| Xiangyun locates in the middle part of, chuandian platform anticline, Lijiang platform margin fold belt, Lanping-Simao depression binding sites of three secondary structure units, because of its tectonic evolution of the complexity and particularity, the deposition of Triassic strata environment and sequence stratigraphy of the rather rough and fuzzy. This inspection of the study area in a large number of regional geological data and the results of previous studies, based on over a long period of geological mapping, surveying and interior stratotype section the main section, the detailed study of geochemical data, to sedimentology, stratigraphy, sequence stratigraphy science, geology, tectonics, paleontology, historical and basin analysis theory and other theories as a guide, combined with regional geological setting and geochemical characteristics of sedimentary rocks, and Triassic sedimentary geochemical characteristics of clouds, depositional environment, depositional systems, sequence stratigraphy, etc. research, and study the evolution of sedimentary basin characteristics of the area.1, Through paleontology, lithology, sedimentary structures of Triassic strata of the study area was divided into sedimentary facies and depositional environment.2, Triassic strata of the study area were constant, trace, rare earth element geochemistry. Same time, through constant, trace, REE geochemical characteristics of the ancient climate, ancient salinity, redox, water depth, source distribution of five aspects of the work area the Late Triassic paleoenvironment.3, under the stratotype section of rock composition, sedimentary sequence, sediments, biological composition and mineral composition and geochemical characteristics of sedimentary rocks, the Triassic strata are divided into four groups of seven kinds of depositional systems:①semi-deep system (Luo the second paragraph of the mountain group);②shelf system;③carbonate platform;④coastal system;⑤delta system;⑥lake system;⑦river system. And a detailed analysis of the sedimentary system.4, in the depositional environment and depositional systems analysis, based on the use of the principles of sequence stratigraphy, the study area of the Upper Triassic of the three characteristics of sequence boundaries, the interface of genetic types in depth. Workers in the region three layer-type interface typesⅠandⅡ, divided into:sedimentary discontinuity (SB11), weathering surface (SB12, SB23, SB14), the end gravel erosion surface (SB15). The work area of the Upper Triassic is divided into five three sequence that Carnian 2 (TSQ1, TSQ2), Norian 2 (TSQ3, TSQ4), Rhaetian 1 (TSQ5).5, analysis of the internal structure of all three sequences:the type and characteristics of the domain system. TSQland TSQ2 missing the LST (LST), TSQ3, TSQ4, TSQ5 three systems within the domain (LST, TST, HST) complete development. Transgression occurred 5 times, including three sequences TSQ1 and TSQ3 transgression within the range of both speed and great. Detailed analysis of the structure, sea-level change, climate, sediment supply four factors in the study area controlling sequence development.6, Late Triassic period, XiangYun area in the separation and compression under the influence of thrust between Lijiang tableland and Kangdian Ancient land, forming a composite basin; for the effect of early separation of rifting and development of rift Basin and thrusting under the late development of the foreland basin. Basement through the rift-stability-rift-Extrusion and Thrust (returned) four stages.Basin-fill sequence.evolution experienced marine facies(molasse, flysch, construction, carbonate rock build)-and sea cross each other facies(the construction of coal-bearing sandstone and mudstone)-continental facies(fluvial coal-bearing shale, sandy rock build) the conversion process. |
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