Late Palaeozoic and Mesozoic evolution of the Amu Darya Basin (Turkmenistan, Uzbekistan)
Résumé
The Amu Darya Basin (ADB) has been studied primarily for its important hydrocarbon
reserves and to a lesser extent for its geodynamic evolution. The ADB is located on the SE portion
of the Turan Platform, between the sutures of the Turkestan and Palaeo-Tethys oceans, which
closed during the Late Palaeozoic and Early Mesozoic, respectively. Blocks and island arcs
accreted to Eurasia during the Palaeozoic form a poorly defined, heterogeneous basement underlying
the ADB. They played an important role in shaping its composite structure into variously
orientated sub-basins and highs. In this paper, depth–structure and isopach maps, and regional
cross-sections, are analysed to unravel the location and origin of the main structural elements
and to characterize the subsidence evolution of the ADB. The main tectonic events leading to
the formation and evolution of the ADB took place: (1) in the Late Palaeozoic–Early Triassic
(back-arc, rollback and extension/strike-slip); (2) from the Middle Triassic to the Triassic–Jurassic
boundary (Eo-Cimmerian collision of Gondwana-derived continental blocks with Eurasia); and
(3) during the Early–Middle Jurassic (post-collision extensional event). The last part of this evolution
reflects shortening and flexure due to Cenozoic collisions to the south. Palaeotectonic maps
are used to relate these events to the geodynamics of the Tethyan domain.