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[Display omitted] • Gold deposition from As-Au-rich fluids is the dominant mechanism of gold enrichment. • Multistage fluid immiscibility plays an important role in gold deposition. • Decoupling of element pairs (Au-As vs Co-Ni) in pyrite is a tracer of immiscibility. Lode gold deposits in the North China Craton (NCC) form the only known giant late Mesozoic gold province in the world's Precambrian cratons. Understanding the ore genesis for these deposits is of great scientific and economic importance. In order to provide constraints on the ore-forming processes, this study presents a combination of micro-textures and in-situ compositions of sulfide from the Wulong gold deposit (80 t @ 5.35 g/t Au; 127–122 Ma), northeastern NCC. Five sub-generations of pyrite (Py1–Py5) are identified based on micro-textural observations and EPMA results. In-situ trace elemental concentrations show that pyrite from the stage 1 (Py1) has high Co and Ni contents but no Au (<0.02 ppm). In contrast, euhedral Py2 and porous Py3 from stage 2 exhibit much higher Au (average 3.08 ppm and 1.66 ppm), As (average 1400 ppm and 946 ppm), and Ag (average 2.81 ppm and 3.21 ppm). Anhedral Py4 from stage 3 shows lower Au (average 0.31 ppm) and As (average 337 ppm) concentrations when compared to Py3. However, Py5 from stage 3 exhibits significant increases of As (average 7102 ppm) and Au (average 5.46 ppm) again and is featured by the alternation of Co-Ni- and Au-As-rich zones. Other sulfides, including pyrrhotite, chalcopyrite, and sphalerite, are poor in Au and As. Apart from visible gold grains related to Bi-rich melts, LA-ICP-MS spot and mapping analyses reveal that invisible gold hosted in Py2 to Py5 occurs dominantly as lattice-bound solid solutions (Au+). Direct gold precipitation from anomalously As-rich auriferous fluids induced by fluid immiscibility is proposed as the dominant mechanism of invisible gold enrichment. In-situ δ 34S values of Py1 to Py4 exhibit narrow ranges of 1.0 to 3.8 ‰, indicating a deep-seated magmatic sulfur source. The elevated δ 34S values (2.3–6.3 ‰) of Py5 are ascribed to some wall-rock contributions during fluid-rock interaction. These findings shed new light on the link between multistage fluid immiscibility and the chemical and micro-textural fingerprints of pyrites and the role of fluid immiscibility in the deposition of invisible gold. [ABSTRACT FROM AUTHOR]

The time gap between diagenesis and mineralization (TGDM) for comagmatic gold deposits (CGD) plays an important role in confirming the genetic relationship between gold deposits and their related intrusions. With the help of preciously published isotopic ages of some typical gold deposits and their related rocks in China, the authors have discussed and quantified the distribution characteristics and scope of the TGDM. Statistical analyses and Kolmogorov tests showed that mineralizing events are either contemporaneous with or slightly postdate their cognate magma. The TGDM conforms with normal distributions at a 0.05 confidence level and clusters between 0 and 16.0 Ma with a mean of 7.0 Ma. Thus, if the TGDM of CGD is less than 16.0 Ma, it is reasonable to consider, with the aid of other evidence, the possibility of its comagmatic genetic affiliation. The authors also emphasized that to get a precise time gap it is necessary to strengthen the diagenesis-mineralization geological background of the deposits studied, and to pay attention to the study of time gap in combination with trace elements and isotope tracing. [ABSTRACT FROM AUTHOR]

Presents a study that discussed the rubidium-strontium isotope data of gold-bearing quartz veins from six gold deposits in the eastern part of North China platform. Importance of the primary gold deposits in the eastern part of China; Mineralization characteristics of the gold ore-concentrated area; Spatial relationship among the gold deposits.

Presents a study which detailed the metallogenic fluid sources of five gold deposits in Zhangjiakou, China. Facts about the geological setting; Features of the orebodies; Hydrogen and oxygen isotopic composition and ore-forming fluid sources.

