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The present tectonic regime of the Qilian Shan is dominated by large northeast and northwest striking strike‐slip faults and northwest striking thrust faults. Deformation distribution between the subparallel Haiyuan Strike‐slip Fault and the Minle‐Damaying Thrust Fault (MDF) is crucial for understanding the orogenic mechanism of the northeastern Tibetan Plateau. However, the uncertain kinematics of the MDF and the stress variation along the strike‐varying Haiyuan Fault inhibit further discussion of their relationship. Five key sites along the MDF were selected for analysis of terrace abandonment ages and vertical offsets to determine the slip rates. Two finite element models were constructed to calculate the stress‐strain relationship between the Haiyuan Fault and MDF. We find that the activity of the MDF can be divided into two segments by a stepover with less activity and lower terrain at the Xida River site. Shortening rates of the MDF vary between 0.2 and 2.4 mm/a since the late Pleistocene with trapezoidal trends on both fault segments. The two finite element models and GPS data reveal that the strain rates are lower at the Xida River site but higher at the Menyuan Bend on the Haiyuan Fault. We infer that long‐term strain accumulation at the Menyuan Bend may have mitigated the tectonic activity northeast to the bend under the northeastward stress field, including the activity of the MDF at the Xida River site, and resulted in the segmentation of the MDF. Plain Language Summary: The Haiyuan strike‐slip fault and the Minle‐Damaying thrust fault (MDF) are two important parallel faults that help us understand the growth of the Qilian Shan. The influence of multiple bends of the Haiyuan fault on the activities of its adjacent faults has not been clearly studied. Therefore, we investigated in detail the terraces of five rivers that were offset by the MDF, and determined the spatial variation of the MDF activity rates based on the vertical separations and abandonment ages of the terraces. We also established two finite element models showing the deformation distribution between the Haiyuan Fault and MDF on the upper crustal and crustal scales, respectively. We have found that the Menyuan Bend of the Haiyuan Fault absorbs a significant amount of shortening deformation under the regional northeastward stress field and probably causes the very low activity rate of the MDF at the Xida River site in the northeast of the bend, in contrast to the obvious higher activity rates on both sides of the site, indicating that the activity of the MDF is segmented at the Xida River. The relationship and seismic risk between the two faults are worthy of continuous attention. Key Points: The slip rates of the Minle‐Damaying Thrust Fault (MDF) show its segmentation at stepover near the Xida River with trapezoidal variation trends on both segmentsThe strain rate is lower at the Xida River site but higher at the Menyuan Bend on the Haiyuan FaultStrain accumulation at the Menyuan Bend has reduced the activity of the MDF at the Xida River site [ABSTRACT FROM AUTHOR]

[1] Slip rates of major active strike-slip faults within and around the Tibetan Plateau provide constraints for understanding the dynamics of continental deformation in general because large slip rates can be taken to imply localized deformation between rigid blocks and low slip rates on faults are more consistent with distributed deformation. Several major strike-slip faults have been studied during the last 3 decades. As one of important active strike-slip faults in and around the Tibetan Plateau, the slip rate of the Haiyuan fault has been discrepantly estimated to be high by proponents of 'escape tectonics' or low by others and GPS observations. To better constrain its slip rate and then to better understand the mechanics of intracontinental deformation, we try to more carefully consider offset geomorphic features and age constraints along the Haiyuan fault. In this paper, we select three sites where both upper and lower bounds of slip rate can be obtained. We find that slip rates are 4.2 [+ or -] 0.8 mm/yr at the Shaomayin, 4.5 [+ or -] 0.7 mm/yr at Gaowanzi, and 5.0 [+ or -] 2.5 mm/yr at Huangliangtan site. Combinations of these rates with those published previously yield an average slip rate of 4.5 [+ or -] 1.0 mm/yr on the Haiyuan fault. This rate agrees with the present-day slip rate of 4.3 [+ or -] 1.5 mm/yr measured by GPS, 4.2-8 mm/yr by interferometric synthetic aperture radar, and ~5 mm/yr through paleoseismological studies. The temporal consistency suggests a steady state process of strain accumulation and release along the Haiyuan fault. The low slip rate suggests that the Haiyuan fault, similar to the Altyn Tagh fault, does not transfer a significant portion of the convergence between India and Asia out of India's path into Eurasia but merely redistributes crustal thickening. Citation: Li, C., P.-z. Zhang, J. Yin, and W. Min (2009), Late Quaternary left-lateral slip rate of the Haiyuan fault, northeastern margin of the Tibetan Plateau, Tectonics, 28, TC5010, doi: 10.1029/2008TC002302.