湖北枣阳石英-正长岩中的环带状锆石研究

湖北省枣阳县石英-正长岩中的锆石,晶体大,粒径达10-50mm。整个晶体从中心向边缘由约600条灰白色与黑褐色相间的环带组成。物性、化学成分、X射线粉晶衍射、红外光谱、差热和阴极射线发光等测试分析结果表明,灰白色环带为遭受非晶质化的变水锆石,黑褐色环带为普通锆石。两种环带性质上的差别;主要与锆石中杂质元素UO_2和HfO_2含量的不同有关,反映了锆石晶体形成过程中杂质元素浓度的波浪式变化。

A STUDY OF ZONAL STRUCTURE ZIRCON IN QUARTZ SYENITE FROM ZAOYANG COUNTY HUBEI PROVINCE

Zircon in quartz syenite from Zaoyang County, Hubei Province, is characterized in largecrystals with zonal structure. Crystal size 10-50mm, short prism with bipyramids, length/widthratio 1.7-2.1. About 600 interbanded greyish white and black brown layerings are recognized in onecrystal. The greyish white zones are identified as metamict malacon, Hv=1018-1114 kg/mm~2,SG=4.502, unit cell parameters a_0=b_0=6.624 A, c_0=6.005 A, EDS analysis gives: SiO_2 33.15-33.52%, ZrO_2 61.31-62.57%, HfO_2 2.13-2.57%, UO_2 0.76-1.59%. FeO 0.37-1.04%, CaO 0.20-1.02%.The black brown zones consist of ordinary zircon. Hv=1353-1504 kg/mm~2. SG=4.626, unitcell parameters a_0=b_0=6.608 A. c_0=5.985 A. Major chemical composition is SiO_2 33.34-34.74%ZrO_2 62.27-64.14%, HfO_2 2.04-2.62%. UO_2 0.00-0.06%, FeO 0.27-0.44%, CaO 0.00-0.08%.Difference in properties of the two zones mainly relates to their different contents of UO_2 andHfO_2.