Mo Mineralization Types, in Space and Time

The classification of hydrothermal deposits has always been a confusing issue in mineral deposit studies. In this chapter, the term “epizonogenism” is introduced, and the hydrothermal deposits are grouped into three classes, namely, epizonogenic, metamorphic, and magmatic hydrothermal mineral systems. The features and differences of three kinds of hydrothermal fluids are discussed, and the fluid inclusion indicators are proposed to discriminate the three classes of hydrothermal deposits. According to this trichotomy, 49 Mo deposits in Qinling Orogen are assigned into the porphyry, porphyry-skarn, magmatic hydrothermal vein, and orogenic types, with representative deposits being introduced in detail in Chaps. 3–6. Thirty-two of these 49 deposits contain ~8.7 Mt. Mo metal. Mo deposits have been discovered in three tectonic units (Southern Qinling Fold Belt, Northern Qinling Accretion Belt, and Huaxiong Block), clustering in the Huaxiong Block which contributes 98% of the total Mo resources in Qinling Orogen. Nearly all the significant Mo deposits were formed in the Mesozoic, particularly in the 160–130-Ma mid-Yanshanian Orogen associated with the compression-to-extension transition of the continental collision between the North China and Yangtze cratons.