Polyphase tectonothermal evolution of the Scandinavian Caledonides

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6876033

Dalimeyer, R D

A polyphase tectonothermal evolution appears to characterize allochthonous sequences within the Scandinavian Caledonides. Late Cambrian consumption of Iapetus oceanic crust occurred outboard of the Blatoscandian margin with development of an island arc terrane above a west-dipping subduction complex. Imbrication, polydeformation, and variably high-grade metamorphism (including eclogite formation) of Baltoscandian miogeoclinal rocks and underlying Precambrian crystalline basement occurred within an accretionary prism which developed in the subduction complex. This resulted in eastward younging, diachronous metamorphism throughout the Early and Middle Ordovician. This early Caledonian activity has been collectively termed the Finnmarkian Orogeny. Nearly complete closure of the Iapetus Ocean appears to have been accomplished by the late Ordovician when eugeoclinal terranes which had developed along the Laurentian margin were juxtaposed with eroded remnants of the Late Cambrian-Middle Ordovician arc. This sequence of Early Silurian through Early Devonian tectonic events has been collectively termed the Scandian Orogeny. Scandian radiometric dates of 425-430 Ma are recorded in allochthons along eastern portions of the orogen and likely closely date initial nappe translation to higher crustal levels along the Baltoscandian margin. Scandian dates range from 410 Ma in central to 385 Ma in western portions of the orogen and likely date rapid cooling during uplift which resulted from crustal rebound following the eastward translation of overridding allochthons.

• Research Organization: Univ. of Georgia, Athens (USA)
• OSTI ID: 6876033
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
580201* -- Geophysics-- Seismology & Tectonics-- (1980-1989)
CAMBRIAN PERIOD
EARTH CRUST
EUROPE
GEOLOGIC AGES
GEOLOGIC HISTORY
IGNEOUS ROCKS
METAMORPHIC ROCKS
METAMORPHISM
OCEANIC CRUST
ORDOVICIAN PERIOD
OROGENESIS
PALEOZOIC ERA
PETROGENESIS
PLATE TECTONICS
ROCKS
SCANDINAVIA
SILURIAN PERIOD
SUBDUCTION ZONES
TECTONICS
WESTERN EUROPE