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    浙西开岭脚和里陈家花岗闪长岩锆石SHRIMP U-Pb年龄及其地质意义

    SHRIMP U-Pb ages of zircons from Kailingjiao and Lichenjia granodiorites in western Zhejiang and their geological implications

    • 摘要: 提要:浙江中生代侵入岩遍布全省,且绝大多数岩体与火山岩共生。其时代也随火山岩划分为燕山早期与燕山晚期。近年来,随着生物地层与年代地层的研究表明,浙江晚侏罗世—白垩纪火山沉积岩系时代改为白垩纪;中生代侵入岩同位素年龄为135~85 Ma,据此,侵入岩也由分燕山早、晚两期改为燕山晚期。通过对浙江西部与金属矿产有密切关系的开岭脚、里陈家花岗闪长岩体进行锆石SHRIMP U-Pb同位素测年,其加权平均年龄值分别为(151±3)Ma(MSWD=0.74),(148 ± 2)Ma(MSWD=1.2),说明浙西存在晚侏罗世侵入岩,该时期也为重要的成矿期。

       

      Abstract: Abstract:Mesozoic intrusive rocks are distributed in whole Zhejiang Province, mostly coexistent with volcanic rocks. Their ages can be divided into Early Yanshanian period and Late Yanshanian period in consistency with ages of volcanic rocks. However, recent researches on biostratigraphy and chronostratigraphy show that the age of Late Jurassic–Cretaceous volcanic-sedimentary rocks should be changed to Cretaceous. The isotopic ages of the Mesozoic intrusive rocks are between 135 Ma and 85Ma. Therefore, the ages of Mesozoic intrusive rocks should be changed from Early and Late Yanshanian period to Late Yanshanian period. The authors conducted zircon SHRIMP U-Pb dating of Kailingjiao and Lichenjia granodiorite closely related to the metallic ore resources in western Zhejiang. Weighted average ages of (151±3) Ma(MSWD=0.74) and (148±2.4)Ma(MSWD=1.2)are interpreted as the formation time of the granodiorite, suggesting the existence of Late Jurassic intrusive rocks in western Zhejiang. This period is also important for mineralization.

       

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