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The large‐scale concentration of Au associated with Mesozoic granitoid intrusions in the North China Craton (NCC) has inspired many investigations to explore the genetic relationship between the magmatism and gold metallogeny. The Xiaoqinling gold province is located in the southern margin of the North China Craton. The Wenyu and Huashan monzonitic granites formed at Early Cretaceous represent two of the important intrusions in this region, and a large number of gold deposits occur around the Wenyu pluton. Here we present results from an integrated study using in situ zircon U–Pb ages, trace elements, and Hf isotope to infer the composition and environmental changes during different evolution stages of the fertile Wenyu pluton and compare with the infertile Huashan pluton. The Huashan pluton was emplaced at 144.0 ± 0.6 Ma, whereas the fertile Wenyu pluton experienced multistage magmatic activity from 141.4 ± 0.6 to 129.6 ± 0.5 Ma. Temperatures computed from Ti‐in‐zircon thermometry indicate that the late‐stage Wenyu magma crystalized at 644°C, the Huashan magma, and early‐stage Wenyu magma crystalized at around 750°C. And the oxygen fugacity (Ce4+/Ce3+ > 200 and Eu/Eu* > 0.7) and the water content of the late‐stage Wenyu magma stay at higher levels. The U/Yb–Hf and U/Yb–Y relationship with εHf(t) (−15.63 to −17.89) of the late‐stage Wenyu magma suggest that the ancient lower crust with subsequent inputted basaltic components make up the source of the fertile and infertile plutons. Combined with previous geochronological data and geodynamics studies, we propose that the late‐stage intrusion of the Wenyu pluton experienced intensive magma mixing. And the formation of Wenyu pluton created conducive heat energy, oxygen fugacity, and water conditions for the formation of high‐grade gold deposits. [ABSTRACT FROM AUTHOR]

The Yongxin gold deposit is a large, fracture-controlled ore deposit in the Duobaoshan gold-copper metallogenic belt within the eastern domain of the Central Asian Orogenic Belt (CAOB). Silicification, sericitization and potassic alteration are the main hydrothermal alteration types which display successive zoning surrounding the ore-bodies. Pyrite, galena, sphalerite and chalcopyrite are the major metallic minerals in the deposit, and gold is mainly distributed in pyrite. Here we investigate the trace element composition and isotope (Pb and S) characteristics of pyrite from this deposit. The auriferous pyrite is mainly allotriomorphic and homogeneous in chemistry with a homogenous distribution of As, Ni, Mo and Fe from the core to rim of grains. These features are consistent with the 207 Pb/ 206 Pb- 206 Pb/ 204 Pb, and 208 Pb/ 204 Pb- 206 Pb/ 204 Pb of the grains that suggest a single source with no evidence for involvement of late fluids. The δ 34 S values range from +3.5‰ to +5.4‰ with an average of +4.48‰, suggesting a mantle-derived magmatic provenance for the sulfur. The high Co content and Co/Ni ratios, low Ni and Mo/Ni ratios suggest a mafic/ultramafic source for the Yongxin gold deposit. The Co-Ni-As relation indicates a magmatic hydrothermal affinity with a classification as epithermal gold deposit. High arsenic and gold contents on the rims of pyrite grains indicate that Au and As were simultaneously precipitated in anoxic, low temperature and near-surface conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bitumen Sm-Nd age of 234.6 Ma is interpreted as the hydrocarbon deposition timing. • The ore-forming age of Erdaokan is constrained at middle Triassic. • Bitumen Sm-Nd can be used to constrain the hydrothermal mineralization age. Dating of bitumen can potentially constrain both the timing of mineralization and hydrocarbon deposition in hydrocarbon-bearing hydrothermal deposits. Here we report for the first time direct Sm-Nd dating on bitumen from the Erdaokan Ag-Pb-Zn deposit, a newly discovered, large, hydrocarbon-bearing hydrothermal deposit with 2964 kt of ore and 1535 t Ag with