中国地质2013，Vol.40Issue(1)：191-216,26.
湘中地区冷家溪群和板溪群锆石U-Pb年龄、Hf同位素特征及对华南新元古代构造演化的意义
Zircon U-Pb age and Hf isotope compositions of Lengjiaxi and Baxi Groups in middle Hunan Province: implications for the Neoproterozoic tectonic evolution in South China
摘要
Abstract
Zircon LA -ICPMS U -Pb ages and Hf isotope compositions of the tuff and clastic rocks from Lengjiaxi Group and Banxi Group in the middle section of the Jiangnan orogenic belt were determined. The results reveal that the sedimentary time of the Lengjiaxi Group is 860-820Ma. On the other hand, the lower limit of sedimentation of the Banxi Group which overlies the Lengjiaxi Group in angular unconformity is ca.820Ma, suggesting the quick transformation from the assemblage between Cathysia and Yangtze to the extension of the Jiangnan orogenic belt. Zircon Hf isotope compositions exhibit a rapid increase of the initial Hf values during 850 -820 Ma, indicating significant addition of the depleted mantle materials during this period. The quick increase of εHf (t) could be ascribed to the following factors: (1) most clastic materials were derived from arc igneous rocks (e.g., Ⅰ-type granites) and (2) some materials were derived from the mixed substances (such as tuff) between crust -derived magma and mantle -derived magma during the quick collapse after the orogeny). In combination with previous studies, the authors hold that the plate-rift model is a most plausible geodynamic model for the Neoproterozoic tectonic evolution of South China.关键词
江南造山带/冷家溪群/板溪群/锆石U-Pb年龄/Hf同位素/地球动力学背景Key words
Jiangnan orogenic belt/ Lengjiaxi Group/ Banxi Group/ zircon U-Pb dating /Hf isotope/ geodynamic settings分类
天文与地球科学引用本文复制引用
孟庆秀,张健,耿建珍,张传林,黄文成..湘中地区冷家溪群和板溪群锆石U-Pb年龄、Hf同位素特征及对华南新元古代构造演化的意义[J].中国地质,2013,40(1):191-216,26.基金项目
中国地质调查局地质调查项目(1212011121097,1212011120130)资助. （1212011121097,1212011120130）
