胶东海阳所斜长角闪岩的锆石U－Pb年龄──多期变质作用对锆石不一致线年龄影响的实例  

U-P6 ZIRCON AGES OF AMPHIBOLITE FROM THE HAIYANGSUO AREA,EASTERN SHANDONG PROVINCE──AN EXAMPLE FOR INFLUENCE OF MULTIMETAMORPHISM TO LOWER AND UPPER INTERCEPTS OF ZIRCON DISCORDIA LINE AT THE CONCORDIA CURVE

作　　者：李曙光[1] 陈移之 宋明春[1] 张志敏 杨淳[1] 赵敦敏[1] 

机构地区：[1]中国科学技术大学地球与空间科学系,山东省地质矿产局区域地质调查队,中国地质科学院地质研究所

出　　处：《地球学报》1994年第Z1期37-42,共6页Acta Geoscientica Sinica

基　　金：国家自然科学基金

摘　　要：胶东海阳所胶南群斜长角闪岩中的锆石有２类：（１）捕掳晶锆石，它给出２１４９Ｍａ的￣（２０７）Ｐｂ／￣（２０６）Ｐｂ年龄，证明该区存在有早元古基底；（２）岩浆结晶锆石，它的不一致线上下交点年龄分别为１７８４±１１Ｍａ和４４８±１３Ｍａ。然而该锆石在晋宁期和印支期曾发生２次铅丢失事件，从而使其下文点年龄（４４８±１３Ｍａ）无地质意义．其上交点年龄指示了该锆石的最小结晶时代，它表明在１８亿年时该地区曾有一次玄武质火山岩事件。There are two kind of zircons in amphibolite from the Haiyangsuo area, eastern ShandongProvince:(1)Xenocrysts,they give ￣(207) Pb/￣(206)Pb age of 2149 Ma,which suggests an early proterozoicbasement in this area;(2)Magmatic euhedral zircons,they give an upper intercept age of 1784±11Ma and lower intercept age of 448±13 Ma.The lower intercept age of 448±13 Ma could be resultfrom two lead loss events during the Jinning(700-1000Ma)and Indosinian(190-245Ma)move-ments and have no geological significance.The upper intercept age indicats a low limit of crystal age ofthe zircons and suggests a basaltic volcanic event at 1.8 Ga ago in this area.

关 键 词：锆石U-PB定年 斜长角闪岩 胶东海阳所 

分 类 号：P5[天文地球—地质学]