Abstract
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.
Highlights
Strain patterns adjacent to convergent plate boundaries, especially along continent-continent collision zones such as the Tibetan Plateau and Anatolian Plateau, remains a source of active investigation (England et al, 1985; Tapponnier, 2001; Reilinger et al, 2006)
Known as the “roof of the world,” the Tibetan Plateau is famous for its high average elevation of 4,000 m, as well as complex tectonics and deformation patterns those are driven by the India-Eurasia convergence (Molnar & Tapponnier, 1975; Tapponnier et al, 1982; Tapponnier, 2001)
The 3-D crustal deformation model presented in this study indicates that crustal deformation in the northeastern Tibetan plateau is primarily characterized by horizontal contraction, as large as 15 × 10–9/yr, as well as vertical uplift/thickening, with the magnitude of 0–3 mm/yr
Summary
Strain patterns adjacent to convergent plate boundaries, especially along continent-continent collision zones such as the Tibetan Plateau and Anatolian Plateau, remains a source of active investigation (England et al, 1985; Tapponnier, 2001; Reilinger et al, 2006). Since the middle Miocene, the Tibetan Plateau has exhibited expansion and outward growth (Molnar & Tapponnier, 1975; Royden, 1997, 2008). Unlike the clear extrusion in the southeastern Tibetan Plateau (Bai et al, 2010; Bao et al, 2015; Li et al, 2020; Wang & Shen, 2020), the expansion passage and strain pattern are still under debate within the northeastern Tibetan Plateau
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