安徽铜陵新屋里岩体黑云母、斜长石^(40)Ar-^(39)Ar年龄及其地质意义  

^(40)Ar-^(39)Ar Plateau Ages of Biotite and Plagioclase from Xinwuli Granitoids in Tongling Area,Anhui Province and its Geological Significance

作　　者：王永磊[1,2] 裴荣富[1,2] 王浩琳[1] 瞿泓滢[1,2] 李进文[1] 

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点开放实验室,北京100037 [2]内生金属矿床成矿机制研究国家重点实验室(南京大学),南京210093

出　　处：《高校地质学报》2012年第1期150-157,共8页Geological Journal of China Universities

基　　金：南京大学内生金属矿床成矿机制研究国家重点实验室基金项目“长江中下游酸性侵入岩体的冷速率、热效应与其成矿强度的示范研究”(15-09-01);中国地质调查局危机矿山项目“铜陵市凤凰山铜矿深部岩石地球化学找矿预测”(200799093);中央级公益性科研院所基本科研业务费专项资金资助项目(K0907);深部探测项目(Sinoprobe-03-01)共同资助

摘　　要：通过对凤凰山铜矿床新屋里岩体的黑云母、斜长石单矿物进行阶段加热法40Ar-39Ar定年,获得石英二长闪长岩中黑云母及斜长石坪年龄分别为(152.1±1.7)Ma和(135±1)Ma,花岗闪长岩中黑云母及斜长石坪年龄分别为(143.8±0.9)Ma和(140.4±0.9)Ma,反映了长江中下游地区燕山期岩浆活动的一个重要阶段。石英二长闪长岩中黑云母的40Ar-39Ar年龄显著高于前人的锆石U-Pb年龄,可能为含过剩Ar的结果。结合已知年龄资料,作出新屋里岩体不同单元的冷却曲线,显示新屋里岩体在晚侏罗世的冷却速率很大,暗示当时处于一种伸展的构造背景之下,其形成可能与中国东部中生代晚期的岩石圈减薄事件有关。Biotite and plagioclase samples from the quartz monzodiorite of Xinwuli granitoids yield 40 Ar-39 Ar plateau ages of 152.1±1.7 and 135±1 Ma.Samples from the granodiorite give 40 Ar-39 Ar plateau ages of 143.8±0.9 Ma and 140.4±0.9 Ma.The similar ages suggest an important stage of Yanshanian magmatic activity in the Middle and Lower Yangtze regions.The 40 Ar-39 Ar age of biotite from quartz monzodiorite is older than the previous zircon U-Pb isotopic ages,which is probably due to excess argon.Together with the age data of Xinwuli granitoids,we obtain the cooling curves of the granodiorite and quartz monzodiorite.The cooling curves show that the cooling rates of Xinwuli granitoids have been fast since the Late Jurassic,indicating an extensional tectonism.The formation of Xinwuli granitoids may be related to the Late Mesozoic lithosphere thinning in Eastern China.

关 键 词：新屋里岩体 40AR-39AR 冷却曲线 安徽铜陵 凤凰山铜矿床 

分 类 号：P597.1[天文地球—地球化学]