Magma Plumbing System of Emeishan Large Igneous Province at the End-Permian: Insights from Clinopyroxene Compositional Zoning and Thermobarometry

Jun-Hao Hu,Tao Song,Bai-Shun Shi,Jing-Wen Liu

doi:10.3390/min10110979

Abstract

The end-Permian Emeishan Large Igneous Province (ELIP) in SW China is widely accepted to have formed by mantle plume activities, forming voluminous flood basalts and rare picrites. Although many studies were performed on the petrogenesis and tectonic setting, the detailed conditions and processes within the magma chamber(s) remain unsolved. In this study, we studied the sector-/oscillatory-zoned clinopyroxene (Cpx) phenocrysts and performed Cpx-liquid thermobarometric calculation to constrain the physicochemical processes within the magma chambers. The results show that Cpx phenocrysts from the high-Mg basalts were crystallized at 4–27 (average 17) km, whilst those from the low-Mg basalt were crystallized at 0–23 (average 9) km depth. The sector and oscillatory Cpx zoning in the high-Mg basalts show that the magma had experienced undercooling and multistage recharge events in the deep-staging chamber(s). The magma replenishments may have eventually led to the eruption of high-Mg basalts, and magma ascent to the upper crust for further fractionation to form the low-Mg basalts and mafic intrusions.

Highlights

The research on the large igneous provinces (LIPs) is key to understanding continental uplift and breakup, and the associated environmental change, mass extinction, and magmatic Cu-Ni-PGE andFe-Ti-V metallogeny [1]
For the end-Permian Emeishan LIP in SW China, several studies have shown that the flood basalts and picrites are genetically link to the regional magmatic Cu-Ni-PGE and Fe-Ti-V
In this study, we investigate the compositional zoning of the Cpx of the application and precision in P-T calculation) in thermobarometric calculation compared to the phenocrysts from the Emeishan Large Igneous Province (ELIP) high-Mg and low-Mg flood basalts

Summary

Introduction

The research on the large igneous provinces (LIPs) is key to understanding continental uplift and breakup, and the associated environmental change, mass extinction, and magmatic Cu-Ni-PGE andFe-Ti-V metallogeny [1]. For the end-Permian Emeishan LIP in SW China, several studies have shown that the flood basalts and picrites are genetically link to the regional magmatic Cu-Ni-PGE and Fe-Ti-V metallogeny [2,3,4,5,6,7,8,9,10]. ELIP exposed in southwestern China and northern Vietnam contains a wide variety of magmatic rocksexposed including mafic-ultramafic intrusions, flood abasalts and picrites. Vietnam contains wide variety of magmatic including mafic-ultramafic intrusions, basalts and picrites (Figure 1b) [52].rocks. Geochemical suggested that the overlies intrusive the andLower extrusive rocks in the ELIP are genetically linked [53,54,55].studies.

Results

Discussion

Conclusion