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Rheological controls on the geometry of deep faults and the tectonic delamination of the continental crust
Author(s) -
White S. H.,
Bretan P. G.
Publication year - 1985
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/tc004i003p00303
Subject(s) - geology , crust , continental crust , mylonite , tectonics , delamination (geology) , seismology , petrology , mantle (geology) , lithosphere , geophysics , shear zone
Recent seismic reflection profiles indicate that the deep faults in the continental crust may decouple deep within the crust or at the Moho. In the contribution it is argued that the decoupling horizons were initially zones across which variations in flow strength occur due to mineralogical differences in the principal rock types. These can result in the tectonic delamination of the crust and at the Moho. Calculations reveal marked strength differences across the Moho. Once initial delamination occurs, weak planes of mylonite develop along such surfaces and are preferentially reactivated during any subsequent deformation. It is postulated that during tectonism, the continental crust (1) does not act, at depth, as a single rigid entity, (2) should not be considered as being firmly attached to the upper mantle and (3) is capable of moving independantly of the upper mantle.