The Longquanzhan deposit is one of the largest gold deposits in the Yi-Shu fault zone (central section of the Tan-Lu fault zone) in Shandong Province, China. It is an altered-rock type gold deposit in which ore bodies mainly occur at the contact zone between the overlying Cretaceous rocks and the underlying Neoarchean gneissic monzogranite. Shi et al. reported that this deposit formed at 96 ± 2 Ma using pyrite Rb–Sr dating method and represents a new gold mineralization event in the Shandong Province in 2014. In this paper, we present new He–Ar–S isotopic compositions to further decipher the sources of fluids responsible for the Longquanzhan gold mineralization. The results show that the δ34S values of pyrites vary between 0.9‰ and 4.4‰ with an average of 2.3‰. Inclusion-trapped fluids in ore sulfides have 3He/4He and 40Ar/36Ar ratios of 0.14–0.78 Ra and 482–1811, respectively. These isotopic data indicate that the ore fluids are derived from a magmatic source, which is dominated by crustal components with minor mantle contribution. Air-saturated water may be also involved in the hydrothermal system during the magmatic fluids ascending or at the shallow deposit site. We suggest that the crust-mantle mixing signature of the Longquanzhan gold deposit is genetically related to the Late Cretaceous lithospheric thinning along the Tan-Lu fault zone, which triggers constantly uplifting of the asthenosphere surface and persistent ascending of the isotherm plane to form the gold mineralization-related crustal level magma sources. This genetic model can be applied, to some extent, to explain the ore genesis of other deposits near or within the Tan-Lu fault belt. [ABSTRACT FROM AUTHOR]

[Display omitted] • There is mineralization zoning of Pb + Zn and Au + Ag in spatial distribution. • The Kengdenongshe polymetallic ore deposit attributes to the Au-related VMS-type. • Initial mineralization is associated with submarine volcanism in back-arc basin. • The ore deposit underwent structural modification during later basin closure. The Kengdenongshe giant Au-Ag-Pb-Zn polymetallic deposit is located in the East Kunlun Orogen (EKO). It contains about 42.2 t of Au, 608.6 t of Ag and 1.05 Mt of Pb and Zn with an average grade of Au 2.31 g/t, Ag 19.29 g/t and Pb + Zn 3.49 wt% (Pb: 1.23 wt%, Zn: 2.26 wt%). The NWW-trending ore bodies are predominantly hosted in Late Permian to Triassic rhyolitic tuff, which formed during Late Permian back-arc extension to Triassic arc-continental collision. The ore bodies are subdivided into Pb-Zn rich ore bodies on the top with high grades of Pb and Zn and low grades of Au and Ag, and Au-Ag rich ore bodies below with high grades of Au and Ag and low grades of Pb and Zn. The Pb-Zn rich ore bodies occur as vein, stockwork, and in breccia, and comprise quartz, pyrite, galena, sphalerite, and small amounts of chalcopyrite. The Au-Ag rich ore bodies consist of auriferous barite-sulfide-oxide veins and contain barite, pyrite (early strawberry and oolitic pyrite and later eu- to subhedral pyrite), galena, sphalerite, chalcopyrite, tetrahedrite and covellite. Gold is present as electrum, kustelite and native gold and silver is present as polybasite, pearceite, kongsbergite, and as minor native silver in microfractures in sulfides. The hydrothermal alteration minerals include, from bottom to top, quartz + barite + calcite around the Au-Ag rich orebodies, quartz + chlorite + epidote around the Pb-Zn rich orebodies, and quartz + K-feldspar within the tuff. Fluid inclusions from both the Pb-Zn rich and the Au-Ag rich orebodies consist of two phases (V–L-type) fluid inclusions of which the vapor phase has a size of 10–40 vol%. Fluid inclusions microthermometry reveal homogenization temperatures of fluid inclusions in Pb-Zn rich and Au-Ag rich ore bodies of 128–230 °C and 110–320 °C, with corresponding salinities of 0.7–9.9 and 0.2–18.3 wt% NaCl equivalent, respectively. H-O-S-Pb stable isotope and He-Ar noble gas isotope data indicate a mixed magmatic water-seawater source for both the Pb-Zn and Au-Ag rich ore bodies, and an additional meteoric water component for the Au-Ag rich ore bodies. The Pb-Zn and Au-Ag rich ore bodies share the same sulfur and lead sources, i.e. sulfur is derived from crustal magma and seawater/marine sulfate, and the lead originated from a mixed magmatic-ancient crustal sedimentary source. Collectively, the regional geology, mineralogy, alteration, and geochemistry indicate that the Kengdenongshe Au-Ag-Pb-Zn polymetallic deposit can be characterized as a VMS-type (volcanic-associated massive sulfide) deposit. Formation of the ore-hosting rhyolite tuff and mineralization are associated with Late Permian to Triassic marine volcanic exhalation. Middle to Late Triassic basin closure and arc-continent collision modified the deposit and resulted in the location inversion of the Pb-Zn and Au-Ag rich orebodies. [ABSTRACT FROM AUTHOR]