【摘要】 研究四川盆地北部柳湾乡震旦系灯影组第三段(简称“灯三段”)沉积特征及其演化模式。综合剖面详测、薄片组分鉴定及样品地化数据分析等，对灯三段混积岩的成因及特征进行研究，最终确立灯三段古环境沉积模式。灯二段与灯三段之间呈假整合接触，灯三段下亚段(18.98 m)为混积潮坪相的石英砂岩-泥晶白云岩的混积岩层，上亚段(30.1 m)为潟湖相的泥岩-粉砂岩层。Sr/Ba、V/Ni、U/Th、V/Cr与V/(V+Ni)质量分数比值等痕量元素参数表明灯三段沉积时期主体是滨海相微咸水、弱氧化-弱还原环境，其中部分白云岩段是氧化环境。灯三段沉积初期受桐湾运动Ⅰ幕的影响，海水动荡导致陆源碎屑物与碳酸盐岩相互影响，产生混积岩层；后期海平面下降，沉积碎屑岩。灯三段碎屑物质来源与古地貌指示桐湾运动Ⅰ幕时期汉南古陆发生隆升并伴随海平面的下降，为盆地内提供陆源碎屑物从而形成混积层序。更多还原

【Abstract】 Through detailed section survey, thin section component identification and sample geochemical data analysis, the genesis and characteristics of the third member of the Sinian Dengying Formation mixed rock in Liuwanxiang area, northern Sichuan are studied, and its sedimentary characteristics, evolution model and paleoenvironmental sedimentary model are discussed. The results show that there is a disconformable contact between the second member and the third member of the Dengying Formation. The lower submember(18.98 m) of the third member of the Dengying Formation is a mixed layer of quartz sand-micrite dolomite of tidal flat facies, and the upper submember(30.1 m) is a mudstone-siltstone of lagoon facies. Trace element parameters such as Sr/Ba, V/Ni, U/Th, V/Cr and V/(V+Ni) mass fraction ratio show that the main part of the third member of the Dengying Formation is briny water of coastal facies, weak oxidization-weak reduction environment, and some of the dolomite belongs to oxidized environment. In the early sedimentary stage of the third member of the Dengying Formation, terrigenous detritus and carbonate rocks interacted with each other due to the sea water turbulence in the first stage of Tongwan Movement, resulting in the formation of mixed rocks. In the later stage, the sea level dropped steadily and the clastic rocks were deposited. The source of detrital material and the reduction of palaeogeomorphology in the third member of the Dengying Formation indicate that the uplift of Hannan ancient land accompanied with the decrease of sea level during the first episode of Tongwan Movement, which provided terrigenous detrital material for the basin deposition and formed the mixed sedimentary sequence.更多还原