Very high anisotropies of the magnetic susceptibility in ductile shear zones: first quantitative results from a metamorphic nappe in the Central Scandinavian Caledonides, Sweden
Grimmer, J.C.
Universitätsverlag Göttingen
Article in Anthology
Verlagsversion
Deutsch
Grimmer, J.C., 2006: Very high anisotropies of the magnetic susceptibility in ductile shear zones: first quantitative results from a metamorphic nappe in the Central Scandinavian Caledonides, Sweden. In: Philipp, S.; Leiss, B; Vollbrecht, A.; Tanner, D.; Gudmundsson, A. (eds.): 11. Symposium "Tektonik, Struktur- und Kristallingeologie"; 2006, Univ.-Verl. Göttingen, p. 72 - 73., , DOI: 10.23689/fidgeo-1853.
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Shear zones in the Seve crystalline basement
nappes of the central Scandinavian
Caledonides contributed to exhumation
and translation of these highgrade
metamorphic rocks. The Seve
unit is considered to represent the former
distal passive margin of the continent
Baltica, which was subducted beneath
an island arc during Ordovician
times and subsequently collided with
the continent Laurentia during Silurian
and early Devonian times. Strongly textured
mylonitic garnet mica schists with
well developed mica fish and S–C-fabrics
from a shear zone within the Seve unit
show unusual high anisotropies of the
magnetic susceptibility (AMS). The corrected
degrees of anisotropy of the magnetic
susceptibility (P0) range from 1.78
to 4.24. Bulk susceptibilities range from
2.8 × 10−3 to 96.9 × 10−3. The shape
factors range from 0.32 to 0.62, documenting
an oblate shape. Magnetic foliation
is subparallel with metamorphic
foliation. Magnetic lineation scatters
due to permutations of the maximum
and intermediate principal susceptibility
axes...