Annakaisa, Korja and Raimo, Lahtinen and Pekka, Heikkinen and Ilmo T., Kukkonen (2006) A geological interpretation of the upper crust along FIRE 1. In: Finnish Refl ection Experiment FIRE 2001–2005. Special Paper (43). GEOLOGICAL SURVEY OF FINLAND, Espoo, pp. 45-76. ISBN 951-690-963-9
Full text not available from this repository.Abstract
The 500 km long FIRE 1 deep seismic reflection profile crosses over a major Palaeoproterozoic plate boundary in the Fennoscandian Shield – the Svecofennian – Karelian suture zone, where Archaean Karelian craton and its cover have been juxtaposed with the Palaeoproterozoic Svecofennian island arc rocks during the Svecofennian Orogeny, c. 1.9 Ga ago. The upper crustal reflection properties along FIRE 1 are described and the correlation with surface geology is discussed. In addition, a geological interpretation or a vertical lithological map of the uppermost 8 km of the crust is presented. The upper crustal reflectors correlate well with surface geology in the scale of hundred meters. Major lithological units have different seismic patterns that change across the boundaries. The most prominent reflections seem to originate from lithological contrast associated with mafic intrusions, dykes or volcanic units. Shear zones are seen as white bands disrupting the seismic patterns. The upper crust along FIRE 1 is composed of ten units belonging to three tectonic domains: Archaean nucleus, A-P boundary zone and Proterozoic Central Finland. Of these, the upper crustal structure of the Archaean Nucleus is dominated by Archaean structures, the A-P boundary zone by both Palaeoproterozoic extensional structures related to rifting and collisional structures related to Svecofennian orogeny and the Proterozoic Central Finland domain is characterized by both collisional and gravitational collapse structures of the Svecofennian orogen. During the continental arc/continent collision the Western Kianta block, Kainuu Belt, Kajaani, Rautavaara, Iisalmi Complexes as well as Savo Belt belonging to the Archaean proterozoic boundary zone were all thrust sequentially on the Eastern Kianta block belonging to the Archaean Nucleus. The scale of thrusting varies from less than 1 km to 10–20 km thick stacks where the deformation is concentrated mainly to the block boundaries. The Central Finland Granitoid Complex, which is further divided into Pihtipudas and Keuruu blocks, is a shallow (3–8 km) upper crustal unit, whose lower surface is a detachment zone. The detachment surface is associated with upper crustal graben and horst -structures.
| Item Type: | Book Section |
|---|---|
| Subjects: | Methodology > Other-additional study Inducing technology > Underground mining |
| Project: | EPOS-IP > PYHASALMI MINE: in situ underground laboratory |