【作者】 吴荣新； 郑永飞； 吴元保；

【Author】 WU Rongxin ZHENG Yongfei WU Yuanbao CAS Key Laboratory of Crust-Mantle Materials and Environments,School of Earth and Space Sciences,University of Science and Technology of China,Heft,Anhui,230026

【机构】 中国科学院壳幔物质与环境重点实验室中国科学技术大学地球和空间科学学院；

【摘要】 对皖南蛇绿岩套辉长岩分别进行锆石微区U-Pb 定年、全岩主微量元素分析和Sr-Nd 同位素分析、矿物氧同位素分析。结果表明,皖南蛇绿岩存在3个时代的岩浆锆石,对应的U-Pb 年龄分别为891±13 Ma、826±4 Ma 和764±10 Ma。元素和Sr-Nd 同位素地球化学特征显示出明显的岛弧岩浆岩特征,表明辉长岩来源于俯冲带上覆地幔楔的部分熔融。矿物氧同位素分析表明,辉长岩遭受了亚固相高温热液蚀变。笔者解释辉长岩构造就位年龄为891±13 Ma,在826±4 Ma 受到前裂谷期岩浆活动的改造,并在764±10 Ma 受到同裂谷岩浆活动的影响而发生亚固相热液蚀变。更多还原

【Abstract】 Zircon U-Pb dating,whole-rock major and trace elements,Sr-Nd isotopes,and mineral O isotopes were determined forsamples from ophiolites in south Anhui.LA-ICPMS and SHRIMP zircon U-Pb analysis reveals three age phases of magmatic zirconsformed at 891±13 Ma,826±4 Ma and 764±10 Ma respectively.The features of dements and isotopes display apparent signaturesof island-arc magmatic rocks,suggesting that they were derived from partial melting of mantle lithosphere of the supra-subductionzone(SSZ).O isotope analyses suggest that they experienced different degrees of subsolidus hydrothermal air eration.Based on ele-ment and isotope analyses in combination with the records of Neoproterozoic magmatism in this area,the authors interpret 891±13Ma as the age of ophiolite emplacement.It is also thought that at 826±4 Ma the rocks were rebuilt by pre-rift magrnatic activities,and at 764±10 Ma they were affected by syn-rift magmatism and subsolidus hydrothermal alteration.更多还原