辽东五龙地区燕山期侵入岩类同源岩浆演化微量元素、同位素证据与金矿成矿

Metallogeny of Gold Deposits and Evidence of Isotopes and Trace Elements for the Comagmatic Evolution of the Yanshanian Intrusive Rocks in the Wulong area, Eastern Liaoning

辽东五龙地区中生代燕山期侵入岩类在时空上与金矿关系密切。该类侵入岩具有接近的微量元素Th/U、Zr/Hf、Nb/Ta值。随着不同岩石类型中的SiO_2、MgO的含量的变化,(^(87)Sr/^(86)Sr)_i和(^(143)Nd/^(144)Nd)_i值保持不变,说明岩浆在侵位过程中没有明显受到围岩物质混染,且该类侵入岩有着相同的岩浆源区。Sr、Nd同位素组成表明成岩物质以下地壳为主。三股流花岗岩和矿石有相似的Pb同位素组成,结合含金石英脉(矿体)切穿已固结三股流花岗岩的地质事实,暗示了三股流花岗岩不太可能是直接的矿质提供者,推测成矿物质与成岩物质主体来自深部的同一岩浆源区,金矿成矿是同一岩浆源区岩浆演化不同阶段的产物。

There is a close space-time relation between Mesozoic Yanshanian intrusive rocks and gold deposits in the Wulong area, eastern Liaoning province. This kind of intrusive rocks have similar ratios of trace elements (Th/ U, Zr/Hf, Nb/Ta). The ratios of (87Sr/86Sr)i and (143Nd/144Nd)i keep unchanged despite of the change of the SiO2 and MgO contents in different rocks, which shows that the magma was not obviously contaminated in the emplacement process, and that different rocks have the same magma source. Compositions of Sr and Nd isotopes show that diagenetic materials mainly came from the lower crust. The similar Pb isotopic compositions of the Sanguliu granite and ores in addition to the fact that the Au-bearing quartz veins cut through the Sanguliu granite body indicate that the Sanguliu granite is not a direct supply of metallogenic materials, It is considered that the diagenetic and metallogenic materials mainly came from the same deep sources, and that the gold deposits are products of magmatic evolution of the same provenance but different stages.