Textural and compositional evolution of Au-hosting Fe-S-As minerals at the Axi epithermal gold deposit, Western Tianshan, NW China

Zhang, Bo; Li, Nuo; Shu, Sun-ping; Wang, Wei; Yu, Jie; Chen, Xi; Tian, Ye; Chen, Yanjing

doi:10.1016/j.oregeorev.2017.08.002

Cited by 13 publications

(6 citation statements)

References 34 publications

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“…The Tulasu Basin in Western Tianshan, NW China, hosting several Late Paleozoic porphyry, skarn, and epithermal deposits, is sandwiched between the NWW-striking North Yili Basin Fault and South Keguqinshan Mountain Fault (Figure 1) [33][34][35]. The basement of the Tulasu basin is mainly subdivided into the lower part with mesoproterozoic and neoproterozoic sedimentary clastic rocks and the upper part with ordovician shallow marine clastic rocks with interlayered carbonates [36,37].…”

Section: Regional and Deposit Geologymentioning

confidence: 99%

“…In general, pyrite-sericite-quartz and silicification close to gold mineralization occur in the hanging wall of fault F2, and the pervasive propylitic alteration affects all lithologies in the Axi district. The Axi gold deposit, located in the central part of the Tulasu Basin, is hosted in andesitic and dacitic volcanic rocks and breccia of the uppermost member of the Dahalajunshan formation (Figure 1b) [34,35,37]. The strike-slip fault (F 2 ), which is N-trending and east-dipping, controls nearly all economic orebodies in the Axi gold deposit.…”

Section: Regional and Deposit Geologymentioning

confidence: 99%

“…The fault F 2 displays variable strikes from south to north due to multiple phases of deformation associated with pre-ore strike-slip extension, syn-ore normal-strike slip extension, and post-ore compression and overprinting by secondary reverse faults (Figure 1b) [41]. The well-developed alteration-mineralization zoning pattern in the Axi epithermal deposit, from the core outward, mainly consists of silicification, quartz-carbonate, pyrite-sericite-quartz, and propylitic alteration (Figure 2) [33][34][35][36]. In general, pyrite-sericite-quartz and silicification close to gold mineralization occur in the hanging wall of fault F 2 , and the pervasive propylitic alteration affects all lithologies in the Axi district.…”

Section: Regional and Deposit Geologymentioning

confidence: 99%

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3D Mineral Prospectivity Modeling for the Low-Sulfidation Epithermal Gold Deposit: A Case Study of the Axi Gold Deposit, Western Tianshan, NW China

et al. 2020

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The Axi low-sulfidation (LS) epithermal deposit in northwestern China is the result of geological controls on hydrothermal fluid flow through strike-slip faults. Such controls occur commonly in LS epithermal deposits worldwide, but unfortunately, these have not been quantitatively analyzed to determine their spatial relationships with gold distribution and further guide mineral prospecting. In this study, we conduct a 3D mineral prospectivity modeling approach for the Axi deposit involving 3D geological modeling, 3D spatial analysis, and prospectivity modeling. The spatial analysis of geometric features revealed the gold mineralization trends in convex segments (0–20 m) with a specific distance from fault 2, the lower interface of late volcanic phase, and the upper interface of phyllic alteration with steep slopes (>65°), implying that gold deposition was significantly controlled by the morphological characteristics and distance fields of geologic features. The present alteration–mineralization zone at Axi has a larger width in bending sites (sections No. 35–15 and No. 40–56) than elsewhere, indicating the location of two fluid conduits extending to depth. The prediction-area plots and receiver operating characteristic curves demonstrated that (genetic algorithm optimized support vector regression (GA-SVR)) outperformed multiple nonlinear regression and fuzzy weights-of-evidence, which was proposed as a robust method to solve complicated nonlinear and high-dimensional issues in prospectivity modeling. Our study manifests spatial controls of structure, host rock, and alteration on LS epithermal gold deposition, and highlights the capability of GA-SVR for identifying deposit-scale potential epithermal gold mineralization.

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Section: Regional and Deposit Geologymentioning

confidence: 99%

Section: Regional and Deposit Geologymentioning

confidence: 99%

Section: Regional and Deposit Geologymentioning

confidence: 99%

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3D Mineral Prospectivity Modeling for the Low-Sulfidation Epithermal Gold Deposit: A Case Study of the Axi Gold Deposit, Western Tianshan, NW China

et al. 2020

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“…1a), can be divided into four tectonic domains ( Fig. 1b; Wang et al, 2018): the Northern Tianshan Accretionary Complex (NTAC), the Kazakhstan (North Tianshan-Issyk-Kul)-Yili Block (K-YB), the Central Tianshan Arc Terrane (CTAT), and the Southern Tianshan Accretionary Complex (STAC), separated by the Northern Central Tianshan, the Nikolaev Line-North Nalati, and the Southern Central Tianshan suture zones, respectively (Zhang et al, 2017).…”

