桂林鸡血玉地球化学特征与成因*

以龙胜上朗和平野的桂林鸡血玉样品为研究对象，测试分析了样品的主量元素和稀土元素。结果表明，桂林鸡血玉中SiO2含量高达85.34%~98.10%，平均93.59%；TFe2O3的含量相对富集，w(Al)/w(Al+Fe+Mn)平均为0.19，大部分样品均落在Al Fe Mn三角判别图的富Fe端，表现出热水沉积的特点。稀土元素总量极低，δCe为0.90~1.12，平均为1.02，无明显异常，δEu平均值为1.96，明显的正异常，(La/Ce)N平均为1.0，与典型热水沉积岩石的稀土元素特征存在一定差异，但表明桂林鸡血玉的形成与热水沉积关系密切，受热液活动影响大。

Geochemical Characteristics and Genesis of Guilin Chicken Blood Jade

The major elements and rare earth elements of Guilin Chicken Blood Jade(GCBJ) from Shanglang and Pingye were tested and analyzed.The results showed that the SiO2 content of GCBJ is 8534%~98.10%,with an average of 93.59%.The content of TFe2O3 is relatively enriched,and the average w（Al）/w(Al+Fe+Mn) ratio is 0.19.Most of the samples fall on the Fe rich end of Al Fe Mn Triangle diagram,showing the characteristics of hydrothermal sedimentary rocks.The content of REE in GCBJ is very low,δCe is 0.90~1.12,the average is 1.02,there is no obvious anomaly,the average value of δEu is 1.96,obviously positive anomaly,(La/Ce)N is 1.0 on average,which is different from the characteristics of rare earth elements in typical hydrothermal sedimentary rocks,but it shows that the formation of GCBJ is closely related to hydrothermal deposition,and is greatly influenced by hydrothermal activity.