东昆仑野马泉铁多金属矿床花岗闪长岩年代学、地球化学特征及其地质意义

Geochronology,geochemical characteristics and geological significance of granodiorite in Yemaquan iron polymetallic deposit of the East Kunlun

野马泉矿床位于柴达木盆地西南缘与青海祁漫塔格的结合部位,是青海省重要的铁多金属成矿区。采用LA-LCP-MS锆石U-Pb法测得矿区花岗闪长岩年龄为(220.53±0.69)Ma和(400.8±1.4)Ma,表明矿区成岩有两期,即加里东晚期和印支晚期。岩石地球化学分析结果显示,岩石明显具有富硅富钾铝过饱和的特点,属高钾钙碱性系列,其成因类型为I型花岗岩,源区经历了俯冲板块流体交代,为壳幔混合源区。岩石形成于东昆仑造山带的早古生代和晚古生代——早中生代这两期构造——岩浆旋回的末期,由碰撞挤压环境转向后碰撞的伸展环境,岩石具有良好的成矿性。野马泉铁多金属矿床的形成与两次构造——岩浆旋回末期的中酸性侵入岩密切相关,是两期成矿的结果。

Yemaquan iron polymetallic deposit is located at binding sites of the southwest margin of the Qaidam Basin and the Qinghai Qimantage,and is an important iron ore region in Qinghai province.The LA-LCP-MS zircon U-Pb dating shows that the mining granite age is 220.53 ± 0.69 Ma and 400.8 ± 1.4Ma,indicating there are two diagenesis periouds,late Caledonian and Indosinian movement.Geochemical analysis results show that the rock is obviously rich in silicon,saturated potassium and aluminum,belonging to high potassium calc alkaline series.The type formation was I-type granite.The source region experienced subduction metasomatic fluids,as the crust mantle mixed source area.The rocks were formed in the late of two tectonic-magmatic cycle,Eopaleozoic and Neopaleozoic-early Mesozoic,at the East Kunlun orogenic belt.The tectonic environment was from extrusion to extension.The genesis of the rock has good mineralization.The formation of Yemaquan iron polymetallic deposits is closely related to the intermediate-acid intrusive rocks at the end of two tectonic-magmatic cycle.The deposit is the result of two stages of mineralization