南京蒋庙岩体的年代学、地球化学及其地质意义  

Geochronology and geochemistry of the Jiangmiao intrusion in Nanjing:Its geological significance

作　　者：洪文涛[1] 徐夕生[1] 贺振宇[1] 闫峻[2] 

机构地区：[1]南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室,南京210093 [2]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《岩石学报》2010年第5期1577-1588,共12页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40730313);国家重点基础研究发展规划项目(2006CB403508)联合资助

摘　　要：南京蒋庙侵入岩体的主体为辉长岩-闪长岩,并伴有少量的二长岩。LA-ICP-MS锆石U-Pb定年表明,其形成于118±1.1Ma,为长江中下游地区中生代最晚的一次岩浆活动。岩石地球化学资料表明,在岩浆上升及结晶过程中无明显的地壳物质混染。蒋庙岩体的εNd(t)值为-0.49～-2.29,介于DMM及EMII之间。简单二单元混合计算表明,其源区中有较高比例的软流圈物质加入。综合其它年龄资料,长江中下游地区中生代岩浆活动可分为3期:早期为151～133Ma,中期为131～126Ma,晚期为125～118Ma。中生代时期该区总体处于板内伸展的构造环境,经历了岩石圈拉张、软流圈持续上涌的地幔过程。Jiangmiao intrusion is mainly composed of gabbro and diorite,and minority of monzonite.It belongs to the latest episode of Mesozoic magmatism in the Milddle-Lower Yangtze region,with its LA-ICP-MS zircon U-Pb age of 118 ± 1.1Ma.There is no significant crustal contamination during magma ascending and crystallization by petrochemical analysis.The εNd(t) values of Jiangmiao intrusion range from-0.49 to-2.29,situated in the field between the DMM and EM II end-members in the εNd(t) vs.(87Sr/86Sr) i diagram,and the simple binary mixing calculation indicates that its magma source contains a large proportion of materials from the depleted asthenosphere.Integration with previous age data,the Mesozoic magmatism in the Middle-Lower Yangtze region can be divided into three episodes:Early(151 ～ 133Ma),middle(131 ～ 126Ma) and late(125 ～ 118Ma) episodes.This region was under intraplate extensional environment in Mesozoic and experienced a series of processes of lithospheric extension and asthenosphere upwelling.

关 键 词：辉长岩-闪长岩 锆石U-PB定年 岩石地球化学 软流圈上涌 长江中下游地区 

分 类 号：P588.122[天文地球—岩石学]