Age and Tectonic Setting of Mesothermal Magmatic Hydrothermal Vein‐Type Pb–Zn–(Ag) Mineralization in the Xiaohongshilazi Deposit, Central Jilin Province, Northeast China

Abstract

The Xiaohongshilazi deposit located in central Jilin Province, Northeast China, is a newly discovered and medium‐scale Pb–Zn–(Ag) deposit with ore reserves of 34,968 t Pb, 100,150 t Zn, and 158 t Ag. Two‐stage mineralization has been identified in this deposit. Stratiform volcanic‐associated massive sulfide (VMS) Pb–Zn mineralization interbedding with the marine volcanic rocks of the Late Carboniferous–Early Permian Daheshen Formation was controlled by the premineralization E–W‐trending faults. Vein‐type Pb–Zn–(Ag) mineralization occurs within or parallel to the granodiorite and diorite porphyries controlled by the major‐mineralization N–S‐trending faults that cut the stratiform mineralization and volcanic rocks. To constrain the age of vein‐type Pb–Zn–(Ag) mineralization and determine the relationship between mineralization and magmatism, we conducted LA–ICP–MS U–Pb dating on zircon from the ore‐bearing granodiorite and diorite porphyries and Rb–Sr dating on metal sulfide. Granodiorite and diorite porphyries yield zircon U–Pb weighted‐mean 206Pb/238U ages of 203.6 ± 1.8 Ma (Mean Standard Weighted Deviation [MSWD] = 1.8) and 225.6 ± 5.1 Ma (MSWD = 2.3), respectively. Sulfides from four vein‐type ore samples yield a Rb–Sr isochron age of 195 ± 17 Ma (MSWD = 4.0). These results indicate a temporal relationship between the granodiorite porphyry and vein‐type Pb–Zn–(Ag) mineralization. The granodiorite associated with vein‐type mineralization has high SiO2 (68.99–70.49 wt.%) and Na2O (3.9–4.2 wt.%; Na2O/K2O = 1.07–1.10) concentrations, and A/CNK values of 0.95–1.04; consequently, the intrusion is classified as a high‐K, calc‐alkaline, metaluminous I‐type granite. The granodiorite porphyry is enriched in large‐ion lithophile elements (e.g. Rb, Th, U, and K) and light REE and is depleted in high‐field‐strength elements (e.g. Nb, Ta, P, and Ti) and heavy REE, indicating that it represents a subduction‐related rock that formed at an active continental margin. Furthermore, the granodiorite porphyry has Mg# values of 31–34, indicating a lower crustal source. Based on petrological and geochemical features, we infer that the ore‐bearing granodiorite porphyry was derived from the partial melting of the lower crust. In summary, mineralization characteristics, cross‐cutting relationships, geochronological data, and regional tectonic evolution indicate that the region was the site of VMS Pb–Zn mineralization that produced stratiform orebodies within the Late Carboniferous–Early Permian marine volcanic rocks of the Daheshen Formation, followed by mesothermal magmatic hydrothermal vein‐type Pb–Zn–(Ag) mineralization associated with granodiorite porphyry induced by the initial subduction of the Paleo‐Pacific Plate beneath the Eurasia Plate during the Late Triassic–Early Jurassic.

Age and Tectonic Setting of Layered Lead–Zinc Ore Bodies in the Xiaohongshilazi Deposit: Constraints from Geochronology and Geochemistry of the Volcanic Rocks in Central Jilin Province, NE China

“…Nevertheless, the volcanic rocks from the Daheshen Formation were spatially, temporally, and genetically related to the layered Pb-Zn mineralization, which is evidenced by the following: (1) Dacite samples of the Daheshen Formation from Dongfeng and Xifeng mine in the Xiaohongshilazi ore district were all interbedded with the layered orebodies (Figures 2B and 4A). ( 2) The volcanic rocks from the Daheshen Formation and the layered orebodies were overlain by the volcanic rocks from the Sihetun Formation (~225Ma), and both of them were cut by the vein-type Pb-Zn-(Ag) orebodies and the granodiorite porphyry (~200Ma) (Figure 2A) [20]. (3) No Pb-Zn mineralization was found in the rhyolite and andesite from the Sihetun Formation (Figure 3A-F).…”

“…In light of the research of the vein-type Pb-Zn-(Ag) mineralization in the Xiaohongshilazi deposit (~200 Ma) [20], it can be concluded that there were three stages of tectonomagmatic-hydrothermal events that occurred in the Xiaohongshilazi area from the early Permian to the early Jurassic: (1) the early Permian (~278 Ma) forming of the Daheshen Formation marine volcanic rocks related to the layered Pb-Zn mineralization; (2) the late Triassic (~225 Ma) forming of the Sihetun Formation volcanic rocks and the diorite porphyry dikes; (3) the early Jurassic (~200 Ma) forming of the granodiorite porphyry associated with the vein-type Pb-Zn-(Ag) mineralization.…”

“…In addition, the existence of bimodal volcanic rocks and A-type rhyolites in the eastern Heilongjiang-Jilin provinces during the late Triassic [5], as well as Hongqiling magmatic Cu-Ni sulfide deposit in the XMOB (~223 Ma) [8,63], further indicate that this region evolved into a period of post-collisional extensional setting involving lithosphere delamination in the late Triassic (Figure 10C). The granodiorite porphyry associated with the vein-type Pb-Zn-(Ag) mineralization was emplaced in the initial subduction stage of the Paleo-Pacific plate in the early Jurassic (~200 Ma; Figure 10D) [20]. Mg + Al).…”

“…It is a medium-scale Pb-Zn-(Ag) deposit containing reserves of 34,968 t Pb, 100,150 t Zn, and 158 t Ag at average grades of 1.39% Zn, 0.486% Pb, and 21.94 g/t Ag [18]. Until recently, studies of the Xiaohongshilazi deposit were still focused on the vein-type orebodies [13,19,20], but the studies on the layered Pb-Zn orebodies were scarce. Based on current research, the vein-type Pb-Zn-(Ag) mineralization is related to an early Mesozoic (~200 Ma) tectono-magmatic-hydrothermal event induced by the initial subduction of the Paleo-Pacific Plate [18][19][20].…”

“…Until recently, studies of the Xiaohongshilazi deposit were still focused on the vein-type orebodies [13,19,20], but the studies on the layered Pb-Zn orebodies were scarce. Based on current research, the vein-type Pb-Zn-(Ag) mineralization is related to an early Mesozoic (~200 Ma) tectono-magmatic-hydrothermal event induced by the initial subduction of the Paleo-Pacific Plate [18][19][20]. The layered Pb-Zn orebodies have the characteristics of VMS-type mineralization, according to the limited studies of the ore-forming conditions [21,22].…”