Crustal electrical structure and deep metallogenic mechanism in the Xiongcun and Niangre districts of the Tibetan Plateau

Abstract

The Gangdese metallogenic belt in the Tibetan Plateau hosts many large ore deposits, of which the Xiongcun and Niangre ore concentration districts are two typical examples. Due to the insufficient geophysical evidence about the deep metallogenic dynamics across these two districts, the electrical structure was obtained by modeling magnetotelluric data to study the relationship of the crustal structure and metallogenic dynamics. Although the mineralization occurred in the past, the continuous magmatic activities after the mineralization could reactivate the previous migration channels to remain some traces, which can be revealed by some geophysical methods. The resistors at depths of less than 20 km may represent the multiple overlapping volcanic rocks related to a serious of magmatic events in the Lhasa-Gangdese terrane. Some conductors that revealed at different depths may be related to the partial melt, aqueous fluids and/or formation of metallic minerals, and were also further indicated as the possible magma chambers. Connecting the conductors at different depths may be further indicated as some ancient migration channels which were probably related to the shear zones and faults. As the ore deposits in both districts belonged to the magmatic-hydrothermal type, the upwelling magma played a crucial role in the metallogenic dynamics. These possible magma chambers at different depths and channels may be also related to the evolution and emplacement of the deep-seated magma, and contributed to the mineralization of both districts. This study can also offer a reference of significance for the deposits in the eastern Gangdese metallogenic belt.