中国南方二叠纪层序岩相古地理特征及演化

Sequence-Based Lithofacies and Paleogeographic Characteristics and Evolution of Permian in South China

在层序地层研究基础上,以沉积体系域和相关界面为编图单元,采用体系域压缩法和瞬时作图法,以油气勘探为目标,有针对性的编制了中国南方二叠纪11张层序岩相古地理图。在此基础上,全面系统地阐述了该区二叠纪层序岩相古地理特征及演化。结果表明,中国南方二叠纪层序古地理演化具有明显的继承性、不均一性、阶段性、方向性和同步性。与传统的岩相古地理图相比,层序岩相古地理图具有动态、精确、等时、成因连续和勘探实用等优点。

Based on the research on sequence stratigraphy of Permian in the south China with the purpose of oil-gas exploration,11 sequence-based lithofacies and paleogeography maps of Permian in the south china have been drawn up by ways of condensation and instantenity with mapping units of sedimentary systems tracts and key sequence boundary surfaces.In the light of sequence-based lithofacies and paleogeography maps,the characteristics and evolution of Permian sequence-based lithofacies and paleogeography have also been discussed in detail.The authors suggest that the evolution of sequence-based lithofacies and paleogeography of Permian bave obvious characteristics of inheritance,inhomogeneity ,phase,orientation and synchronism.Inheritance is that the distrbutive feature of sea and land area.the extension direction and distrbutive precipitation of sedimentary facies zone of each stage of Lower Permian are approximately consistent with the tectonic setting and paleogeographic framework of Devonian and Carboniferous.The inhomogeneity shows that there are different characteristics and development process in different sedimentary basin.The phase indicates that the evolution of sequence-based lithofacies and paleogeography can be divided into 2 phases and 11 stages.The tectonic setting,basin feature and paleogeography of Upper Permian are different from that of Lower Permian,but in different depositional area ,the development stags is similar.The paleogeography feature of Upper Permian is related to that of Lower Permian,and the evolution and development of biota approximately keep consistence with that of paleogeography. Compared to traditional lithofacies and paleogeography map sequence-based lithofacies and paleogeography map owns distinct advantages fo accuracy,isochronity,genetic succession and exploratory practicality etc.It deeply reflects the sedimentation,tectonic movement,sea-level change,distribution and evolution of sea and land, volcanic action and oil-formation etc.It also reasonably discloses the relationship of corrosion exposure field of old landmass and the development of sedimentary system with sea-level change and synsedimentary tectonic movement,and vividly describes the special distrbution and evolution of the sedimentary facies zone of coverage area.especially potential oil source,reservoir and cover,Clearly,sequence-based lithofacies and paleogeography map not only objectively and dynamically reflects the basin forming,development and evolution process but also have significant practical significance oil-gas exploration.