胶东地区玲珑岩基隆升机制探讨  

Discussion on Uplifting Mechanism of the Linglong Batholith in Eastern Shandong

作　　者：林少泽[1] 朱光[1] 严乐佳[1] 姜芹芹[1] 赵田[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《地质论评》2013年第5期832-844,共13页Geological Review

基　　金：国家自然科学基金重大研究计划资助项目(编号91214301)资助的成果

摘　　要：本文通过详细的野外构造观察,综合主干正断层运动学观测、擦痕应力场反演、岩体变形分析、岩脉与石英脉展布方位等多个方面,对胶东地区玲珑岩基的构造演化进行了有效地制约。研究结果表明,其为早白垩世的伸展穹窿构造,是NW—SE向区域性伸展的结果,并且北部的伸展与岩浆活动及金矿化作用要强于南部。在早白垩世强烈伸展与岩浆活动背景下,晚侏罗世侵位的玲珑岩基沿着倾向相背的两条大型脆性正断层(招平断裂带与焦家断裂带)以地垒构造形式发生隆升而最终出露地表,并非变质核杂岩型伸展构造。玲珑岩基在晚侏罗世侵位后并没有立即出露地表,而是在早白垩世区域伸展中才隆升与剥露,并伴随区内大规模金矿形成。玲珑伸展穹窿的厘定,一方面证实了区内早白垩世强烈岩浆活动是发生在NW—SE向伸展背景下,另一方面进一步验证了华北克拉通东部破坏的峰期出现在早白垩世。On the basis of detailed field structure investigation, tectonic evolution of the Linglong batholith in Eastern Shandong is constrained by main normal fault kinematic observation, stress field inversion from slip-data, pluton deformation analysis and arrangement of dikes and quartz veins in Eastern Shandong. The results show that the Linglong batholith is an Early Cretaceous extensional dome produced by regional NW--SE extension. The extension, magmatism and gold mineralization in the north is more intense than those in the south. Under the Early Cretaceous strong extension and magmatism setting,the late Jurassic Linglong batholith was exhumed to the surface as a horst, rather than a metamorphic core complex, due to normal faulting along two boundary faults, i.e. the Zhaoping and Jiaojia fault zones, with opposite dip directions. It is suggested therefore that the Linglong batholith had not uplifted to the surface right after its Late Jurassic emplacement, and its exhumation was caused by the regional extension of Early Cretaceous and associated with the formation of large scale gold mineralization in this region. Determination of the Linglong extensional dome confirms that Early Cretaceous strong magmatic activity in this region happened under NW--SE extensional background. It further verifies that peak destruction of the eastern North China Craton took place in the Early Cretaceous.

关 键 词：华北克拉通 伸展穹窿 玲珑岩基 正断层 应力场 北西—南东向拉伸 

分 类 号：P542[天文地球—构造地质学]