Petrogenesis and tectonic setting of the Shiduolong skarn Pb–Zn deposit in the East Kunlun Orogenic Belt: Constraints from whole‐rock geochemical, zircon U–Pb and Hf isotope analyses

Abstract

The Shiduolong Pb–Zn deposit, located in the East Kunlun Orogenic Belt, is a medium‐scale skarn deposit (0.4 Mt metal reserves with a grade of 1.46% Pb and 4.38% Zn). The mineralization occurs along the contact zone between Carboniferous marbles and Triassic quartz diorite and granodiorite. Zircon LA‐ICP‐MS dating indicates that the Shiduolong quartz diorite is coeval with the granodiorite (245 Ma). Whole‐rock geochemical analysis shows that both phases are high‐K calc‐alkaline metaluminous (A/CNK < 1) I‐type granites with similar rare earth (REE) element contents and (La/Yb)N values, indicating that they formed via crystal fractionation from a common parental magma. However, the granodiorite has higher SiO2 contents, lower total Fe2O3, TiO2, MgO, Sr, and Ba contents, and more negative Eu anomalies than the quartz diorites, suggesting that the granodiorite experienced stronger fractional crystallization during magmatic evolution. The zircon εHf(t) values of the quartz diorite range from −3.3 to 1.6. The two‐stage model ages (TDM2) vary from 1,175 to 1,487 Ma. Hf isotope data indicate that the magma of the quartz diorite was mainly derived from partial melting of Mesoproterozoic lower crustal materials with contributions from mantle‐derived magmas. Combined with the regional tectonic and magmatic activities, we propose that the Shiduolong Pb–Zn deposit might have formed during the hydrothermal event associated with the release of magmatic water from the granodiorite‐quartz diorite intrusions, which were generated by the subduction of the Paleo‐Tethys oceanic slab in the Early Triassic.

Petrogenesis and tectonic setting of Mid‐Triassic volcanic rocks in the East Kunlun orogenic belt, NW China: Insights from geochemistry, zircon U–Pb dating, and Hf isotopes

“…In the Late Triassic, with the progressive closure of the A'nyemaqen Ocean, the E-KOB and BH-SG collided with each other, ultimately forming the Palaeo-Tethys ophiolite mélange belt (A'nyemaqen ophiolite mélange belt, Ding et al, 2011;Hu et al, 2016, Figure 1). A large number of previous studies have shown that the E-KOB experienced a largescale mantle-derived magmatic underplating event during the Mid-Triassic (Li et al, 2012;Shao et al, 2017;Wu et al, 2020;Xin et al, 2019;Xiong et al, 2016;Zhong, Feng, Seltmann, Dolgopolova, Andersen, et al, 2018); in this period, the eastern E-KOB indicates an extensional tectonic regime accompanied by amounts of calc-alkaline magmatism (Figure 6c,d), specifically expressed as the eruption of a large number of mafic-intermediatefelsic magmatic rocks Shao et al, 2017;Wang et al, 2018;Xia et al, 2015;Xia et al, 2017;Xin et al, 2019). The presence of extensive magmatism is clearly also considered a product of Palaeo-Tethys plate subduction (Xia et al, 2017;Xin et al, 2019).…”

“…The major and trace element compositions of the DHB volcanic rocks are listed in Table S3. The samples of the volcanic rocks (RCT and RWT) numerous precise geochronologic ages (Liu et al, 2012;Ren et al, 2016;Shao et al, 2017;Wang et al, 2016;Wang et al, 2018;Wu et al, 2020;Xia et al, 2015;Xia et al, 2017;Xin et al, 2019). As mentioned earlier, both the Xilikete Formation and Elashan Formation at the eastern margin of the E-KOB contain volcaniclastic rocks.…”

“…Magmatism in the E-KOB during the Late Permian to Late Triassic can be divided into four stages, corresponding to four different tectonic settings (Xia et al, 2015;Xia et al, 2017;Xin et al, 2019). , the~243 Ma Nangetan granodiorites (Xia et al, 2015;Xia et al, 2017), the~245 Ma Haishigou volcanic rocks (Li et al, 2015), and the~244 Ma Shiduolong quartz diorite (Wang et al, 2018 (Hu et al, 2016), and the~212 Ma Dulan rhyolite (Ding et al, 2011). These rocks suggest that during this period, the E-KOB experienced delamination of the lower lithospheric mantle (Hu et al, 2016;Xin et al, 2019).…”

“…Volcanic activity in the region commenced during the Triassic and peaked in the Late Triassic (Ding et al, 2011;Hu et al, 2016;Li et al, 2015). Mesozoic magmatism and accompanying ore formation have been the focus of numerous studies (Qi, 2015;Sun et al, 2009;Wang, Guo, Zeng, & Guo, 2018;Zhong, Feng, Seltmann, Li, & Dai, 2018). Compared to the Mesozoic granites in the E-KOB, the volcanic rocks have rarely received detailed petrological and geochemical investigations.…”

Fluid Inclusions and S–Pb Isotopes of the Reshui Porphyry Mo Deposit in East Kunlun, Qinghai Province, China

“…Many porphyry-skarn deposits have been discovered and explored in this area (e.g., the Kaerqueka Cu-Mo porphyry deposit, Hutouya Cu-Pb-Zn skarn deposit, and Galinge Fe skarn deposit [9][10][11][12][13]). Many publications have focused primarily on the geochemistry of the granite [14][15][16][17][18] and on the description of the geological characteristics of typical deposits and their host rocks [19][20][21]. The mineralization age has also been investigated, yielding Re-Os dates of 226.5 ± 5.1 Ma [9] for the Shuangqing Fe deposit and 236.2 ± 2.1 Ma [22] for the Shenduolong Pb-Zn polymetallic deposit.…”