Mineralization and ore-controlling implications of low-angle faults

Low-angle faults include those occurring in thrust-nappe structures in a co mpressive setting and the detachment of metamorphic core complexes in an ex tensional setting. All low-angle faults have their own particularities. The low-angle fault plays an important role in controlling over some endogenet ic metallic ore deposits. Based on studies of the Xiaoban gold deposit, Xin zhou gold deposit, and Longfengchang polymetallic ore deposit, and comparis ons with other mines, the authors conclude the ore-controlling implications of low-angle faults as follows. (1) Because of high temperature and high p ressure, as well as strong ductile deformation, the internal energy of the elements rises in the large-scale deep ductile low-angle faults, which caus es the elements to activate and differentiate from the source rocks, formin g ore-bearing hydrothermal solution, and bring mineralization to happen. (2 ) When rising from depths and flowing along the low-angle faults, the ore-b earing hydrothermal solution will alter and replace the tectonites in the f ault zone. The rocks of the hanging side and the heading side differ in lit hology, texture and structure, which results in changes or dissimilarities of the physical-chemical conditions. This destroys the balance of the hydro thermal solution system and causes the dissolved ore-forming elements to pr ecipitate; as a result, a deposit is formed. Therefore, the meso-shallow du ctile-brittle low-angle faults play the role of a geochemical interface in the process of mineralization. (3) Low-angle faults are often one of the im portant host structures.