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Tectonic setting of post‐orogenic granites within SW Fennoscandia based on deep seismic and gravity data
Author(s) -
Andersson M.,
Lie J. E.,
Husebye E. S.
Publication year - 1996
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.1996.tb00785.x
Subject(s) - geology , seismology , anatexis , tectonics , extensional definition , crust , submarine pipeline , geophysics , partial melting , geotechnical engineering
Within the Svecononvegian Province of SW Scandinavia granite intrusions are abundant. Prominent ones are the Bohus‐Iddefjord and the Flå granites, the so‐ called Bohus‐Flå Granite belt. The age of these granites, consistent at ≅ 900 Ma, coincides with the late extensional stage of the Svecononvegian‐Grenvillian orogen. Gravity observations and deep seismic profiling lines are presented that also cover the Skagerrak Sea. The geophysical data suggest that the Bohus granite continues seaward for at least 80 km and its thickness, offshore, is estimated to be 2–4 km. Where the seismic profiling lines intersect the inferred seaward extension of the Bohus granite, a distinct reflection pattern is observed at ≅ 1.6 s. TWT. This coincides with a gravity modelled thickness of ≅ 4 km. The seismic profiles also show a large Moho offset beneath the modelled granite. It is proposed that this offset is related to Svecononvegian crustal underthrusting and that the granite melt could have formed by anatexis of mid‐crustal rocks downthrusted to greater depths in the vicinity of the seismically observed Moho offset.