乌克兰米丘林铀矿床的成矿蚀变作用

米丘林铀矿床是乌克兰基洛沃格勒地区发现的第一个受构造-岩性和蚀变分带特征控制的典型钠交代型大型铀矿床。通过总结归纳前人对乌克兰米丘林铀矿床的铀矿化特征、蚀变作用及分带特征,对米丘林矿床的成矿蚀变作用进行分析探讨。米丘林矿床主要发育石榴石-黑云母片麻岩和钾质花岗岩两种岩石;矿床的围岩蚀变发育,主要表现出广泛的岩石退变质作用,如斜长石的绢云母化、微斜长石化、黑云母化、绿泥石化,沿断裂还发育有大规模、强烈的钠交代作用;铀矿化与钠交代作用密切相关,主要发育在花岗岩与片麻岩接触带的断裂带中,由沿断裂活动的流体交代片麻岩、花岗岩、糜棱岩和碎裂岩而形成,铀矿体主要产于钠交代岩体中。因此,钠交代岩控制着该类型铀的成矿作用,它的分布特征决定着铀矿体的规模大小,并对铀的成矿具有重要指示意义。

Metallogenic alteration of Michurinsk uranium deposit in Ukraine

Michurinsk uranium deposit is the first large typical sodium metasomatism type uranium deposit which is controlled by tectonic-lithology and alteration zones in the Kirovograd region of Ukraine.By summing up the uranium mineralization characteristics,alteration and zonation of the deposit,this paper analyzed and discussed the metallogenic alteration of the Michurinsk uranium deposit.There are mainly two types of rocks in the Michurinsk deposit,namely garnet-biotite gneisses and potassic granite;the alteration in the host rock of the deposit presented extensive retrometamorphism,such as sericitization of plagioclase,microclinization,biotitization,chloritization and large scale and strong sodium metasomatism developed along the fault;uranium mineralization is closely related to the sodium metasomatism and mainly developed in the fracture zone along the contact between granite and gneiss,which formed by the fluid metasomatism of gneiss,granite,mylonite and cataclastic rock formation.The uranium ore bodies are hosted by sodium-metasomatic pluton.Thus,sodium metasomatic rocks control the formation of this type of uranium mineralization and its distribution characteristics and ore body sized.