Structural features and emplacement of the late Svecofennian Pernio granite sheet in southern Finland

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Authors:Selonen, Olavi; Ehlers, Carl; Lindroos, Alf
Author Affiliations:Primary:
Abo Akad. Univ., Turku, Finland
Volume Title:Bulletin of the Geological Society of Finland
Source:Bulletin of the Geological Society of Finland, 68(2), p.5-17. Publisher: Geological Society of Finland, Helsinki, Finland. ISSN: 0367-5211
Publication Date:1996
Note:In English
Summary:The 1840-1830 m.y. old Perniö granite occupies the S margin of the Sauvo-Perniö granite area in the W part of the late Svecofennian granite-migmatite zone in S Finland; it is red, medium- to coarse-grained with euhedral K-feldspar phenocrysts. The high-grade supracrustal volcanic rocks and mica gneisses in this area show polyphase deformation. The Perniö granite intruded along subvertical mid-crustal feeder channels and was emplaced as a sheet or sheets along subhorizontal shear zones during the latest stage of folding, and the viscous granite magma became deformed. The K-feldspar phenocrysts in the granite acted as rigid particles in the viscous matrix and were rotated and imbricated in response to shearing along the subhorizontal shear zones, indicating movement of the upper side of the granite sheet towards the west. It is suggested that a possible emplacement mechanism was strike-slip dilatancy pumping along the subvertical shear zones in a regional transpressional setting. [R.A.H.]
Subjects:Dilatancy; Emplacement; Faults; Folds; Gneisses; Granites; Igneous rocks; Metamorphic rocks; Paleoproterozoic; Phenocrysts; Plutonic rocks; Precambrian; Proterozoic; Shear zones; Svecofennian; Tectonics; Upper Precambrian; Europe; Finland; Scandinavia; Western Europe; Halikko Finland; Kemio Finland; Pernio Finland; Sauvo Finland; Southern Finland; Turku and Pori Finland; Upper Svecofennian
Abstract Numbers:98M/827
Record ID:1997077086
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from FINGEO, Geological Survey of Finland
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