【摘要】 作者在桂北资源县吴家和全州市木皮口的下寒武统清溪组剖面修测过程中，对所采集的岩石样品进行偏光显微镜观察研究，发现清溪组～Ｃ１－１ｑ、～Ｃ１－３ｑ和～Ｃ１－５ｑ中原定名为“粉砂岩”和“变余长石石英砂岩”的岩石中含有大量火山凝灰碎屑（晶屑），继而在桂北龙胜、融水和湘西南城步、武岗、新宁等地同时代的富铀黑色岩系中发现存在着２－３层厚度不等的沉凝灰岩。根据岩石的化学成分、结构特征和利用化学成分分析数据所作的各种变异图，确认这些岩石是火山作用形成的沉凝灰岩，通过成岩后的浅变质作用成为变质沉凝灰岩更多还原

【Abstract】 During the field work for profile observation of Qingxi Formation,Lower Cambrian in Wujia,Ziyuan county,northern Guangxi and Mupikou,Quanzhou City the authors discovered in the previously identified “Siltstone” and “blastic feldspar quartz sandstone” of the Qingxi Formation,Lower Cambrian ～C 1 1 q,～C 1 3 q and ～C 1 5 q,a lot of tuffaceous fragments (crystalloclastic fragments).Later 2 3 horizons of tuffite with different thickness were found in uranium rich black shale series of the same age in Longshen and Rongshui counties,norther Guangxi,in Chengbu,Wugang and Xingnin counties, Southwestern Hunan.Based on chemical composition,texture features of the rocks and various variation diagrams it is certain that these rocks are tuffite which have turned into metamorphic sedimentary tuffite after the diagenesis and epimetamorphic process.更多还原