摘要:
宁夏卫宁北山地区划属北祁连成矿带之宁夏香山-卫宁北山-固原铜、金、铁、铅锌多金属成矿带,铜、金、铁多金属成矿作用显著.金矿体主要以似层状、透镜状产出,受断裂破碎带控制.矿石大部分为氧化矿石,少许为原生硫化物矿石.金矿床岩石稀土总量变化较大(∑REE=12.04×10-6~136.167×10-6),轻稀土富集,重稀土亏损;La/Yb值为0.609~16.158,Sm/Nd值为0.18~0.275,表明轻重稀土发生一定程度的分馏;δEu=0.447~0.91,表现为Eu的亏损.研究认为:金场子金矿应属于沉积-构造-热液改造型金矿,其形成受地层、岩性、构造控制,但成矿作用主要与石英闪长玢岩侵入有关,主要发生了黄铁矿化、高岭土化、黄钾铁矾化和硅化,后期经历了较强烈的氧化淋滤作用,对该矿床的形成具有非常重要的意义.
Abstract:
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.