湘东南—赣西地区加里东期沉积演化特征

Characteristics of Sedimentary Evolution in the Southeastern Hunan—Western Jiangxi Region in Caledonian Stage

通过对研究区加里东期沉积物的野外地质调查、剖面横向对比和岩相古地理编图,发现研究区加里东期主要发育五种沉积相类型,分别为碳酸盐岩陆棚相、碎屑岩—碳酸盐岩混积陆棚相、冰海相、欠补偿型硅质岩—页岩盆地相和补偿型浊积岩盆地相。剖面横向对比显示,研究区加里东期沉积物由西向东为连续相变沉积,横向上各种沉积相指状交叉、相互过渡;岩相古地理研究表明,加里东期湘东南—赣西地区主要发育硅质岩—页岩盆地相和浊积岩盆地相两大相带,从南华纪—奥陶纪时期两大相带的发育规模略有差异,在两大相带的结合部往往发育两种沉积相的交叉过渡带。笔者认为该区沉积相的过渡性质对探讨华南洋加里东期属性的问题有重要意义。

Based on the geological surveys of Caledonian sediments,comparison of horizontal profiles and palaeogeographical mapping in southeastern Hunan and western Jiangxi area,five types of sedimentary facies were found in the study region,which were carbonate shelf facies,mixed continental shelf facies,glaciomarine facies,undercompensation silicalite—shale basin facies and turbidite basin facies.The comparison of horizontal profiles showed that in study region,the Caledonian sediments were normal continuous sedimentary sequence from west to east,while horizontally,a variety of facies were crossed and mutually transitional.Lithofacies study showed that two facies belts were mainly developed in southeastern Hunan and western Jiangxi.They were silicalite—shale basin facies and turbidite basin facies.There were slightly differences in development scale between the two facies belts.A crossed transitional belt was often developed in the connecting part of the two facies belts.We believe that the sedimentary facies is transitional in this area,which will play an important role in discussing the attribution of south-China sea in Caledonian period.