GO 568 Northern Europe I

Northern Europe I
GO 568 Structural Geology
James S. Aber

Tectonic overview

Northern Europe, including the British Isles, Scandinavia and the Baltic region, has a geologic history similar to that of eastern North America throughout much of the Phanerozoic. This is the tectonically stable portion of Europe, which has seen little in the way of crustal deformation since the Paleozoic. Geologic history of the Precambrian and Paleozoic may be summarized as a sequence of orogenies and intervening stable periods.

Precambrian -- Crystalline rocks of the Fennoscandian Shield represent several episodes of crustal formation and deformation during the Archean and Proterozoic. These rocks are exposed primarily in southern Norway, most of Sweden and Finland, and adjacent parts of Russia. The southernmost outcrops of shield rocks are on the Danish island of Bornholm in the Baltic Sea. Basement (shield) rocks extend beneath largely undeformed younger sedimentary strata of the southern and eastern Baltic region.
Early Paleozoic -- This was a time of general tectonic stability as the Iapetus Sea opened, sea level rose, and marine transgressions took place particularly in the Baltic region. Widespread sequences of sedimentary strata were deposited on the crystalline basement (shield) rocks.
Caledonian Orogeny -- Continental collision involving North America and Europe led to mountain building and associated sedimentation across most of Ireland, Wales, northern England, Scotland and Norway. This orogeny is parallel in timing and cause to the Acadian Orogeny of the northern Appalachians during the Devonian. A large landmass--the so-called Old Red Continent--resulted with sediment accumulation around the uplifted mountains.
Variscan Orogeny -- Another continental collision involving Europe and Gondwana took place during the late Carboniferous. This event, also known as the Hercynian Orogeny, was equivalent to the Allegheny Orogeny in the southern Appalachians in the Pennsylvanian Period. Deformation reworked rocks and structures of the previous Caledonian Orogeny across southernmost Ireland and England.
Permian -- Pangaea came into existence as a supercontinent, as a consequence of several continental collisions, and northern Europe tectonically was relatively stable. An exception is the Oslo Graben of southern Norway, where continental rifting began, but failed to develop beyond the initial stage.

Proterozoic Geology

	Svaneke Granite exposed on the shoreline of northeastern Bornholm, Denmark. The pink-red granite is coarse grained with crystals up to 2 cm in size and has numerous pegmatites and inclusions of mafic rocks. Photo date 6/79, © J.S. Aber.
	Snorrebakken granite quarry, Bornholm, Denmark. Crystalline rocks of Bornholm date from the late Proterozoic--Gothide province of the Fennoscandian Shield. It's said that half the streets in old cities of northern Europe were paved with stone from Bornholm. Photo date 6/79, © J.S. Aber.
	Granite cliff at Hammer lighthouse, northwestern Bornholm, Denmark. The Hammer Granite is the youngest and lightest in color on Bornholm. This is a typical situation that younger granites are lighter in color (Jørgart 1977). Photo date 6/79, © J.S. Aber.
	Middle Proterozoic crystalline rock (gneiss) of the Fennoscandian Shield, Stockholm, Sweden. See closeup view in next image. Photo date 4/87, © J.S. Aber.
	Vertical foliation and diagonal fractures in gneiss, Stockholm, Sweden. This example is part of the extensive middle Proterozoic Svecofennide province of the Fennoscandian Shield. Photo date 4/87, © J.S. Aber.
	Glacially scoured Proterozoic granite and granodiorite, Kvaløy, near Tromsø, northern Norway. Photo date 6/98, © J.S. Aber.
	Proterozoic amphibolite and metagabbro, Sommarøy, near Tromsø, northern Norway. Photo date 6/98, © J.S. Aber.
	Precambrian gneiss exposed in vicinity of the glacier, Nigardsbreen, south-central Norway. Photo date 6/87, © J.S. Aber.
	Proterozoic gneiss displayed in the Granvin potholes, south-central Norway. Photo date 7/87, © J.S. Aber.

Paleozoic Geology

	Quarry in Nexø sandstone, basal Cambrian strata, Bornholm, Denmark. This terrestrial sandstone lacks fossils and was deposited in a floodplain environment directly on the stable basement rocks of southern Scandinavia (Bruun-Petersen 1977). Photo date 6/79, © J.S. Aber.
	The so-called "Orthoceratite limestone" (lower Ordovician) in a small quarry on Bornholm, Denmark. The limestone was deposited in relatively shallow water during a marine transgression of the Baltic region. Photo date 6/79, © J.S. Aber.

Map of bedrock geology of Estonia, eastern Baltic region. The northern portion is underlain mainly by Ordovician limestones (green); Devonian sandstone (brown) is found in the southern portion--see next three photos. The Paleozoic strata rest on crystalline basement and dip gently to the south.

