玲珑-焦家式金矿床流体包裹体的稀土和微量元素特征

Xu JH,Xie YL,Liu JM,Zhu HP and Jia CS.2005.Trace elements in fluid inclusions of Linglong-Jiaojia type gold deposits.

应用热爆提取和 ICP-MS 方法,研究了玲珑-焦家式金矿床脉石英和绢英岩中流体包裹体的微量元素特征。结果表明,流体包裹体中 REE 配分模式均表现为 LREE 富集型,轻、重稀土具有较好的分馏,LREE/HREE=6.07～26.41。但轻重稀土内部分异不明显,(La/Sm)、=2.15～5.11,(Gd/Lu)=0.72～5.24。成矿流体具有弱的 Eu 正异常,δEu=1.05～7.09,与中高温、弱酸性的现代地热成矿系统相似。流体包裹体/中国陆壳元素丰度标准化后表明,流体中富集的重金属元素有 Cu、Mo、Pb、Bi 等,它们的富集系数大于1。成矿流体中亏损的元素有 Ti、V、Cr、Co、Li、Zr、Nb、Th、U 等。流体包裹体微量元素、稀土元素特征为金矿床的成因研究增添了新的证据。玲珑-焦家式金矿床的流体包裹体具相似的 REE 特征,而与其它地区的金矿床或其它类型的矿床则明显不同,说明该区金矿床成矿地球动力学背景相同,都与中生代燕山期构造体制转折条下热液活动有关。

Trace elements in fluid inclusions in vein quartz and sericite-quartzite of Linglong, Jiaojia and Sanshandao gold deposits have been studied by using heating-decrepitation and ICP-MS method. The results show that REE patterns of fluid inclusions appear as LREE-rich type, with better fractionation of lighter and heavy REEs and LREE/HREE = 6.07 ～ 26.41. However, the fractionation within lighter and heavy REEs is not clear, with （La/Sm）N = 2.15～5.11 and （Gd/Lu）N = 0.72～5.24. Ore-forming fluids have weak positive Eu abnormity, with δEu = 1.05～7.09, which is in agreement with acid and hydrothermal solutions of present submarine system. Normalized data of fluid inclusions/element abundance of China Continent Crust show that heavy metal elements, such as Cu, Mo, Pb, Bi, are rich in fluid inclusions, with enrichment coefficient large than 1 , while Ti, V, Cr, Co, Li, Zr, Nb, Th and U and depletion elements in fluids. Fluid inclusions in various gold deposits of Jiaojia-Linglong Type have similar REE characteristics, but are differ from gold deposits of other areas. It is indicated again that gold deposits in Jiaodong Peninsula emplaced in the similar geological settings and were related with hydrothermal solutions in Mesozoic tectonic inversion.