Microstructures associated with the Sottunga-Jurmo shear zone and their implications for the 1.83-1.79 Ga tectonic development of SW Finland

This petrographic study of rock samples from the area of a large-scale shear zone, the Sottung-Jurmo shear zone, in SW Finland, illuminates the thermal development of and strain distribution within the rocks during the last development stages of the shear zone. The results indicate relatively high t...

Full description

Bibliographic Details
Published in:Bulletin of the Geological Society of Finland
Main Authors: T. Torvela, C. Ehlers
Format: Article in Journal/Newspaper
Language:English
Published: Geological Society of Finland 2010
Subjects:
shear zones
gneisses
mylonites
pseudotachylite
cataclasites
deformation
tectonics
Paleoproterozoic
Sottunga
Jurmo
Åland
Finland
Geology
QE1-996.5
Fennoscandia
Online Access:https://doi.org/10.17741/bgsf/82.1.001
https://doaj.org/article/fbcb9af64338491d847f4a2c5e672cf0
Description
Summary:This petrographic study of rock samples from the area of a large-scale shear zone, the Sottung-Jurmo shear zone, in SW Finland, illuminates the thermal development of and strain distribution within the rocks during the last development stages of the shear zone. The results indicate relatively high temperatures during the deformation phases that created the gneisses and the mylonites, strain partitioning through time and continued transpression from S-SW until at least c. 1.79 Ga. This has implications to the latest tectonic models since the results together with previous studies suggest a compartmentalisation of regional stresses between the area SW of the shear zone and central Fennoscandia. The results also suggest that the uplift rate increased during the late stage of the transpression.

Similar Items