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Baltica is a
paleocontinent A paleocontinent or palaeocontinent is a distinct area of continental crust 350px, The thickness of Crust (geology)#Earth's crust, Earth's crust (km) Continental crust is the layer of Igneous rock, igneous, Sedimentary rock, sedimentary, and m ...
that formed in the
Paleoproterozoic The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6 Year, Ga), is the first of the three sub-divisions (era (geology), eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest ...
and now constitutes northwestern
Eurasia Eurasia () is the largest continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a ...

Eurasia
, or Europe north of the
Trans-European Suture Zone The Trans-European Suture Zone (TESZ), also known as the Tornquist Zone, is the crustal boundary between the Precambrian East European Craton and the Phanerozoic orogens of South-Western Europe. The zone runs from the North Sea to the Black Sea. T ...
and west of the
Ural Mountains The Ural Mountains (; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈgorɨ; ba, Урал тауҙары, ''Ural tauźarı'') or simply the Urals, are a mountain range that runs approximately from north to south ...
. The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the
Rodinia Rodinia (from the Russian родить, ''rodit'', meaning "to beget, to give birth", or родина, ''rodina'', meaning "motherland, birthplace") was a Neoproterozoic supercontinent that assembled 1.1–0.9 billion years ago and broke up 750 ...

Rodinia
supercontinent at 1 .


Tectonic history

Baltica formed at 2.0–1.7 Ga by the collision of three
Archaean
Archaean
-
Proterozoic The Proterozoic () is a geological eon spanning the time interval from 2500 to 541million years ago. It is the most recent part of the Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest par ...
continental blocks:
Fennoscandia __NOTOC__ Fennoscandia (Finnish Finnish may refer to: * Something or someone from, or related to Finland * Finnish culture * Finnish people or Finns, the primary ethnic group in Finland * Finnish language, the national language of the Finnish peop ...

Fennoscandia
(including the exposed
Baltic Shield The Baltic Shield (or Fennoscandian Shield) is a segment of the Earth's Crust (geology), crust belonging to the East European Craton, representing a large part of Fennoscandia, northwestern Russia and the northern Baltic Sea. It is composed mostly ...
), Sarmatia (
Ukrainian Shield In geology the Ukrainian Shield (or Ukrainian Crystalline Massif) is the southwest 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 specifi ...
and
Voronezh MassifVoronezh Massif (also Voronezh Anteclise russian: Воронежская антеклиза, or Voronezh Uplift) is a tectonic anteclise in the south of the Central Russian Upland with a high occurrence of the Precambrian Basement (geology), basement ...
), and Volgo-Uralia (covered by younger deposits). Sarmatia and Volgo-Uralia formed a proto-
craton A craton (, , or ; from el, κράτος ''kratos'' "strength") is an old and stable part of the continental lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial p ...
(sometimes called "Proto-Baltica") at c. 2.0 Ga which collided with Fennoscandia c. 1.8–1.7 Ga. The sutures between these three blocks were reactivated during the Mesoproterozoic and Neoproterozoic. 750–600 million years ago, Baltica and
Laurentia Laurentia or the North American Craton is a large continental craton A craton (, , or ; from el, κράτος ''kratos'' "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the ...
rotated clockwise together and drifted away from the Equator towards the South Pole where they were affected by the
Cryogenian The Cryogenian (, from grc, κρύος, krýos, meaning "cold" and , romanized: , meaning "birth") is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy ...
Varanger glaciations. Initial rifting between the two continents is marked by the c. 650 Ma Egersund dike swarm in southern Norway and from 600 Ma they began to rotate up to 180° relative to each other, thus opening the
Iapetus Ocean upright=1.35, Reconstruction of how the Iapetus Ocean and surrounding continents might have been arranged during the late Ediacaran period (geology), period The Iapetus Ocean (pronounced ) was an ocean that existed in the late Neoproterozoic and e ...
between them. Laurentia quickly moved northward but Baltica remained an isolated continent in the Southern Hemisphere closer to
Gondwana Gondwana () or Gondwanaland was a supercontinent In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (g ...

Gondwana
on which endemic
trilobite Trilobites (; meaning "three lobes") are a group of marine s that form the Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the of the ( ...

trilobite
s evolved in the Early Ordovician. During the Ordovician, Baltica moved northward approaching Laurentia again allowing trilobites and brachiopods to cross the Iapetus Ocean. In the Silurian, c. 425 Ma, the final collision between Scotland-Greenland and Norway resulted in the Scandian Orogeny.


