北黄海侏罗系碎屑锆石UPb定年及地质意义

Zircon UPb Dating and Geological Significance for Jurassic Igneous Rocks in North Yellow Sea Basin

摘要:

对北黄海钻遇的侏罗系地层的4个变质火成岩样品进行锆石UPb定年分析，主要获得了2类年龄记录，一类是前寒武纪变质基底形成演化的年龄，另一类是印支期碰撞造山改造的年龄记录.变质基底的年龄区间分布在1.0 Ga至2.6 Ga，其中1.4 Ga至1.8 Ga是一个主要构造岩浆期，包括(1 792±140)Ma，(1 447±110)Ma和(1 524±68)Ma三组UPb谐和年龄.与华北和扬子印支期碰撞造山作用有关的定年结果为200 Ma至240 Ma.这2类年龄与邻区胶北地体及苏鲁造山带获得的年龄数据具有很好可比性，可为进一步认识北黄海侏罗系物源区构造演变特点提供重要依据.

Abstract:

Zircon UPb dating analysis was performed on four igneous rock samples taken from the Jurassic debris of the drilling wells in North Yellow Sea Basin. Two sorts of ages are obtained, one is about the formation and evolvement of Precambrian metamorphosed basement and the other is about the collisional orogeny in Indo Chinese epoch. The age about metamorphism basement is distributed in 1.0—2.6 Ga, its main tectonic magma period is 1.4—1.8 Ga which includes three groups of UPb Concordia ages: 1 792±140 Ma, 1 447±110 Ma and 1 524±68 Ma. The age connected to the collisional orogeny between North China block and Yangze block in Indo Chinese epoch is distributed in 200—240 Ma. These two ages have a good relationship with neighboring blocks as Jiaobei terrane and Sulu orogene. They can provide important evidence for the tectonic evolvement of source area in Jurassic strata in North Yellow Sea Basin.