Geological Characteristics, Ore-Controlling Factors and Mineralization Law of Gold Ore in the North Mountain of Weining Area, Ningxia

Weining north mountain area lies in the copper, gold and multi-metal metallogenetic belt ranged from Weining north mountain area to Guyuan area of Ningxia, which belongs to the metallogenetic belt of North Qilian, where the gold, copper and iron mineralization has a significant effect. The gold orebodies occur as bed-like or lense, and mainly controlled by the faulted zone. The oxide ores are the main ore types, with few primary sulfide ores. It has a very sharp fluctuation in the amount of REE(∑REE=12.04×10^-6-136.167×10^-6)in the rocks of the gold deposit, with enriched LREE and depleted HREE. La/Yb value is 0.609-16.158 and Sm/Nd value is 0.18-0.275, which shows that the fractional distillation occurred in HREE and LREE. The value of δEu is 0.447-0.91, showing a depleted amount of Eu. The research suggests that the deposit appeared as a polygenic formation cause, relating to comprehensive factors from sedimentation and hot fluids and tectonic effects. The formation of the deposit is controlled by lithology, stratum and geological structure. But, the mineralization of the deposit subjected to the intrusion of the quartz diorite porphyrite. Pyritization, kaolinization, jarosite, silicification has occurred in the process of the ore mineralization, followed by a strong effect of oxidation leaching in the late period, which played a very significant role in the formation of the gold deposit.