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The Hexi Corridor lies along the northeastern margin of the Tibetan Plateau forming its northern boundary. The late Cenozoic tectonic and landscape evolution of this area are key to understanding the growth of the Tibetan Plateau. We investigate the river profile morphology of 36 drainage areas located on the southern flanks of the Heli Shan, which is the outermost range of the Hexi Corridor. Here, bedrock channels are segmented by steep downstream channels and upper segments with lower gradients. A synthesis of tectonics, climate, lithology, and river reorganization indicates that this area has experienced accelerated tectonic uplift. We constrain the response times for knickpoint evolution based on a knickpoint celerity model and reconstruct paleo-channel profiles. Combined with onset ages for the growth of the Qilian Shan (10 Ma) and Yumu Shan (4 Ma), we propose that the Hexi Corridor and Heli Shan were affected by the outward growth of the Tibetan Plateau at 0.6–2.1 Ma ago. • Tectonic geomorphological analysis applied to the Heli Shan, NE Tibetan Plateau • Stream power and knickpoint celerity models applied to bedrock river channels • Lower and upper channel profiles were relatively steep and gentle, respectively. • Knickpoints are attributed to tectonic activity and date to 0.6–2.1 Ma. • This timing constrains the outwards growth of the Tibetan Plateau in the region. [ABSTRACT FROM AUTHOR]

The southern Liupanshan fault zone (SLFZ) has been active during the Holocene and accommodates complex deformation between the compressional Liupanshan Mountain and the extensional Weihe Graben. We characterized the active faulting of the SLFZ using interpretations of high-resolution satellite images, digital elevation models derived from structure-from-motion models, combined with field investigations. The presence of well-preserved linear fault troughs, scarps, knickpoints, offset streams and ridges, and landslides along the SLFZ indicate that surface-rupturing earthquakes have occurred along the SLFZ in the Holocene. Evidence from paleoseismic trenching indicates that the most recent earthquake occurred between 1607 ± 77 BCE and 1070 ± 90 CE, and thus may have been the 600 CE historical earthquake. The estimated magnitude of this earthquake is Mw 6.7. Radiometric dating of an offset fluvial terrace indicates a late Pleistocene to Holocene left-lateral slip rate of ~1.5 ± 0.3 mm/yr. Our geologic and geomorphic observations show that the SLFZ may extend into the Weihe Graben where the slip is transferred onto other active faults within the Weihe Graben. • The southern Liupanshan fault zone is a major block-bounding fault in NE Tibet. • Remote sensing and fault trenching were used to analyze paleoseismic activity. • Faulting spans the late Quaternary, including the 1607 BCE–1070 CE earthquake. • Late Quaternary faulting is left-lateral with a slip rate of ~1.5 mm/yr. • The fault zone accommodates deformation along the Liupanshan Range and Weihe Graben. [ABSTRACT FROM AUTHOR]