Geomorphic dating of across-fault gully incision reveals time-invariant late Quaternary slip-rates at the eastern termination of the Altyn Tagh Fault

<p>Interpretation of fault slip-rates inferred from tectonically offset fluvial landforms is often limited by uncertainties associated with difficulties to explicitly date fluvial incision across the fault. Here, we employed morphology-based modeling to ameliorate this universal dating limitation for gullies that were differentially offset in a sinistral sense across the Altyn Tagh Fault near its eastern termination at ~97&deg;E. Using a stream-power erosion model with locally calibrated coefficients we calculated across-fault gully incision ages that decrease with offset magnitude, are up to threefold younger than the age of the terrace they incised and all-together point towards time-invariant sinistral slip. Luminescence dating of offset alluvial terraces at the same site suggests constant sinistral slip at 0.5&plusmn;0.1 mm/yr since 52&plusmn;4 ka. Our results are consistent with northeastward expansion of the Tibetan Plateau into stable parts of central Asia through an episodic, &ldquo;stepwise&rdquo; process punctuated by prolonged geologic time intervals of constant deformation rates.</p>