Section: Regional Geological Settingmentioning

confidence: 99%

Cu–Mo Differential Mineralization Mechanism of the Dabate Polymetallic Deposit in Western Tianshan, NW China: Evidence from Geology, Fluid Inclusions, and Oxygen Isotope Systematics

et al. 2019

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Classic porphyry Cu–Mo deposits are mostly characterized by close temporal and spatial relationships between Cu and Mo mineralization. The northern Dabate Cu–Mo deposit is a newly discovered porphyry Cu–Mo polymetallic deposit in western Tianshan, northwest China. The Cu mineralization postdates the Mo mineralization and is located in shallower levels in the deposit, which is different from most classic porphyry Cu–Mo deposits. Detailed field investigations, together with microthermometry, laser Raman spectroscopy, and O‐isotope studies of fluid inclusions, were conducted to investigate the origin and evolution of ore‐forming fluids from the main Mo to main Cu stage of mineralization in the deposit. The results show that the ore‐forming fluids of the main Mo stage belonged to an NaCl + H2O system of medium to high temperatures (280–310°C) and low salinities (2–4 wt% NaCl equivalent (eq.)), whereas that of the main Cu stage belonged to an F‐rich NaCl + CO2 + H2O system of medium to high temperatures (230–260°C) and medium to low salinities (4–10 wt% NaCl eq.). The δ18O values of the ore‐forming fluids decrease from 3.7–7.8‰ in the main Mo stage to −7.5 to −2.9‰ in the main Cu stage. These data indicate that the separation of Cu and Mo was closely related to a large‐scale vapor–brine separation of the early ore‐forming fluids, which produced the Mo‐bearing and Cu‐bearing fluids. Subsequently, the relatively reducing (CH4‐rich) Mo‐bearing, ore‐forming fluids, dominantly of magmatic origin, caused mineralization in the rhyolite porphyry due to fluid boiling, whereas the relatively oxidizing (CO2‐rich) Cu‐bearing, ore‐forming fluids mixed with meteoric water and precipitated chalcopyrite within the crushed zone at the contact between rhyolite porphyry and wall rock. We suggest that the separation of Cu and Mo in the deposit may be attributed to differences in the chemical properties of Cu and Mo, large‐scale vapor–brine separation of early ore‐forming fluids, and changes in oxygen fugacity.

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“…During the past decades, a number of Paleozoic epithermal deposits (e.g. the Axi, Jiamante, Kuruer) (Zhai et al, ; Wu et al, ; Zhang et al, ; Yu et al, , b) and porphyry Cu‐Mo deposits (e.g. Kendenggao'er; Dabate) (Duan et al, ; Wang et al, ) have been discovered in this area.…”

Section: Introductionmentioning

confidence: 99%

Genesis of the Xiuwenghala Gold Deposit in the Beishan Orogen, Northwest China: Evidence from Geology, Fluid Inclusion, and H–O–S–Pb Isotopes

et al. 2019

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The Xiuwenghala gold deposit is located in the Beishan Orogen of the southern Central Asian Orogenic Belt. The vein/lenticular gold orebodies are controlled by Northeast-trending faults and are hosted mainly in the brecciated/ altered tuff and rhyolite porphyry of the Lower Carboniferous Baishan Formation. Metallic minerals include mainly pyrite and minor chalcopyrite, arsenopyrite, galena, and sphalerite, whilst nonmetallic minerals include quartz, chalcedony, sericite, chlorite, and calcite. Hydrothermal alterations consist of silicic, sericite, chlorite, and carbonate. Alteration/mineralization processes comprise three stages: pre-ore silicic alteration (Stage I), syn-ore quartz-chalcedony-polymetallic sulfide mineralization (Stage II), and post-ore quartz-calcite veining (Stage III). Fluid inclusions (FIs) in quartz and calcite are dominated by L-type with minor V-type and lack any daughter mineral-bearing or CO 2 -rich/-bearing inclusions. From Stages I to III, the FIs homogenized at 240-260 C, 220-250 C, and 150-190 C, with corresponding salinities of 2.9-10.9, 3.2-11.1, and 2.9-11.9 wt.% NaCl eqv., respectively. The mineralization depth at Xiuwenghala is estimated to be relatively shallow (<1 km). FI results indicate that the ore-forming fluids belong to a low to medium-temperature, low-salinity, and low-density NaCl-H 2 O system. The δ 18 O H2O values decrease from Stage I to III (3.7‰, 1.7-2.4‰, and −1.7 to 0.9‰, respectively), and a similar trend is found for their δD H 2 O values (−104 to −90‰, −126 to −86‰, and −130 to −106‰, respectively). This indicates that the fluid source gradually evolved from magmatic to meteoric. δ 34 S values of the hydrothermal pyrites (−3.0 to 0.0‰; avg. −1.1‰) resemble those of typical magmatic/mantle-derived sulfides. Pyrite Pb isotopic ) are similar to those of the (sub)volcanic ore host, indicating that the origin of ore-forming material was mainly the upper crustal (sub)volcanic rocks. Integrating evidence from geology, FIs, and H-O-S-Pb isotopes, we suggest that Xiuwenghala is best classified as a low-sulfidation epithermal gold deposit.

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Textural and compositional evolution of Au-hosting Fe-S-As minerals at the Axi epithermal gold deposit, Western Tianshan, NW China

Cited by 13 publications

References 34 publications

3D Mineral Prospectivity Modeling for the Low-Sulfidation Epithermal Gold Deposit: A Case Study of the Axi Gold Deposit, Western Tianshan, NW China

3D Mineral Prospectivity Modeling for the Low-Sulfidation Epithermal Gold Deposit: A Case Study of the Axi Gold Deposit, Western Tianshan, NW China

Cu–Mo Differential Mineralization Mechanism of the Dabate Polymetallic Deposit in Western Tianshan, NW China: Evidence from Geology, Fluid Inclusions, and Oxygen Isotope Systematics

Genesis of the Xiuwenghala Gold Deposit in the Beishan Orogen, Northwest China: Evidence from Geology, Fluid Inclusion, and H–O–S–Pb Isotopes

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