【摘要】 边缘洼陷受盆缘沉降幅度小、粗碎屑物质输入多等不利因素的影响，一般难以发育优质烃源岩。然而具有适度遮挡条件的洼陷在边缘发育“沉砂池”截留粗碎屑，然后越过低凸起在主洼区卸载细粒泥质沉积物，就具备了发育优质烃源岩的潜质。为探究具备适度遮挡条件的边缘洼陷砂泥岩沉积分布规律，推动富烃洼陷形成机制理论发展，本研究利用水槽实验，按照中水—洪水—中水—枯水的供水方式模拟其沉积和充填过程。研究结果发现：（1）沉砂池和低凸起对粗碎屑沉积物具有明显的遮挡作用，可以减缓砂体推进速度，强化砂泥分异作用；（2）泥质沉积物的厚度受沉积时长及后期再改造的强度影响。沉积时间越长，泥质沉积物厚度越大；后期水流冲刷作用越强，泥质沉积物残留厚度越小；砂质沉积物可改变主洼区先期未固结泥质沉积物厚度，在主洼区内，砂质沉积物底部下伏的泥质沉积物厚度最小，前端泥质沉积物厚度最大；（3）适度遮挡有利于边缘洼陷烃源岩发育。边缘洼陷对粗碎屑物质供给敏感，易过补偿，而适度遮挡通过分流粗碎屑物质输入有利于成烃物质的保存，保障主洼区长时间接收泥质沉积物堆积，相对安静的水体易于发育烃源岩。实验结果为边缘洼陷富烃机理提供了理论依据，并指出具备适度遮挡条件的边缘洼陷主洼区是有利烃源岩发育区。更多还原

【Abstract】 Generally, it is difficult for high-quality source rocks to develop in marginal sags due to the influence of unfavorable factors such as small subsidence and large input of coarse clastic materials. However, the sag with moderate shielding conditions has the potential for high-quality source rocks to develop through the development of ’grit chamber’ to intercept coarse debris at the edge,and then unloading fine-grained argillaceous sediments in the main depression area across the low uplift. In order to explore the sedimentary distribution of sandstone and mudstone in marginal subsags with moderate shielding conditions and promote the theoretical formation mechanism of hydrocarbon-rich subsags, this study used flume experiments to simulate the deposition and filling process according to the water supply mode of medium flow–flood–medium flow–low flow. The results show that:(1) The grit chamber and low bulge have obvious shielding effect on coarse clastic sediments, which can slow down the advancing speed of sand bodies and strengthen the differentiation of sand and mud.(2) The thickness of muddy sediments is affected by the deposition time and the intensity of reworking. The longer the deposition time, the greater the thickness of muddy sediments; the stronger the scouring effect of water flow in the later stage, the thinner the residual thickness of muddy sediments; sandy sediments can change the thickness of pre-consolidated muddy sediments in the main depression area. In the main depression area, the thickness of mud sediment is thinnest under sandy deposits and thickest at the front.(3) Moderate shielding is conducive to the development of source rocks in marginal sags. The marginal sag is sensitive to the supply of coarse clastic materials and is easy to overcompensate, while the moderate shielding is conducive to the preservation of hydrocarbon-forming materials by diverting the input of coarse clastic materials, ensuring that the main sag area receives the accumulation of argillaceous sediments for a long time, and the relatively still water body makes it easy for source rocks to develop. The experimental results provide a theoretical basis for the hydrocarbon-rich mechanism of the marginal sag, and point out that the main subsag of the marginal sag with moderate shielding conditions is a favorable area for source rock development.更多还原