Primary geochemical haloes study of the possibly Carlin-like Dashui gold deposit for gold exploration in southern Gansu Province, central China

摘要

To increase the reserves of the possibly Carlin-like Dashui gold deposit in Maqu county, Gansu Province, central China, exploration techniques to detect mineralization in the subsurface of the mining district are required. Orebodies in the Dashui deposit are usually controlled by structures closely associated with the Ge'erkuohe granitoid. Samples collected from the deposit area indicate that the mineralization is primarily associated with the indicator elements, Au-Ag-As-Hg-Te-Sb, and less so with the indicator elements, K2O-Rb-F-Ba. The supra- and/or near-ore haloes are characterized by an As-Sb-Hg-Te-Au-Ag association and sub-ore haloes by a W-Mo-Bi-Co-Sc-Ni-V-Cd association. The primary geochemical haloes of the two main orebodies show that they were formed by up to three hydrothermal events. These results indicated that the two orebodies may extend downward to great depths, as was later confirmed by drilling down to depths of c. 3500-3400 m.