Ro. Greiling et Pk. Verma, Strike-slip tectonics and granitoid emplacement: an AMS fabric study from the Odenwald Crystalline Complex, SW Germany, MINER PETR, 72(1-3), 2001, pp. 165-184
AMS fabric studies supported by field and microscopic work were applied to
identify the internal structure and possible emplacement processes of the V
ariscan late-tectonic granodiorite-granite intrusions of the Unit III in th
e Odenwald Crystalline Complex. This Unit is bounded towards NW and NNE by
steeply inclined shear zones, the southern part is unexposed. The magnetic
susceptibility ranges between 10(-3) and 10(-6) SI units and is caused by p
aramagnetic and subordinately by ferromagnetic components. AMS ellipsoids a
re typically oblate with gently plunging long axes (lineations). AMS foliat
ions and lineations trend mainly WSW-ENE and NNW-SSE, parallel with the NNW
and ENE trending marginal shear zones of Unit III, respectively. As reveal
ed by microstructural studies, a penetrative foliation in the plutons is re
lated to emplacement processes. Therefore the observed AMS foliation and li
neation are also interpreted as the result of syn-emplacement deformation w
hich is dominantly strike-slip. Weakly inclined foliations around pluton ro
of xenoliths point to a component of buoyant rise of magma. It is suggested
that the granitoid magma was generated in a low level anatectic zone along
a left-lateral transpressive shear zone during local extension at releasin
g bends. During successive fault movements magma ascended through extension
al parts of the shear zone. Local normal faults and the Otzberg zone at the
eastern margin of Unit III document mostly brittle extension, which overpr
inted the strike-slip fabrics after the emplacement of the plutons.