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- Title
Tajik Depression and Greater Pamir Neotectonics From InSAR Rate Maps.
- Authors
Metzger, Sabrina; Gągała, Łukasz; Ratschbacher, Lothar; Lazecký, Milan; Maghsoudi, Yasser; Schurr, Bernd
- Abstract
Using E‐W and vertical deformation‐rate maps derived from radar interferometric time‐series, we analyze the deformation field of an entire orogenic segment, that is, the Tajik depression and its adjoining mountain belts, Tian Shan, Pamir, and Hindu Kush. The data‐base consists of 900+ radar scenes acquired over 2.0–4.5 years and global navigation satellite system measurements. The recent, supra‐regional kinematics is visualized in an unprecedented spatio‐temporal resolution. We confirm the westward collapse of the Pamir‐Plateau crust, inverting the Tajik basin into a fold‐thrust belt (FTB) with shortening rates decaying westward from ∼15 to 2 mm/yr. Vertical rates in the Hindu Kush likely record slab‐dynamic effects, that is, the progressive break‐off of the Hindu Kush slab. At least 10 mm/yr of each, uplift and westward motion occur along the western edge of the Pamir Plateau, outlining the crustal‐scale ramp along which the Pamir Plateau overrides the Tajik depression. The latter shows a combination of basin‐scale tectonics, halokinesis, and seasonal/weather‐driven near‐surface effects. Abrupt ∼6 mm/yr horizontal‐rate changes occur across the kinematically linked dextral Ilyak strike‐slip fault, bounding the Tajik FTB to the north, and the Babatag backthrust, the major thrust of the FTB, located far west in the belt. The sharp rate decay across the Ilyak fault indicates a locking depth of ≤1 km. The Hoja Mumin salt fountain is spreading laterally at ≤350 mm/yr. On the first‐order, the modern 20–5 and fossil (since ∼12 Ma) 12–8 mm/yr shortening rates across the FTB correspond. Plain Language Summary: The Tian‐Shan‐Pamir‐Tibet‐Himalaya mountain belts result from the Cenozoic collision of the Asian and Indian continents. Currently, the Pamir is colliding with the Tian Shan and collapsing westward into its foreland depression, creating the Tajik‐basin fold‐thrust belt (FTB). We use ∼5‐years of regularly acquired satellite radar imagery and pointwise positioning data to monitor the surface‐deformation of the whole region. The resulting rate maps visualize crustal‐scale tectonic and near‐surface processes with an accuracy of a few millimeters and a spatial resolution of ∼400 m. The FTB formed above a low‐friction décollement, detached from the underlying basement, and terminates in the west and north along a kinematically linked thrust‒strike‐slip fault system. In the eastern FTB, salt rises forming a salt fountain that spreads up to 350 mm/yr. In agricultural areas, subsidence of >10 mm/yr is partially due to anthropogenically caused water‐level changes. Key Points: East‐ and up‐rate maps exhibit tectonic and anthropogenic processes with mm‐accuracy in high spatial resolution (400 m)Rate map quality depends on interferometric data coherence and the availability of stabilizing Global Navigation Satellite System dataMajor tectonic signal is E–W shortening in the Tajik fold‐thrust belt due to the westward collapse of the Pamir‐Plateau crust
- Subjects
PAMIR; NEOTECTONICS; GLOBAL Positioning System; THRUST belts (Geology); RADAR interferometry; STRUCTURAL geology
- Publication
Journal of Geophysical Research. Solid Earth, 2021, Vol 126, Issue 12, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2021JB022775