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[1] Across contractional orogens, the equivalency between decadal convergence rates from geodetic GPS data and geologic shortening rates at time scales of thousands or millions of years has rarely been documented. Here, we present an example from the northern margin of Chinese Pamir, where the Main Pamir Thrust is tectonically quiescent, and recent deformation is concentrated on the Pamir Frontal Thrust (PFT). Based on dated and faulted fluvial terraces, magnetostratigraphy, and mapping, the horizontal shortening rate of the PFT is $6-7 mm/a at time scales of both $18.4 ka and $0.35 Ma, comparable to the geodetic rate of $6-9 mm/a across the same zone, implying that modern geodetic rates are a reasonable proxy for geologic rates since $0.35 Ma. Comparing this example with studies in other contractional orogens, we conjecture that a match or mismatch of geologicgeodetic rates typically depends on the time scale of observation, fault geometry, and fault mechanics. Citation: Li, T.,

Fold scarps, a type of geomorphic scarp formed by folding mechanisms of hinge migration or limb rotation, serve to delineate both fault‐bend characteristics and folding histories, which can, in turn, illuminate tectonic processes and seismic hazards associated with thrust systems. Because the subsurface geometry of folds is commonly difficult to determine, existing fold‐scarp models, which rely on both the fold type and its causative fault geometries, remain uncertain with respect to the kinematic evolution of a given fold. In this paper, we develop a model to illustrate that, irrespective of specific fold type and subsurface geometries, fold‐scarp growth in the mechanism of hinge migration can be successfully reconstructed based on analyses of bed geometry. This model reveals that the underlying bed dips and the ratio of hinge migration distance/hinge width control the fold‐scarp shape and slope. During initial growth (ratio < 1), the scarp slope increases gradually with migration of the hinge. When the hinge totally exits from its original position (ratio > 1), the slope reaches a maximum, which solely depends on underlying bed dips. The scarp height, however, is independent of the hinge width and can be used to quantify folding magnitude. Application of our model to fold scarps in the Mingyaole anticline in the southern foreland of Chinese Tian Shan indicates that the modeled fold‐scarp geometry can roughly match with field observations. The Mingyaole shortening rate is estimated to be ≥5.0 mm/a since ~15 ka, such that this single fold has accommodated about half of the regional convergence during the Holocene.

The Pamir‐Tian Shan collision zone in the western Tarim Basin, northwest China, formed from rapid and ongoing convergence in response to the Indo‐Eurasian collision. The arid landscape preserves suites of fluvial terraces crossing structures active since the late Neogene that create fault and fold scarps recording Quaternary deformation. Using geologic and geomorphic mapping, differential GPS surveys of deformed terraces, and optically stimulated luminescence dating, we create a synthesis of the active structures that delineate the timing, rate, and migration of Quaternary deformation during ongoing convergence. New deformation rates on eight faults and folds, when combined with previous studies, highlight the spatial and temporal patterns of deformation within the Pamir‐Tian Shan convergence zone during the Quaternary. Terraces spanning ~130 to ~8 ka record deformation rates between ~0.1 and 5.6 mm/yr on individual structures. In the westernmost Tarim Basin, where the Pamir and Tian Shan are already juxtaposed, the fastest rates occur on actively deforming structures at the interface of the Pamir‐Tian Shan orogens. Farther east, as the separation between the Pamir‐Tian Shan orogens increases, the deformation has not been concentrated on a single structure, but rather has been concurrently distributed across a zone of faults and folds in the Kashi‐Atushi fold‐and‐thrust belt and along the NE Pamir margin, where shortening rates vary on individual structures during the Quaternary. Although numerous structures accommodate the shortening and the locus of deformation shifts during the Quaternary, the total shortening across the western Tarim Basin has remained steady and approximately matches the current geodetic rate of 6–9 mm/yr.

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