Ordovician limestone on the island of Vormsi, northwestern Estonia. Bedrock occurs at sea level, and the beach is composed of limestone gravel (see next image). Photo date 8/00, © J.S. Aber.
Closeup view of limestone bedrock strand flat with a scattering of glacial erratics, Vormsi, Estonia. Ordovician limestone is found across the central Baltic region, especially on Swedish islands and in Estonia. Photo date 8/00, © J.S. Aber.
Cliff and caves in Devonian sandstone on the shore of Lake Peipsi, eastern Estonia. The sandstone is poorly consolidated and erodes easily. It is an eastern representative of the Old Red Continent. Photo date 9/00, © J.S. Aber.
Tunnel boring machine drilling into granitic gneiss. This Precambrian gneiss was reworked during the Caledonian Orogeny (Devonian). Bergen, western Norway. Photo date 5/87, © J.S. Aber.
Anorthosite section near Indre Arna, vicinity of Bergen, western Norway. Anorthosite is typical of the Grenvillian Orogeny (late Proterozoic), and this rock was reworked during the Caledonian Orogeny (Devonian). Photo date 5/87, © J.S. Aber.
Greenstone (soapstone) architecture at Lyse Kloster, a medieval cloister south of Bergen, western Norway. Caledonian metamorphic rock from the Bergen structural arch. Photo date 5/87, © J.S. Aber.
Phyllite bedrock exposed on the shore at Clogga, south of Dublin, Ireland. This rock was deformed during the Caledonian Orogeny (Devonian). Photo date 5/91, © J.S. Aber.
Glaciated highlands are supported by massive Devonian sandstone, Molls Gap, southwestern Ireland. Thick sandstones resulted from rapid erosion of the Caledonian mountains and sediment accumulation in adjacent basins. Photo date 5/91, © J.S. Aber.
Metamorphic strata exposed in the strand flat at Wembury Bay, southwestern England, United Kingdom. These Devonian strata were deformed during the Variscan Orogeny (Carboniferous). Photo date 10/88, © J.S. Aber.
Granite quarry in Dartmoor, southwestern England, United Kingdom. This region was subjected to the Variscan Orogeny during the Carboniferous. Photo date 9/92, © J.S. Aber.
Red, black, and gray sandstone and shale tilted up in a vertical position, south coast of Ireland. These Devonian strata were deformed during the Variscan Orogeny in the Carboniferous. Photo date 5/91, © J.S. Aber.
Permian dike (red) cuts through Cambro-Ordovician shale and limestone, Oslo Fjord, Norway. Rhyolitic intrusions mark reactivation of the Oslo Graben during the Permian. Photo date 4/87, © J.S. Aber.
Permian dike (red) branches into Cambro-Ordovician shale and limestone, Oslo Fjord, Norway. These intrusions are evidence for crustal tension associated with rifting of the Oslo Graben. Photo date 4/87, © J.S. Aber.

References

Bruun-Petersen, J. 1977. Nedre Kambrium. In, Geologi på Bornholm, p. 33-39. Varv, Ekskursionsfører Nr. 1.
Jørgart, T. 1977. Præcambrium. In, Geologi på Bornholm, p. 8-32. Varv, Ekskursionsfører Nr. 1.

Northern Europe II.

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Notice: Structural Geology is presented for the use and benefit of students enrolled at Emporia State University. Others are welcome to view the course webpages. Any other use of text, imagery or curriculum materials is prohibited without permission of the instructor. GO 568 © J.S. Aber (2002).

	Ordovician limestone on the island of Vormsi, northwestern Estonia. Bedrock occurs at sea level, and the beach is composed of limestone gravel (see next image). Photo date 8/00, © J.S. Aber.
	Closeup view of limestone bedrock strand flat with a scattering of glacial erratics, Vormsi, Estonia. Ordovician limestone is found across the central Baltic region, especially on Swedish islands and in Estonia. Photo date 8/00, © J.S. Aber.
	Cliff and caves in Devonian sandstone on the shore of Lake Peipsi, eastern Estonia. The sandstone is poorly consolidated and erodes easily. It is an eastern representative of the Old Red Continent. Photo date 9/00, © J.S. Aber.
	Tunnel boring machine drilling into granitic gneiss. This Precambrian gneiss was reworked during the Caledonian Orogeny (Devonian). Bergen, western Norway. Photo date 5/87, © J.S. Aber.
	Anorthosite section near Indre Arna, vicinity of Bergen, western Norway. Anorthosite is typical of the Grenvillian Orogeny (late Proterozoic), and this rock was reworked during the Caledonian Orogeny (Devonian). Photo date 5/87, © J.S. Aber.
	Greenstone (soapstone) architecture at Lyse Kloster, a medieval cloister south of Bergen, western Norway. Caledonian metamorphic rock from the Bergen structural arch. Photo date 5/87, © J.S. Aber.
	Phyllite bedrock exposed on the shore at Clogga, south of Dublin, Ireland. This rock was deformed during the Caledonian Orogeny (Devonian). Photo date 5/91, © J.S. Aber.
	Glaciated highlands are supported by massive Devonian sandstone, Molls Gap, southwestern Ireland. Thick sandstones resulted from rapid erosion of the Caledonian mountains and sediment accumulation in adjacent basins. Photo date 5/91, © J.S. Aber.
	Metamorphic strata exposed in the strand flat at Wembury Bay, southwestern England, United Kingdom. These Devonian strata were deformed during the Variscan Orogeny (Carboniferous). Photo date 10/88, © J.S. Aber.
	Granite quarry in Dartmoor, southwestern England, United Kingdom. This region was subjected to the Variscan Orogeny during the Carboniferous. Photo date 9/92, © J.S. Aber.
	Red, black, and gray sandstone and shale tilted up in a vertical position, south coast of Ireland. These Devonian strata were deformed during the Variscan Orogeny in the Carboniferous. Photo date 5/91, © J.S. Aber.
	Permian dike (red) cuts through Cambro-Ordovician shale and limestone, Oslo Fjord, Norway. Rhyolitic intrusions mark reactivation of the Oslo Graben during the Permian. Photo date 4/87, © J.S. Aber.
	Permian dike (red) branches into Cambro-Ordovician shale and limestone, Oslo Fjord, Norway. These intrusions are evidence for crustal tension associated with rifting of the Oslo Graben. Photo date 4/87, © J.S. Aber.