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武夷山地区加里东期深熔混合岩化-岩浆作用普遍,且两者时代一致或相近,但是加里东期深熔作用的启动时间尚不明确。赣南寻乌县岐山岩体位于武夷山构造带南部,该岩体形成时代缺乏精确的年代学依据。基于锆石LA-ICP-MS U-Pb测年手段,在该岩体中发现两期锆石,早期锆石为深熔成因,晚期为岩浆成因。本次研究获得的晚期锆石形成时代为445~440Ma,具有从外向内年龄渐新的规律,表明该岩体形成于晚奥陶世晚期-早志留世,可能是从源区上升的不同批次岩浆就位的结果,即该岩体为加里东期深熔-幕式、多期次岩浆活动的结果。边缘部位与岩体中心部位分别获得早期深熔锆石加权平均年龄值(458±4Ma)与岩浆锆石加权平均年龄值(460±4Ma),两者在误差范围内一致。表明武夷山地区在加里东早期,大约460Ma左右发生了一期深熔-岩浆活动,为武夷山构造带加里东运动深熔作用的启动时代提供了制约。
The deep Caledonian mafic-magmatic-magmatic processes in the Wuyishan area are common and the two ages are consistent or similar, but the start-up time of the Caledonian smelt is not yet clear. The Qishan granite in Xunwu County, southern Jiangxi Province is located in the south of the Wuyishan tectonic belt. The age of the rock mass lacks accurate geochronology. Based on zircon U-Pb dating of LA-ICP-MS, two stages of zircons are found in this rock mass, while the early zircons are the deep-melt genesis and the late magmatic origin. The age of the late zircons obtained in this study is 445 ~ 440Ma, with a gradual new age rule from outside to inside, indicating that the rock mass formed in the late Ordovician-Early Silurian, probably from different batches rising from the source area The result of sub-magmatism in place is that the rock mass is the result of the Caledonian deep-melt episodic and multi-stage magmatic activity. The weighted average age value of early deep zircon (458 ± 4Ma) and the weighted average age of magmatic zircon (460 ± 4Ma) were obtained from the margin and the central part of the rock mass, respectively, which are consistent within the error range. The results show that a deep-magmatic-magmatic event occurred about 460 Ma during the early Caledonian period in Wuyishan area, which provided a restriction for the start-up era of the Caledonian movement in the Wuyishan tectonic belt.