华东南晚白垩世陆相断陷盆地以发育红色粗碎屑岩为特征.通过对赣杭构造带西段的江西抚崇盆地上白垩统河口组19个砾岩露头测点的砾组分析,对河口组砾岩的砾性、粒度、砾态和砾向等进行了详细研究.总体上砾石成分复杂,分选性较差,磨圆程度中等,呈次棱角-次圆状,风化程度较低.结合红盆周边基岩地层特点,对红盆不同区域砾岩的物质来源、成因和形成条件等进行分析和讨论.研究结果表明,河口组砾岩为晚白垩世半干旱-干旱气候条件下的一套冲积扇和辫状河相粗碎屑沉积,具有多物源和快速堆积的特点.盆地不同地区砾石成分组合特征具有明显差别,反映了盆地周围复杂的物源供应条件.根据盆地基岩地层岩性特点和扁平状砾石倾向玫瑰花图,认为河口组沉积时期,红盆碎屑沉积物主要来自盆地的北东、北、北西和南东部.%Continental basins of the Late Cretaceous in southeast China are characterized by red coarse terrestrial clastic rocks.Fabric analysis of gravels was carried out at 19 outcrops of the Upper Cretaceous Hekou Formation of Fuzhou-Chongren basin in western Gan-Hang tectonic belt,and the composition,particle size,shape and preferred orientations of gravels were also studied in detail.As a whole,the gravel deposits are featured by complex composition,poor sorting,subangular to subrounded particles and low degree of weathering.Combined with lithologic features of bedrocks,the source,genesis and formation conditions of gravels at different areas are analyzed and discussed.The research result shows that the gravels of the Late Cretaceous Hekou Formation were the products of alluvial fan and braided river facies in a semiarid to arid climate condition with multi-source and rapid accumulation.The composition assemblages of gravels from different areas of the basin are obviously different,reflecting complex provenance condition around the basin.Based on the characteristics of bedrock strata and the rose diagrams of the maximum fiat planes (ab-planes) of gravels,the sediment source was inferred to come mainly from northeastern,northern,northwestern and southeastern parts of the basin during the sedimentation period of Hekou Formation.
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