东准噶尔北缘老山口铁铜金矿床古生代岩浆岩锆石U-Pb年代学、氧逸度特征及地质意义

老山口矿床位于新疆东准噶尔北缘，是区域内重要的铁铜金矿床。矿区内岩浆岩发育广泛，对其中的奥陶纪玄武安山岩(约449 Ma)，奥陶纪安山岩(约447 Ma)，泥盆纪火山岩(393~376 Ma)、二长闪长岩(约379 Ma)、黑云母闪长岩(约379 Ma)、石英正长岩(约376 Ma)、细粒闪长岩(约370 Ma)，石炭纪碱性花岗岩(约330 Ma)和粗粒闪长玢岩(约310 Ma)进行了成岩年代学的统计和测试，结果表明老山口矿床存在3期岩浆活动：450~440 Ma、约390~370 Ma以及330~310 Ma。结合区域构造演化可知，其中450~440 Ma和390~370 Ma的岩浆活动形成于不同时期俯冲相关的岛弧环境，而330~310 Ma的岩浆活动则形成于后碰撞板内伸展环境。根据铜金矿化的时代，可将矿区内的岩浆岩分为3期：成矿前、同成矿及成矿后。老山口同成矿期岩浆岩(泥盆纪火山岩、二长闪长岩、闪长玢岩和黑云母闪长岩)具有相对较高的(Eu/Eu*)N、(Ce/Ce*)N和CeⅣ/CeⅢ值，分别为0.13~0.86、1.14~445.92和33.34~1 165.04，说明铁铜金矿化与高氧逸度的岩浆活动有关。

Geochemistry,geochronology and oxygen fugacity of volcanic and intrusive rocks from the Laoshankou Fe-Cu-Au deposit in the northern margin of East Junggar,NW China.

The Laoshankou deposit is an important Fe-Cu-Au deposit in the northern margin of the East Junggar, NW China. LA-ICP-MS U-Pb dating of zircon constrains the timing of crystallization of Ordovician basaltic andesite (~449 Ma), Ordovician andesite (~447 Ma), Devonian volcanic rocks (393376 Ma), monzodiorite (~379 Ma), biotite diorites (~379 Ma), quartz syenites (~376 Ma), fine-grained diorite (~370 Ma), alkali granite (~330 Ma) and coarse-grained diorite porphyry (~310 Ma). Zircon dating indicates three periods of magmatism in Laoshankou: 450440 Ma, ~390370 Ma and 330310 Ma. The magmatism for the first two periods occurred in a subduction-related island arc setting; the magmatism for the last one occurred in a post-collision or inplate extensive setting. Pre-, syn- and post-mineralization volcanic and intrusive rocks are divided based on the Fe-Cu-Au mineralization timing. Syn-mineralization intrusions in Laoshankou have relatively high (Eu/Eu*)N, (Ce/Ce*)N and CeIV/CeIII values of 0.130.86, 1.14445.92 and 33.341165.04, respectively, indicating Fe-Cu-Au mineralization was associated with high oxygen fugacity magmatism.