粤桂边境煌斑岩地球化学特征及其地质意义

通过对粤桂边境贵金属矿床紧密相关的云煌岩进行地球化学分析，结果显示N-MORB标准化的微量元素蛛网图表现为相对富集Rb、Ce和Sm及亏损Ta和Sr。煌斑岩的稀土总量为（82.33~215.30）×10^-6，平均值为143.20×10^-6，是原始地幔的20倍。轻稀土含量为（75.01~199.01）×10^-6，重稀土含量为（7.31~16.29）×10^-6，轻重稀土含量比值为9.26~12.22、平均为10.90。经球粒陨石标准化，煌斑岩的稀土配分曲线表现为右倾和极弱的Eu负异常。研究区的煌斑岩具有地幔和下地壳的双重特点，其中煌斑岩的幔源地球化学指标δZr/δNb、δTh/δLa值分别为16.02~20.01和0.14~0.20，而壳源组成特征δLa/δNb、δSm/δNd和δNb/δU值分别为2.06~3.78、0.18~0.19、5.29~22.37，这可能说明煌斑岩属于原始幔源岩浆经下地壳物质混染的产物。在研究区的贵金属成矿作用过程中，煌斑岩可能扮演了“矿化剂来源”和“能量供体”的角色。

Geochemical Characteristics and Geological Significances of Lamprophyre in the Provincial Border Areas around Guangdong and Guangxi Province

The analysis on the geochemical characteristics of the lamprophyre that is closely related with the metal deposit in the provincial border areas around Guangdong and Guangxi province，showed that Rb，Ce and Sm are relative enriched，while Ta and Sr are relatively loss，based on the N-MORB standardized spider diagram of trace elements.The ΣREE values of lamprophyre are（82.33~215.30)×10^-6，and its average values are 143.20 × 10^-6，which is the 20 times that of the original mantle.The contents of LREE and HREE are（75.01~199.01)× 10^-6 and（7.31~16.29)× 10^-6 respectively，the LREE/HREE value between 9.26~12.22 and the average value is 10.90.The REE distribution curves showed as right deviation and extremely weak Eu anomaly，after normalized by the chondrite.The lamprophyre in research area has the characteristics of both mantle and lower crust，the values of mantle-derived geochemical indicators δZr/δNb and δTh/δLa are 16.02~20.01 and 0.14~0.20 respectively，the crust source composition include δLa/δNb，δSm/δNd and δNb/δU with the values of 2.06~3.78，0.18~0.19 and 5.29~22.37 respectively.It maybe indicate that，lamprophyre is the product of the original mantle-derived magma that is contaminated by the lower crust materials.During the process of the precious metal mineralization in research areas，lamprophyre maybe plays the roles of “mineralizer source” and “energy donor”.