西天山备战铁矿成岩年代厘定及矿床成因研究

Study on the Metallogenic Epoch and Mineral Genesis of Beizhan Iron Ore in Western Tianshan

运用同位素定年技术厘定西天山备战铁矿成岩年代,结合成矿地质背景研究矿床成因。通过对备战铁矿矿带南侧花岗斑岩样品中分选出的锆石单矿物颗粒进行锆石U-Pb法同位素定年,获得谐和年龄为(301.36±0.39)Ma。初步认为备战铁矿成岩时代为晚石炭世早期。结合区域构造背景认为,备战铁矿成矿环境为晚石炭世裂谷闭合环境,成矿岩浆形成于海陆交互相。矿石与围岩在成因上有联系,来自富集地幔,喷发过程中含矿岩浆与陆壳物质或花岗岩发生混染,形成铁矿床。综合分析认为,该矿床为火山沉积后期矽卡岩化改造富集型磁铁矿床。

This paper uses isotope dating techniques determined the diagenetic age of the West Tianshan preparing iron ore,combined with the geological background to study the genesis. U-Pb isotopic dating of Zircon from the southern of Beizhan iron ore shows the age of 301.36 ± 0.39Ma. The preliminary view is that the diagenetic age in beizhan iron ore is 301.36 ± 0.39Ma,belong to the early late Carboniferous.Combined with regional tectonic setting,Beizhan iron ore min-eralized in the Late Carboniferous rift closed environment,mineralization magma formed in paralic.Ore and wall rock genesis from enriched mantle source of the eruption process containing ore magma with continental crust or granite con-tamination,and then formed the iron ore deposit. Comprehensive analysis shows that the deposit is a enriched magnetite bed transformed by skarnization in the late volcanic sedimentary.