Deformation geometry and timing of the Wupoer thrust belt in the NE Pamir and its tectonic implications

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 (N₂) and the underlying Miocene (N₁) or Paleogene (Pg) strata associated with two other local unconformities between Lower Pleistocene (Q₁) and N₂ and between Middle Pleistocene (Q_2-4) and Q₁ 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 décollement along which both the extensional and compressional faults merged.

Keywords

Pamir / Kongur / Wupoer / gravitational collapse / fold-and-thrust belt

References

[1] Amidon W H, Hynek S A (2010). Exhumational history of the north central Pamir. Tectonics, 29(5): TC5017

[2] Armijo R, Tapponnier P, Mercier J L, Han T (1986). Quaternary extension in southern Tibet: Field observations and tectonic implications. J Geophys Res, 91(B14): 13803–13872

[3] Arnaud N O, Brunel M, Cantagrel J M, Tapponnier P (1993). High cooling and denudation rates at Kongur Shan, eastern Pamir (Xinjiang, China) revealed by ⁴⁰Ar/³⁹Ar alkali feldspar thermochronology. Tectonics, 12(6): 1335–1346

[4] Bershaw J, Garzione C N, Schoenbohm L, Gehrels G, Li T (2012). Cenozoic evolution of the Pamir plateau based on stratigraphy, zircon provenance, and stable isotopes of foreland basin sediments at Oytag (Wuyitake) in the Tarim Basin (west China). J Asian Earth Sci, 44: 136–148

[5] Brunel M, Arnaud N, Tapponnier P, Pan Y, Wang Y (1994). Kongur Shan normal fault: Type example of mountain building assisted by extension (Karakoram fault, eastern Pamir). Geology, 22(8): 707– 710

[6] Chemenda A I, Mattauer M, Malavieille J, Bokun A N (1995). A mechanism for syn-collisional rock exhumation and associated normal faulting: Results from physical modeling. Earth Planet Sci Lett, 132(1-4): 225–232

[7] Clark M K, Royden L H (2000). Topographic ooze: building the eastern margin of Tibet by lower crustal flow. Geology, 28(8): 703–706

[8] Cowgill E (2010). Cenozoic right-slip faulting along the eastern margin of the Pamir salient, northwestern China. Geol Soc Am Bull, 122 (1/2): 145–161

[9] Fu B, Ninomiya Y, Guo J (2010). Slip partitioning in the northeast Pamir-Tian Shan convergence zone. Tectonophysics, 483(3-4): 344–364

[10] Mercier J L, Armijo R, Tapponnier P, Carey-Gailhardis E, Lin H T (1987). Change from Tertiary compression to Quaternary extension in southern Tibet during the India-Asia collision. Tectonics, 6(3): 275–304

[11] Molnar P (2005). Mio-Pliocene growth of the Tibetan Plateau evolution of East Asian climate. Palaeontol Electronica, 8(1): 1–23

[12] Molnar P, Chen W P (1983). Focal depths and fault plane solutions of earthquakes under the Tibetan plateau. J Geophys Res, 88(B2): 1180–1196

[13] Molnar P, England P, Martinod J (1993). Mantle dynamics, uplift of the Tibetan Plateau, and the Indian monsoon. Rev Geophys, 31(4): 357–396

[14] Molnar P, Lyon-Caen H (1989). Fault plane solutions of earthquakes and active tectonics of the Tibetan Plateau and its marigins. Geophys J Int, 99: 123–153

[15] Molnar P, Tapponnier P (1975). Cenozoic tectonic of Asia: Effects of a continental collision. Sciences, 189: 419–426

[16] Molnar P, Tapponnier P (1978). Active tectonics of Tibet. J Geophys Res, 83(B11): 5361–5375

[17] Murphy M A, Yin A, Kapp P, Harrison T M, Ding L, Guo J H (2000). Southward propagation of the Karakoram fault system, southwest Tibet: Timing and magnitude of slip. Geology, 28(5): 451–454

[18] Ni J, York J E (1978). Late Cenozoic tectonics of the Tibetan Plateau. J Geophys Res, 83(B11): 5377–5387

[19] Ratschbacher L, Frisch W, Liu G, Chen C C (1994). Distributed deformation in southern and western Tibet during and after the India-Asian collision. J Geophys Res, 99(B10): 19917–19945

[20] Robinson A C (2009). Evidence against Quaternary slip on the northern Karakorum fault suggests kinematic reorganization at the western end of the Himalayan-Tibetan orogen. Earth Planet Sci Lett, 286(1-2): 158–170

[21] Robinson A C, Yin A, Manning C E, Harrison T M, Zhang S H, Wang X F (2004). Tectonic evolution of the northeastern Pamir: Constraints from the northern portion of the Cenozoic Kongur Shan extensional system, western China. Geol Soc Am Bull, 116(7/8): 953–973

[22] Robinson A C, Yin A, Manning C E, Harrison T M, Zhang S H, Wang X F (2007). Cenozoic evolution of the eastern Pamir: Implications for strain-accommodation mechanisms at the western end of the Himalayan-Tibetan orogen. Geol Soc Am Bull, 119(7/8): 882–896

[23] Rowley D B (1996). Age of initiation of collision between India and Asia: a review of stratigraphic data. Earth Planet Sci Lett, 145(1-4): 1–13

[24] Royden L H, Burchfiel B C, King R W, Wang E C, Chen Z L, Shen F, Liu Y P (1997). Surface deformation and lower crustal flow in eastern Tibet. Science, 276(5313): 788–790

[25] Sippl C, Schurr B, Tympel J, Angiboust S, Mechie J, Yuan X, Schneider F M, Sobolev S V, Ratschbacher L, Haberland C (2013). Deep burial of Asian continental crust beneath the Pamir imaged with local earthquake tomography. Earth Planet Sci Lett, 384: 165–177

[26] Sobel E R, Dumitru T A (1997). Thrusting and exhumation around the margins of the western Tarim basin during the India-Asia collision. J Geophys Res, 102(B3): 5043–5063

[27] Sobel E R, Schoenbohm L M, Chen J, Thiede R, Stockli D F, Sudo M, Strecker M R (2011). Late Miocene-Pliocene deceleration of dextral slip between Pamir and Tarim: Implications for Pamir orogenesis. Earth Planet Sci Lett, 304(3-4): 369–378

[28] Strecker M R, Frisch W, Hamburger M W, Ratschbacher L, Semiletkin S, Zamoruyev A, Sturchio N (1995). Quaternary deformation in the Eastern Pamirs, Tadzhikistan and Kyrgyzstan. Tectonics, 14(5): 1061–1079

[29] Tapponnier P, Peltzer G, Armijo R (1986). On the mechanics of the collision between India and Asia, in Collision Tectonics, edited by M P Coward and A C Ries, Geological Society of London, London: 115–157

[30] Yin A, Robinson A, Manning C E (2001). Oroclinal bending and slab-break-off causing coeval east-west extension and east-west contraction in the Pamir-Nanga Parbat syntaxis in the past 10 m.y.. In: AGU Fall Meeting 2001, Abstracts, Vol 1 San Francisco: AGU, 03

[31] Yin A, Rumelhart P E, Butler R, Cowgill E, Harrison T M, Foster D A, Ingersoll R V, Zhang Q, Zhou X Q, Wang X F, Hanson A, Raza A (2002). Tectonic history of the Altyn Tagh fault system in northern Tibet inferred from Cenozoic sedimentation. Geol Soc Am Bull, 114(10): 1257–1295

RIGHTS & PERMISSIONS

Higher Education Press and Springer-Verlag Berlin Heidelberg