海南岛东部黄竹岭地区变质火山岩锆石U-Pb同位素年龄及其地质意义

Zircon U-Pb ages of metavolcanic rocks in the Huangzhuling area, eastern Hainan Island, and their geological significance.

海南岛东部黄竹岭地区出露一套中浅变质岩系,其中夹变质火山岩。变质火山岩中存在2组不同成因的锆石,获颗粒锆石U-Pb一致曲线上交点年龄为527Ma±48Ma,可解释为火山岩生成年龄的下限,下交点年龄为230Ma±13Ma,为岩石后期经受变质热事件的年龄。据上述颗粒锆石U-Pb年龄,结合区域地质背景分析,认为变质火山岩的形成年龄介于498.9～(527±48)Ma之间,该套地层形成时代为早古生代。

There outcrops a medium- to low-grade metamorphic series intercalated with metavolcanic rocks in the Huangzhuling area, eastern Hainan Island. The metavolcanic rocks contain two groups of zircon of different origins. The zircon U-Pb concordia upper intercept age is 527±48 Ma, whereas the lower intercept age is 230±13 Ma. The former may be interpreted as the lower limit of the formation ages of volcanic rocks, while the latter may represent the age of the metamorphic-thermal event suffered by volcanic rocks in the late stage. According to the above-mentioned zircon U-Pb ages, combined with the regional geological setting, the authors think that this strata formed in Early Paleozoic.