Genesis of the Maanqiao gold deposit in the western Qinling orogen, central China: Constraints from fluid inclusions and in-situ sulfur isotopes

摘要

The western Qinling orogen (WQO) is one of the most important prospective gold provinces in China. The Maanqiao gold deposit, located on the southern margin of the Shangdan suture, is a representative gold deposit in the WQO. The Maanqiao deposit is hosted by the metasedimentary rocks of the Upper Devonian Tongyusi Formation. The EW-trending brittle-ductile shear zone controls the orebodies; they occur as disseminated, and auriferous quartz-sulfide vein. The ore-related hydrothermal alteration comprises silicification, sulfidation, sericitization, chloritization, and carbonatization. Native gold is visible and mainly associated with pyrite and pyrrhotite. Mineralization can be classified into the following three stages: bedding-parallel barren quartz-pyrite-(pyrrhotite) (early-stage), auriferous quartz-polymetallic (middle-stage), and carbonate-(quartz)-sulfide (late-stage).