Re-Os pyrite geochronology of Zn-Pb mineralization in the giant Caixiashan deposit, NW China

Abstract

The newly discovered Caixiashan Irish-type Zn-Pb deposit (∼131 Mt at 3.95 % Zn + Pb), located in the Eastern Tianshan of Xinjiang, is one of the largest Zn-Pb deposits in NW China. Massive colloform/framboidal textured syn-sedimentary pyrite yielded a Re-Os isochron age of 1019 ± 70 Ma (MSWD = 3.5), which is interpreted to be the depositional age of the Kawabulake group that hosts the ore. The age of the main mineralization stage is constrained by two types of pyrite: the layered pyrite coexists with recrystallized calcite and dolomite and is locally replaced by sphalerite, whereas the euhedral pyrite occurs with galena that crosscuts the massive sphalerite. The layered pyrite yielded a Re-Os age of 859 ± 79 Ma (MSWD = 6.7; initial 187 Os/ 188 Os ratio [I Os ] = 0.19 ± 0.25) and the euhedral pyrite 837 ± 39 Ma (MSWD = 6.5; [I Os ] = 0.16 ± 0.09), which are interpreted to be the Zn and Pb mineralization ages, respectively. The low radiogenic initial Os values of the Zn-Pb mineralization suggest interaction between a hydrothermal fluid and a mafic or ultramafic source rock with a mantle Os signature with some contamination with Mesoproterozoic Kawabulake group. Based on our new Re-Os ages, we conclude that the giant Caixiashan Zn-Pb deposit formed in the early Neoproterozoic and it represents a newly identified mineralization epoch in the Eastern Tianshan of the Central Asia Orogenic Belt.

Re-Os systematics and age of pyrite associated with stratiform Zn-Pb mineralization in the Howards Pass district, Yukon and Northwest Territories, Canada

“…However, Red Dog is the only CD Zn-Pb deposit that has been dated successfully by Re-Os methods, due in part to the coarse-grained nature of the sulphide minerals there and to the relatively high Re contents (tens to hundreds of parts per billion) of pyrite within the vein and massive ore (Morelli et al Kirkham et al (2012) 2004). Base-metal sulphides in other types of sediment-hosted deposits have also been directly dated using Re-Os geochronology, including the Lince-Estefanía Cu deposit in northern Chile (Tristá-Aguilera et al 2006), the Kipushi Cu-Co deposit in the Democratic Republic of Congo (Schneider et al 2007), the Ruby Creek Cu-Co deposit in Alaska ), the Tuolugou Co-Au deposit in northwestern China (Feng et al 2009), the Lisheen and Silvermines Zn-Pb deposits in Ireland (Hnatyshin et al 2015), and the Caixiashan deposit in northwestern China (Li et al 2016).…”

Genesis of the Changba–Lijiagou Giant Pb‐Zn Deposit, West Qinling, Central China: Constraints from S‐Pb‐C‐O isotopes

“…This result suggests that multiple S reservoirs were the sources for S 2− in the studied deposit (Ohmoto et al, 1990). This result could reflect inheritance of the signatures of host rock sulfides, which is a very common occurrence in carbonate-hosted deposits as sulfides may be inherited partly, or wholly, from the precursor by the mineral (Seal, 2006); alternatively there may have been mixing with some magmatic sulfur (Li et al, 2016). Wilkinson and Hitzman (2014) have proposed that magmatic heat, derived from the underplating of mid-crustal sills, may be a driver for the regional flow associated with Irish-type deposits, and similarly Slack et al (2015) have shown that the black shale-hosted Red Dog Zn-Pb-Ag deposit ore-forming fluid was derived from hydrothermal fluids leached from mafic and ultramafic rocks at depth under the deposit.…”

Pyrite and magnetite Re–Os isotope systematics at the Laoshankou Fe–Cu–Au deposit in the northern margin of the East Junggar terrane, NW Xinjiang, China: Constraints on the multistage mineralization and metal sources

“…Recently, the Re–Os system of sulfide minerals and oxide iron minerals have significantly advanced our standing of ore‐forming process of Fe and sulfide ore deposits, as it can be used directly to date the mineralization and to trace the metal source (Stein, Morgan, & Scherstén, ; Selby, Kelley, Hitzman, & Zieg, ; X. Huang, Zhou, Qi, Gao, & Wang, ). Re–Os pyrite and magnetite geochronology have been tested at a variety of hydrothermal systems, for example, VMS (Deng et al, ; D. Li et al, ), porphyry Cu–Au (Jiang, Bagas, & Liang, ), sediment‐hosted Cu–Au (Selby et al, ), orogenic Au (Lawley, Selby, & Imber, ), volcanic‐hosted Fe (X. Huang et al, ; X. Huang et al, ), and IOCG (Zhao et al, ; Zhu & Sun, ; X. Huang, Qi, Wang, & Liu, ), which are shown to provide reliable ages. In addition, Os isotopes have been verified as a good proxy for the major ore‐forming metals (Shirey & Walker, ; Zhu & Sun, ), as the decimal differences between the crustal and the mantle 187 Os/ 188 Os ratios and common Os content.…”