Constraints on the timing and genetic link of the large-scale accumulation of proximal W–Sn–Mo–Bi and distal Pb–Zn–Ag mineralization of the world-class Dongpo orefield, Nanling Range, South China

Abstract

The world-class Dongpo orefield, located in the Nanling Range, South China, is famous for its large-scale accumulation of W–Sn–Mo–Bi–Pb–Zn–Ag deposits, which includes the giant Shizhuyuan W-Sn-Mo-Bi, Jinchuantang Sn-Bi, Yejiwei Sn-Cu and Congshuban Pb-Zn-Ag deposits. The polymetallic mineralization around the Qianlishan pluton exhibits systematic zoning and comprises proximal W–Sn–Mo–Bi skarn-greisen and distal Pb–Zn–Ag veins. However, the timing and genetic link of its proximal skarn-greisen W–Sn–Mo–Bi and distal vein-type Pb–Zn–Ag mineralization are not well constrained. Here, we present systematic geochronological data to constrain the geochronological framework and genetic model of the giant Dongpo orefield. The muscovite 40Ar–39Ar age of the greisen-type ore in the Shizhuyuan W–Sn–Mo–Bi deposit is 151 ± 1 Ma, which is consistent with the formation of the skarn-type ore and the Qianlishan pluton, thus indicating that they are genetically related and both formed contemporaneously at ∼151 Ma. The large-scale accumulation of W–Sn–Mo–Bi in the Shizhuyuan deposit may have occurred in a short duration of ∼1 Ma. The muscovite 40Ar–39Ar ages (155.5 ± 1.1 and 156.8 ± 1.1 Ma) and molybdenite Re–Os age (153.8 ± 4.2 Ma) of the Ma’naoshan W–Sn–Fe–Mn–Pb–Zn deposit, as well as the zircon U–Pb age (152.7 ± 0.9 Ma) of the Yejiwei Sn–Cu deposit in the Dongpo orefield, are consistent with the age of the Qianlishan pluton, thus indicating that the proximal skarn-greisen W–Sn–Mo–Bi mineralization in the Dongpo orefield is genetically related to the Qianlishan pluton. In addition, the Rb–Sr dating of sphalerite indicates that the vein-type Pb–Zn–Ag mineralization in the Congshuban area formed at 152 ± 2 Ma, which is consistent with the LA–MC–ICP–MS zircon U–Pb age (156–155 Ma) of the equigranular biotite granite, indicating that the distal vein-type Pb–Zn–Ag mineralization is genetically associated with the Qianlishan equigranular biotite granite. By integrating the high-precision geochronological data of this study with those of previous studies, the new genetic model of the large-scale accumulation of W–Sn–Mo–Bi–Pb–Zn–Ag in the Dongpo orefield suggests that the proximal skarn-greisen W–Sn–Mo–Bi and distal vein Pb–Zn–Ag mineralization in the Dongpo orefield are genetically related to the Qianlishan pluton and that the mineralization type is mainly controlled by the characteristics of the wall rock.