山东长岛地区蓬莱群辅子夼组碎屑锆石年龄谱研究

U-Pb age spectrum of detrital zircons from the Fuzikuang Formation,Penglai Group in Changdao,Shandong Province

山东烟台长岛地区出露的蓬莱群辅子夼组浅变质沉积岩主要为变质石英砂岩夹变质粉砂岩和变质粘土岩。前人对蓬莱群的沉积时代存在较大争议,本文根据长岛地区蓬莱群辅子夼组碎屑锆石年龄谱资料,将辅子夼组的地层时代置于新元古代。碎屑锆石中出现1600Ma和1200～1100Ma左右两个年龄峰值,后者表明辅子夼组曾接受来自具有格林威尔期构造热事件物源区的碎屑物质。这一物源区所反映的地质演化特点既不同于华北陆块,也不同于扬子陆块,应引起高度重视和进行深入的探索。

The low-grade metasedimentary rocks of the Fuzikuang Formation,Penglai Group in Changdao,Yantai,Shandong Province are mainly composed of metamorphic quartz sandstones,with metamorphic siltstone and mud rock intercalations.The depositional age of the Penglai Group has long been dabeted.Based on the U-Pb age spectrum of detrital zircons,the authors conjecture that the age of the Fuzikuang Formation,Penglai Group in Changdao is Neoproterozoic.There are two age peaks,~1600Ma and 1200~1100Ma,in the age spectrum of the detrital zircons.The younger age peak shows that the Fuzikuang Formation was sourced from a provenance with typical Greenville-period tectono-thermal events,which is different both from the North China and Yangtze blocks in geological evolution characteristics.Hence further work is needed to decipher the special source region.