Application of the AMT Method to Gold Deposits: A Case Study in the Qinling Metallogenic Belt of North China Craton

Li, Fengchun; Zeng, Qingdong; Zhu, Rixiang; Chu, Shaoxiong; Xie, Wenchun; Zhang, Bolin; Zhang, Xingxing

doi:10.3390/min11111200

Cited by 7 publications

(1 citation statement)

References 29 publications

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“…Consequently, lower frequencies possess the ability to penetrate to greater depths, whereas higher frequencies are confined to shallower regions. At the Earth's surface, orthogonal electromagnetic field components are observed, and these components provide insights into the frequency response, reflecting the distribution of electrical properties within the subsurface medium [47]. The variation in the magnetotelluric field component over time is transformed into a frequency spectrum, enabling the computation of magnetotelluric frequency domain responses, such as apparent resistivity and impedance phase.…”

Section: Audio Magnetotelluric (Amt) Methodsmentioning

confidence: 99%

Application of Audio-Magnetotelluric and Dual-Frequency Induced Polarization Joint Inversion in a Pb-Zn Deposit Exploration in Inner Mongolia, China

Fahad,

Liu,

Chen

et al. 2024

Preprint

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Models of subsurface structures are important for successful deposit exploration but are challenged by the need to integrate data from different geophysical methods. In the present study, we evaluated a method of joint inversion in which audio-magnetotelluric (AMT) and dual frequency induced polarization (DFIP) data sets are inverted simultaneously to produce a consistent 2D resistivity model to show a clear image of subsurface structures. To achieve the objectives, we conducted AMT and DFIP surveys first on the same survey line within the Dongjun lead-zinc deposit in inner Mongolia by developing 31 AMT survey sites with an interstation separation of 40 m on a 1440 m survey track and operated in fifty-three frequencies in the range 1–10,400 Hz to record the resistivity distribution of subsurface to depths exceeding 800 m. The same survey setup up was applied to the DFIP method by utilizing the SQ-3C model with a pole-dipole array configuration and conducted measurements at frequencies of 4 Hz and 4/13 Hz. We first separately inverted AMT and DFIP measurements. The two-dimensional (2D) model obtained from AMT data revealed distinct low resistivity anomalies in the middle of the 2D inversion model. In contrast, the DFIP inversion model showed a high resistive body in the same region. In response to the discrepancies observed in the separate 2D inversion models, we implemented a joint inversion for both the AMT and DFIP datasets. The joint inversion resistivity model shows surficial conducting bodies and a high conductive body along the profile with relatively high Percent Frequency Effect (PEF) indicating high chargeability. The final joint inversion resistivity model clearly images the large silica alteration zone and the Pb-Zn mineralization. This study demonstrates the feasibility of a joint inversion methodology and highlights the value of integrating geophysical methods through joint inversion for enhanced characterization and exploration of lead-zinc ores.

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Section: Audio Magnetotelluric (Amt) Methodsmentioning

confidence: 99%

Application of Audio-Magnetotelluric and Dual-Frequency Induced Polarization Joint Inversion in a Pb-Zn Deposit Exploration in Inner Mongolia, China

Fahad,

Liu,

Chen

et al. 2024

Preprint

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Unusual HREE enrichment and mineralization age in the Jialu deposit from the Qinling Orogen, central China

Li,

Zeng,

Kang

et al. 2024

Ore Geology Reviews

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Genesis of the Jianbeigou Gold Deposit on the Southern Margin of the North China Craton: Insights from Fluid Inclusions, H‐O‐S Isotopes, and Pyrite in situ Trace Element Analyses

LI,

ZENG,

ZHU

et al. 2024

Acta Geologica Sinica (Eng)

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The Jianbeigou gold deposit is a typical lode gold deposit in the Qinling metallogenic belt, located on the southern margin of the North China Craton. Three stages of the hydrothermal process can be distinguished, including the quartz ± pyrite, quartz‐polymetallic sulfide, and quartz‐carbonate ± pyrite stages. From the early to late stages, the homogenization temperatures of primary fluid inclusions are 281–362°C, 227–331°C, and 149–261°C, respectively. The corresponding salinities estimated for these fluids are 3.9–9.9 wt%, 0.4–9.4 wt%, and 0.7–7.2 wt% NaCl equiv. Combined with laser Raman spectroscopy data, the ore‐forming fluid belongs to a H2O‐CO2‐NaCl ± CH4 system with medium–low temperature and salinity. The δ18Ofluid and δD values for the quartz veins are –1.0‰ to 6.0‰ and –105‰ to –84‰, respectively, which indicates that the ore‐forming fluid is of mixed source, mainly derived from magma, with a contribution from meteoric water. Pyrite has been identified into three generations based on mineral paragenetic sequencing, including Py1, Py2, and Py3. The pyrites have δ34S sulfur isotopic compositions from three stages between 3.7‰ and 8.4‰, indicating that sulfur mainly originated from magma. Te, Bi, Sb, and Cu contents in pyrite were all high and showed a strong correlation with Au concentrations. Native gold and the Au‐Ag‐Bi telluride minerals were formed concurrently, and the As concentration was low and decoupled from the Au content. Therefore, Te, Bi, Sb and other low‐melting point chalcophile elements play an important role for gold mineralization in arsenic‐deficient ore‐forming fluid. Combined with the geological setting, evolution of pyrite, and ore‐fluids geochemistry, we propose that the Jianbeigou deposit can be classified as a magmatic–hydrothermal lode gold deposit. Gold mineralization on the southern margin of the North China Craton is related to Early Cretaceous magmatism and formed in an extensional setting.

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Application of the AMT Method to Gold Deposits: A Case Study in the Qinling Metallogenic Belt of North China Craton

Cited by 7 publications

References 29 publications

Application of Audio-Magnetotelluric and Dual-Frequency Induced Polarization Joint Inversion in a Pb-Zn Deposit Exploration in Inner Mongolia, China

Application of Audio-Magnetotelluric and Dual-Frequency Induced Polarization Joint Inversion in a Pb-Zn Deposit Exploration in Inner Mongolia, China

Unusual HREE enrichment and mineralization age in the Jialu deposit from the Qinling Orogen, central China

Genesis of the Jianbeigou Gold Deposit on the Southern Margin of the North China Craton: Insights from Fluid Inclusions, H‐O‐S Isotopes, and Pyrite in situ Trace Element Analyses

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