient continent, the Baltic Shield grew in size through collisions with neighbouring crustal fragments. The mountains created by these tectonic processes have since been eroded to their bases, the region being largely flat today. Through five successive
The scouring and compression of the Baltic Shield by glacial movements created the area's many lakes and streams, the land retaining only a thin layer of sandy sediment collected in depressions and eskers. Most soil consists of moraine, a grayish yellow mixture of sand and rocks, with a thin layer of humus on top. Vast forests, featuring almost exclusively the three species pine, spruce and birch, dominate the landscape, clearly demarcating its boundaries. The soil is acidic and has next to no carbonates such as limestone. The scouring by the ancient glaciers and the acidity of the soil have destroyed all palaeontologically interesting materials, such as fossils.
The Baltic Shield yields important industrial minerals and ores, such as those of iron, nickel, copper and platinum group metals. Because of its similarity to the Canadian Shield and cratons of southern Africa and Western Australia, the Baltic Shield had long been a suspected source of diamonds and gold. Currently, the Central Lapland Greenstone Belt in the north is considered to be an unexplored area that has the potential to hold exploitable gold deposits.
Recent exploration has revealed a significant number of diamond-bearing kimberlites in the Kola Peninsula, and (possibly extensive) deposits of gold in Finland.
Denudation chronology
Mountains that existed in Precambrian time were eroded into a subdued terrain already during the late Mesoproterozoic, when the rapakivi granites intruded.[1] Further erosion made the terrain rather flat at the time of the deposition of Jotnian sediments.[2][3] With Proterozoic erosion amounting to tens of kilometers,[4] many of the Precambrian rocks seen today in Finland are the "roots" of ancient massifs.[5] The last major leveling event resulted in the formation of the Sub-Cambrian peneplain in late Neoproterozoic time.[6][7]
Denudation in the Mesozoic is counted at most in hundreds of meters.[13] The inselberg plain of Finnish Lapland is estimated to have formed in Late Cretaceous or Paleogene times, either by pediplanation or etchplanation. Any older Mesozoic surface in Finnish Lapland is unlikely to have survived erosion.[14] Further west, the Muddus plains and its inselbergs formed —also by etching and pediplanation— in connection to the uplift of the northern Scandinavian Mountains in the Paleogene.[15]
The northern Scandinavian Mountains had their main uplift in the Paleogene, while the southern Scandinavian Mountains and the
While being repeatedly covered by glaciers during the
See also
- Geology of Finland
- Geology of Norway
- Geology of Sweden
- Kola Superdeep Borehole
- List of shields and cratons
- Nickel deposits of Finland
- Swedish iron ore (WWII)
References
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
- ^ Lundmark, Anders Mattias; Lamminen, Jarkko (2016). "The provenance and setting of the Mesoproterozoic Dala Sandstone, western Sweden, and paleogeographic implications for southwestern Fennoscandia". Precambrian Research. 275: 197–208.
- JSTOR 521265.
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
- .
- ^ Gabrielsen, Roy H.; Faleide, Jan Inge; Pascal, Christophe; Braathen, Alvar; Nystuen, Johan Petter; Etzelmuller, Bernd; O'Donnel, Sejal (2010). "Latest Caledonian to Present tectonomorphological development of southern Norway". Marine and Petroleum Geology. 27: 709–723. doi:10.1016/j.marpetgeo.2009.06.004.
- doi:10.34194/geusb.v30.4673. Archived from the originalon 2015-09-24. Retrieved 30 April 2015.
- ^ Murrell, G.R.; Andriessen, P.A.M. (2004). "Unravelling a long-term multi-event thermal record in the cratonic interior of southern Finland through apatite fission track thermochronology". Physics and Chemistry of the Earth, Parts A/B/C. 29 (10): 695–706. Retrieved December 10, 2017.
- ^ Murrell, G.R.; Andriessen, P.A.M. (2004). "Unravelling a long-term multi-event thermal record in the cratonic interior of southern Finland through apatite fission track thermochronology". Physics and Chemistry of the Earth, Parts A/B/C. 29 (10): 695–706. Retrieved December 10, 2017.
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
- ^ Lidmar-Bergström, Karna (1997). "A long-term perspective on glacial erosion". Earth Surface Processes and Landforms. 22: 297–306.
- ^ Kaitanen, Veijo (1985). "Problems concerning the origin of inselbergs in Finnish Lapland". Fennia. 163 (2): 359–364.
- ^ Lidmar-Bergström, K.; Näslund, J.O. (2002). "Landforms and uplift in Scandinavia". In Doré, A.G.; Cartwright, J.A.; Stoker, M.S.; Turner, J.P.; White, N. Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration. Geological Society, London, Special Publications. The Geological Society of London. pp. 103–116.
- ^ Lidmar-Bergström, K.; Näslund, J.O. (2002). "Landforms and uplift in Scandinavia". In Doré, A.G.; Cartwright, J.A.; Stoker, M.S.; Turner, J.P.; White, N. Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration. Geological Society, London, Special Publications. The Geological Society of London. pp. 103–116.
- GFF.
- ^ Green, Paul F.; Lidmar-Bergström, Karna; Japsen, Peter; Bonow, Johan M.; Chalmers, James A. (2013). "Stratigraphic landscape analysis, thermochronology and the episodic development of elevated, passive continental margins". Geological Survey of Denmark and Greenland Bulletin. 30: 18. Retrieved 30 April 2015.
- ^ Japsen, Peter; Chalmers, James A.; Green, Paul F.; Bonow, Johan M. (2012). "Elevated, passive continental margins: Not rift shoulders, but expressions of episodic, post-rift burial and exhumation". Global and Planetary Change. 90-91: 73–86.
- ^ Løseth and Hendriksen 2005
- ^ Redfied, T.F.; Osmundsen, P.T. (2013). "The long-term topographic response of a continent adjacent to a hyperextended margin: A case study from Scandinavia". GSA Bulletin. 125 (1): 184–200. doi:10.1130/B30691.1.
- GFF.
- ^ Lidmar-Bergström, Karna (1997). "A long-term perspective on glacial erosion". Earth Surface Processes and Landforms. 22: 297–306.
- ^ Kleman, J.; Stroeven, A.P.; Lundqvist, Jan (2008). "Patterns of Quaternary ice sheet erosion and deposition in Fennoscandia and a theoretical framework for explanation". Geomorphology. 97 (1–2): 73–90.
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
- ^ Lidmar-Bergström, K.; Olsson, S.; Roaldset, E. (1999). "Relief features and palaeoweathering remnants in formerly glaciated Scandinavian basement areas". In Thiry, Médard; Simon-Coinçon, Régine. Palaeoweathering, Palaeosurfaces and Related Continental Deposits. Special publication of the International Association of Sedimentologists. 27. Blackwell Science Ltd. pp. 275–301. ISBN 0-632 -05311-9.
- ^ Lindberg, Johan (April 4, 2016). "berggrund och ytformer". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
External links
- Rb-Sr Data for Diamond-Bearing Kimberlite and Alkaline Massives in NE Fennoscandia
- Precambrian evolution of the major Archaean blocks of the Baltic Shield (archived version)
- Geology of Fennoscandia
- Why does the East European Platform has (sic) 3 km of sediments? Insights from lithospheric structure, thermal regime, and composition (PDF file)
- The geological history of the Baltic Sea: A review of the literature and investigation tools (2008). Report number: 2009:21 ISSN 2000-0456