an average grade of 517 g/t Ag, 0.6 wt% Pb and 0.41 wt% Zn in the Back-Arc basin of NE Great Xing'an Range, NE China. Dating results show that Sm-Nd isochron age of four bitumen samples is 234.6 ± 1.2 Ma and an isochron age that includes three galena and four bitumen samples is 234.9 ± 1.4 Ma. In order to verify these ages, we performed Rb-Sr dating on pyrite and galena from the same deposit and U-Pb dating of zircon from the adjacent diorite porphyrite dike, which yielded ages of 232.9 ± 2.3 Ma and 234.2 ± 2.8 Ma, respectively. The highly concordant ages from multiple techniques confirms that bitumen Sm-Nd isotopic dating is reliable, and that the ages obtained in our study represent the hydrocarbon deposition as well as mineralization timing in the deposit. We conclude that, in the Duobaoshan metallogenic belt, the Erdaokan Ag-Pb-Zn deposit is the first identified large, Middle Triassic, hydrocarbon-bearing silver-lead–zinc deposit and is of great significance to the regional metallogenesis research and prospecting work in the Great Xing'an Range. [ABSTRACT FROM AUTHOR]

• Porphyry and epithermal type of gold deposits in the hinterlands of the Bagrote valley. • Proximal source and high content of gold in pyrite suggest probable mineralization beneath the current level of erosion. • Gold occurs in pyrite in the form of micro to nano inclusions as Au0 instead of Au+1. • Ore forming fluids were derived from orogenic belts with minor contribution of lower crust. The Bagrote valley in North Pakistan, belonging to the Kohistan island arc, is well-known for regional placer gold mining. However, no economically feasible in situ hydrothermal gold deposits have been discovered in this region due to rugged terrain and remote nature of its location in the western Himalaya. The streams draining the Main Karakoram Thrust (MKT)/Shyoke suture zone carry placer gold in sediments as well as old river terraces, although the primary source remains unknown. In this paper, we employ a multiparametric approach including, X-ray Diffraction (XRD) analysis, thermoelectricity, major and trace element geochemistry and isotopic characteristics of pyrite associated with placer gold with a view to identify the nature of the unknown deposits and ore forming fluids on the catchment of the Bagrote valley. Pyrite in the Bagrote valley placers is euhedral to subhedral indicating the proximal gold sources. The high rate of occurrence of N-type thermoelectric coefficients (89%) with low P-type (11%) and crystallization temperature (290 °C−380 °C) combined with chemical features indicate that the pyrite was derived from porphyry or epithermal type of magmatic hydrothermal gold deposits from the hinterlands of the Bagrote valley. The X-Ray elemental maps show that Fe, As, Mo and Ni are homogenously distributed from core to rim suggesting stable crystallization condition without any alteration by later fluids. The calculated chemical formula of pyrite of our samples is [Au0.0006Fe] S2.004], plots of Au-As and Au-Fe shows that gold occurs in pyrite as micro to nano inclusion as Au0. The δ 34 S V - CDT values of pyrite range from – 0.6‰ to 0.9‰ with an average of −0.02‰, indicating the derivation of sulfur from a homogeneous magmatic source. The Pb isotope data indicates that the Pb was sourced from orogenic-type source, with minor contribution of lower crust. The narrow variations in 206Pb/204Pb and 208Pb/204Pb values suggest a single lead source. The low, medium and high Mo/Ni ratios reflect a mixed provenance for the auriferous pyrite. The average value of γ (71.8%), of pyrite computed from thermoelectric parameters (XnP), suggests that the dominant part of the primary source that contributes to the placers might have already been eroded. However, the proximal source and with high content of gold in the pyrite grains (up to 1160 ppm) suggest the possibility of significant economic mineralisation below the present erosion level of the deposits in the hinterlands of Bagrote Valley. [ABSTRACT FROM AUTHOR]