Tajik Basin and Southwestern Tian Shan, Northwestern India‐Asia Collision Zone: 2. Timing of Basin Inversion, Tian Shan Mountain Building, and Relation to Pamir‐Plateau Advance and Deep India‐Asia Indentation

Abstract

The Tajik basin and southwestern Tian Shan constitute the northwestern tip of the India-Asia

Tajik Basin and Southwestern Tian Shan, Northwestern India‐Asia Collision Zone: 3. Preorogenic to Synorogenic Retro‐foreland Basin Evolution in the Eastern Tajik Depression and Linkage to the Pamir Hinterland

“…(b) The Afghan‐Tajik depression in the geography of Central Asia. (c) Digital elevation model of the Afghan‐Tajik depression and its surrounding mountain belts with the major fault and fold traces modified from Abdulhameed et al (). The Tajik basin is the part of the Afghan‐Tajik depression north of the Amu‐Darya floodplain and west of the Darvaz fault zone.…”

“…The orange rectangles locate the study areas at the eastern margin of the Tajik basin. (d) Cross‐sectional sketch of the ~23‐ to 15‐Ma evolution of the Pamir and is foreland modified from Abdulhameed et al (). The ~37‐ to 20‐Ma crustal thickening is sketched by the thrust stacks and recumbent fold nappes of the Central Pamir.…”

“…The model geometries and kinematics are akin to models proposed for foreland‐directed plateau collapse (e.g., Rey et al, ). (e) Cross‐sectional sketch of the constraints imposed by the foreland shortening of the Tajik crust on the geometry of the Tajik lithosphere beneath the Pamir (modified from Gągała et al, , and Abdulhameed et al, ). The seismicity cluster and subducted Tajik middle crust approximate the down‐dip extension of the detachments of the Tajik foreland.…”

“…The Amu Darya river drains the depression to the Aral Sea. The inversion of the depression into the Tajik fold‐thrust belt since the Miocene (e.g., Abdulhameed et al, ; Chapman et al, , ; Gągała et al, ; Hamburger et al, ; Kufner et al, ; Leith & Alvarez, ; Nikolaev, ) has produced arcuate, grossly N trending synform and antiforms, subparallel to the western edge of the Pamir; the antiforms are defined by intrabasin mountain ranges (Figure c). About E‐W shortening in the fold‐thrust belt was accompanied by anticlockwise rotation (e.g., Pozzi & Feinberg, ; Thomas et al, ) that decreases from up to 50° to negligible from the Pamir margin to the western foreland buttress.…”

“…Dominant ~N‐S shortening is accompanied by westward flow (lateral extrusion) of Pamir‐plateau crust into the Afghan‐Tajik depression where it is causing thin‐skinned shortening of the Tajik‐basin sediments above a décollement in Jurassic evaporites, producing the Tajik fold‐thrust belt (Figure c; e.g., Gągała et al, ; Kufner et al, ; Nikolaev, ; Rutte, Ratschbacher, Schneider, et al, ; Rutte, Ratschbacher, Khan, et al, ; Stübner, Ratschbacher, Rutte, et al, ; Schurr et al, ). Using thermochronology, Abdulhameed et al () showed that inversion of the Tajik basin indeed started at ~12 Ma.…”