Idetification of the coral and Schwagerina in the ore-hosted strata of Sawaya’erdun gold deposit shows that the fossil age ranges from the late Carboniferous to the early Permian. By combining this with the Rb-Sr isochron age, it is concluded that the ore-hosted strata age is possibly the late Carboniferous rather than the Silurian and Devonian, even impossibly the Precambrian.

Numerous steel-gray microspherules were recently unexpectedly discovered in ore and rock samples from several disseminated gold deposits hosted in Middle–Upper Triassic turbidites in northwestern Sichuan Province, China. Both nature surfaces and part sections of 227 microspherules have been observed by reflected light microscope, scanning electron microscope (SEM), electron microprobe analyses, X-ray energy spectra, X-ray powder patterns, the results reveal them to be cosmic dust. It is the first discovery of cosmic dust in this kind of deposits in China. The size of the microspherules ranges from 25 to 185 Am and generally is less than 100 Am. According to their composition, they belong to chromium-rich iron cosmic dust. The microspherules have complex, diverse and diagnostic microscope structures and textures, and such as very distinct airprint structure that are compatible with extraterrestrial material. Variation of geochemical content of the microspherules in the gold deposits in generally positively correlates with both the Ir content of the enclosing strata and the intensity of mineralization and hydrothermal alteration. The abnormally high content of Ir is important evidence for an extraterrestrial source for the microspherules. The fact that a geological body with strong alteration and mineralization is rich in microspherules may raise a new concept: Under endogenic conditions, it is not only possible but also realistic for mineralized material to be transported mechanically, in addition to the generally accepted chemical transport of ore constituents in hydrothermal solution because it is obviously impossible for cosmic spherules to fall directly from space into cemented hydrothermal ore veins more than 1 km deep in the earth.

The Sawaya'erdun gold deposit in the western segment of the South Tianshan, Xinjiang, China, is a large, low-grade orogenic gold deposit. An abundance of index fossils in the ore-hosting strata, including brachiopoda, corals and Schwagerina, show that the fossil age of the country rocks ranges from Late Carboniferous to Early Permian. Whole rock Rb–Sr and Sm–Nd isochron ages, ranging from 292.43±0.38 to 304.7±11.6 Ma, are concordant with a Late Carboniferous age. Gold mineralization is strictly controlled by a fault zone. Ore minerals are dominated by sulfides, with gold inhomogeneously distributed within them; gangue minerals are quartz, siderite or calcite. Data suggest that the ore-forming fluid was derived predominantly from an active meteoric groundwater system. Ore-forming temperatures are estimated to have been within the range 110 to 220 °C. New 40Ar/39Ar isotope age determinations of auriferous quartz are in excellent agreement with Rb–Sr ages obtained from fluid inclusions in quartz. They suggest gold mineralization at 206 to 213 Ma (Late Indosinian). Such an age is consistent with the age of formation given for other gold deposits in the region, such as Bulong and Dashankou. Combined with K–Ar geochronological data and observed geological features, it is concluded that the Indosinian metallogentic epoch represents a previously unrecognized, major period of gold metallogeny in the southwestern Chinese Tianshan. In some ways, the Sawaya'erdun gold deposit can be compared with the Muruntau gold deposit in Uzbekistan with respect to geological setting, host lithology, mineralization style, mineral assemblages, geochemical association and metallogenic processes involved. Despite this, the Sawaya'erdun gold deposit possesses a number of characteristics typical of only low-temperature metallogenesis.

The microdisseminated gold deposits at La’erma and Qiongmo are typically hosted in Cambrian chert formation in western Qinling Mountains, China. Both in the host rocks and the gold ores selenium is present in high abundance, as selenide minerals or isomorphous admixtures in sulfides, with independent selenium orebodies can be delineated in some localities. Intergrowth of selenides and native gold is commonly observed. Selenium is also noticed in considerably high content in fluid inclusions in quartz and barite, which are closely related to gold mineralization. Studies show that gold and selenium may have been transported together in ore solutions as Au–S–Se complex. In view of the wide difference in electrode potential between selenium and sulfur, the two elements would be separated under oxidizing conditions. Selenium would mostly occur as isomorphic mixtures in sulfides during the early stage of mineralization when the environment is more reducing but would precipitate as selenides during the late, oxidizing stage. Simultaneous enrichment of gold and selenium would be favored by boiling of the ore solution or mixing of ore solution with oxygen-rich water at shallow depths.

The vein copper deposits in Lanping-Simao basin of western Yunnan occur in a salt-bearing red clastic rock formation composed of sandstone, siltstone and shale. An excellent fossil wood cell texture is considerably developed in the ores. The metallic minerals making up the fossil wood cell texture include pyrite, chalcopyrite, bornite and chalcocite. Studies on the samples and examination of their micrographs and electron micrographs have confirmed that they belong to xenoxylon, reflecting that the ore-hosting rock series is the product of sedimentation in the terrestrial environment.