DataSheet1_Strain Transformation Adjacent to the West Qinling Orogen: Implications for the Growth of the Northeastern Tibetan Plateau.docx

The West Qinling orogen has played an important role in accommodating the deformation in the northeastern Tibetan Plateau induced by the India-Eurasia convergence. Here we construct a vertical land motion (VLM) model based on the latest leveling observations adjacent to the West Qinling orogen. Combined with the horizontal deformation field, the crustal deformation pattern in this area is investigated. Additionally, slip rate and coupling coefficients of the West Qinling fault, the longest fault separating the West Qinling orogen from the Lanzhou (Longxi) block, are inverted and constrained with GPS and VLM observations. Results show that the West Qinling fault slips slowly at a rate of 1–2 mm/yr and is strongly coupled with a moment magnitude deficit of Mw7.4. The crustal uplift rates adjacent to the West Qinling orogen are 0–3 mm/yr; which combined with 0–12.5 × 10−9/yr contraction rates, suggests that strain transformation plays a key role in controlling the tectonic uplift in the West Qinling orogen, and furthers our understanding of the contemporary geomorphic and topographic features. We identify a significant deformation transition belt at longitudes of 105°–106°E, which indicates that crustal deformation, induced from the northeastern expansion of the Tibetan Plateau, is mainly constrained to the plateau, rather than accommodated by crustal materials escaping eastward along the Qinling Mountains.

西秦岭造山带（West Qinling orogen）在调节印度-欧亚板块汇聚引发的青藏高原东北部形变过程中发挥了关键作用。本文基于西秦岭造山带周边最新的水准观测数据构建了垂直陆地运动（vertical land motion, VLM）模型。结合水平形变场，本研究对该区域的地壳形变格局开展了系统分析。此外，针对分隔西秦岭造山带与兰州（陇西）地块的最长断裂——西秦岭断裂，本文利用GPS与垂直陆地运动观测数据反演并约束了其滑动速率与耦合系数。研究结果显示，西秦岭断裂以1~2 mm/yr的速率缓慢滑动，且处于强耦合状态，矩震级亏缺达Mw7.4。西秦岭造山带周边的地壳抬升速率为0~3 mm/yr；结合0~12.5×10^−9/yr的收缩速率，表明应变转换在调控西秦岭造山带的构造抬升过程中起到核心作用，同时加深了我们对该区域现代地貌与地形特征的认知。本研究在东经105°~106°范围内识别出一条显著的形变过渡带，这意味着由青藏高原东北向扩展引发的地壳形变主要局限于高原内部，而非通过地壳物质沿秦岭山脉东向逃逸来实现形变调节。