Discovery of Yaozhuang Stock and Deep Ore Prospecting Implication for the Western Mangling Orefield in North Qinling Terrane, Central China

Peng Fan,Wenbo Yang,Aihua Xi,Li Wei,Hongyu Zhu,Jiaxin Sun,Xu Chao,Bin Zhou

doi:10.3389/feart.2022.830453

Abstract

In the western Mangling orefield, the molybdenum (Mo) polymetallic deposits are closely related to the ore-bearing porphyry stocks (individual outcrop size: &lt;1 km2). In this study, we have discovered several granitic stocks at Yaozhuang. Systematic petrologic, zircon U-Pb-Hf isotope and whole-rock geochemical studies show that both the granitic stocks of porphyritic granite (157 ± 2 Ma) and the intruding monzogranite dike (153 ± 1 Ma) were emplaced in the Late Jurassic. These granitic stocks are characterized by high SiO2(66.83–75.63 wt%), high K2O (4.15–5.05 wt%), high Al2O3(12.90–16.93 wt%), and low MgO (0.06–0.73 wt%) and are metaluminous to weakly peraluminous, being highly fractionated I-A-type transition granites. The content of the total rare Earth element (ΣREE) of the porphyritic granite (139.6–161.7 ppm) is lower than that of the monzogranite (151.4–253.6 ppm). The porphyritic granite has weakly negative Eu anomalies (Eu/Eu* = 0.77–0.93), whereas the monzogranite has weakly positive Eu anomalies (Eu/Eu* = 0.97–1.21) and are more enriched in light rare Earth elements. Both of them are enriched in large ion lithophile elements (LILEs, e.g., K, Rb, and Ba) but depleted in high-field-strength elements (HFSEs, e.g., Nb, Ta, Ti, Zr, and Hf). The zircon εHf(t) values of all the samples range from −16.1 to −6.9, and the two-stage model ages (tDM2) are 1.78–2.16 Ga. The magma may have originated from partial melting of the lower crust (more than 40 km in depth) caused by mantle-derived magma underwelling. The plutons and stocks were emplaced into the intersection of the early EW-trending faults and the late (Yanshanian) NE-trending faults. The fertile magma with high water content (H2O &gt; 4%) and high oxygen fugacity (Delta FMQ &gt; 1.5) indicates that the Yaozhuang area has significant potential for porphyry Mo polymetallic ore discovery.

Highlights

The Qinling orogen is well-known for its multistage magmatism and orogeny (Mattauer et al, 1985; Kröner et al, 1998; Meng and Zhang, 1999; Liu et al, 2016)
The magmatism occurred in four major stages: Neoproterozoic, Paleozoic, Early Mesozoic, and Late Mesozoic (Ratschbacher et al, 2003; Wang et al, 2012; Wang et al, 2015b)
The Late Jurassic–Early Cretaceous Mangling pluton and the western porphyries are developed in the orefield, and the latter is closely related to the local Mo polymetallic mineralization (Mao et al, 2008, 2010; Zeng et al, 2012; Zhai and Santosh, 2013)

Summary

INTRODUCTION

The Qinling orogen is well-known for its multistage magmatism and orogeny (Mattauer et al, 1985; Kröner et al, 1998; Meng and Zhang, 1999; Liu et al, 2016). Many workers have studied the age, magma evolution, petrogenesis, and mineralization of the Mangling pluton and Nantai, Taoguanping, and Xigou granitic stocks on the western side of the orefield (Ke et al, 2012a, 2012b; Qin et al, 2012; Yang et al, 2014; Hu et al, 2017), whereas granitic stock in the Yaozhuang area was rarely studied. On the western side of the Mangling pluton, shallow granitic stocks (e.g., Taoguanping, Xigou, Nantai, and Panhe) are present with lithology mainly of porphyritic granite, monzogranite, alaskite, and granodiorite (Figure 1). The individual stock has an exposed area of

ANALYSIS RESULTS

DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT