根据混积岩的分类命名、沉积环境和沉积模式等的研究现状及其在石油地质领域的研究进展,综合分析得出:有利于混合沉积的沉积相主要是滨海相、滨浅湖相,其次是浅海陆棚、陆表海、三角洲相等;对其沉积环境的分析表明,滨海相混积岩发育的控制因素是潮汐作用、相对比较强的水动力条件以及有利于低等生物发育的浅海环境,控制滨浅湖相混积岩发育的因素是频繁的湖平面和气候的变化;因此认为深入探讨混积岩的沉积微相及其环境因素,对于完善和统一混积岩独立的分类方案和命名体系是一有效途径。在此基础上,结合柴西北区古近系和新近系中深层湖相混积岩的研究实例,初步提出了湖相和海相的混合沉积综合模式示意图;根据与混积岩相关的烃源岩和油气储层的研究资料认为,滨、浅海相和滨、浅湖等海(湖)陆过渡地带的混合沉积,也可成为优质储层和烃源岩的勘探靶区。
The present progress in research on mixed rock of terrigenous clastics and carbonates is reviewed in this paper,mainly including classification,terminology,depositional environment,depositional modes and petroleum-gas geological significance.It is proposed by a comprehensive analysis that the depositional facies favorable for the mixed deposition mainly cover coastal and shallow-lake faicies,following by shallow-sea shelf,shore-shallow lacustrine and delta facies.The study on the depositional environment implies that the factors controlling the development of coastal mixed-rocks include tidal effect,relatively strong hydrodynamic condition and a shallow sea environment favorable for the living of lower organisms.In contrast,with respect to the shore-shallow lacustrine rocks,the factors are frequent lake-level and climate changes.Consequently,a deep discussion on the depositional micro-facies and associated environmental factors may be an effective way to improve and better the classification and terminology of the mixed rocks.Furthermore,a synthetic depositional model for the marine and lacustrine environment is suggested based on above-mentioned analyses,combined with case studies in Paleogene and Neogene middle-deep mixed rocks in the northwestern Qaidam Basin.In addition,the shore-shallow sea and lake areas of mixed deposition can form high-quality targets of reservoir and source rocks,based on factual research data on source and reservoir sequences associated with mixed rocks.