Quantification
of strain localization in the continental lithosphere is hindered by
the lack of reliable deformation rate measurements in the deep crust.
Quartz-strain-rate metry (QSR) can be a convenient tool for performing
such measurements once calibrated. We achieve this calibration by
comparing the estimated strain rates with those measured independently
on an outcrop. We indentify the best piezometer - rheological law
association, defining the QSR-S-H method that yields reliable strain
rates measurements. Applied to two major continental strike-slip shear
zones, the Ailao Shan-Red River (ASRR; China) and the Karakorum
(Tibet), QSR-S-H highlights across-strike strain-rate variations, from
< 1x10-15s-1 in zones where deformation is weak, to > 1x10-13s-1
in zones where strain is localized and the shear stress is higher than
50 MPa. Strain rates
integrated across the shear zones imply high
fault slip rates of the order of 0.9 (Karakorum) and 4 cm yr-1 (ASRR),
implying strong strain localization in these strike-slip continental
shear zones.
GEOLOGY, August 2013, DOI:10.1029/G33723.1.