宁镇地区燕山期侵入岩锆石U-Pb定年:长江中下游新一期成岩成矿作用的年代学证据  

Zircon U-Pb dating of Yanshanian intrusive rocks in Ningzhen District,Jiangsu:The chronology evidence for a new stage of petrogensis and metallogeny in the Middle and Lower Reaches of Yangtze River

作　　者：王小龙[1] 曾键年[1] 马昌前[2] 李小芬[1] 吴亚飞[1] 陆顺富[1] 

机构地区：[1]中国地质大学(武汉)资源学院,湖北武汉430074 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074

出　　处：《地学前缘》2014年第6期289-301,共13页Earth Science Frontiers

基　　金：国家自然科学基金重点项目(40334037);科学技术部国际科技合作项目(2007DFA21230);中国地质调查局资源评价项目(1212010781014;12120114038101);中国地质大学地质过程与矿产资源国家重点实验室基金课题(MGMR2001-1)

摘　　要：对宁镇地区3个典型燕山期岩体(安基山-伏牛山岩体、下蜀-高资岩体和石马岩体)的中酸性侵入岩进行LA-ICP MS锆石U-Pb定年,给出(109.1±1.9)^(101.6±1.1)Ma的年龄值,代表了这些侵入岩体的形成年代,为该地区中酸性侵入岩形成时代提供了精确的约束。宁镇地区铜-多金属成矿作用在时间、空间和成因上与100~110Ma左右的中酸性钙碱性岩浆活动相关联,区内成岩成矿作用是一个连续的过程。宁镇地区燕山期中酸性侵入岩形成于早白垩世晚期,而长江中下游九瑞等地区的同类型侵入岩形成于早白垩世早期,二者相差约25~35Ma;结合白垩纪以来太平洋板块活动特征对中国东部陆区成岩成矿的制约,这些年代学数据揭示出宁镇地区燕山期岩浆活动及其成矿响应是中生代长江中下游成矿带大规模岩浆-成矿活动的新一期成岩成矿事件,深部地球动力学背景对应中国东部中生代岩石圈拆沉-减薄事件。长江中下游地区的岩石圈减薄从135Ma左右开始,可能持续到100Ma左右。The LA-ICP MS zircon U-Pb dating for three typical Mesozoic intrusions（Anjishan-Funiushan rockmass,Xiashu-Gaozi rock-mass and Shima rock-mass）in Ningzhen district yielded 109.1±1.9-101.6±1.1 Ma,which represents the formation of these intrusions age and provides a precise formation time constraints for the intrusive rocks in the region.Copper polymetallic mineralization in Ningzhen district was related to the calcium alkaline magma activity around 100-110 Ma in time,space and genesis,and both magmatism and mineralization in the area were continuous processes.Yanshanian intrusive rocks in Ningzhen district formed during the Early Cretaceous,while the calc-alkaline intrusive rocks in Jiurui region and other regions formed in the Early Cretaceous;there are a difference of about 25-35 Ma between both.Combined with the restrict from the Pacific plate activity characteristics since the Cretaceous to the petrogensis and metallogeny in the eastern China,the chronology data reveals that the magmatic activities in Yanshanian and metallogenetic response in Ningzhen region were the new diagenesis-mineralization events belonging to the large-scale magmatic and metallogenic activities of the metallogenic belt in the middle and lower reaches of Yangtze River in the Mesozoic Era,as well as the geodynamic setting corresponds to the Mesozoic Era lithospheric thinning in eastern China.Lithospheric thinning of middle and the middle and lower reaches of Yangtze River started from 135 Ma,and might continue until around 100 Ma.

关 键 词：宁镇地区 燕山期侵入岩 锆石U-PB定年 长江中下游成矿带 成岩成矿作用 

分 类 号：P588.12[天文地球—岩石学] P597.3[天文地球—地质学]