广西大福楼矿床铅同位素组成及其对矿床成因的约束(英文)

利用大福楼矿床新开采坑道的矿石样品进行铅同位素分析,探讨了矿床的成矿物质来源及其构造背景。结果表明,206Pb/204Pb、207Pb/204Pb以及208Pb/204Pb分别位于17.478～18.431、15.440～15.717以及37.556～38.839,Φ值位于0.592～0.638,μ值为9.26～9.69,Th/U取值范围为3.74～3.97。比较大厂矿田不同矿带的铅同位素组成的结果表明,西矿带的铅源可能更加单一,中矿带的铅同位素值相对最大,而东矿带的铅同位素值则最小;大厂矿集区的铅源主要由上地壳铅、壳幔混合俯冲带铅以及造山带铅所组成。根据铅同位素构造判别图,矿石铅主要来自于地幔和地壳,尤其是上地壳以及岩浆活动在成矿作用过程中发挥了重要作用。然而,造山作用也提供了少量铅源,矿床应该属于壳幔联合作用的产物,更可能形成于造山带成矿环境中。

Lead isotope composition and constraints on origin of Dafulou ore deposit,Guangxi, China

To discuss the material source and tectonic setting, the lead isotope composition was analyzed based on the samples from the latest tunnel of the Dafulou deposit. The lead isotope values are 17.478-18.431, 15.440-15.717, and 37.556-38.839 for ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb, respectively. The values of Φ, μ, and Th/U are 0.592-0.638, 9.26-9.69 and 3.74-3.97. By comparing the lead isotope composition of the different ore belts, it indicates that the lead source of the west belt may be more single than the other ore belts. The lead isotope value in the middle and east belts are the maximum and minimum, respectively. In the Dachang ore district, the lead sources are comprised of the upper crust lead, the mixed crust and mantle subduction zone lead and the orogenic lead. The tectonic distinguish model suggests that the ore lead derived from both the mantle and crust. And, the upper crust and magmatism played an important role during the mineralization. The orogenesis also supplied a minority of ore lead. The ore deposit should be the result of the crust-mantle interaction and maybe had been formed in the orogenic environment.