The Satakunta dyke swarms are a series of
dyke swarms, a group of magmatic intrusions, of
Mesoproterozoic age in the
Bothnian Sea
The Bothnian Sea ( sv, Bottenhavet; fi, Selkämeri) links the Bothnian Bay (also called the Bay of Bothnia) with the Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, t ...
and western and central
Finland
Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...
. They are made up of
Subjotnian diabase
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-graine ...
dikes
Dyke (UK) or dike (US) may refer to:
General uses
* Dyke (slang), a slang word meaning "lesbian"
* Dike (geology), a subvertical sheet-like intrusion of magma or sediment
* Dike (mythology), ''Dikē'', the Greek goddess of moral justice
* Dikes, ...
, associated with
rapakivi magmatism. They were most likely formed on the
Columbia supercontinent
Columbia may refer to:
* Columbia (personification), the historical female national personification of the United States, and a poetic name for America
Places North America Natural features
* Columbia Plateau, a geologic and geographic region in ...
.
Föglö dyke swarm
Häme dyke swarm
The Häme dyke swarm formed due to the upwelling of mantle, possibly related to the
Gothian orogeny The Gothian orogeny ( sv, Gotiska orogenesen) or Kongsberg orogeny was an orogeny in western Fennoscandia that occurred between 1750 and 1500 million years ago. It precedes the younger Sveconorwegian orogeny that has overprinted much of it. The Go ...
. The swarms were triggered by
extensional In any of several fields of study that treat the use of signs — for example, in linguistics, logic, mathematics, semantics, semiotics, and philosophy of language — an extensional context (or transparent context) is a syntactic environment in w ...
plate tectonics and convection of hot
upper mantle.
Tholeiitic magmas, formed under the
continental lithosphere, were probably encouraged by elevated mantle temperature underneath the
Columbia supercontinent
Columbia may refer to:
* Columbia (personification), the historical female national personification of the United States, and a poetic name for America
Places North America Natural features
* Columbia Plateau, a geologic and geographic region in ...
. The time of formation was approximately 1640 million years ago.
Satakunta-Ulvö dyke swarm
The dyke swarm has been considered to be a result of a
failed rift in the Bothnian Sea that developed as part of an
extensional tectonic setting within the
supercontinent of
Columbia. At various location dykes of the swarm cut across
Jotnian sediments indicating a
Postjotnian age for the dyke swarm. Viewed in a map the dyke swarm has the form of a 90-degrees fan radiating open to the east from a point in the Bothnian Sea.
See also
*
Gothian orogeny The Gothian orogeny ( sv, Gotiska orogenesen) or Kongsberg orogeny was an orogeny in western Fennoscandia that occurred between 1750 and 1500 million years ago. It precedes the younger Sveconorwegian orogeny that has overprinted much of it. The Go ...
*
Kattsund-Koster dyke swarm
The Kattsund-Koster dyke swarm is a collection of dykes of Mesoproterozoic age in southeastern Norway and the West Coast of Sweden. The most prominent outcrops are in the Koster Islands in Sweden and Kattsund in Norway, hence the name. The dykes a ...
References
{{Geology of Fennoscandia
Dike swarms
Mesoproterozoic magmatism
Geology of Finland
Geology of Sweden