Dating of the Giant Huize Zn‐Pb Ore Field of Yunnan Province, Southwest China: Constraints from the Sm‐Nd System in Hydrothermal Calcite

Abstract

The Huize ore fi eld, which is the most famous high-grade Mississippi Valley-type Zn-Pb ore fi eld in China, consists of the Kuangshanchang and Qilinchang deposits. The Sm-Nd isotopic compositions of gangue calcite were analyzed to constrain the timing of mineralization. Eight calcite samples from the No. 6 orebody in the Qilinchang deposit have Sm and Nd concentrations of 1.82 -25.93 and 15.25 -79.02 ppm, respectively, and yielded an age of 225 ± 9.9 Ma with epsilon Nd = −10.6 and MSWD = 0.13. Five calcites from the No. 1 orebody in the Kuangshanchang deposit contain 2.37 -2.90 ppm Sm and 8.18 -16.85 ppm Nd, and yielded an age of 228 ± 16 Ma, with epsilon Nd = −10.6 and MSWD = 0.28. These two ages are close to the age of the Emeishan fl ood basalt, which is ca 255 Ma, and agree with the reported 40 Ar/ 39 Ar plateau and isochron ages of the native copper mineralization related to the Emeishan fl ood basalt in this region, which are 226 -228 Ma. Moreover, previous study shows that the magnitude of uplift resulting from the Emeishan fl ood basalts is >1000 m. It indicates that the Kuangshanchang and the Qilinchang deposit formed during the same geological event and originated by fl uid migration during uplift resulting from the Emeishan fl ood basalt.

Sm–Nd dating and rare earth element geochemistry of the hydrothermal calcites from Guling carbonate-hosted talc mineralization in the central Guangxi province, South China

“…Many calcite Sm-Nd dating studies were succeeded to interpret the timing of hydrothermal fluid activities in the mineralization and basin evolution processes (e.g. Hu et al 1996;Peng et al 2003;Li et al 2007;Uysal et al 2007;Su et al 2009). There are some evidence shows that high Sm/Nd ratios and a large range of these ratios for calcite samples enable application of Sm-Nd geochronology to constrain the age of relatively young hydrothermal events (Peng et al 2003).…”

“…Therefore, Sm-Nd isotope system of the hydrothermal calcites has been widely used to determine the age of a variety of hydrothermal systems (e.g. Hu et al 1996;Peng et al 2003;Li et al 2007;Uysal et al 2007; Barker et al 2009;Su et al 2009). …”

Isotope geochemistry of the Huize Zn-Pb ore field, Yunnan Province, Southwestern China: Implication for the sources of ore fluid and metals

“…1 and No. 6 ore bodies constrained from Sm-Nd system in hydrothermal calcite are 228 ± 16 Ma and 225 ± 9.9 Ma (Li et al, 2007b). The center of the Emeishan large igneous province is "Panxi rift" (He et al, 2003), which trends north to south in the west of Xichang to Huili (on the left on Fig.…”

“…Zhou et al (2001) considered the mineralization in the Huize Zn-Pb ore field is related to the closure of the paleo-Tethys ocean, so they supported an Eocene age. Li et al (2007b) reported an age of 225 ± 9.9 Ma for No. 6 and an age of 228 ± 16 Ma for No.…”

“…Some researchers consider that the Kuangshanchang and Qilinchang deposits are MVT deposits (Zhou et al, 2001;Li et al, 2007b). Others do not think that they are MVT deposits because of their high ore grades, large size for single orebody (nearly 1 Mt Pb + Zn reserve) and may have relationship with Emeishan basalt magmatic event (Chen, 1993;Liu and Lin, 1999;Fig.…”