胶西北玲珑、焦家金矿田锆石(U-Th)/He年龄及其对成矿后剥露程度的指示

玲珑和焦家矿田是胶西北地区最负盛名的两个金矿田.目前有关这两个矿田成矿研究的成果已十分丰富，但是，成矿后隆升剥蚀程度的研究尚属空白.为此，利用最近兴起的低温热年代学技术，对两个矿田成矿后剥露程度进行了尝试研究.结果表明，玲珑矿田锆石(U-Th)/He年龄主要为80~100 Ma，焦家矿田锆石(U-Th)/He年龄主要为90~105 Ma.这些年龄与前人运用其他方法获得的成岩成矿年龄不同，其不是本区岩浆－热液成矿事件的年龄，而是成矿后花岗岩隆升剥蚀的热年龄.基于锆石(U-Th)/He年龄制约，估算本区成矿后隆升剥蚀速率大致与全球造山型金矿剥露速率相当(大约60 m/Ma).玲珑矿田总体比焦家矿田成矿后多剥露了600~900 m，焦家矿田深部找矿潜力应比玲珑矿田大. 

Zircon (U-Th)/He Age and Its Implication for Post-Mineralization Exhumation Degree of Linglong and Jiaojia Goldfields,Northwest Jiaodong,China

The Linglong and Jiaojia goldfields are the two most famous goldfields in the Northwest Jiaodong with voluminous publication focused on gold mineralization. Whereas it is still a barren land as far to pay attention to the post-mineralization exhumation. Utilizing the latest low-temperature thermochronological technique, this work carries out a tentative research on the exhumation degree in the two goldfields. The results show that the zircon (U-Th)/He ages in Linglong goldfield vary predominantly between 80 and 100 Ma, while they are of significant concentration between 90 and 105 Ma in Jiaojia goldfield. These ages yielded in this work are different from those of the previous obtained by other methods, they are not the geochronological ages in respond to magmatic-hydrothermal mineralization events, instead they must have recorded the thermochronological ages of the post-mineralization exhumation of the granitoid rocks. Based on the constrain of the zircon (U-Th)/He ages, it can be concluded that the degree of exhumation in this area is roughly in agreement with that from the statistics of the global orogenic gold deposits, about 60 m/Ma. The amount of post-mineralization exhumation in the Linglong goldfield is overall ca. 600-900 m more than that in the Jiaojia goldfield, so the prospecting potential at deep part is larger in the Jiaojia goldfield than that in the Linglong goldfield.