Margins

Baltica is a very old continent and its core is a very well-preserved and thick craton. Its current margins, however, are the
sutures Suture, literally meaning "seam", may refer to: Arts, entertainment, and media * Suture (album), ''Suture'' (album), a 2000 album by American Industrial rock band Chemlab * Suture (film), ''Suture'' (film), a 1993 film directed by Scott McGehee and ...
that are the result of mergers with other, much younger continental blocks. These often deformed sutures do not represent the original, Precambrian–early Palaeozoic extent of Baltica; for example, the curved margin north of the Urals running parallel to Novaya Zemlya was probably deformed during the eruption of the End-Permian
Siberian Traps The Siberian Traps (russian: Сибирские траппы, ) is a large region of volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a Rock (geology), rock formed from lava erupted from a volcano. In other ...
. Baltica's western margin is the Caledonide orogen which stretches northward from the
Scandinavian Mountains #REDIRECT Scandinavian Mountains#REDIRECT Scandinavian Mountains The Scandinavian Mountains or the Scandes is a mountain range that runs through the Scandinavian Peninsula. The Scandinavian Mountains are often erroneously thought to be equivalen ...
across
Barents Sea The Barents Sea ( , also ; no, Barentshavet, ; russian: Баренцево море, Barentsevo More) is a marginal sea This is a list of seas of the World Ocean The ocean (also the sea or the world ocean) is the body of Saline water, ...
to
Svalbard Svalbard ( , ), previously known as Spitsbergen, or Spitzbergen, is a Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic ...

Svalbard
. Its eastern margin is the Timanide orogen which stretches north to the
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island An isl ...

Novaya Zemlya
archipelago. The extent of the Proterozoic continent are defined by the
Iapetus Suture The Iapetus Suture is one of several major geological fault In geology, a fault is a Plane (geometry), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of r ...
to the west; the Trollfjorden-Komagelva Fault Zone in the north; the Variscan-Hercynian suture to the south; the Tornquist Zone to the southwest; and the
Ural Mountains The Ural Mountains (; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈgorɨ; ba, Урал тауҙары, ''Ural tauźarı'') or simply the Urals, are a mountain range that runs approximately from north to south ...
to the east.


Northern margin

At c. 555 Ma during the Timanian Orogeny the northern margin became an active margin and Baltica expanded northward with the accretion of a series of continental blocks: the Timan-Pechora Basin, the northernmost Ural Mountains, and the
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island An isl ...

Novaya Zemlya
islands. This expansion coincided with the Varanger glaciations, also known as
Snowball Earth The Snowball Earth hypothesis proposes that, during one or more of Earth's Greenhouse and icehouse Earth, icehouse climates, the Earth's surface, planet's surface became entirely or nearly entirely frozen. It is believed that this occurred someti ...
.
Terrane In geology Geology (from the γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is a branch of concerned with both the liquid and , the of which it is composed, and the processes by which they change over time ...
s of the
North American Cordillera The North American Cordillera, sometimes also called the Western Cordillera of North America, the Western Cordillera or the Pacific Cordillera, is the North America North America is a continent entirely within the Northern Hemisphere a ...
, including Alaska-Chukotka,
Alexander Alexander is a male given name. The most prominent bearer of the name is Alexander the Great, the king of the Ancient Greek kingdom of Macedonia (ancient kingdom), Macedonia who created one of the largest empires in ancient history. Etymology T ...
, Northern Sierra, and Eastern Klamath, share a rift history with Baltica and most likely were part of Baltica from the Caledonian orogeny to the formation of the Ural Mountains. These terranes can be linked to either northeastern Laurentia, Baltica, or Siberia because of a similar sequence of fossils;
detrital Detritus (; adj. ''detrital'' ) is particles of rock Rock most often refers to: * Rock (geology) A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Ch ...
zircon from 2–1 Ga-old sources and evidence of Grenvillian magmatism; and magmatism and
island arc Island arcs are long chains of active volcano A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical b ...

island arc
s from the Late Neoproterozoic and Ordovician-Silurian.


Southern margin

From at least 1.8 Ga to at least 0.8 Ga the southwestern margin of Baltica was connected to
Amazonia The Amazon rainforest, alternatively, the Amazon jungle or ; es, Selva amazónica, , or usually ; french: Forêt amazonienne; nl, Amazoneregenwoud. In English, the names are sometimes capitalized further, as Amazon Rainforest, Amazon Forest ...
while the southeast margin was connected to the
West African Craton The West African Craton (WAC) is one of the five cratons A craton (, , or ; from el, κράτος ''kratos'' "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust (geology), ...

