Metallogeny, minerogenic series, and gold mineralization of the Qinling Orogen, China

The Qinling orogen extends 1650 km E-W and has a width of 95-255 kin. It ha s a long evolutionary history of similar to3.02 Ca and a mineralization his tory of approximately 2.5 Ga. There are more than 400 mineral deposits of A u, Ag, Pb, Zn, Sb, Hg, Mo, W, Fe, Ni, Mn, rare elements, REE, U, V, P, As, Ba, Sr, Ti, Al, pyrite, gypsum, trona, halite, glauberite, mirabilite, blue asbestos, fluorite, rock crystal, mica, vermiculite, graphite, kyanite, an dalusite, tale, fireclay, and K-feldspar in the Qinling orogen and adjacent areas. The deposits were formed in six tectono-minerogenic cycles and have been grouped into 21 regional minerogenic series. The metallogeny of the Qinling orogen is closely associated with the tecton ic evolution of the orogen, and most of the ore deposits were formed in two important metallogenic periods: (1) Middle Proterozoic to Early Paleozoic, which was characterized by spreading and rifting-related minerogenetic pro cesses; during this period, the minerogenic series are directly associated with basic-ultrabasic magmatism and marine volcanism resulting from spreadi ng-rifting and deep faulting; (2) Mesozoic, when mineralization was control led by intracontinental subduction and postorogenic relaxational taphrogene sis or extension; the minerogenetic series are associated with intermediate -acid magmatism and terrestrial volcanism. Gold is one of the most important ore-forming commodities in the Qinling or ogen. Over 80% of those gold deposits were formed in the Mesozoic and Cenoz oic and are related genetically to magmatism, terrestrial volcanism, and al luvial sedimentation. Most gold deposits in the Qinling orogenic belt are o f hydrothermal origin. The Dashui-type gold deposits may be a new category of high-sulfidation epithermal gold deposits hosted by carbonate rocks of t he Upper Paleozoic and Triassic in the southwestern part of the Qinling oro gen. Shuangwang-type gold deposits in the middle of the Qinling orogen are characterized by low-grade (but large in terms of tonnage) ores hosted by b recciated and banded albitites, which are thought to have been formed by Ya nshanian (late Mesozoic) magmatic-hydrothermal fluids injected into the Dev onian sedimentary rocks. Carlin-type, quartz vein-type, and placer-type dep osits also are important in this continental orogenic belt and adjacent are as.