福建碧田Au-Ag-Cu矿床含金石英脉中磷灰石的阴极发光研究

碧田Au Ag Cu矿床含金石英脉中的磷灰石在阴极射线激发下发明亮的黄绿色光 ,特征峰波长为 5 70～5 80nm。阴极发光 (CL)图像揭示了磷灰石的内部环带结构 ,不同环带微量和稀土元素含量具有明显的差异。发光带w(MnO) >0 .4%、n(Mn) /n(Fe) >2、n(Mn) /n(La+Ce) >4;Mn2 + 为CL的主要激发元素。磷灰石晶体结构中以LREE3 + +Si4+ =Ca2 + +P5+ 为主要的元素替代形式。磷灰石微量与稀土元素的分布特征表明 ,该矿床形成于近地表的低温热液体系 ,成矿流体在矿物共沉淀的晚期向富Si、Na方向演化。

CATHODOLUMINSCENCE STUDY OF APATITE IN GOLD-BEARING QUARTZ VEIN FROM BITAN Au-Ag-Cu DEPOSIT

Apatite crystals in gold-bearing quartz vein from the Bitan Au-Ag-Cu deposit, Fujian Province, display bright yellowish-green luminescence with the characteristic emission bands at 570-580 nm. Cathodoluminescence ( CL ) imaging revealed the concentric growth zoning of apatite crystals with variations in color and luminescence intensity, which is not detectable under petrographic microscope. The concentrations of trace elements and REE are evidenced by significant changes in different zones of individual apatite crystal. Because the bright yellowish-greenzones are rich in MnO(> 0.4 wt.%) with Mn/Fe ratios being larger than 2 and Mn/La+Ce ratios larger than 4, respectively. Mn 2+ is suggested to bethe principal activator for CL in apatite. The cation substitution in apatite is dominated by REE 3+ + Si 4+ = Ca 2+ + P 5+ . The distribution patterns of trace elements and REE in apatite crystals of this case have proved that the Bitan deposit originated from the epithermal system, and it is indicated that the late ore-forming solutions are enriched in Si and Na.