斑岩型钼矿床蚀变岩石类型和蚀变矿化分带特征

CHARACTERISTICS OF ALTERED ROCK TYPES AND ALTERED MINERALIZATION ZONES IN PORPHYRY MOLYBDENUM DEPOSITS

通常的斑岩型钼矿床是指围岩中不含碳酸盐岩石的矿床类型,其实矽卡岩型钼矿床从根本上说其围岩成分只有少部分碳酸盐岩石而仍属于斑岩型钼矿床。对于研究斑岩型钼矿床蚀变矿化分带的目的,就是要总结分带与矿化之间的紧密联系。理论上的分带应该是成矿母岩岩体由里向外存在4个蚀变矿化带:即钾化带、硅化带、绢英岩化带和青盘岩化带,而大部分的工业钼矿体产于硅化带,次为钾化带和绢英岩化带内,青盘岩化带内几乎不含矿。硅化的主要形式就是数以百万计的不同阶段的、不同大小的石英细脉,它们的密集程度不同,含矿浓度不同,展布方向不同,有时构成网脉状。这就是矿床不同部位的矿石品位各异的原因所在。钾化带主要是各种细脉内含有不同程度的钾长石矿物,有的是纯粹的钾长石脉,这类细脉的矿化相对较弱,其带内矿体规模相对较小。以蚀变矿化的分带作为一种找矿标志也是一种地质找矿领域切实可行的应用手段。

The usual porphyry type molybdenum deposit refers to the type of deposit without carbonate rock in surrounding rock.In fact,skarn type molybdenum deposit is basically composed of only a few carbonate rocks and still belongs to porphyry type molybdenum deposit.For the purpose of studying the alteration and mineralization zones of porphyry molybdenum deposits is to summarize the close relationship between zonation and mineralization.In theory,there are four altered mineralization zones in the ore-forming parent rock mass from the inside to the outside,namely,the potassium zone,the silicification zone,the sericite zone and the bluish plate zone.Most of the industrial molybdenum ore bodies are found in the silicification zone,followed by the potash zone and sericite zone,and Qingpan lithiation zone contains little ore.The main form of silicification is millions of quartz veins of different stages and sizes,which have different densities,different mineral concentrations,different distribution directions,and sometimes form a net vein shape.This is the reason for the different ore grade in different parts of the deposit.The potash zone mainly contains different degrees of potassium feldspar minerals in various fine veins,some are pure potassium feldspar veins,the mineralization of such fine veins is relatively weak,and the size of ore bodies in the belt is relatively small.It is also a practical application method in the field of geological prospecting to use altered mineralization as a prospecting mark.