Geochronology, petrogenesis, and tectonic setting of Late Triassic volcanic rocks of the Hadataolegai Formation, central Great Xing'an Range, Northeast China

Abstract

In this study, new geochemical, zircon U–Pb, and Lu–Hf isotopic data are presented for volcanics from the Hadataolegai Formation of the central Great Xing'an Range (GXR) in Northeast China. These new data offer insights into the petrogenesis of the volcanics of the Hadataolegai Formation and the tectonic evolution of the Paleo–Asian Ocean (PAO) and Mongol–Okhotsk Ocean (MOO). These volcanics of the Hadataolegai Formation are divided into andesite‐trachyandesites and dacite‐trachydacites. Zircon U–Pb ages show that the volcanics of the Hadataolegai Formation erupted between 230 Ma and 228 Ma during the Late Triassic, which agrees with recently obtained data. The volcanic rocks in this study have low Y (9.9–21.1 ppm) and Yb (0.78–2.02 ppm) contents, high Sr (444–954 ppm) contents, and slight Eu anomalies (δEu = 0.82 to 0.94), similar to ‘adakite‐like’ rocks. The dacites were formed by fractional crystallization of coeval andesitic magmas. The zircons within the andesite and trachyandesite yield higher positive εHf(t) values (+6.3 to +12.0) and model ages (TDM2) between 860 Ma and 453 Ma, which indicates that the magmas were generated by a newly accreted continental crustal source. Moreover, some of the volcanics are relatively high in MgO contents. These characteristics indicate that the volcanic magmas were derived from the partial melting of delaminated lower crust and mixing with mantle materials. Combining these data with previous studies, we suggest that the magmatism in the central GXR was governed by extension due to the closure of the PAO and the back‐arc extension associated with the southward subduction of the MOO plate (western GXR, near the Erguna Block).

Timing and evolution of Mesozoic volcanism in the central Great Xing'an Range, northeastern China

“…However, given recent high-precision isotopic dating of various units, we propose that the age relationships of the volcanic units require re-evaluation. The Hadataolegai Fm, another volcanic sequence within the CXGR, erupted during the Late Triassic (235-225 Ma; Figure 6a and Table S2; Tang, Sun, Gou, & Yang, 2018;Xu et al, 2017), not during the Early Triassic as previously suggested (IMBGMR, 1996). In this study, we show that the volcanic rocks of the Manketouebo and Manitu formations are Late Jurassic to Early Cretaceous in age, with age ranges from 160 to 135 Ma (peak age at~151 Ma) and 155-120 Ma (peak age at~126 and~131 Ma), respectively (Figure 6b,c; Table S2).…”

“…Recently, “adakite‐like” rocks have been identified from the Hadataolegai Fm (233–226 Ma) in the CGXR. The volcanic rocks of the Hadataolegai Fm do not outcrop parallel to the MO belt, and these rocks originated due to the partial melting of delaminated lower crust and interaction with surrounding mantle material during magma ascent (Tang, Sun, et al, ; Xu et al, ) in an extensional setting associated with the closure of the PAO during the Late Triassic. Moreover, emplacement of A‐type granitoids in the CGXR (236–229 Ma; Ge, Wu, Zhou, & Zhang, ), formation of Mo deposits in the southern GXR, and establishment of the Hongqiling Cu–Ni deposits in the Jilin Province, NE China, occurred within syn‐ and post‐collision tectonic settings that resulted from the closure of the PAO (Jiang et al, ; Jiang, Liang, & Bagas, ; Lü et al, ; Wan et al, ).…”

“…Recently, Triassic igneous rocks and identification of timing of mineralization in the EB have demonstrated the southward subduction of the MO oceanic plate (Gou, Sun, Ren, Hou, & Yang, ; Li et al, ; Li, Xu, et al, ; Liu, Bagas, Jiang, & Wang, ; Liu, Li, He, Huangfu, & Liu, ; Tang et al, ). In addition, contemporaneous bimodal igneous rocks appeared in the eastern EB and western CGXR during the Late Triassic, implying that these areas were dominated by the MO tectonic domain (Tang, Sun, et al, ; Yang et al, ).…”

Geochemistry, geochronology, and zircon Hf isotopes of Late Jurassic–Early Cretaceous granitoids in the Xing'an Massif, NE China: Implication for the Late Mesozoic tectonic evolution and crustal growth

“…Wu et al, 2011;Zhou, Wilde, Zhao, & Han, 2017; Figure 1a). The CAOB experienced the evolution of the Paleo-Asian Ocean, the Mongol-Okhotsk Ocean, and the Paleo-Pacific Ocean (Dong et al, 2014;Z. Y. Tang, Sun, Gou, & Yang, 2018;J.…”