West African Craton
. Baltica, Amazonia, and West Africa rotated 75° clockwise relative to Laurentia until Baltica and Amazonia collided with Laurentia in the 1.1–0.9 Ga Grenville- Sveconorwegian- Sunsás orogenies to form the supercontinent
Rodinia Rodinia (from the Russian родить, ''rodit'', meaning "to beget, to give birth", or родина, ''rodina'', meaning "motherland, birthplace") was a Neoproterozoic supercontinent that assembled 1.1–0.9 billion years ago and broke up 750 ...

Rodinia
. When the break-up of Rodinia was complete c. 0.6 Ga Baltica became an isolated continent — a 200 million year period when Baltica was truly a separate continent. Laurentia and Baltica formed a single continent until 1.265 Ga which broke up some time before 0.99 Ga. After the subsequent closure of the Mirovoi Ocean Laurentia, Baltica and Amazonia remained merged until the opening of the Iapetus Ocean in the Neoproterozoic.


Western Margin

The Western Gneiss Region in western Norway is composed of 1650–950 Ma-old gneisses overlain by
continental Continental may refer to: Places * Continent * Continental, Arizona, a small community in Pima County, Arizona, US * Continental, Ohio, a small town in Putnam County, US Arts and entertainment * Continental (album), ''Continental'' (album), an alb ...
and
oceanic Oceanic may refer to: *Of or relating to the ocean *Of or relating to Oceania **Oceanic climate **Oceanic languages **Oceanic person or people, also called "Pacific Islander(s)" Places *Oceanic, British Columbia, a settlement on Smith Island, Br ...
allochtons that were transferred from Laurentia to Baltica during the Scandian orogeny. The allochtons were accreted to Baltica during the closure of the Iapetus Ocean c. 430–410 Ma; Baltica's
basement A basement or cellar is one or more floors A floor is the bottom surface of a room or vehicle. Floors vary from wikt:hovel, simple dirt in a cave to many-layered surfaces made with modern technology. Floors may be stone, wood, bamboo, ...
and the allochtons were then subducted to UHP depth c. 425–400 Ma; and they were finally exhumed to their present location c. 400–385 Ma. The presence of micro-diamonds in two islands in western Norway, and , indicate that this margin of Baltica was buried c. for at least 25 million years around 429 Ma shortly after the Baltica-Laurentia collision. The Baltica-Laurentia-Avalonia triple junction in the North Sea is the southwest corner of Baltica. The Baltica-Laurentia suture stretching northeast from the triple junction was deformed in the Late Cambrian and early Palaeozoic in the Scandinavian Caledonides as well as the Scandian Orogeny in the Silurian. Some Norwegian terranes have faunas distinct from those of either Baltica or Laurentia and were island arcs that originated in the Iapetus Ocean and were accreted to Baltica. The Baltica craton most likely underlies these terranes and the continent-ocean boundary passes several kilometres off Norway, but, since the North Atlantic opened c. 54 Ma were the Iapetus Ocean closed, it is unlikely the craton also reached into Laurentia. The margin stretches north to
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island An isl ...

Novaya Zemlya
where early Palaeozoic Baltica faunas have been found, but the sparsity of data makes it difficult to locate the margin in the Arctic. Ordovician faunas indicate that most of
Svalbard Svalbard ( , ), previously known as Spitsbergen, or Spitzbergen, is a Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic ...

Svalbard
, including Bjørnøya, was part of Laurentia, but
Franz Josef Land , native_name = , image_name = Map of Franz Josef Land-en.svg , image_caption = Map of Franz Josef Land , image_size = , map_image = Franz Josef Land location-en.svg , map_caption = Location of Franz Josef L ...
and
Kvitøya Kvitøya (English: "White Island") is an island in the Svalbard archipelago in the Arctic Ocean, with an area of . It is the easternmost part of the Kingdom of Norway. The closest Russian Arctic possession, Victoria Island (Russian Arctic), Victor ...
(an eastern island of the Svalbard archipelago) most likely became part of Baltica in the Timanide Orogeny. The
Taymyr Peninsula The Taymyr Peninsula (russian: Полуостров Таймыр, Таймырский полуостров, italic=no) is a peninsula in the Far North (Russia), Far North of Russia, in the Siberian Federal District, that forms the northernmost part ...
, in contrast, never was part of Baltica: southern Taymyr was part of Siberia whilst northern Taymyr and the
Severnaya Zemlya Severnaya Zemlya (russian: link=no, Сéверная Земля́ (Northern Land), ) is a archipelago in the Russian high Arctic. It lies off Siberia's Taymyr Peninsula, separated from the mainland by the Vilkitsky Strait. This archipelago sep ...

