作　　者： ; ; ; ; ; ;

机构地区： 中山大学地球环镜与地球资源研究中心

出　　处： 《矿物岩石地球化学通报》 2004年第4期292-300,共9页

摘　　要： 华南二叠系底部的硅质岩及同一层位对应于华南重要的地幔强活动期和成矿期,有非常重要的动力学指示意义。研究表明,孤峰组剖面的岩性可划分为三段:泥页岩段、厚层状硅质岩段和薄层状硅质岩段。沿剖面自下而上,Al2O3、K2O和TiO2含量逐渐降低,MnO、TFe等组分逐渐升高;稀土元素显示出一定的铈负异常,ΣREE偏低,且向上ΣREE逐渐减少而HREE LREE逐渐增高;一些热水沉积诊断性微量元素如As、Sb、Hg等也显示出一定程度的异常。这些特征均表明硅质岩的成岩过程中包含有正常沉积和热水沉积的共同作用,且自下而上热水沉积作用逐渐增强的趋势。这种成岩作用的演化特征,代表了下扬子地台拉张裂陷盆地对晚古生代伸展背景的沉积响应,对于探讨裂谷盆地阶段性发育的动力学特征有一定的指示意义。 The Gufeng chert formation widely occurs in South China during the Early Permian, which is an intensive period of the mantle activities, so that this strata contains important geodynamic information. The geological and geochemical characters reveal that the Gufeng Formation can be identified as three segments namely the black shales section, the thick-layered chert section and the thin-layered chert section.From the lower section to the upper , the concentrations of Al2O3,K2O and TiO2 display an increasing trend, but the concentrations of MnO and TFe fall down gradually.The REE distribution patterns are characterized with the low ΣREE, the negetive anomaly of Ce and Eu, and the decreasing of LREE/HREE with the samples up to the top sequence.Some trace elements including As,Sb,Hg are enriched, which are commonly associated with the hydrothermal process. All these suggest that the origins of chert are effected by both the hydrothermal process and hydrogeneous process, and that the hydrothermal process gradually play the main role in the upper section. Furthermore, the petrogenesis also suggests that the Gufeng layered chert formation correspond to the extensional backgroud in Late Paleozoic, and that it is a good indicator to study the geodynamic evolution in South China.

关 键 词： 硅质岩 指示意义 二叠系 热水沉积 地球动力学 孤峰组 诊断 中南 正常

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]