CCSD主孔金红石与石榴子石中锆石包裹体的Hf元素地球化学特征

Hf Geochemistry of Zircon Inclusions in Rutile and Garnet from the CCSD

本文样品是采自中国大陆科学钻探(CCSD)主孔的含金红石榴辉岩,在这些样品中常常含有锆石副矿物,锆石可以呈粒间矿物存在,也可以包裹在其他矿物(如石榴子石、金红石)中。背散射电子图像(BSE)显示这些锆石包裹体的亮度较弱,颗粒较小(约10~30μm),发育多晶面,晶体内部结构和成分均匀。采用能谱分析(EDS)方法来测量锆石的元素成分含量,结果表明:1这些锆石具有很高的Hf含量,金红石中达到1.51%~2.45%,石榴子石中为1.77%~2.13%;2Zr/Hf值约为35.92,比一般的基性原岩中的锆石的Zr/Hf值明显要低,这些特征说明它们很可能是形成在超高压条件下的变质锆石。

Except zircons as intergranular grains, zircon inclusions (~10~30 μm) were also found in rutiles as well as garnets in rutile-bearing eclogites recovered from the CCSD main borehole. Backscattered electron (BSE) imaging of such zircons show that they have multi-faceted shape, homogeneous internal structure and weak BSE luminescence. Hf concentrations in these zircons was measured by Energy dispersive spectroscopy (EDS) technique. These data show that these zircons inclusions have (1) relatively high Hf conc...