The granite porphyry hidden in the Shuangjianzishan deposit, southern Great Xing’an Range, NE China: geochronology, isotope geochemistry and tectonic implications

Abstract

The Shuangjianzishan vein-type Ag-Pb-Zn deposit in the southern Great Xing’an Range (GXR), NE China, is hosted in the slate of the Lower Permian Dashizhai Formation intruded by granite porphyry. In this paper, U–Pb zircon ages and bulk-rock and isotope (Sr, Nd, Pb and Hf) compositions are reported to investigate the derivation, evolution and geodynamic setting of this granite porphyry. It is closely associated with Pb-Zn-Ag mineralization in the southern GXR and contains important geological information relating to regional tectonic evolution. Laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) zircon U–Pb dating yields an emplacement age of 131 ± 1 Ma for the granite porphyry. Bulk-rock analyses show that the Shuangjianzishan granite porphyry is characterized by high Si, Na and K contents but low Mg and Fe contents, and that the enrichment of Zr, Y and Ga suggests an A-type granite affinity. Most of the studied samples have relatively low 87Sr/86Sr values (0.70549–0.70558), with positive ϵNd(t) (0.71–0.88) and ϵHf(t) (4.9–6.9) values. The Sr–Nd isotope modelling results, in combination with the young TDM2 ages of Nd and Hf (850–864 and 668–778 Ma, respectively), reveal that the Shuangjianzishan granite porphyry may be derived from the melting of mantle-derived juvenile component, with minor lower crustal components; this finding is also supported by Pb isotopic compositions. Considering the widespread presence of granitoids with coeval volcanic rocks and regional geology data, we propose that the Shuangjianzishan granite porphyry formed in a post-orogenic extensional environment related to the upwelling of asthenospheric mantle following the closure of the Mongol–Okhotsk Ocean.

Genesis of the Jinying gold deposit, southern Jilin Province, NE China: Constraints from geochronology and isotope geochemistry

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Figure 9. Frequency histogram (a) and selected geologically important sulphur reservoirs (b, Wei and Wang, 1988) of δ 34 S values for pyrite from the Jinying deposit.

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Petrogenesis, W metallogenic and tectonic implications of granitic intrusions in the southern Great Xing’an Range W belt, NE China: insights from the Narenwula Complex

“…It is generally accepted that the SGB and all of NE China was under an extensional setting during Late Jurassic -Early Cretaceous times (Wu et al 2011;Ouyang et al 2015;Mao et al 2020;Wei et al 2021;Zhang, G. L. et al 2020;Jing et al 2021). The widespread metamorphic core complexes (Wang et al 2011(Wang et al , 2012 combined with the occurrence of bimodal rock suites, A-type granites (Gou et al 2019;Han et al 2021;Zhang, C. et al 2020), alkaline rhyolites, extensional basins and some Au-Mo-REE mineralization in the SGB (Wu et al 2005;Guo et al 2017;) also indicate a Late Jurassic -Early Cretaceous extensional setting.…”

“…However, the exact closure time of the eastern part of the ocean remains controversial, with suggestions including Early-Middle Jurassic (Zorin, 1999;Tomurtogoo et al 2005), Late Jurassic -Early Cretaceous (Kravchinsky et al 2002) and Early Cretaceous (Ren et al 2016). Regardless of the timing of closure, a substantial number of studies have indicated that the late Mesozoic extensional setting in the SGB is related to post-orogenic gravitational collapse and/or subduction-induced back-arc extension related to the closure of the MOO (Wang, Z. H. et al 2015;Fritzell et al 2016;Guan et al 2018;Ji et al 2018Ji et al , 2020Han et al 2021;Shi et al 2020;Wei et al 2021). On Rb versus (Y þ Nb) and (Yb þ Ta) diagrams, most Late Jurassic W-bearing granitoids in this study and late Mesozoic W-related granitoids from previous studies plot in the post-collision granite field (Fig.…”

“…However, the overprinting of the Palaeo-Asian Ocean (PAO), Mongol-Okhotsk Ocean (MOO) and Palaeo-Pacific Ocean (PPO) tectonic regimes had significant influence on the SGB during late Mesozoic time, which has led to disagreements on the interpretation of the deep geodynamic processes and limited our understanding of regional W-related granitic magmatism and W mineralization. Several models have been proposed for the SGB tectonic setting during late Mesozoic time, including (a) upwelling of a mantle plume (Wang, T. et al 2015), (b) post-orogenic gravitational collapse and/or subductioninduced back-arc extension related to the closure of the MOO (Wang, Z. H. et al 2015;Fritzell et al 2016;Guan et al 2018;Ji et al 2018Ji et al , 2020Han et al 2021;Shi et al 2020;Wei et al 2021), (c) arc/back-arc extension and asthenosphere upwelling induced by subduction of the PPO (Ji et al 2019;Li, S. Z. et al 2019;Suo et al 2019;He et al 2020;Sun et al 2020;Wei et al 2020;Jing et al 2021), and (d) compositional effects resulting from the closure of the MOO and subduction of the PPO (Ouyang et al 2015;Liu, C. F. et al 2017;Liu et al 2020;Pang et al 2020;Zhang, C. et al 2020;Mi et al 2021). Additionally, although researchers generally agree that the disappearance of the PAO occurred along the Solonker-Xar Moron-Changchun Fault (SXCF), the closure time of the PAO remains ambiguous (Liu, Y. J. et al 2017).…”