Intrusion model for Svecofennian (1.9 Ga) mafic-ultramafic intrusions in Finland

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Authors:Makkonen, Hannu V.
Author Affiliations:Primary:
Geological Survey of Finland, Kuopio, Finland
Corporate Authors:Finland, Geological Survey
Volume Title:Geological Survey of Finland, current research 2003-2004
Volume Authors:Autio, Sini, editor
Source:Geological Survey of Finland, current research 2003-2004, edited by Sini Autio; Finland, Geological Survey. Special Paper - Geological Survey of Finland, No.38, p.11-14. Publisher: Geological Survey of Finland, Espoo, Finland. ISSN: 0782-8535. ISBN: 951-690-916-7
Publication Date:2005
Note:In English
Summary:The 1900 Ma tholeiitic magma has been described forming both extrusions and intrusions in Finland. It is now suggested that a high-temperature shear zone (HTSZ) develops between a large mid-crustal magma reservoir and an imbrication zone of thrust folds, probably above the subduction zone (after rifting in a collision zone). The shear zone develops at a depth of 15-20 km, as indicated by P-T calculations from spinel symplectites and reaction rims formed between cumulus olivine and intercumulus plagioclase during cooling of the intrusion. Most of the magma intrudes the HTSZ, but because of local extension caused by uplift of imbrication blocks, some intrusive bodies were formed above the HTSZ, within the lower metamorphic grade rocks. The mafic magma probably reached the surface slightly before the main intrusion event. [R.A.H.]
Sections:Petrology
Subsections:Igneous rocks
Subjects:Faults; Igneous rocks; Intrusions; Mafic composition; Magmatism; Models; Paleoproterozoic; Precambrian; Proterozoic; Shear zones; Svecofennian; Ultramafic composition; Upper Precambrian; Europe; Finland; Scandinavia; Western Europe
Coordinates:N594500 N700000 E0314500 E0190000
Abstract Numbers:06M/783
Record ID:2006065762
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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