吉林红旗岭镍矿田茶尖岩体锆石SHRIMP U-Pb年代学及其意义

茶尖1号岩体是茶尖矿床主要成矿岩体，其岩相组合为辉石橄榄岩、橄榄辉石角闪岩、角闪辉岩、辉长岩和闪长伟晶岩.辉长岩的锆石SHRIMP U-Pb测年结果表明，茶尖镁铁-超镁铁岩的形成时代为239.6±2.6 Ma，属于印支期.结合红旗岭矿田已有年代学数据显示，红旗岭矿田成矿岩体形成时代具有由西南至东北依次变新的趋势.茶尖1号岩体的形成年龄明显早于红旗岭成矿岩体，矿床形成年龄差最大可达20 Ma，红旗岭矿区的镁铁-超镁铁岩浆的活动时间应开始于240 Ma之前且持续时间较长.茶尖矿床1号岩体中发现的捕获锆石核年龄为1.7 Ga和0.6 Ga，为镁铁-超镁铁岩浆混入地壳物质提供了直接证据.捕获锆石年龄与华北地台新元古代和中元古代构造－热事件相对应，表明其来源为华北地台基底. 

SHRIMP Zircon U-Pb Dating of Chajian Mafic-Ultramafic Rocks in Hongqiling Mine Field, Jilin Province, and Its Implications

Chajian No.1 rock mass is the main ore-forming rock mass in Chajian deposit, its lithofacies include pyroxene-peridotite, olivine-pyroxene-amphibolite, Hornblende-pyroxenite, gabbro and diorite-pegmatite.The results of gabbro zircon SHRIMP U-Pb dating show that mafic-ultramafic rock masses formed in the Late Triassic and the age is 239.6±2.6 Ma. The existing age data of mafic-ultramafic rocks indicate that the formation age of the rock masses become new in turn from southwest to northeast. The formation age of Chajian No.1 rock mass is earlier than that of Hongqiling rock mass significantly, age difference between them can reach 20 Ma. Mafic-ultramafic magmatism activities in Hongqiling district began before 240 Ma and lasted for a long time. The finding of 1.7 Ga and 0.6 Ga zircon cores is direct evidence of magma mixed with crustal material. The ages of captured zircons are corresponding with those of Neoproterozoic and Mesoproterozoic tectonic heat events in the North China Platform, suggesting that their origin is North China platform basement.