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

Abstract

Dating of lead-zinc deposits is of critical importance for better understanding of ore genesis, but has long been a big challenge due to the lack of suitable minerals that can be unequivocally linked to the ore genesis and that can be used for tradition radiometric methods. This kind of deposits have simple mineralogy dominated by galena and sphalerite commonly associated with calcite and other gangue minerals. Both galena and sphalerite have low and high variable Re concentrations and thus Re-Os dating of these minerals have been less promising. In addition, the recovery of Re is extremely low for galena when conventional method was applied, lending additional difficulty in precisely dating galena. In this study, we investigate the recovery of Re using different media for anion exchange separation and reporte a revised preparation method for Re-Os dating of galena and sphalerite. By using the new protocol, two reliable Re-Os isochron ages of galena and sphalerite from the Fule (20.4±3.2 Ma) and Laochang (308±25 Ma) Pb-Zn deposits in Yunnan Province, SW China, are achieved.

Ore Genesis and Geodynamic Setting of Laochang Ag-Pb-Zn-Cu Deposit, Southern Sanjiang Tethys Metallogenic Belt, China: Constraints from Whole Rock Geochemistry, Trace Elements in Sphalerite, Zircon U-Pb Dating and Pb Isotopes

“…Newly geochronological data show the basaltic tuff (SHRIMP zircon U-Pb = 312 ± 4 Ma), combined with previous studies (zircon U-Pb = 323.6 ± 2.8 Ma, Chen et al [60]; galena and sphalerite Re-Os = 308 ± 5 Ma, Liu et al [61]), we consider that that the stratabound mineralization occur in the Late Paleozoic (~323-308 Ma).…”

“…Li et al [11] and our view infer that at least two main stages of mineralization occurred in stratabound ores, i.e., at the first dormant period of volcanic activity and at the second intermittent period of volcanism marked by the sediment influx. Liu et al [61] obtained a Re-Os isochron age of 308 ± 5 Ma on galena and sphalerite from upper stratabound ores (1930 m mining tunnel), which is slightly younger than a SHRIMP zircon U-Pb age of 312 ± 4 Ma for the footwall basaltic tuff from 1840 m mining tunnel. This result demonstrated that the ages of upper stratabound mineralization are approximately similar/slightly younger than the footwall volcanic rocks in 1840 m mining tunnel [18].…”

Critical metals in sediment-hosted Pb-Zn deposits in China

“…从空间上来看, 区内矿床分别集中分布在4个矿集区, 包括位于新生代青藏高原碰撞造山带前陆变形区的川 滇黔矿集区 [66] 、位于三叠纪秦岭造山带褶皱逆冲带的 马元-沐浴河矿集区 [58] 、位于早中生代雪峰山褶皱逆 冲带的花垣矿集区 [74] 、位于古生代陆内沉积盆地周缘 的桂中矿集区(延伸入华夏陆块)(图1) [75] . 从时间上来 看, 矿床从新生代(如20.4 Ma)到古生代(如410 Ma)都 有发育 [76,77] . 所以, 扬子地台这些铅锌矿床应由多期成 矿作用在不同的构造背景下形成的.…”