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A paleomagnetic study of tectonically deformed red beds of the Lower Glarus Nappe Complex, eastern Switzerland
Author(s) -
Hirt A. M.,
Lowrie W.,
Pfiffner O. A.
Publication year - 1986
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc005i005p00723
Subject(s) - geology , paleomagnetism , nappe , remanence , lineation , red beds , hematite , fold (higher order function) , anisotropy , shear (geology) , paleontology , seismology , sedimentary rock , magnetization , tectonics , magnetic field , physics , quantum mechanics , engineering , mechanical engineering
A paleomagnetic study at 15 sites (315 samples) in Permo‐Triassic red beds of the Helvetic nappes of eastern Switzerland isolated stable characteristic and secondary remanent directions. Thermal demagnetization and isothermal remanent magnetization experiments suggest pigmentary hematite carries the characteristic direction. Secondary directions are scattered but may have been acquired during the Alpine deformation in the Oligocene and Miocene. The characteristic directions also show large between‐site scatter. Anisotropy of magnetic susceptibility indicates that the hematite grains are flattened within the slaty cleavage, and that there is a north‐south lineation. This anisotropy pattern implies that the magnetic grains were realigned by the Alpine deformation. It is not possible to explain the characteristic remanent magnetization deviations on a site‐by‐site basis, but the site mean directions are streaked along a great circle, the down dip direction of which is approximately parallel to the regional fold axes (60°/20°). This spread could be explained by a penetrative simple shear deformation associated with the nappe‐internal deformation.