Geochemistry and zircon U-Pb-Hf isotopes of the granitoids of Qianjinchang pluton in the Xi Ujimqi, Inner Mongolia: Implications for petrogenesis and geodynamic setting

2017 ◽  
Vol 53 (3) ◽  
pp. 767-787 ◽  
Author(s):  
Guosheng Wang ◽  
Changfeng Liu ◽  
Weixun Pei ◽  
Zhiguang Zhou ◽  
Hongying Li ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Hf Isotopes ◽  
Geodynamic Setting

scholarly journals The Metallogeny of the Lubei Ni–Cu–Co Sulfide Deposit in Eastern Tianshan, NW China: Insights From Petrology and Sr–Nd–Hf Isotopes

2021 ◽  
Vol 9 ◽  
Author(s):  
Ping Li ◽  
Ting Liang ◽  
Yonggang Feng ◽  
Tongyang Zhao ◽  
Jiangtao Tian ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Crustal Contamination ◽  
Primary Magma ◽  
Phase Iii ◽  
Hf Isotopes ◽  
Cobalt Sulfide ◽  
Geodynamic Setting ◽  
Sulfide Deposit ◽  
Eastern Tianshan ◽  
Clastic Rocks

The Lubei Ni–Cu–Co deposit situated in western segment of the Huangshan-Jing’erquan mafic–ultramafic rock belt in eastern Tianshan of the Central Asian Orogenic Belt (CAOB). The estimated reserve is approximately 9.11 million tons of ore resources with average grades of 0.82 wt% Ni, 0.52 wt% Cu, and 0.03 wt% Co. The Lubei intrusion is mainly composed of gabbro (phase I), peridotite (phase II), pyroxene peridotite (phase III), olivine pyroxenite (phase IV), and diorite (phase V), which intruded into the early Carboniferous tuffaceous clastic rocks. Zircon Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA–ICP–MS) U–Pb age of the diorite (phase V) from the edge of the intrusion is interpreted as the top-limit metallogenic age, which is consistent with the formation ages of the Huangshan and Xiangshan Ni–Cu deposits in eastern Tianshan. The roughly parallel rare earth element (REE) curves of the Lubei intrusion indicate the magma originated from a homologous source. The slightly enriched large ion lithophile elements (LILE) are compared to high field strength elements (HFSE) with negative Nb and Ta anomalies show that the Lubei intrusion has arc-affiliate geochemical characteristics. The Sr–Nd–Hf isotopes show that the magma was derived from depleted lithospheric mantle, while suffering 4–10% lower crustal contamination with slight contamination of the upper crust. Based on a comprehensive conservation of regional geological, geochemical, and geochronological evidence, the primary magma of the Lubei intrusion was identified that it was derived from the partial melting of metasomatized lithospheric mantle previously modified by subduction events. The Lubei nickel–copper–cobalt sulfide deposit was formed after the primary magma experienced fractional crystallization, crustal contamination, and sulfide segregation in a post-collisional extensional geodynamic setting after the closure of the Kanggur ocean basin in the early Permian.

Geochemistry and zircon U–Pb–Hf isotopes of the Mante Aobao granite porphyry at East Ujimqin Banner, Inner Mongolia: implications for petrogenesis and tectonic setting

2019 ◽  
Vol 157 (7) ◽  
pp. 1068-1086
Author(s):  
Fei Hu ◽  
Wei Huang ◽  
Zeli Yang ◽  
Simon A. Wilde ◽  
Harald Furnes ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Saturation Index ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Late Ordovician ◽  
Granite Porphyry ◽  
Hf Isotopes ◽  
Margin Setting ◽  
Juvenile Crust ◽  
Early Palaeozoic

AbstractWe present detailed petrography, geochemistry and zircon U–Pb–Hf isotopes of the Mante Aobao granite porphyry in East Ujimqin Banner, Inner Mongolia, with the aim of determining its age and petrogenesis, important for understanding the early Palaeozoic tectonic evolution of the Xing’an–Mongolian Orogenic Belt. The Mante Aobao granite porphyry consists of plagioclase, quartz and minor biotite, but without amphibole. Zircon U–Pb analyses yield ages of 450 ± 1 Ma and 445 ± 2 Ma for the granite porphyry, indicating that it formed during Late Ordovician time. The granite porphyry is metaluminous to slightly peraluminous (aluminous saturation index A/CNK = 0.98–1.11) with high SiO2, K2O and Na2O concentrations and differentiation index (DI = 85–90). Chondrite-normalized rare earth element (REE) patterns display enrichment of light REEs (LREEs) with high ratios of (La/Yb)N and negative Eu anomalies. In the mantle-normalized multi-element variation diagrams, all samples are characterized by depletions of high-field-strength elements (HFSEs; Nb, Ta and Ti) and enrichments of large-ion lithophiles (LILEs; Rb, Th, U and K). These geochemical features indicate that the granite porphyry is a highly fractionated I-type granite and formed in a subduction-related setting. Zircon grains have positive εHf(t) values of +9.2 to +11.2, and TDM2(Hf) ages of 691–821 Ma, suggesting that the granite porphyry was generated by partial melting of Neoproterozoic juvenile crust with involvement of fractional crystallization during magmatic evolution. It is likely that underplating of mantle-derived magmas during Late Ordovician time provided the necessary heat to partially melt this juvenile crust. Combined with the regional geological data, we infer that the Mante Aobao granite porphyry was emplaced in an active continental margin setting that was probably related to the northwards subduction of the Paleo-Asian Plate beneath the South Mongolian Terrane along the Sonid Zuoqi–Xilinhot axis.

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