Origin and Evolution of the Ore-Forming Fluids in the Liyuan Gold Deposit, Central North China Craton: Constraints from Fluid Inclusions and H-O-C Isotopic Compositions

Figure 4

Photomicrographs under transmitted light (a–c), reflected light (d–g, i), and back-scattered electronic images (h) showing the minerals and alteration assemblages in the Liyuan gold deposit. (a) K-feldspar occurring as an early alteration product intergrowth with quartz and sericite. (b) Typical sericite alteration consisting of sericite and muscovite. (c) Quartz-calcite vein with quartz-sericite alteration. (d) Middle stage chalcopyrite and sphalerite replacing the early stage deformed pyrite. (e) Middle stage sphalerite replaced by galena. (f) Ag-bearing native gold replacing the pyrite. (g) Ag-bearing native gold occurring as interstitial fillings between sphalerite, galena, and quartz or as irregular in sphalerite. (h) Ag-bearing native gold filling the microfracture of the pyrite. (i) Irregular Au-bearing native silver grains in pyrite. Ser: “sericite”; Ms: “muscovite”; Qz: “quartz”; Cal: “calcite”; Py: pyrite; Ccp: “chalcopyrite”; Sp: “sphalerite”; Gn: “galena”; Au: “Ag-bearing native gold”; Ag: “Au-bearing native silver.”

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