1. Zhejiang Univ, Sch Earth Sci, Hangzhou 310027, Zhejiang, Peoples R China|Minist Educ, Res Ctr Struct Oil & Gas Bearing Basins, Hangzhou 310027, Zhejiang, Peoples R China
2. China Univ Petr, Dept Explorat Geophys, Coll Geophys & Informat Engn, Beijing 102249, Peoples R China
折叠
Abstract
The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau's tectonic evolution. Here we present new findings on the deformation geometry and timing of the Wupoer thrust belt at the northeastern margin of Pamir. Field investigations and interpretations of seismic profiles indicate that the eastern portion of the Wupoer thrust belt is dominated by an underlying foreland basin and an overlying piggy-back basin. A regional unconformity occurs between the Pliocene (N-2) and the underlying Miocene (N-1) or Paleogene (Pg) strata associated with two other local unconformities between Lower Pleistocene (Q(1)) and N-2 and between Middle Pleistocene (Q(2-4)) and Q(1) strata. Results of structural restorations suggest that compressional deformation was initiated during the latest Miocene to earliest Pliocene, contributing a total shortening magnitude of 48.6 km with a total shortening rate of 48.12%, most of which occurred in the period from the latest Miocene to earliest Pliocene. These results, combined with previous studies on the Kongur and Tarshkorgan extensional system, suggest an interesting picture of strong piedmont compressional thrusting activity concurrent with interorogen extensional rifting. Combining these results with previously published work on the lithospheric architecture of the Pamir, we propose that gravitational collapse drove the formation of simultaneous extensional and compressional structures with a weak, ductile middle crustal layer acting as a d,collement along which both the extensional and compressional faults merged.
Key words
Pamir/Kongur/Wupoer/gravitational collapse/fold-and-thrust belt
NETL
NSTL
Springer Nature