古老碱湖优质烃源岩:准噶尔盆地下二叠统风城组

碱 湖优质烃源岩是陆(湖)相优质烃源岩的一种重要类型, 迄今发现的典型实例主要分布于古近系始新统, 准噶尔盆地下二叠统风城组可能是这类烃源岩的最古老实例, 典型证据包括3方面:沉积学方面的成碱演化序列完整, 岩石矿物学方面的碱性矿物与丰富的微生物和黄铁矿, 地球化学方面的生物标志化合物。在生烃特征上, 风城组具有典型碱湖优质烃源岩的特征, 表现为有机质丰度高、类型好、生烃能力强, 丰富藻类有机质和微生物的存在使得烃源岩长期生烃, 所生油气优质, 成熟-高熟轻质油气连续充注, 这是研究区玛湖百里大油(气)区得以形成的根本资源基础。这一古老碱湖优质烃源岩的发现具有潜在重要 科学与勘探意义。

Ancient high-quality alkaline lacustrine source rocks discovered in the Lower Permian Fengcheng Formation,Junggar Basin

High-quality alkaline lacustrine source rocks are an important type of continental (lacustrine) high-quality source rocks. So far, typical cases are mainly found in the Eocene, and the possible oldest case has been preliminarily reported in this paper, i.e., the Lower Permian Fengcheng Formation, Junggar Basin. Fengcheng Formation belongs to alkaline lacustrine deposition, and the representative evidences mainly include three aspects, i.e., complete alkaligenous evolution sequence in the sedimentology, alkaline minerals as well as plentiful microbes and pyrites in the petromineralogy, and biomarkers in the geochemistry. In terms of hydrocarbon generation, Fengcheng Formation has the typical characteristics of high-quality alkaline lacustrine source rocks, shown as high organic matter abundance, good type and strong hydrocarbon generation capacity. Plentiful algae organic matters and microbes result in continuous hydrocarbon generation with high-quality oil and gas as well as constant charging of light oil and gas with moderate-high maturity, which provides the ultimate resource foundation for the formation of Mahu giant oil (gas) province in hundreds of miles. Such discovery of the old high-quality alkaline lacustrine source rocks has the potential important scientific inspirations and exploration implications.