Abstract
Embedded between the Tian Shan, Pamir, and Hindu Kush, the Tajik
depression is a remnant of the Mesozoic-Miocene Tajik-Tarim basin
system. Since ~12 Ma, westward collapse of the
north-advancing Pamir-Plateau crust inverted the Tajik basin into a
thin-skinned fold-thrust belt with ~150 km of
~E-W shortening distributed between foreland- and
hinterland-vergent structures. Geodetically-derived shortening rates
decay westward from ~15 to 2 mm/yr. Seismicity outlines
the ~east-striking dextral Ilyak fault, bounding the
fold-thrust belt in the north, and distributed shortening in the central
and eastern Tajik depression. We derived E-W and vertical
deformation-rate maps from radar interferometric time-series, consisting
of 900+ radar scenes acquired over 2.0-4.5 years, and available accurate
positioning data. We confirm the westward collapse of the Pamir and the
drastic shortening-rate decline across the Main Pamir Thrust at the
Pamir front. In the Tajik depression, the maps unveil a combination of
basin-scale tectonics, local halokinesis, and seasonal/weather-driven
soil or near-surface effects. Although the Tajik-basin strata move
westward with rates decreasing away from the Pamir, the most external
Babatag backthrust currently absorbs the highest shortening
(~6 mm/yr) as it has done in the past (>20
km). The Ilyak fault accommodates ~5-8 mm/yr,
eastward-increasing slip; rates decay sharply across the fault,
suggesting a locking depth of <1 km - possibly creep. At least
10 mm/yr uplift and westward motion occur across the
Tajik-depression-Pamir transition, including the sinistral Darvaz fault
zone, likely outlining a crustal-scale ramp. The Hoja Mumin salt
fountain is spreading laterally at >300 mm/yr.