Long-lasting intracontinental strike-slip faulting: new evidence from the Karakorum shear zone in the Himalayas
Résumé
P>Zircon crystallization ages for a syntectonic granite and an associated dyke along the Tangtse strand of the Karakorum fault are 18.5 +/- 0.2 and 18.6 +/- 0.2 Ma, respectively. A dyke cross-cutting the foliation in the Karakorum shear zone (Ksz) yielded an age of 16.0 +/- 0.6 Ma. These data show that the Ksz was associated with significant granitic magmatism and was active before 16 Ma, since at least c. 18.5 Ma. Consideration of other data along the Karakorum fault suggests that the fault has most likely been active since c. 22.7-25 Ma at a rate of 8-13 mm a-1. This study conducted in the frontal part of the Himalayan orogen shows that large continental strike-slip faults can be linked with magmatism and be stable for more than 20 Ma, even in the hottest part of the orogen where strain localization is supposed to be at a minimum.