Pliocene‐Pleistocene initiation, style, and sequencing of deformation in the central Tien Shan

Abstract

In response to the Indo-Asian collision, deformation of the Tien Shan initiated at~25 Ma along the northwestern margin of the Tarim Basin. 300 km north, the Kyrgyz Range began deforming~15 Ma later. Although multiple intervening structures across the Tien Shan are currently active, the sequencing of initial deformation across the orogen's entire width remains poorly known. To determine whether deformation migrated sequentially northward or developed less predictably, we documented deformation patterns within the Naryn Basin in south-central Kyrgyzstan. Detailed mapping and a published balanced cross section across the Naryn Basin suggest that deep-seated, relatively steeply dipping thrust faults have disrupted the basin during late Cenozoic deformation. Dating of deformed fluvial terraces with ages between~10 and 250 ka constrains the rate of deformation across relatively young structures in the Tien Shan interior. Based on geodetic surveys of dated terraces, local rates of relative rock uplift span from 0.3 to 3.5 mm/yr. Folding rates and patterns are temporally persistent at a given site. Moreover, they mimic modern geodetic rates measured from interferometric synthetic aperture radar. Extrapolating these rates into the past suggests that structures within the interior of the Naryn Basin formed in the last 1 Myr, whereas the ranges surrounding the basin initiated at least 1-4 Myr earlier. Hence, within the Naryn Basin itself, deformation has migrated from margins to interior. Similarly, these new chronologies indicate that at least some deformation in the interior of the Tien Shan initiated millions of years later than along either orogenic margin.

Folded fluvial terraces in a young, actively deforming intramontane basin between the Yumu Shan and the Qilian Shan mountains, NE Tibet

“…15C). Another simple way commonly chosen to calculate the onset age for an anticline is using the linear relationship between terrace tilting and terrace ages (Goode et al, 2014). According to this linear relationship (Fig.…”

“…The uplifting and folding of the Dahe region provide evidence that between the parallel mountain ranges on the NE Tibetan Plateau, intramontane basins (such as the Dahe region, the Heihe valley, the Changma He valley, and the Danghe valley) are also experiencing a certain amount of shortening and uplift above a south-dipping décollement. Uplift and folding of the intramontane basins may have started later than that of the adjacent mountain ranges (Goode et al, 2014) and would accommodate part of the crustal shortening by folding and basin narrowing.…”

“…In thrust-fold belts, crustal shortening is often accommodated by displacement along range-bounding thrust faults and by growth of fault-related folds distributed within intramontane basins (e.g., Burbank et al, 1999). In addition to recent studies focusing on fault slip along the thrusts bordering mountain ranges (e.g., Hetzel, 2013;Zheng et al, 2013b), the rates and wavelengths of surface deformation within intramontane basins can provide additional insight into crustal deformation in active orogenic belts (Goode et al, 2014). Located between the Qaidam Basin and the Hexi Corridor, the NE Tibetan Plateau is characterized by a series of parallel mountain ranges and narrow intramontane basins ( Fig.…”

Rate of Slip From Multiple Quaternary Dating Methods and Paleoseismic Investigations Along the Talas‐Fergana Fault: Tectonic Implications for the Tien Shan Range

“…The compressive to transpressive deformation in the western Tien Shan area is distributed across the entire width of the range, mainly along thrust faults, with millimetric late Quaternary slip rates of~0.1 to 3 mm/year (Goode et al, 2014;Thompson et al, 2002;Zubovich et al, 2010). The India-Eurasia collision has also reactivated a series of large continental strike-slip faults (Figure 1), which may play a major role in accommodating crustal shortening and in causing block rotations (Bande et al, 2015;Bosboom et al, 2014;Campbell et al, 2013;Yin, 2010).…”

Active Bending‐Moment Faulting: Geomorphic Expression, Controlling Conditions, Accommodation of Fold Deformation

“…The Pamir‐western Kunlun and southern Tian Shan regions, northwestern China, are dominated by active thrusting and folding in their piedmonts and major intermontane basins (e.g., Allen et al, ; Goode et al, ; Huang et al, ; Hubert‐Ferrari et al, ; T. Li et al, , ; Saint‐Carlier et al, ; Scharer et al, ; S. C. Thompson et al, ; Thompson‐Jobe et al, ). Previous studies (Avouac & Peltzer, ; Heermance et al, ; Huang et al, ; T. Li et al, , ) and our new surveys document numerous sets of well‐developed FSF scarps and bending‐moment normal fault (BMnF) scarps (Figure ).…”