Rb-Sr isotopic dating of sphalerite from the giant Huize Zn-Pb ore field, Yunnan Province, Southwestern China

Abstract

The giant Huize Zn-Pb ore field in Yunnan Province, southwestern China, comprises the Qilinchang and Kuangshanchang deposits. The deposits are large in scale (more than 5 Mt of Zn and Pb) and high in grade (average grade of total Zn and Pb is 30%). Reported in this paper are the results of Rb-Sr isotopic dating of sphalerite from this ore field. Two precise ages (223.5±3.9 Ma and 226±6.4 Ma) have been obtained from two isochrons. These two ages are close to the reported ages of native copper mineralizations related to the Emeishan flood basalts in this region, which are 226 Ma to 228 Ma. Previous studies showed that the magnitude of uplift resultant from the Emeishan flood basalts is greater than 1000 m, indicating that the Kuangshanchang and Qilinchang deposits were formed during the same geological event and originated by fluid migration during uplifting resultant from the Emeishan flood basalts.

Geology, isotope geochemistry and geochronology of the Jinshachang carbonate-hosted Pb–Zn deposit, southwest China

“…The fact that 1/Sr values do not co-vary with 87 Sr/ 86 Sr ratios of samples (Fig. 7B) indicates that the isochron age is not a pseudoisochron and has isochronal meaning (e.g., Nakai et al, 1993;Yin et al, 2009;Zhou et al, 2013a), so this age is interpreted to reflect the timing of the Pb-Zn mineralization. The Rb-Sr isotopic age of sphalerite separates from the Jinshachang deposit is similar to the fluorite Sm-Nd isotopic ages of 201.1 ± 2.9 Ma (Mao et al, 2012) and 201.1 ± 6.2 Ma (Zhang et al, 2014), and is broadly similar to those early reported ages of 222 to 192 Ma (Li et al, 2007;Lin et al, 2010;Mao et al, 2012;Wu, 2013;Zhou et al, 2013a, d).…”

“…For example, sphalerite may host Rb in its lattice preferentially than Sr, and thus has high 87 Rb/ 86 Sr ratios, making the mineral suitable for precise radiogenic isotope dating. This method has been applied to hydrothermal deposits (e.g., Brannon et al, 1992;Nakai et al, 1993;Yin et al, 2009;Mao et al, 2012). A modified single grain Rb-Sr isotopic dating with highly precise TIMS and ultra-low procedural blank is also used for pyrite (Li et al, , 2008 and sphalerite (Lin et al, 2010;Zhou et al, 2013a).…”

“…This province contains total Pb + Zn ore reserves of more than 150 million tons (Mt) at an average grades of 5 wt.% Pb and 10 wt.% Zn (Zhou et al, 2011(Zhou et al, , 2013a, making it a major source of base metals in China (Liu and Lin, 1999;Huang et al, 2010;Zhou et al, 2014b). The largest Pb-Zn deposits include the Daliangzi (Zheng and Wang, 1991), Huize (Han et al, 2007a;Li et al, 2007;Yin et al, 2009;Huang et al, 2010), Maoping (Han et al, 2007b) and…”

Re-Os dating of galena and sphalerite from lead-zinc sulfide deposits in Yunnan Province, SW China

“…Recent geochronological studies showed that the large scale Pb-Zn mineralization in the SYG provinces is during the Late Triassic (191-222 Ma;Wu, 2013;Zhou et al, 2013a, b;Mao et al, 2012;Lin et al, 2010;Yin et al, 2009;Li et al, 2007). On the other hand, some researchers considered that the Pb-Zn deposits in the metallogenic province have been reworked during Yanshanian (Xue, 2010(Xue, , 2006Zaw et al, 2007) or Himalayan (Zhou J X, 2011;Zhou et al, 2001;Zhou C X, 1998 colloform texture (Figs.…”

Fluid inclusions and isotopic characteristics of the Jiawula Pb–Zn–Ag deposit, Inner Mongolia, China

“…The resulting leachates were separated from the residual sulfide by repeated centrifuging and rinsing with deionized water. It is difficult to eliminate the influence of secondary fluid inclusions in the sulfide samples (Nakai et al, 1990(Nakai et al, , 1993Brannon et al, 1992;Yin et al, 2009) and to extract synthetic fluid inclusions completely with lower total procedural blanks. The ages only constrained by means of Rb−Sr dating of sulfide residues are very precise (Nakai et al, 1990(Nakai et al, , 1993Brannon et al, 1992;Yin et al, 2009;Tian et al, 2014), so we did not analyze the leachate.…”