津巴布韦大岩墙Darwendale次岩浆房铂族元素成矿分布和成矿机制探讨

大岩墙超铁镁质岩层上部主要有三个硫化物带,铂族元素(PGE)主要分布在这些矿带中,尤其富集在硫化物带的底部。下部两个矿带属星散硫化物成矿,二者距离较远;上部矿带铂族元素品位较高,分布在十分薄的岩层中。目前对层状硫化物矿床形成的模式尚未进行足够的研究。初步认为下部两个矿带是硫化物从硅酸盐岩浆中经连续的结晶分凝作用形成;上部矿带是由于岩浆房底部比较原始的岩浆与顶部伴生浆液混合形成。

Metallogenic distribution and mechanism of platinum group elements in the Darwendale subchamber of the Great Dyke, Zimbabwe

Three sulphide zones with platinum group elements(PGE) mineralization have been discovered in the upper part of the ultramafic rock formations of the Great Dyke,Zimbabwe.The PGE are concentrated at the base of the sulfide zones;the lower two sulphide zones have scattered sulfide mineralization with a thick interval apart;the upper zone concentrates high grade PGE in a thinner rock formation.The models for the formation of stratabound sulphide deposits in bedded intrusions have not been interpreted adequately.It is proposed primarily that the two lower sulphide zones were resulted from continuous fractional segregation of sulphide from the silicate magma,while the upper zone was formed through mixing of a relatively primitive magma at the base of the chamber with an evolved liquid derived from the top of the chamber.