Neoproterozoic magmatic events in the South Qinling Belt, China: Implications for amalgamation and breakup of the Rodinia supercontinent

摘要: Abstract Neoproterozoic magmatic rocks in the South Qinling Belt of China provide important clues for understanding mechanism and timing amalgamation breakup Rodinia supercontinent. Here we report new geochemical high-precision LA-ICP-MS zircon U–Pb–Hf isotopic analyses on suites from Liuba Zhashui areas Belt. Our data show that crystallization ages granitic intrusions Tiefodian Tangjiagou area are 863 ± 22 Ma 794 ± 11 Ma, respectively, whereas those dioritic gabbroic at Chishuigou 925 ± 28 Ma 832.6 ± 4.0 Ma, respectively. The diorites display arc-related affinity, characterized by strong depletion Nb, Ta, P Ti, enrichment large-ion lithophile elements (i.e., Rb, Ba, Th U), indicating a subduction-related arc setting ca. 925 Ma. have high SiO2 (68.46–70.98 wt.%), Na2O (3.87–4.51 wt.%), low K2O (1.34–2.61 wt.%) contents with TTG affinity. However, their Cr, Ni Cr/Ni, Nb/Ta ratios similar to continental crust, together negative eHf(t) values (− 4.87 − 14.84), suggesting margin 863 Ma. gabbros TiO2 content (2.74–3.14 wt.%), Zr/Y (3.93–4.24), Ta/Yb (0.19–0.25) Zr/Nb (11.37–13.17), features within-plate basalts, an intra-continental rift 833 Ma. granitoids exhibit LREE, K Pb, extensional tectonic environment 794 Ma. results indicate formed before 833 Ma might represent supercontinent subduction environment, events peak ~ 740 Ma during 833–680 Ma Rodinia. Integrating our previous works, propose model evolutionary history Neoproterozoic, including four key stages: 1) ocean separated Yangtze Block Early (ca.1000–956 Ma); 2) bidirectional oceanic lithosphere 956–870 Ma; 3) collision between 870–833 Ma, thus was as part this period; 4) rifting 833–680 Ma, although blocks were not entirely rifted apart.