青海囊谦古近纪盆地沉积特征及沉积环境分析

囊谦盆地是在藏东北段沿金沙江-红河构造带分布着一系列呈NNW向展布的中小型古近纪盆地的典型代表.通过野外地质调查、分析测试和室内综合研究,在盆地演化的格架内,系统分析了囊谦盆地贡觉组古气候、沉积相标志、物源以及沉积环境等方面的特征,认为贡觉组可划分为三段式结构,沉积环境为冲积扇-河流-湖泊-三角洲环境;砾石成分较复杂,...

Sedimentary characteristics and environment of Nangqian Paleogene basin in Qinghai Province

Nangqian basin is the typical representative of the medium-mini-type paleogene basins controlled by the local north-northwest-treading faults and distributing along Jinsha-Red River belt in the northeastern margin of Qinghai-Tibet. Combined with results of field geological investigation, and analysis and determination of samples, as well as the indoor comprehensive study, the paleoclimate characteristics, indications of sedimentary facies, the provenance as well as depositional environment of Gonjo group in Nangqian basin are systematically analyzed in the framework of the basin evolution. Authors conclude that the Gonjo group can be divided into the three-stage structure, and the depositional environment is the alluvial fan - river - lake - delta environment; the complex conglomerate gravel composition, the poorly sorted and rounded sandstone, and the fillings being the sub-angular shaped inequigranular grit , the calcite cement or the ferruginous cement indicate that the sedimentary environment is proximal and quickly accumulated, and the paleocurrent direction is versatile; the depositional environments belong to warm and moist-dry climate with strong evaporation.