Severnaya Zemlya
archipelago were part of the independent Kara Terrane in the early Palaeozoic.


Eastern margin

The eastern margin, the Uralide orogen, extends from the Arctic
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island An isl ...

Novaya Zemlya
archipelago to the
Aral Sea The Aral Sea (Aral ; kk, Aral teńizi, Арал теңізі, uz, Orol dengizi, Орол денгизи, kaa, Aral ten'izi, Арал теңизи, russian: Аральское море) was an endorheic lake lying between Kazakhstan Kaza ...

Aral Sea
. The orogen contains the record of at least two collisions between Baltica and intra-oceanic island arcs before the final collision between Baltica and
Kazakhstania Kazakhstania ( kk, Qazaqstaniya), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia Central Asia is a region in Asia which stretches from the Caspian Sea in the west to China and Mongolia in the east, and from ...
-
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 R ...
during the formation of
Pangaea Pangaea or Pangea () was a supercontinent In geology Geology (from the Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí G ...

Pangaea
. The Silurian-Devonian island arcs were accreted to Baltica along the Main Uralian Fault, east of which are metamorphosed fragments of volcanic arc mixed with small amounts of Precambrian and Paleozoic continental rocks. However, no rocks unambiguously originating from either Kazakhstania or Siberia have been found in the Urals. The basement of the eastern margin is composed of an Archaean craton, metamorphosed rocks at least 1.6 Ga old, which is surrounded by the fold belt of the Timanide orogeny and overlain by Mesoproterozoic sediments. The margin became a
passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate Continental margin, margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Contin ...

passive margin
facing the Ural Ocean in the Cambrian–Ordovician. The eastern margin stretches south through the Ural Mountains from the northern end of the Novaya Zemlya archipelago. The margin follows the bent shape of Novaya Zemlya which was caused in the Late Permian by the
Siberian Traps The Siberian Traps (russian: Сибирские траппы, ) is a large region of volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a Rock (geology), rock formed from lava erupted from a volcano. In other ...
. It is clear from Baltic endemic fossils in Novaya Zemlya that the islands have been part of Baltica since the Early Palaeozoic, whereas the Taymyr Peninsula farther east was part of the passive margin of Siberia in the Early Palaeozoic. Northern Taymyr, together with Severnaya Zemlya and parts of the crust of the Arctic Ocean, formed the Kara Terrane. The Urals Mountains formed in the mid and late Palaeozoic when
Laurussia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around (Mya (unit), Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the brea ...
collided with
Kazakhstania Kazakhstania ( kk, Qazaqstaniya), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia Central Asia is a region in Asia which stretches from the Caspian Sea in the west to China and Mongolia in the east, and from ...
, a series of terranes. The eastern margin, however, originally extended farther east to an active margin bordered by
island arc Island arcs are long chains of active volcano A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical b ...

island arc
s, but those parts have been compressed, fractured, and distorted especially in the eastern Urals. The early Palaeozoic eastern margin is better preserved south of the polar region (65 °N) where shallow-water sediments can be found in the western Urals whilst the eastern Urals are characterised by deep-water deposits. The oldest known mid-ocean
hydrothermal vent A hydrothermal vent is a fissure A fissure is a long, narrow crack opening along the surface of the Earth. It is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in the Earth's crust, on ice sheets and glaciers, an ...
in the south-central part of the Urals clearly delimits the eastern extent. The straightness of the mountain chain is the result of continuous strike-slip movements during the Late Carboniferous to
Early Permian 01 or '01 may refer to: * The year 2001 2001 was designated as International Year of Volunteers. Events January * January 1 – Kolkata (in West Bengal, India) officially restores its name from Calcutta. * January 9 – iTunes i ...
(300–290 Ma). Baltic endemic faunas from the Early Ordovician have been found in Kazakhstan near the southern end of the eastern margin, or the triple junction between Baltica, the Mangyshlak Terrane, and the accretionary Altaids. Here the Early Palaeozoic rocks are buried under the
Caspian Depression The Caspian Depression ( kk, Каспий маңы ойпаты, ''Kaspıı mańy oıpaty''; rus, Прикаспи́йская ни́зменность, p=prʲɪkɐˈspʲijskəjə ˈnʲizmʲɪnnəsʲtʲ, Caspian Lowland) or Pricaspian/Peri-Casp ...
.


See also

*


References


Notes


Sources

* * * * * * * * * * * * * * * {{Continents of the world Historical continents Plate tectonics Proterozoic Paleozoic Natural history of Europe