Latest Miocene to Quaternary deformation in the southern Chaiwopu Basin, northern Chinese Tian Shan foreland

Abstract

Basinward propagation of fold and thrust belts is a crucial geological process accommodating Cenozoic crustal shortening within the India‐Eurasia collision zone. Anticlinal growth strata in the southern Chaiwopu Basin (a piggyback basin) of the northern Chinese Tian Shan foreland record basinward encroachment of the Tian Shan along the Junggar Frontal Thrust Fault. A new magnetostratigraphic section constrains the onset of syntectonic growth strata at circa 6.4 Ma and suggests synchronous basinward thrusting and propagation of the Tian Shan. The intense alluviation in the southern Chaiwopu Basin ceased at circa 0.55 Ma due to significant anticlinal growth and its resultant river incision. More recent anticlinal growth and deformation during the late Quaternary are revealed by folded river terraces developing across the anticline. The terrace height profile indicates that terrace T1H has been vertically offset about 0.6 m by thrust faulting since its formation at about 7 Ka. The stratigraphic and geomorphic data presented in this work are helpful to understand the initiation of thrust‐related folding, as well as aggradation and subsequent incision, in foreland basins of the Tian Shan in relation to the India‐Asia collision.

Latest Pleistocene to Holocene Thrusting Recorded by a Flight of Strath Terraces in the Eastern Qilian Shan, NE Tibetan Plateau

“…Our new data show that the proximal fault (here it is the MDF) of the NFT system along the eastern Qilian Shan remains active, even though the distal structures of the NFT system (the Huangcheng‐Taerzhuang Fault, the Fengle Fault, and the Kangningqiao Fault, Figures b, , and ) are tectonically active during the Holocene (e.g., Ai et al, ; Champagnac et al, ; Chen, ; Hu et al, ). A similar pattern of deformation has been documented in the southern Chaiwopu Basin, a piggyback basin in the easternmost part of the northern Chinese Tian Shan foreland (Lu et al, ). There, thrusting on the frontal thrust fault, the Banfanggou Fault, in the southern Chaiwopu Basin has driven continuous growth of the Saerqiaoke anticline during the late Quaternary (Lu et al, ).…”

“…Along the margins of active orogenic belts, detailed sedimentological and geomorphological investigations are necessary to understand the tectonic evolution of mountain belts (e.g., Burchfiel et al, ; Lavé & Avouac, ; Li et al, ; Li & Yang, ; Lu et al, , , ; Molnar et al, ; Thompson et al, ). In particular, deformed river terraces are very useful in reconstructing the history of active deformation and understanding the kinematics of active structures.…”

Neogene Paleomagnetic Study of the Western Baicheng Depression: Implications for the Intensified Deformation of Tian Shan Since the Latest Miocene

“…Based on the magnetostratigraphy of syntectonic deposits on the northern limb of the northern Kalayuergun anticline, we suggest that the anticline growth initiated at~5.3 Ma. The interpreted latest Miocene intracontinental deformation in the western Baicheng Depression is roughly synchronous with tectonic events observed around the Tian Shan Range and the Tarim Basin, such as the tectonic uplift of the Kunlun Mountains (Sun et al, 2008;Zheng et al, 2000), the northward propagation of the northeast Pamir thrust system (Thompson et al, 2015), the eventual collision between the Pamir Plateau and the SW Tian Shan (Fu et al, 2010;Sun et al, 2015Sun et al, , 2017, and the deformation in other parts of Tian Shan forelands (Huang et al, 2006Hubert-Ferrari et al, 2007;Lu et al, 2010Lu et al, , 2015Saint-Carlier et al, 2016;Wang et al, 2008;Zhang et al, 2016). The above mentioned geological facts suggest that the deformation initiating in the latest Miocene was a regionally distributed tectonic event.…”

“…Considering the several episodes of deformation observed in different parts of Tian Shan, the tectonic event since ~5.3 Ma should be an important part during the basinward propagation of deformation. It is worth emphasizing that this episode of deformation must be an intensified one, as nearly synchronous deformation evidenced by syntectonic deposits have been observed on the first and second rows of fold‐and‐thrust belts in the Baicheng Depression (Sun et al, ; Zhang et al, ) and in the northern Tian Shan forelands (Lu et al, , ; Sun & Zhang, ).…”

“…Although numerous studies have been carried out to understand the Cenozoic tectonic evolution of Tian Shan, including low-temperature thermochronology (Bande et al, 2015(Bande et al, , 2017Glorie et al, 2011;Hendrix et al, 1994;Sobel, Chen, et al, 2006;Sobel, Oskin, et al, 2006;Yu et al, 2014), magnetostratigraphy (Charreau et al, 2005(Charreau et al, , 2006(Charreau et al, , 2009Heermance et al, 2007Heermance et al, , 2008Huang et al, 2006Huang et al, , 2010Lu et al, 2010Lu et al, , 2015Sun et al, 2004Thompson et al, 2015;Zhang et al, 2015Zhang et al, , 2016, crustal shortening estimation (Burchfiel et al, 1999;Charreau et al, 2008Charreau et al, , 2018Hubert-Ferrari et al, 2007;Saint-Carlier et al, 2016;Tian et al, 2016;Zhang et al, 2014), and geodynamics (Reigber et al, 2001;Yang et al, 2008;Zubovich et al, 2010), the uplift time and propagation of Tian Shan still remain controversial, which may be caused by different methods used to estimate the onset of mountain building and/or by the diachronous tectonic deformation along the long range.…”