Timing of Orogenic Exhumation Processes of the Qinling Orogen: Evidence From⁴⁰Ar/³⁹Ar Dating

Abstract

The Qinling Orogenic Belt was formed by long-lived subduction and collision between the North and South China blocks. Our 40 Ar/ 39 Ar geochronological data of amphibole, white mica, and biotite reveal different exhumation and cooling histories of the major units in the North Qinling Belt and South Qinling Belt (SQB), constraining the multiple orogenic processes. The exhumation of the Qinling Group in the North Qinling Belt started before 432 Ma, through about 500°C during 432.3-405 Ma, followed by rapid cooling below 425°C at 388.9 ± 1.1 Ma and slow cooling through about 300°C during 333.3-329.5 Ma. A similar exhumation history of the Kuanping Group started from about 383 Ma, cooled below 425°C at 364.9 ± 1.2 Ma and 300°C at 341.8 ± 1.3 Ma. The metamorphic fore-arc sedimentary wedge cooled below 500°C during 322-311.2 Ma, below 425°C at 306.3 ± 2.8 Ma, and 300°C at 249 ± 2.8 Ma. However, the white mica 40 Ar/ 39 Ar ages of 349.4 ± 5.1 and 363.2 ± 2.5 Ma constrain the syntectonic metamorphic crystallization age of the Devonian Liuling Group in the northern SQB, whereas 228.2 ± 0.7 Ma indicates either a delayed cooling of the Wudang Group in the southern SQB or a second stage of low-temperature thermal overprint. Together with previous cooling ages and regional geology, our new data support a tectonic model of Early Paleozoic Andean-type orogeny with subsequent Late Paleozoic continental subduction in the Qinling Orogenic Belt. 40 Ar/ 39 Ar dating. Tectonics, 37, 4037-4067. https://doi.

Permian tectonic evolution of the southwestern Ordos Basin, North China: Integrating constraints from sandstone petrology and detrital zircon geochronology

“…The northward subduction of the east Palaeo‐Tethys oceanic crust from the Early Permian (Dong et al, 2011; Li et al, 2017; Meng & Zhang, 1999; Zhang, Ma, & Ren, 2000; Zhao, Huang, Yan, & Zhang, 2015) led to the formation of the continental arc above the south‐facing subduction system, evidenced by the widespread subduction‐related tectono‐thermal fingerprints extending westward from the South Qinling (Dong et al, 2011, 2015; Meng & Zhang, 1999, 2000; Qin et al, 2009; Yang, Ma, Xu, & Ye, 1992), via the West Qinling (Gu, Wu, & Jiang, 1996; Guo et al, 2012; Qiang, Guo, & Sun, 2007; Wu et al, 2001; Yan et al, 2012), to the South Kunlun (Chen et al, 2015; Dong, Franz, et al, 2018). The resultant continental arc supplied significant mixed detrital fragments composed mainly of the Palaeoproterozoic components along with the younger Permian magmatic arc contributions.…”

“…The NCC is defined by the Engeer Us to Solonker Suture Zone of the eastern Central Asian Orogenic System to the north and the Qilian‐Qiling Orogen of the CCOS to the south (Dong et al, 2011, 2015, Dong, Franz, et al, 2018; Li et al, 2012, 2019; Song, Niu, Su, & Xia, 2013; Song et al, 2017; Xiao, Windley, Hao, & Zhai, 2003; Xiao et al, 2009, 2015). Its western segment discussed in this study is defined by the Taihang Mountain to the east, including the Ordos Basin in the east and the Alxa Massif in the west.…”

High‐P granulites of the Songshugou area (Qinling Orogen, east‐central China): Petrography, phase relations, and U/Pb zircon geochronology

“…420 Ma at ~685°C (Li et al, 2014) dates the earlier D3 shearing at greater depths. 40 Ar/ 39 Ar muscovite and biotite ages of 402–382 Ma (Dong et al, 2018; Xu et al, 2020) may mark the conclusion of D3 and thus give a lower limit of the juxtaposition.…”

“…Lithologically, it comprises metamorphic and pristine granitoids and metamorphic, folded, and in part mylonitized or dismembered siliciclastic and calcsilicate rocks, marbles, and mafic rocks. Cornerstones of its Neoproterozoic–Carboniferous evolution are the intrusion of three suites of granitoids at 983–873 Ma, 863–814 Ma, and 783–718 Ma (Bader, Ratschbacher, et al, 2013), metamorphism and magmatism at c. 520–395 Ma (Bader, Franz, et al, 2013; Liu et al, 2016; Sun, Dong, He, Cheng, & Liu, 2019), cooling through white mica and biotite closure at 402–382 Ma (Dong et al, 2018; Xu et al, 2020), reheating at c. 350 Ma (Bader, Franz, et al, 2013), and low‐ to medium‐grade retrograde metamorphism and reactivation by c. 315 Ma (Bader, Franz, et al, 2013; Zhang et al, 2015).…”

Multi‐Stage Growth in the North Margin of the Qinling Orogen, Central China, Revealed by Both Low‐Temperature Thermochronology and River Profile Inversion

“…The Kunlun – Qinling – Dabie orogenic belt that extends E–W over 3,000 km across Central China (Figure 1) forms the longest active mountain ranges in East Asia. The Qinling belt plays as an important tectonic unit that is not only as the intracontinental collision zone between North and South China Blocks (NCB and SCB) (Dong et al., 2018) but under the effects of both the eastward expansion of the TP and Pacific subduction along East Asia (Clinkscales et al., 2021; Dong et al., 2011; Heberer et al., 2014).…”