Geophysical characterisation of two segments of the Møre-Trøndelag Fault Complex, Mid Norway 1Norwegian University of Science and Technology, 7491 Trondheim, Norway
11 Jul 2011
2NGU, Geological Survey of Norway, 7491 Trondheim, Norway
*now at: Institute of Geology, Mineralogy & Geophysics, Ruhr University, Bochum, Germany
Received: 15 Feb 2011 – Published in Solid Earth Discuss.: 25 Feb 2011 Abstract. The Møre-Trøndelag Fault Complex (MTFC) has controlled the tectonic
evolution of Mid Norway and its shelf for the past 400 Myr through repeated
reactivations during Palaeozoic, Mesozoic and perhaps Cenozoic times, the
very last phase of reactivation involving normal to oblique-slip faulting.
Despite its pronounced signature in the landscape, its deep structure has
largely remained unresolved until now. We focused on two specific segments
of the MTFC (i.e. the Tjellefonna and Bæverdalen faults) and acquired
multiple geophysical datasets (i.e. gravity, magnetic, resistivity and
shallow refraction profiles).
Revised: 09 Jun 2011 – Accepted: 13 Jun 2011 – Published: 11 Jul 2011
A 100–200 m-wide zone of gouge and/or brecciated bedrock steeply dipping to
the south is interpreted as being the Tjellefonna fault sensu stricto. The fault appears
to be flanked by two additional but minor damage zones. A secondary normal
fault also steeply dipping to the south but involving indurated breccias was
detected ~1 km farther north. The Bæverdalen fault, ~12 km
farther north, is interpreted as a ~700 m-wide and highly deformed
zone involving fault gouge, breccias and lenses of intact bedrock. As such,
it is probably the most important fault segment in the studied area and
accommodated most of the strain during presumably Late Jurassic normal
faulting. Our geophysical data are indicative of a Bæverdalen fault
dipping steeply towards the south, in agreement with the average orientation
of the local tectonic grain. Our findings suggest that the influence of
Mesozoic normal faulting along the MTFC on landscape development is more
complex than previously thought.
Citation: Nasuti, A., Pascal, C., Ebbing, J., and Tønnesen, J. F.: Geophysical characterisation of two segments of the Møre-Trøndelag Fault Complex, Mid Norway, Solid Earth, 2, 125-134, doi:10.5194/se-2-125-2011, 2011.