Timing of multiple magma events and duration of the hydrothermal system at the Yu’erya gold deposit, eastern Hebei Province, China: Constraints from U–Pb and Ar–Ar dating
“…2019; Zhang et al . 2020), indicating a typical IRGD characteristic according to Lang and Baker (2001) and Goldfarb et al . (2001).…”
Section: Introductionmentioning
confidence: 70%
“… Figure 1. (a) Tectonic map of the North China Craton (Jiang et al 2013), CAOB – Central Asian Orogenic Belt, SLS – Solonker suture, QDOB – Qinling-Dabie Orogenic Belt. (b) Sketch geological map of the LX district showing the distribution of gold deposits and igneous rocks with ages (modified from Xiong et al 2017; Zhang et al 2020). (c) Sketch map of BZG at the 30m level with photos of contact relationship.…”
The relationship between magmatism and gold mineralization has been a topic of interest in understanding the formation of ore deposits. The Baizhangzi gold deposit, located in the northern margin of the North China Craton, is hosted by the Baizhangzi granite (BZG) and provides a case to evaluate the relation between granite and gold mineralization in Late Triassic. In this study, we present petrography, bulk geochemistry, zircon U-Pb isotope and trace elements data, as well as major elements of biotite and plagioclase for the BZG to evaluate the petrogenesis and link with gold mineralization. The BZG comprises biotite monzogranite, biotite-bearing monzogranite and monzogranite (BZGs). Zircon U-Pb geochronology shows that all the granitoids of BZGs were coeval with a formation age of 232 Ma. The granitoids, with high SiO2, Al2O3 and Sr, while low Y and Yb, show adakitic affinity. They are enriched in LILFs (e.g., Rb, Ba, Th, U and Sr) and LREEs, while depletion in HFSEs (e.g., Nb, Ta, P and Ti). The geochemical and mineral chemical data suggest that the granitoids have experienced the fractional crystallization of biotite + plagioclase + K- feldspar + apatite. Crystallization temperature is estimated as ca. 700°C, and pressure is between 0.71 kbar and 1.60 kbar. The monzogranite shows higher values of logfO2, △FMQ and △NNO than the biotite-bearing monzogranite, ranging from −19.76 to −11.71, −4.93 to +3.67 and −5.48 to +3.11, respectively. The fractional crystallization, together with high fO2, K-metasomatism and low evolution degree, provided favourable conditions for gold mineralization.
“…2019; Zhang et al . 2020), indicating a typical IRGD characteristic according to Lang and Baker (2001) and Goldfarb et al . (2001).…”
Section: Introductionmentioning
confidence: 70%
“… Figure 1. (a) Tectonic map of the North China Craton (Jiang et al 2013), CAOB – Central Asian Orogenic Belt, SLS – Solonker suture, QDOB – Qinling-Dabie Orogenic Belt. (b) Sketch geological map of the LX district showing the distribution of gold deposits and igneous rocks with ages (modified from Xiong et al 2017; Zhang et al 2020). (c) Sketch map of BZG at the 30m level with photos of contact relationship.…”
The relationship between magmatism and gold mineralization has been a topic of interest in understanding the formation of ore deposits. The Baizhangzi gold deposit, located in the northern margin of the North China Craton, is hosted by the Baizhangzi granite (BZG) and provides a case to evaluate the relation between granite and gold mineralization in Late Triassic. In this study, we present petrography, bulk geochemistry, zircon U-Pb isotope and trace elements data, as well as major elements of biotite and plagioclase for the BZG to evaluate the petrogenesis and link with gold mineralization. The BZG comprises biotite monzogranite, biotite-bearing monzogranite and monzogranite (BZGs). Zircon U-Pb geochronology shows that all the granitoids of BZGs were coeval with a formation age of 232 Ma. The granitoids, with high SiO2, Al2O3 and Sr, while low Y and Yb, show adakitic affinity. They are enriched in LILFs (e.g., Rb, Ba, Th, U and Sr) and LREEs, while depletion in HFSEs (e.g., Nb, Ta, P and Ti). The geochemical and mineral chemical data suggest that the granitoids have experienced the fractional crystallization of biotite + plagioclase + K- feldspar + apatite. Crystallization temperature is estimated as ca. 700°C, and pressure is between 0.71 kbar and 1.60 kbar. The monzogranite shows higher values of logfO2, △FMQ and △NNO than the biotite-bearing monzogranite, ranging from −19.76 to −11.71, −4.93 to +3.67 and −5.48 to +3.11, respectively. The fractional crystallization, together with high fO2, K-metasomatism and low evolution degree, provided favourable conditions for gold mineralization.
