3-D granitic pluton model revealed from gravity data of the Nanling Range (South China): Implications for the WSn mineralization differences

Abstract

The Nanling Range (South China) is well known by the multiple and large scale WSn mineralization belts related to intense and multi-stages magmatism in temporal and spatial dimensions. In this paper, we delineated deep concealed structures from the different wavelet order gravity anomalies, and constructed the 3-D model of granitic plutons in the Nanling Range. The delineated structures, including faults, Moho undulation and concealed granitic plutons, and the emplacement depth of granitic plutons show spatially coincident with the differences of the distribution features between the tungsten and tin deposits. The deep structures environment is different between the W and the Sn polymetallic mineralization, the former are mostly concentrated at the edge of Moho depression where the crustal faults are relatively developed, while the latter are mostly concentrated at the Moho uplift-depression connect zone, where the mantle faults are relatively developed. The tungsten deposits are mainly controlled by the crustal fault and the granite plutons with emplacement depth of about 10 km or even shallower, by contrast, the tin deposits are mainly controlled by the mantle fault and the granite plutons with emplacement depth of 20 km or even deeper. The lithospheric extension and asthenospheric upwelling, due to the subduction of the Pacific plate, cause the melting of the mantle and the laterally spreading in the thinned lithosphere zone, resulting the melting of the thickened crust. During the magma migration, influenced by the continuous melting of the crust and the migration distance, the content of the tungsten element and the tin element, and the fractionation degree, have changed, resulting the WSn mineralization differences in the Nanling Range.