Neoproterozoic (750–711 Ma) Tectonics of the South Qinling Belt, Central China: New Insights from Geochemical, Zircon U‐Pb Geochronological, and Sr‐Nd Isotopic Data from the Niushan Complex

Abstract

The Xiejiaba and Fuqiangbei plutons form part of the newly identified Neoproterozoic Niushan complex, which is located in the southern South Qinling belt (SQB). The plutons are compositionally similar, were emplaced at 750–711 Ma, and provide insights into Neoproterozoic tectonism within the South Qinling belt. The Xiejiaba pluton contains diorite, quartz diorite, granodiorite, and granite phases, all of which are sub‐alkaline and have variable major element compositions with negative correlations between SiO2 and MgO, TFe2O3, Al2O3, CaO, TiO2 and P2O5. These rocks are enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs) and have negative Nb, Ta, P and Ti anomalies, all of which are indicative of arc‐type magmatism. The Fuqiangbei pluton contains granitoids that are compositionally similar to the rocks in the Xiejiaba pluton. Samples from these plutons have similar ɛNd(t) values (1.24–5.99) but very variable (87Sr/86Sr)i values (0.7010–0.7054). Combining these data with the geochemical data for these rocks suggests that the magmas that formed the Niushan complex were derived from the crust–mantle boundary. This, combined with the results of previous research, suggests that the transition from low pressure‐low temperature to low pressure‐high temperature conditions within a subduction zone caused melting during a period of late subduction and backarc extension. This constrain the timing of subduction within the South Qinling belt and the northern Yangtze Block (YB) to 750–711 Ma, with this Neoproterozoic subduction associated with an ocean to the north overprinting an existing continental rift‐type tectonic setting within the northern margin of the Yangtze Block and the South Qinling belt.

Petrogenesis and tectonic setting of the Neoproterozoic Douling dioritic–granodioritic–granitic intrusion in the northern Yangtze Block, Central China

“…Age spectra of the Neoproterozoic magmatic rocks in the South Qinling Belt. Data sources: Chen et al, 2006; Dong et al, 2017, Geng, 2010; Hong et al, 2009; He et al, 2022; Hu et al, 2016; Li et al, 2003; Li et al, 2003, 2012; Ling et al, 2008, Liu, Jahn, et al, 2011; Liu et al, 2014, 2022; Liu & Zhang, 2013; Lu et al, 1999; Nie et al, 2019; Niu et al, 2006, Qiu et al, 2020, 2021; Wang et al, 2009, 2017, 2019, 2021; Wang, Liu, et al, 2023; Wu et al, 2012; Xu et al, 2016; Xue et al, 2011, Yan et al, 2011, 2014; Yang et al, 2012, Yang et al, 2020; Zhang et al, 2004, 2013, 2016, 2018, Zhao et al, 2022; Zhu et al, 2014; This study.…”

“…Previous studies indicate that the Neoproterozoic magmatism in the SQB lasted from ca. 956 to 600 Ma (Bader et al, 2013; Dong et al, 2017; Dong & Santosh, 2016; Hu et al, 2016; Li et al, 2012; Ling et al, 2008; Liu et al, 2014, 2022; Wang et al, 2017, 2019, 2021, Wang, Liu, et al 2023; Wang, Xu, et al 2023; Yang et al, 2020; Zhang et al, 2016). Ca.…”

“…The Douling dioritic-granodioritic-granitic rocks have low LOI (loss-on-ignition) values of 0.20-2.85 wt% (Table 3) et al, , Geng, 2010Hong et al, 2009;He et al, 2022;Hu et al, 2016;Li et al, 2003;Li et al, 2003Li et al, , 2012Ling et al, 2008, Liu, Jahn, et al, 2011Liu et al, 2014Liu et al, , 2022Liu & Zhang, 2013;Lu et al, 1999;Nie et al, 2019;Niu et al, 2006, Qiu et al, 2020Wang et al, 2009Wang et al, , 2017Wang et al, , 2019Wang et al, , 2021Wang, Liu, et al, 2023;Wu et al, 2012;Xu et al, 2016;Xue et al, 2011Yang et al, 2012, Yang et al, 2020Zhang et al, 2004Zhu et al, 2014; This study. increasing number of studies suggest that Zr/Hf ratios can be quite variable and fractional crystallization of zircon grains could decrease Zr/Hf ratios (Claiborne et al, 2006;David et al, 2000;Pan, 1997).…”

“…As the northernmost part of the Yangtze Block during the Neoproterozoic (Dong et al, 2011;Zhang et al, 2001), the South Qinling Belt (SQB) in Qinling Orogenic Belt (QOB) preserves a rich record of long-lasting magmatism in various tectonic environments that can be traced back from ca. 960 to 600 Ma (Dong et al, 2011;Dong & Santosh, 2016;Hu et al, 2016;Ling et al, 2008;Liu et al, 2022;Nie et al, 2019;Wang et al, 2017Wang et al, , 2019Wang et al, , 2021Wang, Liu, et al 2023;Wang, Xu, et al 2023;Zhang et al, 2016Zhang et al, , 2018Zhu et al, 2014). Therefore, it may serve as a key element to unravel the geodynamic settings and tectonic processes of the northern Yangtze Block through the entire Neoproterozoic.…”