苏鲁造山带荣成超高压地体片麻岩锆石年龄和铪同位素组成特征

被引:25
作者
李向辉 [1 ]
陈福坤 [1 ]
李潮峰 [2 ]
张华锋 [3 ]
郭敬辉 [1 ]
杨岳衡 [1 ]
机构
[1] 中国科学院地质与地球物理研究所岩石圈演化国家重点实验室
[2] 中国科学院研究生院地球科学学院
[3] 中国地质大学地质过程与矿产资源国家重点实验室
关键词
苏鲁造山带; 片麻岩; 晚元古代; 锆石年龄; Nd-Hf同位素; 荣成;
D O I
暂无
中图分类号
P588.345 []; P597 [同位素地质学与地质年代学];
学科分类号
070901 ; 070902 ;
摘要
本文对苏鲁造山带内荣成超高压地体片麻岩样品进行了锆石U-Pb年龄、Hf同位素和全岩Nd同位素分析,旨于探讨片麻岩的原岩性质及成因。3个片麻岩样品的锆石SHRIMP U-Pb年龄(770Ma和710Ma之间)表明原岩形成于晚元古代,与Rodinia超大陆裂解过程的岩浆活动时间相吻合。14个片麻岩的单阶段钕模式年龄变化在1.70Ga至2.30Ga(平均~1.93Ga),表明荣成超高压地体片麻岩平均地壳存留时间为古元古代,与扬子陆块的平均地壳形成年龄相一致,暗示具有扬子陆块属性。其锆石εHf(t)值(t=750Ma)和模式年龄值变化范围大。2个片麻岩的锆石具有非常负的εHf(t),平均值为-16.4,铪模式年龄为2.70Ga。6个片麻岩的锆石εHf(t)平均值为-7.7,铪模式年龄为2.15Ga。这些结果表明荣成超高压地体部分原岩主要由太古代-古元古代地壳物质在晚元古代时重熔形成的,进一步说明荣成地区可能有扬子陆块的太古代地壳残留。另有6个片麻岩的锆石εHf(t)变化范围为-0.56至6.6之间,其中部分锆石的两阶段Hf模式年龄为0.81Ga至0.94Ga,表明片麻岩原岩晚元古代形成时,有幔源岩浆活动和新生地壳形成,可能同时存在强烈壳-幔相互作用,上侵的幔源岩浆底侵导致上覆扬子陆块太古代-古元古代地壳物质重熔,形成花岗质岩浆。
引用
收藏
页码:351 / 368
页数:18
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