Spatially Variable, Multi‐Mm/Yr Late Pleistocene‐Holocene Slip Rates Along the South Riyueshan Fault Highlight Limitations to Block‐Like Behavior in the NE Tibetan Plateau, China

Abstract Establishing fault slip rates can help resolve the long‐standing question of whether continental deformation focuses along major block boundaries or is distributed more evenly across diffuse fault networks. In the northeastern Tibet Plateau, the ESE‐trending Haiyuan and Kunlun sinistral strike‐slip faults have well‐established slip rates of ∼4–8 mm/yr and ∼10–12 mm/yr, respectively, but the relative importance of intervening NNW‐trending dextral strike‐slip and E–W thrust faults is still controversial. We investigate late Quaternary activity along one of the most prominent of these faults, the NNW‐trending, multi‐segmented South Riyueshan fault (SRYSF). By quantifying geomorphic offsets using remotely sensed digital topography and dating them with Optically Stimulated Luminescence and Radiocarbon, we establish minimum slip rates of ∼3.6 mm/yr for the northern Guide segment and ∼1.7 mm/yr for the southern Duohemao segment. North of 35ºN, magnetotelluric data show the Guide segment and western Waligong segment terminating northwards into the Qinghai Nanshan and West Qinling thrusts, implying a lack of connectivity with the North Riyueshan fault (NRYSF). These multi mm/yr slip rates suggest an important role for NNW‐trending dextral strike‐slip faults in NE Tibet, accommodating shear between the Kunlun and Haiyuan faults by rotating counterclockwise about vertical axes. However, slip rate variations along the SRYSF (∼1.7–3.6 mm/yr) and NRYSF (∼1.1–2.4 mm/yr) caution that regions between these NNW‐trending faults are internally deforming. As well as highlighting limitations to block‐like deformation of NE Tibet, our work emphasizes the importance of measuring fault slip rates at multiple locations to account for variations both along strike and between parallel strands.