摘要
苏鲁造山带产出一系列中生代岩浆岩 ,但是对它们的确切侵位年龄至今尚无正式报道。对其西北部五莲断裂附近四个花岗质侵入岩体进行了锆石U Pb年龄测定 ,结果得到大店复式岩体中角闪二长岩的谐和年龄为 12 3± 4Ma ,七宝山复式火山 -侵入杂岩体中辉石二长岩的谐和年龄为 12 6± 3Ma。五莲山岩体中晶洞花岗岩的谐和年龄为 116± 4Ma,马耳山岩体中不等粒二长花岗岩的谐和年龄为 115± 1Ma。这些锆石U Pb年龄结果说明 ,苏鲁造山带同样存在侵位时间分别为 115Ma和 12 5Ma左右的早白垩纪侵入体 ,与大别造山带内大面积出露的燕山期岩浆岩年龄基本一致 ,代表了扬子板块与华北板块在三叠纪碰撞折返后的岩浆活动 。
Zircon U Pb dating was carried out for four granitoid plutons at Wulian in the northwestern part of the Sulu orogenic belt, whose intrusion ages were not known for a long time and thus were often confused with adjacent granitoids of Neoproterozoic age. The present dating yields concordant ages of 123±4 Ma for amphibole monzonite at Dadian, 126±3 Ma for pyroxene monzonite at Qibaoshan, 116±4 Ma for miraolitic granite at Wulianshan, and 115±1 Ma for monzonitic granite at Maershan. The results show the occurrence of Early Cretaceous intrusions at ～115 Ma and ～125 Ma in the Sulu orogenic belt, being consistent with those coeval magmatic activity in the Dabie orogenic belt and the northeastern part of the Sulu orogenic belt. Although these Yanshanian granitoids occur in the Triassic collisional orogen between the Yangtze and North China plates, they belong to post collisional magmatism and were produced by partial melting of the subducted continental crust.
出处
《高校地质学报》
CAS
CSCD
2003年第2期185-194,共10页
Geological Journal of China Universities
基金
中国科学院知识创新工程项目(KZCX2 1 0 7)
国家自然科学基金 (40 2 72 1 0 0)资助成果
