Rare earth element tetrad effect and negative Ce anomalies of the granite porphyries in southern Qiangtang Terrane, central Tibet: New insights into the genesis of highly evolved granites
Rare earth element tetrad effect and negative Ce anomalies of the granite porphyries in southern Qiangtang Terrane, central Tibet: New insights into the genesis of highly evolved granites
复制标题
藏中羌塘地体南缘花岗斑岩稀土元素四分体效应与Ce负异常：对高度演化花岗岩成因的新认识
DOI：
10.1016/j.lithos.2018.04.018
复制
发表时间：
2018-07
期刊：
影响因子：
3.5
通讯作者：
Zhao Zhen-Hua
中科院分区：
文献类型：
--
作者：
Yang Zong-Yong;Wang Qiang;Zhang Chunfu;Dan Wei;Zhang Xiu-Zheng;Qi Yue;Xia Xiao-Ping;Zhao Zhen-Hua
高度演化的花岗岩在地球化学上与成熟大陆地壳相似，有时与W-Sn-Nb-Ta和稀有金属矿化有关。这些岩石对追踪陆壳成分演化和岩浆成矿作用具有重要意义。本文报道了西藏藏中羌塘地体南部下别错地区的高SiO2花岗斑岩，为深入研究高演化花岗岩的成因提供了新的认识。锆石定年结果表明，它们形成于早白垩世晚期（107 ± 1 Ma）。它们主要由正长石、钠长石和石英组成，副矿物包括锆石、萤石和铁钛氧化物。地球化学特征为高SiO2，低MgO、Fe 2 O3 T、CaO、P2 O 5，富Rb，贫Ba、Sr、Eu、Ti，与高演化花岗岩相似。它们具有明显的稀土元素四分体效应和Ce负异常。它们的εNd（t）值（-0.99至-0.36）也略高于邻近早期花岗岩的εNd（t）值（-2.05至-3.01），以及相对较高且可变的锆石εHf（t）值，范围为-0.3至+5.4。通过与典型的高演化花岗岩和岩石学实验资料的对比，我们认为下别错花岗斑岩是由分离结晶作用产生的高演化熔体。分馏熔体与富F流体的相互作用对稀土元素四分体效应的形成起着重要作用。经过硫化物化学风化作用的变质沉积岩侵入源区是造成Ce负异常的主要原因。这表明，除了分离结晶作用外，熔体-流体相互作用和源区物质的部分熔融作用在高演化花岗岩的形成中也起着重要作用。
Highly evolved granites are geochemically similar to the mature continental crust, and are sometimes associated with W-Sn-Nb-Ta and rare-metal mineralizations. These rocks have important implications for tracing the compositional evolution of continental crust and magma metallogenesis. They were commonly considered to have been produced by partial melting of crustal materials or by high-degree fractional crystallization.In this study, we report on high SiO2granite porphyries in the Xiabie Co area of southern Qiangtang Terrane, central Tibet, which provide new insights into the petrogenesis of the highly evolved granites. Zircon dating results indicate that they were generated in the late Early Cretaceous (107 ± 1 Ma). They consist mainly of orthoclase, albite, and quartz, with accessory minerals including zircon, fluorite, and Fe-Ti oxides. Geochemically, they have high SiO2but low MgO, Fe2O3T, CaO, and P2O5, and are enriched in Rb but depleted in Ba, Sr, Eu, and Ti, similar to highly evolved granitic rocks. They are characterized by distinct rare earth element (REE) tetrad effects and negative Ce anomalies. They also have slightly higher εNd(t) values (−0.99 to −0.36) than those of the adjacent early granites (−2.05 to −3.01), and relatively high and variable zircon εHf(t) values ranging from −0.3 to +5.4. Compared to typical highly evolved granites and petrological experiment data, we suggest that the Xiabie Co granite porphyries represent highly evolved melts produced by fractional crystallization. The interaction between fractionated melts and F-rich aqueous fluids played an important role in the genesis of their REE tetrads effect. Involvement of meta-sedimentary rocks that went through surficial chemical weathering into their source region is the predominant reason for the generation of negative Ce anomalies. This indicates that, in addition to fractional crystallization, the melt-fluid interactions and partial melting of source materials also play important roles in the generation of highly evolved granites.
登录
查看更多内容
影响因子：
5
作者：
Hoskin, PWO
通讯作者：
Hoskin, PWO
影响因子：
3.1
作者：
Calvin G. Barnes;N. Coint;A. Yoshinobu
通讯作者：
Calvin G. Barnes;N. Coint;A. Yoshinobu
影响因子：
3.5
作者：
Quach Duc-Tin;H. Keppler
通讯作者：
Quach Duc-Tin;H. Keppler
影响因子：
3
作者：
L. Gu;Zun-zhong Zhang;Chang‐Zhi Wu;Xiaochen Gou;Jingjuan Liao;Hao Yang
通讯作者：
L. Gu;Zun-zhong Zhang;Chang‐Zhi Wu;Xiaochen Gou;Jingjuan Liao;Hao Yang
玄武质岩浆底侵与大陆弧地壳生长：来自西藏中部羌塘南部晚中生代中长英质侵入岩的证据
影响因子：
3.5
作者：
Fu-Yuan Wu;Jin-Hui Yang;Xiao-Ping Long;Jie Li
通讯作者：
Jie Li