Geochemical contrasts between Late Triassic ore-bearing and barren intrusions in the Weibao Cu\u2013Pb\u2013Zn deposit, East Kunlun Mountains, NW China: constraints from accessory minerals (zircon and apatite)

Shihua Zhong,Zhihui Dai,Reimar Seltmann,Chengyou Feng,Daxin Li

doi:10.1007/s00126-017-0787-8

Shihua Zhong, Zhihui Dai + Show 3 more

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https://doi.org/10.1007/s00126-017-0787-8

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Abstract

The Weibao copper–lead–zinc skarn deposit is located in the northern East Kunlun terrane, NW China. Igneous intrusions in this deposit consist of barren diorite porphyry (U–Pb zircon age of 232.0 ± 2.0 Ma) and ore-bearing quartz diorite and pyroxene diorite (U–Pb zircon ages of 223.3 ± 1.5 and 224.6 ± 2.9 Ma, respectively). Whole-rock major and trace element and accessory mineral (zircon and apatite) composition from these intrusions are studied to examine the different geochemical characteristics of ore-bearing and barren intrusions. Compared to the barren diorite porphyry, the ore-bearing intrusions have higher Ce4+/Ce3+ ratios of zircon and lower Mn contents of apatite, indicating higher oxidation state. Besides, apatite from the ore-bearing intrusions shows higher Cl contents and lower F/Cl ratios. These characteristics collectively suggest the higher productivity of ore-bearing quartz diorite and pyroxene diorite. When compared with ore-bearing intrusions from global porphyry Cu deposits, those from Cu–Pb–Zn skarn deposits display lower Ce4+/Ce3+ and EuN/EuN* ratios of zircon and lower Cl and higher F/Cl ratios of apatite. We conclude that these differences reflect a general geochemical feature, and that zircon and apatite composition is a sensitive tool to infer economic potential of magmas and the resulting mineralization types in intrusion-related exploration targets.

Highlights

Zircon and apatite are widespread accessory minerals in intermediate to felsic igneous rocks and are resistant to Editorial handling: R
Typical CL images of zircon are shown in ESM 2; U–Pb dating data are summarized in ESM 1 (Table S2)
Previous geological studies in the Weibao deposit revealed that it was comparable to other skarn deposits in the Qimantagh metallogenic belt (QMB) in terms of host rocks, alteration, mineralization, and igneous rock types

Summary

Introduction

Zircon and apatite are widespread accessory minerals in intermediate to felsic igneous rocks and are resistant to Editorial handling: R. The Qimantagh metallogenic belt (QMB), located in the East Kunlun Mountains, NW China, is one of the most important and promising exploration areas for porphyry-/skarnrelated Cu–Pb–Zn–Fe deposits in China (Fig. 1a) There is a consensus that mineralization is mainly related to Middle to Late Triassic granitoids that are widespread in the QMB (Feng et al 2012). Published studies showed that not all Middle to Late Triassic intrusions occurring in the QMB were ore-bearing. Understanding the distinct geochemical patterns between ore-bearing and barren intrusions in the QMB is very important since it can enhance the knowledge about the role of magmas in the formation of those deposits and provide useful information for mineral exploration in this area.

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Discussion

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