“…The age of Yu'erya granite intrusion is quoted from T. Zhang et al. (2020). The magma source of Yu'erya granite intrusion is quoted from Kang et al.…”
Section: Resultsmentioning
confidence: 99%
“…The magma source of Qinshankou granite intrusion is quoted fromSong (2011). The age of Yu'erya granite intrusion is quoted from T Zhang et al (2020)…”
The northern margin of the North China Craton (NNCC) hosts Mesozoic gold deposits of significant economic importance. The metal sources of these gold systems have long been debated with mainly magmatic‐hydrothermal versus metamorphic fluid models. Mercury (Hg) isotopes, which undergo unique mass‐independent fractionation, can provide important insights into the source of metals in gold deposits due to the close association between Hg and Au in such systems. Here, we investigated the Hg isotopic composition of six gold deposits of the Middle Jurassic to Early Cretaceous age and potential source rocks in the NNCC. Variable ∆199Hg values were observed in bulk ore and pyrite samples (−0.28‰ to 0.34‰, n = 51) and coeval granites (−0.21‰ to 0.13‰; n = 25). The negative ∆199Hg values of bulk ore and pyrite samples mostly agree with that observed for metamorphic basement rocks (−0.37‰ to 0.11‰; n = 32). The positive ∆199Hg values of bulk ore and pyrite samples agree with those reported in marine sediments (0‰–0.3‰). So the data suggest binary mixing of ocean‐recycled Hg originated from the subducted oceanic slab, and terrestrial‐recycled Hg from the Precambrian basement in Mesozoic gold deposits. The contribution of Hg (and Au, by analogy) from both reservoirs varies depending on active continental arc versus intracontinental setting and is ultimately controlled by translithospheric heat flow driven by paleo‐Pacific plate subduction.
“…40 Ar‐ 39 Ar method of dating of hydrothermal muscovite, occurring within the mineralised quartz veins, was used to determine the timing of emplacement of hydrothermal quartz veins (Chicharro, Boiron, López‐García, Barfod, & Villaseca, 2016; Jingwen, Xiaofeng, Wen, Xiaoming, & Shaoliu, 2004; Selby et al, 2002; T. Zhang et al, 2020). 40 Ar‐ 39 Ar incrementing heating analysis of hydrothermal muscovite from sample NCM‐1 was heated with nine steps and it released around 95.3% 39 Ar.…”
Proterozoic stratiform VMS‐type Ambaji–Deri Zn–Pb–Cu deposits in the Aravalli‐Delhi mobile belt of North‐West India are hosted within meta‐sedimentary sequences of the South Delhi Terrane. Several fracture‐filled discordant late‐stage base metal mineralised quartz veins have intruded along with the fractures and foliation at very high Pf (σ2 < Pf < σ1) with typical hydrothermal alteration zones. Temperatures estimated from hydrothermal chlorite vary from 226 to 293°C (mean. 260°C). 40Ar‐39Ar dating of hydrothermal muscovite yielded a plateau age of 625.5 ± 3.3 Ma. Detailed fluid inclusion (FI) analysis reveals three types of primary and four types of secondary FI. Primary H2O‐NaCl‐CO2 ± N2 type 1a FI has medium to high salinity (11.21–21.96 wt% NaCl equivalent) and high density (0.90–1.04 g/cm3), while the secondary type 1b FI with same compositions are characterized by medium salinity (~12.6 wt% NaCl equivalent) and lower density (0.89–0.90 g/cm3). Phase separation/fluid immiscibility is the primary mechanism of mineralisation in the Ambaji–Deri that caused the original fluid to evolve separately as gaseous (CO2) type 2a, b and aqueous type 3a, b (H2O‐NaCl) with similar salinity and density for the aqueous inclusions and low density for the gaseous inclusions (lowering up to 0.58 g/cm3). The ore‐forming fluid with magmatic signatures possibly originated from the cooling G3 granites, remobilized the pre‐existing metals, and precipitated at ~265°C and ~1 kbar at the epizonal depths in the dilated fractures. Later these fluids are mixed with meteoric water and evolved into low saline aqueous fluids that produced supergene alterations.
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