Magnetostratigraphy of the Kelasu section in the Baicheng depression, Southern Tian Shan, northwestern China

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

“…In addition, the sedimentation rates can be underestimated as the sampled strata just contain the lowest part of the Kuqa formation. However, the sedimentation rate in the Kangcun formation is much higher than that of the Kelasu section (~47 m/Myr; Zhang et al, , ), which can be attributed to the shorter distance of the studied section to the Cenozoic depocenter of the depression. Generally, the variations of sedimentation rates in different parts of the depression are roughly comparable to the coeval sedimentary thickness (Wang et al, ).…”

“…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.…”

Influence of Overlapping décollements, Syntectonic Sedimentation, and Structural Inheritance in the Evolution of a Contractional System: The Central Kuqa Fold‐and‐Thrust Belt (Tian Shan Mountains, NW China)

“…Considering (i) the calculated shortening values in Figure , (ii) the stratigraphic thicknesses of Cenozoic units in depocenters (Figures and ), and (iii) the magnetostratigraphic ages given by Zhang et al () and Zhang et al () for two profiles located close to the studied cross section (in the Kumugeliemu anticline and the eastern continuation of the Tuzimaza structure), a clear distinction can be made between an earlier contractional stage in the Kuqa fold‐and‐thrust belt that was dominated by lower shortening and sedimentation rates and a later period characterized by higher rates of both processes (Figure ). The earlier stage (from top Cretaceous to early Miocene) had average, estimated shortening velocities of about 0.2 mm/year and sediment‐accumulation rates of 0.06 to 0.1 mm/year (these values are approximate and dependent on previously published magnetostratigraphic ages; Zhang et al, , ). In contrast, the later stage (spanning the late Miocene to Pleistocene) was characterized by shortening rates of 1.5 and 3.2 mm/year and estimated sediment‐accumulation rates of 0.5 and 1 mm/year during the sedimentation of the Kangcun Fm.…”

“…The Cenozoic sequence displays common growth‐strata geometries and cross‐cutting relationships and attains a maximum thickness of 7,000 m in the Baicheng syncline. It comprises basal evaporites (Eocene in age; Zhang et al, , ) overlain by fluvial and alluvial detrital sequences. The basal evaporites (Kumugeliemu Group) consist of halite, gypsum, and anhydrite with interbedded dolostone and mudstone layers.…”

“…Conglomerates overlie Mesozoic units (either conformably or with a low‐angle unconformity) in the northernmost outcrops of the Kelasu fold‐and‐thrust system. Overlying units coarse upward from red and gray shales with interbedded gypsum, siltstones, and medium‐grained sandstones (Suweiyi and Jidike Fms of Eocene‐early Oligocene and Oligocene‐early Miocene age, respectively; Zhang et al, , ; although younger ages are given for the Suweiyi Fm by Huang et al, ) to sandstones with interlayered siltstones and conglomerates (Kangcun and Kuqa Fms, late Miocene and Pliocene in age; Charreau et al, ; Huang et al, ; Lin et al, ; Sun et al, ; Ye & Huang, ; Yin et al, ; Zhang et al, , , ) and to dark gray conglomerates (Xiyu Fm, essentially Pleistocene in age; Huang et al, ; Sun et al, ).…”