中亚巴尔喀什成矿带晚古生代岩浆活动与斑岩铜矿成矿时代

巴尔喀什成矿带是中亚成矿域重要的晚古生代斑岩铜钼成矿带。通过该成矿带科翁腊德、博尔雷和阿克斗卡地区与斑岩铜成矿作用密切相关的花岗斑岩类岩体锆石SHRIMP U-Pb定年，主量、稀土和微量元素地球化学，Sr、Nd同位素示踪分析，进一步厘定了斑岩铜成矿作用的时代，并推测了板块构造环境。斑岩铜成矿时代分为两期：早期约为327 Ma，形成科翁腊德和阿克斗卡超大型斑岩铜矿床；晚期约为316 Ma，形成博尔雷大型斑岩铜矿床。与成矿有关的斑岩类主要为高钾钙碱性系列花岗岩，可能为火山岛弧环境，部分具有埃达克岩特征和经典岛弧花岗岩类特征。斑岩类ε_Sr(t)和ε_Nd(t)的变化范围分别为-6.35~34.03和-0.46~5.53。其中，科翁腊德-博尔雷地区斑岩类来源于亏损地幔与大陆地壳表层物质（老地壳物质）的显著混染作用，而阿克斗卡地区斑岩类直接来自于亏损地幔。将巴尔喀什成矿带与我国西准噶尔成矿带进行了对比，认为可能属于同一个晚古生代斑岩铜钼成矿带。

Late Paleozoic Magmatism and Porphyry Copper Metallogenesis in Balkhash Metallogenic Zone, Kazakhstan, Central Asia

The Balkhash metallogenic zone in Kazakhstan is an important porphyry Cu-Mo metallogenic belt in the Central Asia metallogenic domain. In this paper, zircon SHRIMP U-Pb dating, major, rare earth and trace elemental geochemistry, and Sr and Nd isotope tracing of porphyry granitoids from Kounrad, Borly and Aktogai large and super-large porphyry Cu deposits, provide important informations on porphyry Cu metallogenic time and tectonic environment of the zone. Two stages of metallogenesis, one at ~327 Ma with the formation of Kounrad and Aktogai deposits, and the other at ~316 Ma with Borly deposit, are determined. The porphyry granitoids from this zone are mainly high K calc-alkaline series volcanic arc granite, some of them are adakite-like in trace element geochemistry. ε_Sr(t) and ε_Nd(t) of granitoids from three deposits are in the ranges of -6.35-34.03 and -0.46-5.53, respectively. Their Sr-Nd isotopic signatures indicate that porphyry granitoids from Kounrad and Borly were derived from a mixing source between the depleted mantle and the ancient continental crust, whereas that from Aktogai were derived from the depleted mantle directly. Via comparison of the Balkhash metallogenic zone and Junggar metallogenic zone, they are considered to be formed in the same Late Paleozoic Balkhash-Junggar porphyry Cu-Mo Metallogenic zone.