The Fengcheng Formation (P₁f) source rock, which was deposited in an alkaline water body, is one of the most significant source rocks in the Mahu sag, Junggar Basin. However, its evolution and mechanism of organic matter accumulation are still not understood. Using seismic, core, and log data, P₁f is divided into 3 third-order sequences, i.e., SQ1, SQ2, and SQ3, from bottom to top. Pyrolysis data of core samples shows that SQ1 and SQ3 mainly are characterized by poor to fair source rocks, with Type III to Type II₂ kerogen, while SQ2 mainly are characterized by fair to good to excellent source rocks, with Type II₂ to Type I kerogen. The biomarker parameters of 40 source rock samples from different sequences suggest that the reducibility of sedimentary water is characterized by SQ2 > SQ1 > SQ3. The organic matter contribution in different sequences is obviously different. SQ1 organic matter contain more bacteria and algae than that of SQ2 and SQ3, and terrigenous higher plants may have contributed to SQ3 organic matter. Lake level changes and water salinity dominate organic matter origin, accumulation, and preservation. During SQ1 deposition, the lake level was the highest, the salinity of sedimentary water was moderate, and the organic matter contained more conventional algae sources. During SQ2 deposition, the lake level was the lowest and the salinity was the highest, and the organic matter contained special algae characterized by C₂₉ regular steroids. The lake level of SQ3 was higher than that of SQ2, the salinity was the lowest, and terrigenous higher plants may have contributed to organic matter during this period.

风城组（P ₁ f）烃源岩沉积于碱性水体中，是准噶尔盆地玛湖凹陷最重要的烃源岩之一。然而，其演化过程和有机质积累机制仍不清楚。利用地震、岩心和测井资料，P ₁ f从下到上分为3个三阶序列，即SQ1、SQ2和SQ3。岩心热解数据显示，SQ1和SQ3烃源岩以差至中为主要特征，为Ⅲ类至Ⅱ类₂型干酪根，而SQ2主要以烃源岩为中至优至优为特征，Ⅱ类为_2类。至 I 型干酪根。40个不同层序烃源岩样品的生物标志物参数表明，沉积水的还原性表现为SQ2>SQ1>SQ3。不同序列的有机质贡献明显不同。SQ1有机质比SQ2和SQ3含有更多的细菌和藻类，陆源高等植物可能对SQ3有机质有贡献。湖水位变化和水盐度支配着有机物的来源、积累和保存。SQ1沉积期湖水位最高，沉积水盐度适中，有机质中含有较多的常规藻源。SQ2沉积期湖水位最低，盐度最高，有机质中含有以C为特征的特殊藻类。₂₉常规类固醇。SQ3湖水位高于SQ2，盐度最低，此时期陆源高等植物可能对有机质有贡献。