Multiple sources and genesis of the Suoerkuduke Cu-Mo deposit during the Carboniferous, East Junggar: Insights from zircon U-Pb age and C-O-S-Pb isotopes

Abstract

The Suoerkuduke Cu-Mo ore bodies are closely associated with skarns, but this deposit shows distinct characteristics from typical contact metasomatic skarn deposits. No carbonate rocks and coeval magmatic activities were found in the oredistrict. Thus, there is no unidirectional zonation sequence from proximal to distal, but a bidirectional skarn zonation as follow: garnet skarn in the center, and epidote-garnet skarn, epidote skarn and diopside-hedenbergite skarn (with no symmetrical distribution) in outer parts. The sulfides are pyrite, chalcopyrite, molybdenite, sphalerite, galena and pyrrhotite, and no obvious sulfide zonation was observed.The multiple sources of ore-forming fluids and ores imply a complicated and distinct metallogenic process of the Suoerkuduke deposit. The ore-forming fluids mainly consist of magmatic water, meteoric water and seawater. The coeval magmatic-hydrothermal activities took place in the nearby area of the Suoerkuduke oredistrict, but not within the oredistrict, indicating that magmatic water was most likely derived from a batholith at depth. This hidden batholith provided magmatic fluids, most of the sulfur and a portion of Cu metal for the Suoerkuduke deposit. The Mo metal was derived from the leaching of andesitic rocks and tuffaceous sandstone by meteoric water. The ascending magmatic fluids mixed with deeply circulated meteoric water and seawater, and then leached volcanic-pyroclastic rocks to enrich Ca, Fe and Cu metals. These fertile fluids subsequently metasomatised andesitic porphyry, pyroxene andesite and tuffaceous sandstone to form the skarn. The decrease in the temperature and fO2 values facilitated the deposition of sulfides.