Ore fluid, geochronology and tectonic setting of mesothermal gold metallogeny in southeastern Jilin Province, Northeast China: A case study of the Shajingou gold deposit

The quartz‐vein type scheelite deposits distributed in the Hunchun SN‐trending gold‐copper‐tungsten belt in eastern Yanbian, Jilin Province, are a group of recent discovery for the past decade. To determine properties of the ore‐forming fluids and the mineralization mechanism, in situ laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) rare earth elements (REE) analysis of the ore mineral scheelite was carried out for the selected Yangjingou and Sidaogou scheelite deposits in this metallogenic belt. The results showed that the substitution of REE3+ for Ca2+ in scheelite from the Yangjingou scheelite deposit can be accounted for the substitution mechanism: 3Ca2+ = 2REE3+ + □Ca (where □ is a site vacancy). It shows a slightly right‐dipped flat REE pattern with distinct positive Eu anomalies. The Sidaogou scheelite deposit, completes the substitution via the 2Ca2+ = REE3+ + Na+ and Ca2+ + W6+ = REE3+ + Nb5+ mechanisms. It shows left‐dipped REE pattern with relative enrichment of MREEs (mainly Dy) with negative Eu anomalies in the scheelite core and no or insignificant positive Eu anomalies in the scheelite rim. By comparing with the REE of granites which are close related to mineralization in the area, the ore‐forming fluids of these two scheelite deposits are determined to be mainly derived from magmatism. The inapparent correlation between EuN and Eu*N of the Yangjingou scheelite deposit and the high EuN/Eu*N values indicate that its ore‐forming fluids are reducing fluids. Its strong positive Eu anomalies are not entirely inherited from the mineralized tonalite, but is due to the release of Eu from the water‐rock reaction. The good correlation between EuN and Eu*N and the low EuN/Eu*N values in the Sidaogou scheelite deposit indicate that the ore‐forming fluids are oxidizing fluids. This may be caused by the mixing of the original magmatic fluid with a large amount of meteoric water. This study suggests that the water‐rock reaction is an important mineralization mechanism for the quartz vein‐type scheelite deposits in eastern Yanbian. In addition, fluid mixing is also important for the Sidaogou scheelite deposit. All these mechanisms influence the REE compositional characteristics of scheelite. The initial ore‐bearing fluids metasomatized the metamorphic rocks of Wudaogou Group, resulting in water‐rock reaction, and enriched ore‐forming materials such as Ca and W. As the ore‐forming fluids migrated upward along the NW‐trending structures, the escape of CO2 and CH4 caused by the tectonic decompression disrupted the physiochemical balance of the ore‐forming fluid system, catalyzed the combination of Ca2+ and WO42−, resulting in the precipitation and enrichment of the scheelite.

Section: Discussionmentioning

confidence: 99%

The ore‐forming fluids characteristics of quartz‐vein type scheelite deposits in eastern Yanbian, NE China: Evidence from in situ LA‐ICP‐MS rare earth elements of Yangjingou and Sidaogou deposits

Ren

Hao

et al. 2022

“…This recorded the transition from the Paleo-Asian Ocean regime to the circum-Pacific tectonic regime and the initial subduction of the Paleo-Pacific Plate (Wang et al, 2017). Due to the further subduction during the Middle Jurassic (180-160 Ma), abundant Middle Jurassic calc-alkaline igneous rocks occur in the central Jilin and eastern Heilongjiang-Jilin regions, marking the peak of magmatism and mineralization induced by the Mesozoic subduction of the Paleo-Pacific Plate (Zhang et al, 2013(Zhang et al, , 2015Wang et al, 2017;Yang et al, 2019b). In this study, multistage polymetallic mineralization in the Xiaohongshilazi and adjacent areas has been summarized in response to the regional tectonic evolution described above.…”

Section: Tectonic Setting and Associated Mineralizationmentioning

confidence: 98%

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

Yang

Ren

et al. 2019

Self Cite

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.

“…Two groups of NE-trending and NW-trending structures are mainly developed in the area, and the Liangjiang fault and Haigou-Huanggou farm fault are represented in the mining area. The intrusive rocks in the mining area are mainly granitic rocks, including Late Paleozoic granite, Mesozoic granite and diorite dikes; volcanic rocks are only found in local areas as scattered Mesozoic and Cenozoic andesites (Figure 2; Chang et al, 2013;Liu et al, 2021a;Yang et al, 2019;Zhang et al, 2011Zhang et al, , 2012). The regional structure is significantly affected by the superposition of the Mesozoic Pacific tectonic domain and the Hercynian Paleo-Asian tectonic domain (Figure 1).…”

Section: Regional Geologymentioning

confidence: 99%

“…It lies adjacent to Jiapigou and Songjianghe gold deposits to the west. It is a large uranium‐bearing quartz vein type gold deposit with great prospecting potential (Deng et al, 2009; Liu et al, 2021a; Yang et al, 2019; Zeng et al, 2017). The strata exposed in the mining area are mainly Proterozoic Ji'an Group, Seluohe Group (metamorphic rock series) and Qingbaikou sedimentary rock series, as well as Miocene volcanic‐sedimentary rock series.…”

Section: Geological Settingmentioning

confidence: 99%

Ore‐forming process of the Haigou gold deposit in the eastern Central Asian Orogenic Belt, NE China: Constrains from EPMA and LA‐ICP‐MS analysis of Au‐bearing pyrite

Chen

Zheng

et al. 2022

The Haigou lode deposit, containing 40 t of gold at an average grade of 3.5 g/t, is one of the largest deposits in the Jiapigou gold belt located along the eastern segment of the northern margin of the North China Craton. The deposit comprises 15 gold-bearing quartz veins hosted in a Carboniferous monzonitemonzogranite stock. Although many studies relating the genesis of this deposit have been carried previously, the understanding of ore-forming process remains controversial. In this study, we combined field geological mapping with petrography, Electron Probe Micro Analysis (EPMA) and in situ LA-ICP-MS analysis of gold-bearing pyrite to provide new insight into the genesis of the gold deposit. Our results show that Au in the Haigou gold deposit mainly exists in the form of native gold. LA-ICP-MS in situ multi-element mapping shows that Au has a significant positive correlation with Ag, Te, Bi and Pb in Au-bearing pyrite, indicating that these elements co-precipitated with Au in pyrite lattice. The ore-forming fluid existed under medium to low temperature, aiding complexing of the gold with sulfur, chlorine, and tellurium. Decoupling of sulfide and telluride complexes facilitated gold precipitation in the Haigou area. The abundance of lead and nickel tellurides in the Haigou gold deposits with general absence of tellurium in native gold is indicative of expulsion of tellurium through boiling during the process of fluid migration and evolution. Also, coexistence of Bi in native gold indicates that they were at Au-Bi eutectic. The gold-bearing pyrite is characterized by dispersed magnetite in and around the fractures. The Au-Te-Bi-Pb element anomalies indicate that fluid oxygen fugacity increases while sulfur fugacity decreases with time, resulting in Au precipitation. Our results provide a new theoretical basis for the establishment of metallogenic model and deep prospecting of the Haigou gold deposit.