Discovery of late Paleozoic fossils in tectonic blocks of the Dabao Formation in the South Qinling Orogenic Belt and their significance

Zircon U–Pb geochronology and in situ Hf isotopic compositions of the Madao migmatite: Constraints on the Mesozoic orogeny in the South Qinling belt

“…The traditional geodynamic model for the South Qinling belt involves two stages: the opening of an ocean basin due to rifting in the early Late Palaeozoic and the closing of a mature ocean basin due to northward subduction leading up to the Early Mesozoic (Dong, Zhang, Hauzenberger, et al, 2011; Lai, 1997; Li et al, 1996, 2004, 2007; Meng & Zhang, 1999; Xu et al, 2008; Zhang et al, 2004). However, other researchers have reported the presence of Neoproterozoic basic‐ultrabasic blocks, Ordovician volcanic rocks, and Carboniferous radiolarians in the South Qinling belt (Feng et al, 1996; Wang, 2008; Wang, Yan, Yan, et al, 2009; Wang, Yan, Wang, et al, 2009; Wang, Wang, Yan, et al, 2011; Yan et al, 2007; Zhang et al, 2005), which contradict the above model. According to the principle of tectonic facies division, Wang, Yan, Yan, et al (2009) identified the South Qinling belt as a trench‐arc‐basin system (Figure 1a).…”

“…The block‐in‐matrix structure is typical in convergent‐margin mélanges (Codegone, Festa, & Dilek, 2012; Prohoroff, Wakabayashi, & Dumitru, 2012; Wakita, 2012). The ages of the blocks' range from the Neoproterozoic to the Late Palaeozoic (Feng et al, 1996; Wang, 2008; Wang, Wang, Yan, et al, 2011; Wang, Yan, Yan, et al, 2009; Yan et al, 2007; Zhang et al, 2005), and the youngest age of the matrix is reflected by Permian radiolarians (Wang, 2008; Wang, Wang, Yan, Yan, & Li, 2007). Thus, it is likely that an ocean existed in the South Qinling area during the Neoproterozoic and the blocks were likely incorporated into the accretionary wedge during the subduction‐accretion process.…”

“…Thus, special attention has recently been paid to the evolution of this belt (Dong & Santosh, 2016; Feng, Du, Yin, Shen, & Xu, 1996; Gao, Zhang, Wang, Ouyang, & Xie, 1996; Lai, 1997; Li et al, 2003; Liu et al, 2016; Mattauer et al, 1985; Meng & Zhang, 1999, 2000; Ratschbacher et al, 2003; Wang et al, 1989, 2009; Wang, Wang, & Zhang, 2013; Wu & Zheng, 2013; Yan, Andrew, et al, 2004; Yan et al, 2007; Zhang, Meng, & Lai, 1995; Zhang et al, 2005). Although the overall orogenic model of the Qinling orogen is still considerably controversial (Dong, Zhang, Hauzenberger, et al, 2011; Li et al, 2004, 2007; Li, Sun, & Zhang, 1996; Meng & Zhang, 1999; Wang, Yan, Yan, et al, 2009; Wang, Yan, Wang, et al, 2009; Wang, Wang, Yan, Yan, Zhang, et al, 2011; Wang, Wang, Yan, Yan, Tan, et al, 2011; Xu, Zhang, & Han, 2008; Yan, Wang, Wang, et al, 2007), researchers have agreed that the final collision of the Qinling orogen occurred in the South Qinling area and was the result of the Mesozoic orogeny. However, the time period of the orogenic collapse remains a subject of debate and has not yet been accurately determined.…”