胶北地块古元古代花岗伟晶岩脉的锆石SHRIMP U-Pb年代学特征及地质意义

Zircon SHRIMP U-Pb Chronological Characteristics and Geological Significance of Paleoproterozoic Granitic Pegmatite Vein in Jiaobei Block

胶-辽-吉古元古代造山带是近年来国内古老造山带研究的热点地区,胶东半岛的胶北地块位于胶-辽-吉造山带南部,在胶北地块莱西一带发育了大量的古元古代荆山群变质地层,其中发育大量的花岗伟晶岩(脉)体,本次工作利用SHRIMP U-Pb测年技术,首次精确测定了花岗伟晶岩的形成时代为~1.84Ga,同时结合前人资料,确定了胶东半岛发育有与1.84Ga伸展作用相关的花岗伟晶岩类。通过与辽西地区所报道的花岗伟晶岩对比,认为二者在古元古代构造演化的过程中具有时空一致性。

Jiao-Liao-Ji Proterozoic orogenic belt is recently considered as the hot area of old orogenic belt domestically.Jiaobei block(in Jiaodong peninsula)lies in the south of Jiao-Liao-Ji orogenic belt.Huge amount of Proterozoic Jingshan group metamorphic strata occurs in Laixi of Jiaobei block and exists mass granite pegmatite.By using SHRIMP U-Pb dating techniques,the forming age of granite pegmatite is firstly accurately measured(~1.84Ga).Based on previous data,it is reflected that Jiaodong peninsula exists granite pegmatite,which is related to 1.84Ga extensional mechanism.Comparing with granitic pegmatites reported in western Liaoning,it is believed that the two have temporal and spatial consistency in the process of Paleoproterozoic tectonic evolution.