Low-degree metamorphic clastic rocks of the Neoproterozoic Xiajiang Group in southeastern Guizhou Province host numerous quartz vein type gold deposits and prospects. But the origin of the deposits of this kind, especially gold source, has long been a research issue. Therefore, gold-bearing possibility and element geochemical characteristics of formation rocks in the Xiajiang Group have also received extensive concern. This paper conducted a systematic analysis of the trace elements and rare earth elements. Comparative study indicates that the Xiajiang Group is characterized by enrichment in As, Ba, Zr and Ti and depletion in Cr, Rb, Sr, Ta and Sc, and element association shows obvious similarity and inheritance from Fanzhao Formation to Pinglue Formation. In Addition, tuffaceous sequence in the Fanzhao and Pinglue formations has a high content of gold, and horizons which contain high contents of gold have a low REE content. Gold in the sequences has a close relation with crustal elements such as Ag, Hg and As. Therefore, gold migration and enrichment may have been closely related to hydrothermal activities and regional metamorphism. The trace element characteristics of country rocks, sequences and ore, and consistency and inheritance of REE compositions suggest that ore-forming material was derived mainly from sequences. Part of gold-bearing quartz veins in the Pingqiu gold deposit exhibit different geochemical features, indicating that it was more close to lower upper or upper mantle and some of the deep fluids were likely involved into mineralization.%在黔东南出露的一套新元古界下江群浅变质碎屑岩中产出众多石英脉型金矿床(点),有关该类矿床的成因问题,特别是金的物质来源一直是研究的热点,因此下江群地层岩石的含金性以及元素地球化学特征也倍受关注.本文对贵州锦屏地区新元古界下江群浅变质岩及典型矿床的微量及稀土元素进行了系统测试,通过对比分析发现:下江群剖面的每个组均富集As、Ba、Zr、Ti;亏损Cr、Rb、Sr、Ta、Sc等元素,从番召组到平略组,元素组合演化呈明显相似性和继承性.含凝灰质多的番召组和清水江组地层中金含量较高,并且含金高的层位稀土含量较低,地层中Au与壳源特征的Ag、Hg、As等低温元素关系最为密切,该区金的迁移、富集可能与地层的热液活动或区域变质作用有密切的关系.围岩、地层岩石与矿石的微量元素特征及REE组成模式体现了地球化学演化上的一致性及继承性,表明该区金矿成矿物质可能主要来自于地层,而平秋金矿部分含金石英脉矿石表现出与围岩地层不同的地球化学特征,其更接近下地壳或上地幔,说明可能有部分深部流体参与成矿.
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